Sustainability

Research

11 pages, 1986 KiB

Open AccessEditor’s ChoiceArticle

Sustainable Energy Management Benchmark at Wastewater Treatment Plant

by Andrey Kiselev, Elena Magaril, Deborah Panepinto, Elena Cristina Rada, Marco Ravina and Maria Chiara Zanetti

Sustainability 2021, 13(22), 12885; https://doi.org/10.3390/su132212885 - 21 Nov 2021

Cited by 6 | Viewed by 2569

Abstract

Urban wastewater effluents bring large amounts of nutrients, organic matter, and organic microcontaminants into freshwater ecosystems. Ensuring the quality of wastewater treatment (WWT) is one of the main challenges facing the management of wastewater treatment plants (WWTPs). However, achievement of high-quality standards leads [...] Read more.

Urban wastewater effluents bring large amounts of nutrients, organic matter, and organic microcontaminants into freshwater ecosystems. Ensuring the quality of wastewater treatment (WWT) is one of the main challenges facing the management of wastewater treatment plants (WWTPs). However, achievement of high-quality standards leads towards significant energy consumption: usually the more intensive WWT process requires additional energies. Energy efficiency at WWTP is actual mainstream on the current sustainable development agenda. The WWTP processes and methods can be considered from the standpoint of material and energy flows according to circular economy paradigm, which offers great possibilities to reuse waste originating from WWT in order to receive renewable energy. The correlation between energy and quality issues to evaluate WWTP efficiency is of a great scientific and practical interest. The main goal of the paper is to check the dependency between these two main issues in WWTP management—WWT quality and energy efficiency—and to determine possible limits of such relation. The municipal sewerage system of Ekaterinburg, Russia was studied within this paper. The total length of centralized sewerage system in Ekaterinburg is over 1500 km of pipes within two main sewerage basins: northern and southern. The methodological framework for the current research consisted of three steps: (i) WWT quality evaluation, (ii) energy efficiency evaluation, and (iii) WWTP Quality/Energy (Q/E) efficiency dependency matrix. For the purpose of research, authors investigated the 2015–2018 period. The results showed that the outputs correlate with the technical conditions of WWTPs and the implementation of the best available techniques (BATs): most of the northern WWTP values are referred to the green zone (good rank), while the southern WWTP values are situated generally in the orange zone (unsatisfactory rank). The proposed methodological approach for Q/E dependency of WWT process creates a strong but simple tool for managers to evaluate the current success of the operation of WWTP and progress towards circular economy practices implementation. Full article

(This article belongs to the Special Issue Waste Management and Application of the Principles of the Circular Economy)

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16 pages, 2236 KiB

Open AccessArticle

On the Hibernating Electronic Waste in Rio de Janeiro Higher Education Community: An Assessment of Population Behavior Analysis and Economic Potential

by Felipe Seabra D’Almeida, Roberto Bentes de Carvalho, Felipe Sombra dos Santos and Rodrigo Fernandes Magalhães de Souza

Sustainability 2021, 13(16), 9181; https://doi.org/10.3390/su13169181 - 16 Aug 2021

Cited by 7 | Viewed by 2879

Abstract

Brazil is the second largest producer of electronic waste in the Americas, with a production that grows each year and only 10% of it being treated in its own way. Additionally, given the typical chemical composition of this type of residue, it can [...] Read more.

Brazil is the second largest producer of electronic waste in the Americas, with a production that grows each year and only 10% of it being treated in its own way. Additionally, given the typical chemical composition of this type of residue, it can be possible to recover valuable metals, such as copper, gold, silver, and platinum. Presently, Brazil does not have an industrial plant devoted to such extractive activity using electronic waste, with most of its treatment carried out abroad. The research hypothesis of this manuscript is that universities and their communities could develop sources of raw materials for such extraction processes and, therefore, deserve attention for the creation of collection points and partnerships. In this context, there is a need to understand this community behavior regarding the acquisition, storage, and disposal of electronic equipment, as well as information about topics related to electronic waste management and recycling. To implement such a study for the higher education community in Rio de Janeiro, a form was created covering several topics on the subject, which was disseminated among the teachers, students, employees, and family members of two main state universities. It was determined that the studied group has more than 16.96 million mobile phones in hibernation, in addition to other equipment, with an estimated stockpile value of USD 67.45 million for the studied group in the metropolitan area of Rio de Janeiro. If extrapolated to all of Brazil, this could be as high as USD 797.50 million for the studied group. This information will be used in future projects to assess the economic potential of an industrial plant dedicated to metal recovery in Brazil. However, the present study also identified an important lack of knowledge regarding proper waste disposal and solid waste policies among this well-educated group. It became clear that without appropriate information regarding collection points and knowledge on how to deal with obsolete devices, the access to this source of raw material could be a hinderance to future extraction projects in the area. Full article

(This article belongs to the Special Issue Waste Management and Application of the Principles of the Circular Economy)

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15 pages, 306 KiB

Open AccessArticle

How Far Away Are World Economies from Circularity: Assessing the Capacity of Circular Economy Policy Packages in the Operation of Raw Materials and Industrial Wastes

by Margarita Ignatyeva, Vera Yurak, Alexey Dushin, Vladimir Strovsky, Sergey Zavyalov, Alexander Malyshev and Polina Karimova

Sustainability 2021, 13(8), 4394; https://doi.org/10.3390/su13084394 - 15 Apr 2021

Cited by 9 | Viewed by 2221

Abstract

Nowadays, circular economy (CE) is on the agenda, however, this concept of closed supply chains originated in the 1960s. The current growing quantity of studies in this area accounts for different discourses except the holistic one, which mixes both approaches—contextual and operating (contextual [...] Read more.

Nowadays, circular economy (CE) is on the agenda, however, this concept of closed supply chains originated in the 1960s. The current growing quantity of studies in this area accounts for different discourses except the holistic one, which mixes both approaches—contextual and operating (contextual approach utilizes the thorough examination of the CE theory, stricture of the policy, etc.; the operating one uses any kind of statistical data)—to assess the capacity of circular economy regulatory policy packages (CERPP) in operating raw materials and industrial wastes. This article demonstrates new guidelines for assessing the degree level of capacity (DLC) of CERPPs in the operation of raw materials and industrial wastes by utilizing the apparatus of the fuzzy set theory. It scrupulously surveys current CERPPs in three regions: the EU overall, Finland and Russia; and assesses for eight regions—the EU overall, Finland, Russia, China, Greece, France, the Netherlands and South Korea—the DLC of CERPPs in operating raw materials and industrial wastes. The results show that EU is the best in CE policy and its CERPP is 3R. The following are South Korea and China with the same type of CERPP. Finland, France and the Netherlands have worse results than EU with the type of CERPP called “integrated waste management” because of the absence of a waste hierarchy (reduce, recover, recycle). Russia closes the list with the type of CERPP “basic waste management”. Full article

(This article belongs to the Special Issue Waste Management and Application of the Principles of the Circular Economy)

21 pages, 5505 KiB

Open AccessArticle

Advances on the Implementation of Circular Economy Techniques in Rural Areas in Colombia under a Sustainable Development Framework

by Javier Rodrigo-Ilarri, Camilo-A. Vargas-Terranova, María-Elena Rodrigo-Clavero and Paula-A. Bustos-Castro

Sustainability 2021, 13(7), 3816; https://doi.org/10.3390/su13073816 - 30 Mar 2021

Cited by 10 | Viewed by 3880

Abstract

For the first time in the scientific literature, this research shows an analysis of the implementation of circular economy techniques under sustainable development framework in six municipalities with a depressed economy in Colombia. The analysis is based on solid waste data production at [...] Read more.

For the first time in the scientific literature, this research shows an analysis of the implementation of circular economy techniques under sustainable development framework in six municipalities with a depressed economy in Colombia. The analysis is based on solid waste data production at a local scale, the valuation of the waste for subsequent recycling, and the identification and quantification of the variables associated with the treatment and final disposal of waste, in accordance with the Colombian regulatory framework. Waste generation data are obtained considering three different scenarios, in which a comparison between the simulated values and those established in the management plans are compared. Important differences have been identified between the waste management programs of each municipality, specifically regarding the components of waste collection, transportation and disposal, participation of environmental reclaimers, and potential use of materials. These differences are fundamentally associated with the different administrative processes considered for each individual municipality. This research is a good starting point for the development of waste management models based on circular economy techniques, through the subsequent implementation of an office tool in depressed regions such as those studied. Full article

(This article belongs to the Special Issue Waste Management and Application of the Principles of the Circular Economy)

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18 pages, 2994 KiB

Open AccessArticle

Pilot-Scale Composting Test of Polylactic Acid for Social Implementation

by Nobuyuki Kawashima, Tadashi Yagi and Kouya Kojima

Sustainability 2021, 13(4), 1654; https://doi.org/10.3390/su13041654 - 4 Feb 2021

Cited by 16 | Viewed by 4236

Abstract

The chemical industry and subsequent value chain of plastics are facing significant challenges from the viewpoints of resource conversion and environmental burden. Now is the time to explore the future direction of plastics, which will require an integrated scheme using resource circulation, carbon [...] Read more.

The chemical industry and subsequent value chain of plastics are facing significant challenges from the viewpoints of resource conversion and environmental burden. Now is the time to explore the future direction of plastics, which will require an integrated scheme using resource circulation, carbon neutrality, and a social system to promote after-use treatment under the concept of a circular economy. Polylactic acid (PLA) should help reduce greenhouse gas (GHG) emissions as a biobased material and contribute to waste management after use due to its biodegradability if managed properly. That is, it will be necessary to treat biodegradable products appropriately in closed systems such as composting facilities after use and recovery. To realize the implementation of fully approved composting facilities in society, simply evaluating biodegradability in the laboratory is insufficient. In this study, a pilot-scale test using PLA under actual composting conditions was conducted in accordance with both international standards and domestic evaluation methods. The results not only confirm its biodegradability and disintegration, but also demonstrate that the presence of a biodegradable plastic product has a negligible impact on the composting process. The obtained compost did not adversely affect plant germination or growth, demonstrating its safety and high quality. Such a multifaceted perspective makes this study unique and useful for creating a social framework. Full article

(This article belongs to the Special Issue Waste Management and Application of the Principles of the Circular Economy)

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15 pages, 1476 KiB

Open AccessArticle

Value Stream Mapping as a Supporting Management Tool to Identify the Flow of Industrial Waste: A Case Study

by Yolandi Schoeman, Paul Oberholster and Vernon Somerset

Sustainability 2021, 13(1), 91; https://doi.org/10.3390/su13010091 - 23 Dec 2020

Cited by 37 | Viewed by 6757

Abstract

The Value Stream Mapping (VSM) method was applied to a case study in the iron and steel industry in Southern Africa as a supporting management tool to identify, demonstrate, and evaluate industrial waste and comprised of three steps. The first step included collecting [...] Read more.

The Value Stream Mapping (VSM) method was applied to a case study in the iron and steel industry in Southern Africa as a supporting management tool to identify, demonstrate, and evaluate industrial waste and comprised of three steps. The first step included collecting and verifying waste generation and flow data as the VSM data input step. The second step comprises three phases: mapping waste generation and fractions and horizontal and vertical performance analysis. The third step is comprised of actual and future state maps compilation. Following the first year of implementation, waste was reduced by 28%, and waste removal cost by 45%. Implementing the VSM method demonstrated cost savings and reduced waste flow within the study’s first year. The initial waste generation reduction target of 5% per annum was exceeded. The VSM method application proved to be a practical method for the iron and steel industry to visualize and analyze waste flows, identify opportunities and challenges in waste management operations, reduce waste, promote lean manufacturing, and achieve an environmentally responsible zero-waste environment. Full article

(This article belongs to the Special Issue Waste Management and Application of the Principles of the Circular Economy)

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18 pages, 1820 KiB

Open AccessArticle

Characterisation Study of Various Disposable Diaper Brands

by Asiphile Khanyile, Guy C. Caws, S’phumelele L. Nkomo and Ntandoyenkosi M. Mkhize

Sustainability 2020, 12(24), 10437; https://doi.org/10.3390/su122410437 - 14 Dec 2020

Cited by 10 | Viewed by 4253

Abstract

Seven disposable diaper brands that are commonly used in Clermont, Kwa-Zulu Natal (South Africa) and some frequently found along river bodies (due to illegal dumping) were characterised through proximate analysis, thermogravimetric analysis (TGA), ultimate analysis and analytical pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS). A novel [...] Read more.

Seven disposable diaper brands that are commonly used in Clermont, Kwa-Zulu Natal (South Africa) and some frequently found along river bodies (due to illegal dumping) were characterised through proximate analysis, thermogravimetric analysis (TGA), ultimate analysis and analytical pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS). A novel approach entailing separation of the diapers into two fractions, interior (constituting mainly biomass fibres) and exterior (mainly constituting non-biomass polyethylene), assisted in assessing thermochemical conversion of the disposable diaper’s potential as well as likely threats to the environment. In a comparison of the volatile matter between the two fractions, the exterior fraction is more combustible (due to a higher volatile fraction). Hence, it is more suitable for energy recovery. The present study investigates the use of pyrolysis to manage disposable diapers to potentially recover pyro-oil, pyro-gas and pyro-char. In this primary investigation, it was observed that each disposable diaper brand reacts differently to constant heating. However, the proximate and elemental analysis also highlights the likely negative environmental threats, such as that the high volatile content can potentially release dangerous permanent gases such as chlorine and cobalt into the atmosphere after the diaper is disposed of illegally and in landfill. Full article

(This article belongs to the Special Issue Waste Management and Application of the Principles of the Circular Economy)

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16 pages, 5319 KiB

Open AccessArticle

Waste to Catalyst: Synthesis of Catalysts from Sewage Sludge of the Mining, Steel, and Petroleum Industries

by Gabriela Castro-León, Erik Baquero-Quinteros, Bryan G. Loor, Jhoselin Alvear, Diego E. Montesdeoca Espín, Andrés De La Rosa and Carolina Montero-Calderón

Sustainability 2020, 12(23), 9849; https://doi.org/10.3390/su12239849 - 25 Nov 2020

Cited by 8 | Viewed by 3247

Abstract

The generation of sewage sludge presents a problem for several manufacturing companies as it results from industrial processes or effluent treatment systems. The treatment of this type of waste requires high economic investment, for this reason, it is necessary to find alternatives to [...] Read more.

The generation of sewage sludge presents a problem for several manufacturing companies as it results from industrial processes or effluent treatment systems. The treatment of this type of waste requires high economic investment, for this reason, it is necessary to find alternatives to recover the valuable materials of the sludges. In this study, metal catalysts were synthesized using waste sludge from the steel, mining, and hydrocarbon industries. The waste sludge was subjected to thermal treatments for the removal of organic content and the reduction of metals with hydrogen current to activate their catalytic properties. The sludge and synthesized catalysts were analyzed to determine their physical, chemical, thermoenergetic, and catalytic properties. Catalytic activity was evaluated using CO chemisorption and by thermal–catalytic decomposition of crude oil. The best conditions for synthesizing the catalysts were a calcination temperature between 300 and 500 °C and a reduction temperature between 300 and 900 °C. The catalysts presented a specific surface between 2.33 and 16.78 m²/g. The catalytic material had a heat capacity between 0.7 and 1.2 kJ/kg∙K. The synthesized materials presented catalytic activity comparable to that of commercial catalysts. With this recovery technique, the industrial waste can be valorized, obtaining catalyst derived from the sludges and promoting the circular economy of manufacturing companies. Full article

(This article belongs to the Special Issue Waste Management and Application of the Principles of the Circular Economy)

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13 pages, 960 KiB

Open AccessArticle

New Policy Framework with Plastic Waste Control Plan for Effective Plastic Waste Management

by Sun-Kyoung Shin, Namil Um, Yong-Jun Kim, Na-Hyeon Cho and Tae-Wan Jeon

Sustainability 2020, 12(15), 6049; https://doi.org/10.3390/su12156049 - 28 Jul 2020

Cited by 44 | Viewed by 10137

Abstract

With an increasing use of plastic, considerable plastic waste is generated, threatening the environment and public health. In particular, changes in living patterns in urban areas have significantly impacted the rate at which plastic waste increases every year. Thus, governments in many developed [...] Read more.

With an increasing use of plastic, considerable plastic waste is generated, threatening the environment and public health. In particular, changes in living patterns in urban areas have significantly impacted the rate at which plastic waste increases every year. Thus, governments in many developed countries have implemented numerous policies to reduce plastic waste generation. Among them is the concept of circular economy that aims to protect the environment from plastic pollution and promote growth and innovation in industry and human life through overall changes in designing, producing, using, and recycling plastic products. The Korean government has implemented the Resource Circulation Act (RCA), which includes the concept of circular economy and resource efficiency policy for overall waste management. Following the concept of RCA, the Plastic Waste Control Plan (PWCP) was established for the comprehensive management of plastic waste. Therefore, this study introduces the goals and strategies of PWCP, which has a circulation system of four stages of production, consumption, discharge, and recycling, as well as the major roadblocks in the stages impeding the achievement of the goals and strategies. This study also suggests countermeasures at the government level for solving the major problems in the four stages. Full article

(This article belongs to the Special Issue Waste Management and Application of the Principles of the Circular Economy)

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28 pages, 2372 KiB

Open AccessArticle

Directions and Challenges in the Management of Municipal Sewage Sludge in Poland in the Context of the Circular Economy

by Ksymena Rosiek

Sustainability 2020, 12(9), 3686; https://doi.org/10.3390/su12093686 - 2 May 2020

Cited by 42 | Viewed by 5605

Abstract

Landfilling was the main method of sewage sludge disposal in Poland for decades. After Poland’s accession to the European Union (EU), many investments have been made into providing better access to tap water as well as to collect and treat municipal sewage. However, [...] Read more.

Landfilling was the main method of sewage sludge disposal in Poland for decades. After Poland’s accession to the European Union (EU), many investments have been made into providing better access to tap water as well as to collect and treat municipal sewage. However, sewage sludge treatment has not been treated as an integral part of the implementation of wastewater management obligations. Stricter European Union regulations regarding the management of municipal sewage sludge (MSS) pose new challenges for Poland. The aim of this study was to analyze changes in the direction of the final management of municipal sewage sludge in Poland based on the analysis of strategic documents, regulations, literature, and available statistical data. The aim of the analysis was to search for directions to modify how sewage sludge is managed, given the approach promoted by the circular economy concept. The results prove that investments in wastewater treatment plants according to the EU sewage directive are not applied to the development of infrastructure that would enable the disposal of sewage sludge, which, for many years, has been stored (landfilling) or used directly in agriculture and ground reclamation. The introduction of stricter regulations in the area of sewage sludge usage and better wastewater treatment have increased the level of difficulties concerning sewage sludge management. Poland faces the challenge of defining sewage sludge management directions. The circular economy concept offers an approach that can be the basis for the creation of a new sewage sludge management strategy for Poland. The concept allows the combined goals of sewage sludge disposal and of energy and nutrients recovery to be achieved. Full article

(This article belongs to the Special Issue Waste Management and Application of the Principles of the Circular Economy)

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13 pages, 1266 KiB

Open AccessArticle

Treatment of Wastewater Containing Runway De-Icing Agents in Biofilters as a Part of Airport Environment Management System

by Joanna Rodziewicz, Artur Mielcarek, Wojciech Janczukowicz, Kamil Bryszewski and Kamila Ostrowska

Sustainability 2020, 12(9), 3608; https://doi.org/10.3390/su12093608 - 29 Apr 2020

Cited by 4 | Viewed by 3490

Abstract

Large volumes of pavement de-icing and anti-icing fluids, collectively termed de-icing agents, are used at airports to facilitate wintertime safe air travel. After use, most of the them get typically mixed with storm water runoff and may enter soil and waters near the [...] Read more.

Large volumes of pavement de-icing and anti-icing fluids, collectively termed de-icing agents, are used at airports to facilitate wintertime safe air travel. After use, most of the them get typically mixed with storm water runoff and may enter soil and waters near the airports. Wastewater resulting from airports’ winter operations is contaminated mainly with nitrogen and carbon compounds. Previous research results have shown that the use of biofilters filled with lightweight aggregates prepared from fly ash from sewage sludge thermal treatment (FASST LWA) could be an effective method for removing nitrogen and organic compounds at low temperatures, i.e., 0–8 °C. For this to be possible, it is necessary to maintain a proper ratio between the amounts of carbon and nitrogen in the treated wastewater, through the simultaneous application of de-icing agents containing urea and carbon compounds. Biofilter technology is part of the concept of sustainable development. Their filling is made of waste materials and one of the pollutants (organic compounds) present in the wastewater is used to remove other pollutants (nitrogen compounds). In this study, technological systems for the treatment of wastewater containing airport runway de-icing agents with biofilters were proposed, which allow for the treated wastewater to be discharged into natural waters, soil, and sewerage network. Full article

(This article belongs to the Special Issue Waste Management and Application of the Principles of the Circular Economy)

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22 pages, 6297 KiB

Open AccessEditor’s ChoiceArticle

Assessment of the Possible Reuse of Extractive Waste Coming from Abandoned Mine Sites: Case Study in Gorno, Italy

by Neha Mehta, Giovanna Antonella Dino, Iride Passarella, Franco Ajmone-Marsan, Piergiorgio Rossetti and Domenico Antonio De Luca

Sustainability 2020, 12(6), 2471; https://doi.org/10.3390/su12062471 - 21 Mar 2020

Cited by 22 | Viewed by 4369

Abstract

Supply of resources, a growing population, and environmental pollution are some of the main challenges facing the contemporary world. The rapid development of mining activities has produced huge amounts of waste. This waste, found in abandoned mine sites, provides the potential opportunity of [...] Read more.

Supply of resources, a growing population, and environmental pollution are some of the main challenges facing the contemporary world. The rapid development of mining activities has produced huge amounts of waste. This waste, found in abandoned mine sites, provides the potential opportunity of extracting raw material. The current study, therefore, focuses on testing the validation of a shared methodology to recover extractive waste from abandoned mines, and applies this methodology to a case study in Gorno, northwest Italy. The methods focused on: (1) analyzing the impact of tailings and fine fraction of waste rock (<2 mm) on plants (Cress - Lepidium Sativum) to assess usability of both as soil additive, and (2) recovering raw materials from tailings and coarse fraction (>2 mm) of waste rock, by means of dressing methods like wet shaking table and froth flotation. The results indicated that the fine fraction of waste rock and tailings did not have detrimental effects on seed germination; however, there was marked decrease in plant growth. As for the recovery of raw materials, the coarse waste rock samples, crushed to <0.5 mm, produced a recovery of Cd, Ga, and Zn—as much as 66%, 56%, and 64%, respectively—using the wet shaking table. The same samples when crushed to 0.063–0.16 mm and used for froth flotation produced a recovery of Cd, Ga, and Zn of up to 61%, 72%, and 47%, respectively. The flotation experiment on tailings showed a recovery of Cd, Ga and Zn at pH 7 of 33%, 6% and 29% respectively. The present investigation highlights the methodologies used for extracting raw materials from extractive waste. Full article

(This article belongs to the Special Issue Waste Management and Application of the Principles of the Circular Economy)

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22 pages, 14033 KiB

Open AccessArticle

The Potential of Food Packaging Attributes to Influence Consumers’ Decisions to Sort Waste

by Babak Nemat, Mohammad Razzaghi, Kim Bolton and Kamran Rousta

Sustainability 2020, 12(6), 2234; https://doi.org/10.3390/su12062234 - 13 Mar 2020

Cited by 38 | Viewed by 8620

Abstract

Food packaging waste is a valuable resource for material recovery, if it is properly separated and sorted by consumers. The packaging itself may have the potential to assist consumer sorting by, for example, communicating a correct sorting practice. This is partly due to [...] Read more.

Food packaging waste is a valuable resource for material recovery, if it is properly separated and sorted by consumers. The packaging itself may have the potential to assist consumer sorting by, for example, communicating a correct sorting practice. This is partly due to the fact that the sorting of packaging waste, which is a habitual behavior of consumers, can be perceived as being confusing and inconvenient. Consumers can, therefore, choose not to sort. It is argued that material recovery could be enhanced if packaging can afford easy and proper sorting and separation. To investigate the potential of packaging to support proper sorting, six types of yogurt and cream packaging were examined across 15 households in Karlskrona (a medium-sized Swedish city). The aim is to investigate the effect of selected packaging attributes on consumer decisions regarding waste sorting. The results reveal that some of the selected packaging waste is not properly separated and sorted. It is concluded that the design of food packaging based on user-centered needs could affect consumer decisions for the proper sorting of packaging waste, which enables improved material recovery. The design should focus especially on the package’s visual attributes, the material selection, and the package´s waste sorting related functions. Full article

(This article belongs to the Special Issue Waste Management and Application of the Principles of the Circular Economy)

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11 pages, 2430 KiB

Open AccessArticle

Response Surface Methodology to Optimize Methane Production from Mesophilic Anaerobic Co-Digestion of Oily-Biological Sludge and Sugarcane Bagasse

by Aiban Abdulhakim Saeed Ghaleb, Shamsul Rahman Mohamed Kutty, Yeek-Chia Ho, Ahmad Hussaini Jagaba, Azmatullah Noor, Abdulnaser Mohammed Al-Sabaeei and Najib Mohammed Yahya Almahbashi

Sustainability 2020, 12(5), 2116; https://doi.org/10.3390/su12052116 - 9 Mar 2020

Cited by 66 | Viewed by 4849

Abstract

Oily-biological sludge (OBS) generated from petroleum refineries has high toxicity. Therefore, it needs an appropriate disposal method to reduce the negative impacts on the environment. The anaerobic co-digestion process is an effective method that manages and converts organic waste to energy. For effective [...] Read more.

Oily-biological sludge (OBS) generated from petroleum refineries has high toxicity. Therefore, it needs an appropriate disposal method to reduce the negative impacts on the environment. The anaerobic co-digestion process is an effective method that manages and converts organic waste to energy. For effective anaerobic digestion, a co-substrate would be required to provide a suitable environment for anaerobic bacteria. In oily-biological sludge, the carbon/nitrogen (C/N) ratio and volatile solids (VS) content are very low. Therefore, it needs to be digested with organic waste that has a high C/N ratio and high VS content. This study investigates the use of sugarcane bagasse (SB) as an effective co-substrate due to its high C/N ratio and high VS content to improve the anaerobic co-digestion process with oily-biological sludge. The sugarcane bagasse also helps to delay the toxicity effect of the methane bacteria. Batch anaerobic co-digestion of oily-biological sludge was conducted with sugarcane bagasse as a co-substrate in twelve reactors with two-liter capacity, each under mesophilic conditions. The interaction effect of a C/N ratio of 20-30 and a VS co-substrate/VS inoculum ratio of 0.06-0.18 on the methane yield (mL CH₄/g VS_removed) was investigated. Before the anaerobic digestion, thermochemical pre-treatment of the inoculum and co-substrate was conducted using sodium hydroxide to balance their acidic nature and provide a suitable pH environment for methane bacteria. Design and optimization for the mixing ratios were carried out by central composite design-response surface methodology (CCD-RSM). The highest predicted methane yield was found to be 63.52 mL CH₄/g VS_removed, under optimum conditions (C/N ratio of 30 and co-substrate/inoculum ratio of 0.18). Full article

(This article belongs to the Special Issue Waste Management and Application of the Principles of the Circular Economy)

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14 pages, 1666 KiB

Open AccessArticle

Upcycling Phosphorus Recovered from Anaerobically Digested Dairy Manure to Support Production of Vegetables and Flowers

by Katherine K. Porterfield, Robert Joblin, Deborah A. Neher, Michael Curtis, Steve Dvorak, Donna M. Rizzo, Joshua W. Faulkner and Eric D. Roy

Sustainability 2020, 12(3), 1139; https://doi.org/10.3390/su12031139 - 5 Feb 2020

Cited by 5 | Viewed by 3985

Abstract

Dissolved air flotation (DAF) separates phosphorus (P)-rich fine solids from anaerobically digested dairy manure, creating opportunities to export surplus P to the marketplace as a bagged plant food product. Seedlings of tomato and marigold were amended at various volume per volume (v/v [...] Read more.

Dissolved air flotation (DAF) separates phosphorus (P)-rich fine solids from anaerobically digested dairy manure, creating opportunities to export surplus P to the marketplace as a bagged plant food product. Seedlings of tomato and marigold were amended at various volume per volume (v/v) ratios with plant foods consisting of fine solids upcycled (i.e., transformed into a higher quality product) by drying and blending with other organic residuals. A plate competition assay was conducted to assess the fine solids’ potential to suppress the plant pathogen Rhizoctonia solani. Plant foods were comprised of 2.0–2.1% N, 0.8–0.9% P and 0.6–0.8% K. Extractions indicated that plant foods contained a mixture of plant-available and slow-release P. At 6% v/v plant food, dry biomass of marigold and tomato were six-times greater than the unamended control and not significantly different from a market alternative treatment. Fine solids exhibited negligible potential to suppress R. solani. This study indicates that DAF-separated fine solids could be used to support horticulture, providing information for design of a circular economy approach to dairy manure nutrient management. Life cycle assessment and business model development for this nutrient recovery strategy are necessary next steps to further guide sustainability efforts. Full article

(This article belongs to the Special Issue Waste Management and Application of the Principles of the Circular Economy)

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20 pages, 9332 KiB

Open AccessArticle

Reuse of Excavated Clayey Silt in Cement–Fly Ash–Bentonite Hybrid Back-fill Grouting during Shield Tunneling

by Jun Xu, Chao Xiao, Huai-Na Wu and Xin Kang

Sustainability 2020, 12(3), 1017; https://doi.org/10.3390/su12031017 - 31 Jan 2020

Cited by 15 | Viewed by 4307

Abstract

Excavated soils from tunnel construction need high treatment cost and pollute the environment. To investigate the feasibility of excavated clayey silt reused in back-fill grout, the flowability, stability and strength were taken as measurement indexes of grouting performance. The clayey silt was tested [...] Read more.

Excavated soils from tunnel construction need high treatment cost and pollute the environment. To investigate the feasibility of excavated clayey silt reused in back-fill grout, the flowability, stability and strength were taken as measurement indexes of grouting performance. The clayey silt was tested to be reused as substitutes for fly ash, bentonite and sand, respectively. The experimental results indicated that the clayey silt reused as a substitute for fly ash decreased the flowability and strength of grout mixes, and the clayey silt reused as a substitute for bentonite decreased the stability of grout mixes, and neither of them was feasible. The clayey silt reused as a substitute for sand decreased the flowability, but the grouting performance could be improved by adjusting the mix proportion to meet all grouting requirements. After adding the proportion of water to improve the flowability and increasing the cement:fly ash ratio to improve the strength, a scheme of clayey silt reutilization was suggested, which was cement:fly ash:bentonite:clayey silt:water = 280:230:100:680:660. At the end of this paper, the pore structure feature tests, X-ray diffraction (XRD) tests and scanning electron microscope (SEM) tests were performed to analyze the different morphology, microstructure and mineralogy characteristics before and after the clayey silt was reused as a total substitute for sand in grout mixes. Full article

(This article belongs to the Special Issue Waste Management and Application of the Principles of the Circular Economy)

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13 pages, 2873 KiB

Open AccessArticle

Zero-Liquid Discharge Treatment of Wastewater from a Fertilizer Factory

by Svetlana B. Zueva, Francesco Ferella, Giuliana Taglieri, Ida De Michelis, Inna Pugacheva and Francesco Vegliò

Sustainability 2020, 12(1), 397; https://doi.org/10.3390/su12010397 - 3 Jan 2020

Cited by 12 | Viewed by 5454

Abstract

This article describes the improvement of wastewater treatment in a fertilizer plant located in Central Italy (municipality of Vasto). In this facility, water is used for the removal of dust and fluorinated gases from the air. The resulting wastewater contains fluorides and phosphates [...] Read more.

This article describes the improvement of wastewater treatment in a fertilizer plant located in Central Italy (municipality of Vasto). In this facility, water is used for the removal of dust and fluorinated gases from the air. The resulting wastewater contains fluorides and phosphates in hazardous forms. Its treatment ordinarily does not result in a Zero-Liquid Discharge (ZLD) process. To achieve this purpose, several reagents were tested, focusing on the correlation linking pH, type of reagent and the effect on the separation of fluorides and phosphates from the wastewater. It was eventually found, and explained with a model, that hydrated lime at pH = 12 was so effective as a precipitating agent that phosphate and fluoride separation reached a value of 99.9%, thus allowing for reuse of the water in the plant process. Furthermore, phosphates and fluorides precipitated in a non-hazardous form, so that the material could also be recycled. In synthesis, wastewater treatment of the fertilizer plant was upgraded so that it became a ZLD process coupled with the recovery and recycling of fluorides and phosphates. Full article

(This article belongs to the Special Issue Waste Management and Application of the Principles of the Circular Economy)

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18 pages, 423 KiB

Open AccessArticle

Consumer’s Waste Classification Intention in China: An Extended Theory of Planned Behavior Model

by Min Tian, Bo Pu, Yini Chen and Zhian Zhu

Sustainability 2019, 11(24), 6999; https://doi.org/10.3390/su11246999 - 7 Dec 2019

Cited by 29 | Viewed by 6376

Abstract

Although there have been a variety of studies on waste classification management, there are few studies on how governments can effectively publicize waste classification knowledge in order to enhance citizen participation. Government publicity may be the key to the effective implementation of waste [...] Read more.

Although there have been a variety of studies on waste classification management, there are few studies on how governments can effectively publicize waste classification knowledge in order to enhance citizen participation. Government publicity may be the key to the effective implementation of waste classification management in China. The purpose of this study is to examine the effects of government publicity, consumer attitudes, subjective norms, perceived behavioral control and consumer knowledge on consumers’ willingness to classify waste in the process of waste management in China. The methodology used for the study included data collected from a survey conducted among citizens from four cities in China, the extended theory of planned behavior model and a moderating effect analyses using the statistical software Amos17.0 and SPSS 22.0, utilizing structural equation modeling, hierarchical regression, and the interpretation of the results. The results show that government publicity has a significant positive impact on consumer attitudes, subjective norms, and perceived behavioral control. The positive effect of consumer attitudes and perceived behavioral control on waste classification intentions are significant. Consumer knowledge plays a significant role in moderating the effect of perceived behavioral control on waste classification intentions. The findings of this study are of great significance to government and public decision-making. The results strongly suggest that the government should vigorously publicize the knowledge of waste classification at the initial stage of implementation of waste classification. Furthermore, a detailed distinction between types of consumers and the role of personal values in the implementation of waste classification is considered as a direction of future research. Full article

(This article belongs to the Special Issue Waste Management and Application of the Principles of the Circular Economy)

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17 pages, 2441 KiB

Open AccessArticle

Waste to Carbon: Estimating the Energy Demand for Production of Carbonized Refuse-Derived Fuel

by Paweł Stępień, Małgorzata Serowik, Jacek A. Koziel and Andrzej Białowiec

Sustainability 2019, 11(20), 5685; https://doi.org/10.3390/su11205685 - 15 Oct 2019

Cited by 17 | Viewed by 4479

Abstract

We have been advancing the concept of carbonized refuse-derived fuel (CRDF) by refuse-derived fuel (RDF) torrefaction as improved recycling to synergistically address the world’s energy demand. The RDF is a combustible fraction of municipal solid waste (MSW). Many municipalities recover RDF for co-firing [...] Read more.

We have been advancing the concept of carbonized refuse-derived fuel (CRDF) by refuse-derived fuel (RDF) torrefaction as improved recycling to synergistically address the world’s energy demand. The RDF is a combustible fraction of municipal solid waste (MSW). Many municipalities recover RDF for co-firing with conventional fuels. Torrefaction can further enhance fuel properties and valorize RDF. Energy demand for torrefaction is one of the key unknowns needed for scaling up CRDF production. To address this need, a pioneering model for optimizing site-specific energy demand for torrefaction of mixed RDF materials was developed. First, thermogravimetric and differential scanning calorimetry analyses were used to establish thermal properties for eight common RDF materials. Then, the model using the %RDF mix, empirical thermal properties, and torrefaction temperature was developed. The model results for individual RDF components fitted well (R² ≥ 0.98) with experimental torrefaction data. Finally, the model was used to find an optimized RDF site-specific mixture with the lowest energy demand. The developed model could be a basis for estimating a net energy potential from the torrefaction of mixed RDF. Improved models could be useful to make plant-specific decisions to optimize RDF production based on the energy demand that depends on highly variable types of MSW and RDF streams. Full article

(This article belongs to the Special Issue Waste Management and Application of the Principles of the Circular Economy)

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16 pages, 15272 KiB

Open AccessArticle

Influence of Lignocellulosic Waste Pre-Treatment on the Characteristics of Bond Rupture

by Štěpán Hýsek, Jaroslav Čermák and Martin Lexa

Sustainability 2019, 11(17), 4784; https://doi.org/10.3390/su11174784 - 2 Sep 2019

Cited by 4 | Viewed by 2626

Abstract

Post-harvest crop residues are an interesting raw material for the production of composite materials. However, their surface often contains waxy and siliceous substances, which can cause adhesion problems. Therefore, various surface pre-treatment methods have been developed to increase the surface tension of these [...] Read more.

Post-harvest crop residues are an interesting raw material for the production of composite materials. However, their surface often contains waxy and siliceous substances, which can cause adhesion problems. Therefore, various surface pre-treatment methods have been developed to increase the surface tension of these particles and hence to improve adhesive adhesion. The influence of hydrothermal, chemical, plasma and enzymatic treatment was investigated. The aim of the paper is to evaluate the effect of pre-treatments of post-harvest crop residues on the nature of joint failure and adhesive dispersion on the particles. The evaluation is based on microscopic analysis of particles obtained from the rupture area after internal bonding tests. The nature of bond failure and adhesive dispersion on the particle surface is evaluated. The results show a clear influence of material pre-treatment on the failure bond of the bond and, to a large extent, correlate with the mechanical properties of composites published in previous studies. The most suitable treatment appears to be a plasma treatment at a properly adjusted intensity. Conversely, the unsuitable treatment was alkaline, which, although it increased adhesion, deteriorated the overall mechanical properties. Hydrothermal treatment could be also considered as an industrially suitable method. Full article

(This article belongs to the Special Issue Waste Management and Application of the Principles of the Circular Economy)

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16 pages, 2647 KiB

Open AccessArticle

The Opportunities of Sustainable Biomass Ashes and Poultry Manure Recycling for Granulated Fertilizers

by Ramūnas Mieldažys, Eglė Jotautienė and Algirdas Jasinskas

Sustainability 2019, 11(16), 4466; https://doi.org/10.3390/su11164466 - 18 Aug 2019

Cited by 13 | Viewed by 3472

Abstract

A need for the disposal of poultry manure and the reduction of its impact on the environment encourages the search for cleaner and more efficient ways to utilize and recycle production waste. It is known that granulated ash and manure are the most [...] Read more.

A need for the disposal of poultry manure and the reduction of its impact on the environment encourages the search for cleaner and more efficient ways to utilize and recycle production waste. It is known that granulated ash and manure are the most effective alternatives for ash and manure recycling, as compared to the unprocessed product. This paper presents an investigation of ash and poultry manure recycling for granulated fertilizers. Accepted standard experimental methods were used. The physical and mechanical characteristics of the granules, elemental composition ratio, and the process of compression of the raw material mill were determined experimentally. This research shows that, when a higher ash concentration was determined, the initial bulk density was larger and the density and pressure in the granulation process increases faster. The content of ash in the raw material increased granule strength; however, when increasing the ash mass in the raw material from 25% to 50%, energy consumption increased from 6.59 kJ·kg⁻¹ to 17.72 kJ·kg⁻¹. The process of compression of the raw material mill was obtained in two stages. In the first stage of compression, the mass density varied from 3–11 kg·m⁻³ and the pressure varied from 1.25–8.27 MPa. In the second pressure stage, the mass deformation was elastic and the pressure process was described by indicator functions. Full article

(This article belongs to the Special Issue Waste Management and Application of the Principles of the Circular Economy)

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13 pages, 6141 KiB

Open AccessArticle

Modelling the Spatial Distribution of Asbestos—Cement Products in Poland with the Use of the Random Forest Algorithm

by Ewa Wilk, Małgorzata Krówczyńska and Bogdan Zagajewski

Sustainability 2019, 11(16), 4355; https://doi.org/10.3390/su11164355 - 12 Aug 2019

Cited by 10 | Viewed by 4183

Abstract

The unique set of physical and chemical properties of asbestos has led to its many industrial applications worldwide, of which roofing and facades constitute approximately 80% of currently used asbestos-containing products. Since asbestos-containing products are harmful to human health, their use and production [...] Read more.

The unique set of physical and chemical properties of asbestos has led to its many industrial applications worldwide, of which roofing and facades constitute approximately 80% of currently used asbestos-containing products. Since asbestos-containing products are harmful to human health, their use and production have been banned in many countries. To date, no research has been undertaken to estimate the total amount of asbestos–cement products used at the country level in relation to regions or other administrative units. The objective of this paper is to present a possible new solution for developing the spatial distribution of asbestos–cement products used across the country by applying the supervised machine learning algorithm, i.e., Random Forest. Based on the results of a physical inventory taken on asbestos–cement products with the use of aerial imagery, and the application of selected features, considering the socio-economic situation of Poland, i.e., population, buildings, public finance, housing economy and municipal infrastructure, wages, salaries and social security benefits, agricultural census, entities of the national economy, labor market, environment protection, area of built-up surfaces, historical belonging to annexations, and data on asbestos manufacturing plants, best Random Forest models were computed. The selection of important variables was made in the R v.3.1.0 program and supported by the Boruta algorithm. The prediction of the amount of asbestos–cement products used in communes was executed in the randomForest package. An algorithm explaining 75.85% of the variance was subsequently used to prepare the prediction map of the spatial distribution of the amount of asbestos–cement products used in Poland. The total amount was estimated at 710,278,645 m² (7.8 million tons). Since the best model used data on built-up surfaces which are available for the whole of Europe, it is worth considering the use of the developed method in other European countries, as well as to assess the environmental risk of asbestos exposure to humans. Full article

(This article belongs to the Special Issue Waste Management and Application of the Principles of the Circular Economy)

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20 pages, 2999 KiB

Open AccessArticle

A System Dynamics-Based Approach to Help Understand the Role of Food and Biodegradable Waste Management in Respect of Municipal Waste Management Systems

by Micky A. Babalola

Sustainability 2019, 11(12), 3456; https://doi.org/10.3390/su11123456 - 24 Jun 2019

Cited by 13 | Viewed by 10001

Abstract

The long-term plan of any city in Japan is to become a material recycling society. The use of all types of municipal waste is essential in maximizing the full potential of material recovery. As such, municipalities are responsible for managing their waste, including [...] Read more.

The long-term plan of any city in Japan is to become a material recycling society. The use of all types of municipal waste is essential in maximizing the full potential of material recovery. As such, municipalities are responsible for managing their waste, including food and biodegradable waste (FBW), and this results in some complex schemes. This study uses the system dynamics approach to illustrate and investigate the benefits of separate treatment of FBW. At the same time, to understand the dynamic interactions between all aspects and elements of the current municipal solid waste management system in Oita City. The developed model includes total environmental benefit, motivation to manage waste and resources, and yield from treatment facilities. The result shows that with the introduction of an anaerobic digester (AD) plant for FBW increases the efficiency of incineration. Furthermore, the result indicates that strengthening the regulation of waste sorted and the reduction in the amount of FBW treated in incineration will improve the current system. This study concludes that any policy or regulation less than the proposed result will yield less benefit. Thus, strengthening regulation is a crucial part of the sustainability of FBW management in the long run. Full article

(This article belongs to the Special Issue Waste Management and Application of the Principles of the Circular Economy)

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12 pages, 3552 KiB

Open AccessEditor’s ChoiceArticle

Sustainable Sewage Sludge Management: From Current Practices to Emerging Nutrient Recovery Technologies

by Sina Shaddel, Hamidreza Bakhtiary-Davijany, Christian Kabbe, Farbod Dadgar and Stein W. Østerhus

Sustainability 2019, 11(12), 3435; https://doi.org/10.3390/su11123435 - 21 Jun 2019

Cited by 123 | Viewed by 11923

Abstract

Nutrient recovery from secondary resources, such as wastewater, has received increasing attention in recent years. Nutrient cycle sustainability and recycling approaches are important measures under development and considerations. This paper aims to present an overview of routes and technologies for nutrient recovery from [...] Read more.

Nutrient recovery from secondary resources, such as wastewater, has received increasing attention in recent years. Nutrient cycle sustainability and recycling approaches are important measures under development and considerations. This paper aims to present an overview of routes and technologies for nutrient recovery from sewage sludge and measures for improving their sustainability. First, current routes for nutrient recovery from sewage sludge are briefly reviewed. Next, an overview of commercial nutrient recovery technologies, projects, and emerging techniques around the world with the key factors for a successful phosphorus recovery technology is presented. Finally, a proposal for improving the sustainability of these practices is presented. It is concluded that the gap between demand and supply can be a major driver for the shift from ‘removal and treat’ to ‘recovery and reuse’. Moreover, there is not, and will never be, a one-size-fits-all solution. Future strategies and roadmaps need to be adapted to the local economy and geographical context more than ever. Full article

(This article belongs to the Special Issue Waste Management and Application of the Principles of the Circular Economy)

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20 pages, 2920 KiB

Open AccessArticle

Construction and Demolition Waste in Romania: The Route from Illegal Dumping to Building Materials

by Florin-Constantin Mihai

Sustainability 2019, 11(11), 3179; https://doi.org/10.3390/su11113179 - 6 Jun 2019

Cited by 37 | Viewed by 8638

Abstract

The paper performs a critical overview concerning the construction and demolition waste (C&DW) management issues in Romania. Five main stages related to C&DW management are highlighted such as: (i) illegal dumping on public lands; (ii) C&DW collection and disposal in urban landfills; (iii) [...] Read more.

The paper performs a critical overview concerning the construction and demolition waste (C&DW) management issues in Romania. Five main stages related to C&DW management are highlighted such as: (i) illegal dumping on public lands; (ii) C&DW collection and disposal in urban landfills; (iii) C&DW treatment and reuse in civil constructions (roads, coating material for landfills); (iv) regional integrated waste management systems; (v) recycling of building materials (e.g., cement industry and recycled aggregates). The paper reveals the poor monitoring of C&DW flows across Romanian counties and the geographical dimension of this waste stream collected by waste operators. The paper examines the current challenges in Romania and it reveals the future prospects to provide a reliable transition towards sustainable C&DW management activities. The targeted route: waste fractions can be recycled and/or reused as building materials via integrated waste management systems, which enable a circular economy in urban and rural municipalities. Full article

(This article belongs to the Special Issue Waste Management and Application of the Principles of the Circular Economy)

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15 pages, 874 KiB

Open AccessArticle

Realizing the Circular Economy for Sanitation: Assessing Enabling Conditions and Barriers to the Commercialization of Human Excreta Derived Fertilizer in Haiti and Kenya

by Berta Moya, Ruben Sakrabani and Alison Parker

Sustainability 2019, 11(11), 3154; https://doi.org/10.3390/su11113154 - 4 Jun 2019

Cited by 36 | Viewed by 8299

Abstract

Efficient fecal sludge management solutions are especially challenging in densely populated urban informal settlements, where space is limited and land tenure uncertain. One solution is to collect and treat human excreta to produce soil conditioners for use in agriculture, through container-based sanitation, thus [...] Read more.

Efficient fecal sludge management solutions are especially challenging in densely populated urban informal settlements, where space is limited and land tenure uncertain. One solution is to collect and treat human excreta to produce soil conditioners for use in agriculture, through container-based sanitation, thus realizing the circular economy for sanitation. This study focused on container-based sanitation ventures that produce and sell fertilizers from human excreta. Stakeholder interviews showed that challenges faced by these ventures were similar: unclear regulations on the use of fertilizers derived from source-separated excreta, undeveloped markets for organic fertilizers, difficulties in securing secondary sources of organic matter for composting as well as complex transport and distribution logistics. The findings of this study emphasized the need for clear policies with respect to human excreta derived fertilizer, as well as institutional involvement in order to incentivize the sale and use of human excreta derived fertilizer locally to ensure that sustainable and safely managed sanitation systems are available in urban areas. Full article

(This article belongs to the Special Issue Waste Management and Application of the Principles of the Circular Economy)

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24 pages, 7376 KiB

Open AccessArticle

Dynamic Incentive Mechanism Design for Recycling Construction and Demolition Waste under Dual Information Asymmetry

by Qidan Hu, Ying Peng, Chunxiang Guo, Dong Cai and Peiyang Su

Sustainability 2019, 11(10), 2943; https://doi.org/10.3390/su11102943 - 23 May 2019

Cited by 16 | Viewed by 4192

Abstract

The generation of construction and demolition waste (CDW) is a problem for societies aspiring to sustainability. In this regard, governments have the responsibility to support the CDW recycling through subsidies. However, the information asymmetry, as well as the “dynamic nature” of the CDW [...] Read more.

The generation of construction and demolition waste (CDW) is a problem for societies aspiring to sustainability. In this regard, governments have the responsibility to support the CDW recycling through subsidies. However, the information asymmetry, as well as the “dynamic nature” of the CDW recycling market, results in a number of barriers for the government to promote CDW recycling. In this paper, we establish a mathematical model that includes the government and the recycling enterprise in the presence of dual information asymmetry including the unknown recycling technology level and unobservable recycling efforts in one-stage and two-stage cooperation. Using the incentive theory, the static and dynamic optimal recycling incentive contracts of the government were designed, and the optimal decisions of the recycler were identified. A numerical simulation revealed that by designing reasonable contracts, the government can encourage the recycler to report the true technical level and achieve information screening. Furthermore, the subsidy of the high-tech recycler remained unchanged under different circumstances. However, the subsidy of the low-tech recycler was closely related to the probability of misreporting and the proportion of technology types. This finding suggests that the government and recycler are inclined towards long-term dynamic cooperation. Full article

(This article belongs to the Special Issue Waste Management and Application of the Principles of the Circular Economy)

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16 pages, 3881 KiB

Open AccessEditor’s ChoiceArticle

Recycling of Communal Waste: Current State and Future Potential for Sustainable Development in the EU

by Marcela Taušová, Eva Mihaliková, Katarína Čulková, Beáta Stehlíková, Peter Tauš, Dušan Kudelas and Ľubomír Štrba

Sustainability 2019, 11(10), 2904; https://doi.org/10.3390/su11102904 - 22 May 2019

Cited by 39 | Viewed by 6868

Abstract

The constant consumption of resources exerts pressure on the environment. In this sense, waste management has obtained increasing attention from the view of a circular economy. The European Union deals with these mentioned aspects, trying maintain long-term competitiveness and to provide sustainable development [...] Read more.

The constant consumption of resources exerts pressure on the environment. In this sense, waste management has obtained increasing attention from the view of a circular economy. The European Union deals with these mentioned aspects, trying maintain long-term competitiveness and to provide sustainable development in accordance with all related environmental aspects. This paper focuses on the evaluation of the production of communal waste in 36 EU countries. The main aim is to evaluate the success of countries’ efforts to decrease waste production and increase recycling rates. The methodology used for the evaluation included data collected from the publicly available database Eurostat, consequent analyses and evaluation in the statistical software JMP 13 through regression, distribution, and cluster analysis, and the interpretation of the results. The results of the cluster analysis showed that despite clear EU waste management legislation, EU member states have significantly different waste management systems at the national level. However, generally, we could see positive correlation between the generation of waste and recycling rates. Although, Malta, Austria, Greece, and Norway recorded a decreasing level of waste recycling over the last several years, some countries (Slovakia, Poland, Czech Republic, Latvia, Lithuania) had significantly lower recycling rates accompanied by low landfill taxes. The evaluation of waste production and recycling can be used for government policy in the area of waste management, as well as for individual communities dealing with communal waste. Full article

(This article belongs to the Special Issue Waste Management and Application of the Principles of the Circular Economy)

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Review

Jump to: Research, Other

21 pages, 1752 KiB

Open AccessReview

Red Mud from the Aluminium Industry: Production, Characteristics, and Alternative Applications in Construction Materials—A Review

by Nathália C. G. Silveira, Maysa L. F. Martins, Augusto C. S. Bezerra and Fernando G. S. Araújo

Sustainability 2021, 13(22), 12741; https://doi.org/10.3390/su132212741 - 18 Nov 2021

Cited by 55 | Viewed by 9607

Abstract

About 120 million tons of red mud is produced worldwide each year. Due to its high basicity and potential leaching, its storage is a critical environmental problem. This material is typically stored in dams, which demands prior care of the disposal area and [...] Read more.

About 120 million tons of red mud is produced worldwide each year. Due to its high basicity and potential leaching, its storage is a critical environmental problem. This material is typically stored in dams, which demands prior care of the disposal area and includes monitoring and maintenance throughout its useful life. Consequently, it is crucial to figure out an industrial solution able to consumes large volumes of this material. At this moment, there are several studies, the majority in metallurgical procedures, building materials, and in the chemical industry, discussing how to reuse red mud. This paper provides a review of the aluminium process, including metal importance, its global production, and the environmental impact due to its manufacture process. It presents a review of the potential application of red mud showing its overall generation, some relevant characterisation results collected from the literature, and its utilisation in diverse areas of engineering. The study aimed to highlight applications where red mud characteristics may be favourable. Full article

(This article belongs to the Special Issue Waste Management and Application of the Principles of the Circular Economy)

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23 pages, 1373 KiB

Open AccessReview

Exploring the Potential for Utilization of Medium and Highly Sulfidic Mine Tailings in Construction Materials: A Review

by Natalia Pires Martins, Sumit Srivastava, Francisco Veiga Simão, He Niu, Priyadharshini Perumal, Ruben Snellings, Mirja Illikainen, Hilde Chambart and Guillaume Habert

Sustainability 2021, 13(21), 12150; https://doi.org/10.3390/su132112150 - 3 Nov 2021

Cited by 32 | Viewed by 6810

Abstract

Medium and highly sulfidic tailings are high-volume wastes that can lead to severe environmental damage if not properly managed. Due to the high content of sulfide minerals, these tailings can undergo weathering if put in contact with oxygen and water, generating acid mine [...] Read more.

Medium and highly sulfidic tailings are high-volume wastes that can lead to severe environmental damage if not properly managed. Due to the high content of sulfide minerals, these tailings can undergo weathering if put in contact with oxygen and water, generating acid mine drainage (AMD). The moderate-to-high sulfide content is also an important technical limitation for their implementation in the production of construction materials. This paper reviews the use of sulfidic tailings as raw material in construction products, with a focus on cement, concrete, and ceramics. When used as aggregates in concrete, this can lead to concrete degradation by internal sulfate attack. In building ceramics, their implementation without prior treatment is undesirable due to the formation of black reduction core, efflorescence, SO_x emissions, and their associated costs. Moreover, their intrinsic low reactivity represents a barrier for their use as supplementary cementitious materials (SCMs) and as precursors for alkali-activated materials (AAMs). Nevertheless, the production of calcium sulfoaluminate (CSA) cement can be a suitable path for the valorization of medium and highly sulfidic tailings. Otherwise difficult to upcycle, sulfidic tailings could be used in the clinker raw meal as an alternative raw material. Not only the SO₃ and SiO₂-rich bulk material is incorporated into reactive clinker phases, but also some minor constituents in the tailings may contribute to the production of such low-CO₂ cements at lower temperatures. Nevertheless, this valorization route remains poorly explored and demands further research. Full article

(This article belongs to the Special Issue Waste Management and Application of the Principles of the Circular Economy)

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24 pages, 4161 KiB

Open AccessReview

A Review of Challenges and Opportunities for End-of-Life Vehicle Recycling in Developing Countries and Emerging Economies: A SWOT Analysis

by Solange Ayuni Numfor, Geoffrey Barongo Omosa, Zhengyang Zhang and Kazuyo Matsubae

Sustainability 2021, 13(9), 4918; https://doi.org/10.3390/su13094918 - 27 Apr 2021

Cited by 24 | Viewed by 11561

Abstract

The importance of recycling end-of-life vehicles (ELVs) has been widely acknowledged as a means of reducing ELV waste to the environment. This reduced environmental waste contributes to achieving a number of UN SDGs, including the creation of sustainable cities. The recovery of secondary [...] Read more.

The importance of recycling end-of-life vehicles (ELVs) has been widely acknowledged as a means of reducing ELV waste to the environment. This reduced environmental waste contributes to achieving a number of UN SDGs, including the creation of sustainable cities. The recovery of secondary resources, such as metals, from the recycling of ELVs also reduces over-dependence on primary resources. This promotes efficient resource utilization and resource conservation. While recycling systems have been established and laws governing ELV recycling have been implemented in some developed countries, there are no such systems in much of the world, and regulations are few if any. To determine the challenges and opportunities for ELV recycling in developing countries, the literature on ELV recycling processes and activities was reviewed, and a SWOT analysis was done based on the data compiled from the literature, to identify the strengths, weaknesses, opportunities, and threats. From the SWOT analysis, the common features identified as opportunities were large market size, low labor cost, and the presence of recyclers of ELV parts. The common strengths were identified to be the vehicle registration system, vehicle manufacturing, ELV legislation, ELV recycling, and the waste management system. In the case of weaknesses, the identified features were the technological capacity, waste regulatory framework, vehicle deregistration, ELV regulatory framework, environmental impact and pollution, and the lack of access to information regarding ELVs, and ELV recycling infrastructure. The common threats were perceived as the little attention given to ELV recycling by the governing authorities, the difficulty of doing business, and political and social instability. The results of the SWOT analysis also showed that the opportunities were considerable and the threats were significant for all of the countries in this study. The weaknesses were significant in Nigeria and the other developing countries, and the strengths of the emerging economies tended to be greater. While weaknesses and threats were clearly identified by the SWOT analysis, the SWOT analysis also revealed the strengths and opportunities for recycling ELVs in developing and emerging countries. Full article

(This article belongs to the Special Issue Waste Management and Application of the Principles of the Circular Economy)

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20 pages, 1646 KiB

Open AccessReview

From Circular Economy to Circular Ecology: A Review on the Solution of Environmental Problems through Circular Waste Management Approaches

by Luca Adami and Marco Schiavon

Sustainability 2021, 13(2), 925; https://doi.org/10.3390/su13020925 - 18 Jan 2021

Cited by 41 | Viewed by 7973

Abstract

(1) Background: The application of concepts linked to the circular economy (CE) has led to a sudden development of studies in numerous fields. However, the level of environmental sustainability of CE strategies could be improved and this topic deserves more attention by the [...] Read more.

(1) Background: The application of concepts linked to the circular economy (CE) has led to a sudden development of studies in numerous fields. However, the level of environmental sustainability of CE strategies could be improved and this topic deserves more attention by the scientific community. This research addresses this gap and aims at presenting a new concept, named circular ecology (CE_L), and its application to the field of waste management. (2) Methods: The paper presents a literature review on the criticalities of CE and on examples of studies that implement the CE_L principles. (3) Results: The review highlights that CE_L principles are widely applied to several fields of waste management, showing promising opportunities to export the results to other geographical contexts. (4) Conclusions: If supported by governments, CE_L approaches may allow solving multiple environmental problems at once, with clear economic, time, resources, and emission savings. Full article

(This article belongs to the Special Issue Waste Management and Application of the Principles of the Circular Economy)

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13 pages, 394 KiB

Open AccessReview

A Review of the Financial Value of Faecal Sludge Reuse in Low-Income Countries

by Adrian Mallory, Rochelle Holm and Alison Parker

Sustainability 2020, 12(20), 8334; https://doi.org/10.3390/su12208334 - 10 Oct 2020

Cited by 18 | Viewed by 5711

Abstract

Faecal sludge reuse could promote responsible waste management and alleviate resource shortages. However, for this reuse to be carried out at scale, it needs to be financially viable. This paper reviews the financial values of resource recovery from 112 data points from 43 [...] Read more.

Faecal sludge reuse could promote responsible waste management and alleviate resource shortages. However, for this reuse to be carried out at scale, it needs to be financially viable. This paper reviews the financial values of resource recovery from 112 data points from 43 publications from academic and grey literature. The results found 65% of the existing literature is projected rather than being based on observed data from products in practice, with limited studies providing actual experiences of revenue in practice. Some of the estimates of the potential value were ten times those observed in data from operating businesses. Reasons for this include pricing of products against unrealistic competitors, for example, pricing briquettes against diesel fuel, or difficulties in marketing or regulation of products in practice. The most common form of reuse in practice is agricultural composting, which is also the lowest value product. Few cases were able to achieve more than $5/person/year from sludge reuse, therefore other drivers are needed to promote proper human waste disposal, including the health and dignity of citizens, but which are not easily monetised. Certification and recognition of product safety can improve the perception of value and products. Resource recovery has a limited role in the financial viability of providing Circular Economy sanitation in low-income countries. Instead, there is a need to focus on supportive policies and subsidies enabling the transition towards a Circular Economy supporting environmental quality, ecological health and human health. Full article

(This article belongs to the Special Issue Waste Management and Application of the Principles of the Circular Economy)

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22 pages, 1406 KiB

Open AccessEditor’s ChoiceReview

Legislation for the Reuse of Biosolids on Agricultural Land in Europe: Overview

by Maria Cristina Collivignarelli, Alessandro Abbà, Andrea Frattarola, Marco Carnevale Miino, Sergio Padovani, Ioannis Katsoyiannis and Vincenzo Torretta

Sustainability 2019, 11(21), 6015; https://doi.org/10.3390/su11216015 - 29 Oct 2019

Cited by 214 | Viewed by 13927

Abstract

The issues concerning the management of sewage sludge produced in wastewater treatment plants are becoming more important in Europe due to: (i) the modification of sludge quality (biological and chemical sludge are often mixed with negative impacts on sludge management, especially for land [...] Read more.

The issues concerning the management of sewage sludge produced in wastewater treatment plants are becoming more important in Europe due to: (i) the modification of sludge quality (biological and chemical sludge are often mixed with negative impacts on sludge management, especially for land application); (ii) the evolution of legislation (landfill disposal is banned in many European countries); and (iii) the technologies for energy and material recovery from sludge not being fully applied in all European Member States. Furthermore, Directive 2018/851/EC introduced the waste hierarchy that involved a new strategy with the prevention in waste production and the minimization of landfill disposal. In this context, biological sewage sludge can be treated in order to produce more stabilized residues: the biosolids. In some European countries, the reuse of biosolids as soil improver/fertilizer in arable crops represents the most used option. In order to control the quality of biosolids used for land application, every Member State has issued a national regulation based on the European directive. The aim of this work is to compare the different approaches provided by European Member States for the reuse of biosolids in agricultural soils. A focus on the regulation of countries that reuse significant amount of biosolids for land application was performed. Finally, a detailed study on Italian legislation both at national and regional levels is reported. Full article

(This article belongs to the Special Issue Waste Management and Application of the Principles of the Circular Economy)

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19 pages, 3738 KiB

Open AccessEditor’s ChoiceReview

The Changing Role of CO₂ in the Transition to a Circular Economy: Review of Carbon Sequestration Projects

by Pavel Tcvetkov, Alexey Cherepovitsyn and Sergey Fedoseev

Sustainability 2019, 11(20), 5834; https://doi.org/10.3390/su11205834 - 21 Oct 2019

Cited by 108 | Viewed by 11437

Abstract

Despite the diversity of studies on global warming and climate change mitigation technologies, research on the changing role of CO₂ in the industrial processes, which is connected with the introduction of circular economy principles, is still out of scope. The purpose of [...] Read more.

Despite the diversity of studies on global warming and climate change mitigation technologies, research on the changing role of CO₂ in the industrial processes, which is connected with the introduction of circular economy principles, is still out of scope. The purpose of this review is to answer the following question: Is technogenic CO₂ still an industrial waste or has it become a valuable resource? For this purpose, statistical information from the National Energy Technology Library and the Global CCS Institute databases were reviewed. All sequestration projects (199) were divided into three groups: carbon capture and storage (65); carbon capture, utilization, and storage (100); and carbon capture and utilization (34). It was found that: (1) total annual CO₂ consumption of such projects was 50.1 Mtpa in 2018, with a possible increase to 326.7 Mtpa in the coming decade; (2) total amount of CO₂ sequestered in such projects could be 2209 Mt in 2028; (3) the risk of such projects being cancelled or postponed is around 31.8%; (4) CO₂ is a valuable and sought-after resource for various industries. It was concluded that further development of carbon capture and utilization technologies will invariably lead to a change in attitudes towards CO₂, as well as the appearance of new CO₂-based markets and industries. Full article

(This article belongs to the Special Issue Waste Management and Application of the Principles of the Circular Economy)

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14 pages, 1881 KiB

Open AccessReview

A Review of Reverse Logistics: An Upstream Construction Supply Chain Perspective

by NNC Pushpamali, Duzgun Agdas and Timothy M. Rose

Sustainability 2019, 11(15), 4143; https://doi.org/10.3390/su11154143 - 1 Aug 2019

Cited by 30 | Viewed by 6740

Abstract

Construction industry activities, from material extraction to the end of the structure life, affect the environment negatively. For a sustainable construction process, economically, environmentally, and socially friendly practices are essential, and reverse logistics is one solution that can provide such an approach. In [...] Read more.

Construction industry activities, from material extraction to the end of the structure life, affect the environment negatively. For a sustainable construction process, economically, environmentally, and socially friendly practices are essential, and reverse logistics is one solution that can provide such an approach. In reverse logistics, obsolete products are reused in a new production, while reducing negative effects to the environment. In this study, we assess the current state of research on reverse logistics practices in the construction industry. The study presents a comparative data mining analysis, followed by a content analysis. The results show that the construction industry literature ignores the impact of reverse logistics practices on upstream construction activities. We argue that industry practitioners must take reverse logistics decisions in the early phases of the construction process by considering both upstream and end-of-life construction activities, and we recommend a reverse logistics decision framework for successful reverse logistics implementation. The findings of this research are significant for decision-makers in the industry. We urge that sustainable practices be employed in the industry. Furthermore, a quantitative analysis is suggested to strengthen the arguments made in this article. Full article

(This article belongs to the Special Issue Waste Management and Application of the Principles of the Circular Economy)

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2 pages, 632 KiB

Open AccessErratum

Erratum: Porterfield, K.K., et al. Upcycling Phosphorus Recovered from Anaerobically Digested Dairy Manure to Support Production of Vegetables and Flowers. Sustainability 2020, 12, 1139

by Katherine K. Porterfield, Robert Joblin, Deborah A. Neher, Michael Curtis, Steve Dvorak, Donna M. Rizzo, Joshua W. Faulkner and Eric D. Roy

Sustainability 2020, 12(24), 10441; https://doi.org/10.3390/su122410441 - 14 Dec 2020

Viewed by 1450

Abstract

The authors would like to make the following correction for the published paper [...] Full article

(This article belongs to the Special Issue Waste Management and Application of the Principles of the Circular Economy)

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