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Research

16 pages, 3819 KiB

Open AccessArticle

Sustainable Remediation of Polluted Soils from the Oil Industry Using Sludge from Municipal Wastewater Treatment Plants

by Cristian Mugurel Iorga, Lucian Puiu Georgescu, Constantin Ungureanu and Mihaela Marilena Stancu

Processes 2025, 13(1), 245; https://doi.org/10.3390/pr13010245 - 16 Jan 2025

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Soil pollution with hydrocarbons is a consequence of activities associated with the petroleum industry and related sectors. The effects of petroleum pollution are devastating, making the remediation of contaminated sites imperative. Consequently, soil decontamination represents a significant and costly challenge for the petroleum [...] Read more.

Soil pollution with hydrocarbons is a consequence of activities associated with the petroleum industry and related sectors. The effects of petroleum pollution are devastating, making the remediation of contaminated sites imperative. Consequently, soil decontamination represents a significant and costly challenge for the petroleum industry. The article proposes a dual-recovery bioremediation solution that is both efficient and cost-effective, exploring the potential use of dehydrated sewage sludge from municipal wastewater treatment plants to treat petroleum-contaminated soils. Over the three-month bioremediation experiment, changes in the density of indigenous bacteria in petroleum-contaminated soil samples, treated or untreated with sludge, were monitored along with the reduction in petroleum hydrocarbon concentrations. In parallel, the evolution of other contaminants, such as heavy metals, was monitored during the bioremediation experiment. Geotechnical tests were also conducted to evaluate the feasibility of returning the treated soil to its original location after the bioremediation experiment. Our results demonstrate that the proposed method effectively addresses both the remediation of petroleum-contaminated soils (hazardous waste) and the reuse of sewage sludge from municipal wastewater treatment plants. Full article

(This article belongs to the Special Issue Novel Recovery Technologies from Wastewater and Waste)

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19 pages, 3623 KiB

Open AccessFeature PaperArticle

Advancing Energy Recovery: Evaluating Torrefaction Temperature Effects on Food Waste Properties from Fruit and Vegetable Processing

by Andreja Škorjanc, Sven Gruber, Klemen Rola, Darko Goričanec and Danijela Urbancl

Processes 2025, 13(1), 208; https://doi.org/10.3390/pr13010208 - 13 Jan 2025

Viewed by 414

Abstract

Most organic waste from food production is still not used for energy production. From the perspective of energy production, one option is to valorise the properties of organic waste. The fruit juice industry is growing rapidly and generates large amounts of waste. One [...] Read more.

Most organic waste from food production is still not used for energy production. From the perspective of energy production, one option is to valorise the properties of organic waste. The fruit juice industry is growing rapidly and generates large amounts of waste. One of the main wastes in food and fruit juice processing is peach pits and apple peels. The aim of this study was to analyse the influence of torrefaction temperature on the properties of food waste, namely apple peels, peach pits and pea shells, in order to improve their energy value and determine their potential for further use and valorisation as a renewable energy source. The aim was to analyse the influence of different torrefaction temperatures on the heating value (HHV), mass yield (MY) and energy yield (EY) in order to better understand the behavior of the thermal properties of individual selected samples. The torrefaction process was carried out at temperatures of 250 °C, 350 °C and 450 °C. The obtained biomass was compared with dried biomass. For apple peels, HHV after torrefaction was (28 kJ/kg), MY decreased by (66–34%), while EY fell by (97–83%). Peach pits, despite a higher HHV after torrefaction (18 kJ/kg), achieved low MY (38–89%) and EY (59–99%), which reduces their efficiency in biochar production. Pea peels had EY (82–97%) and a lower HHV after torrefaction (11 kJ/kg), but their high ash content limits their wider use. The results confirm that, with increasing temperature, MY and EY for all selected biomasses decrease, which is a consequence of the degradation of hemicellulose and cellulose and the loss of volatile compounds. In most cases, increasing the torrefaction temperature improved the resistance to moisture adsorption, as this is related to the thermal process that causes structural changes. The results showed that the torrefaction process improved the hydrophobic properties of the biomass samples. Temperature was seen to have a great impact on mass energy efficiency. Apple peels generally had the highest mass and energy yield. Full article

(This article belongs to the Special Issue Novel Recovery Technologies from Wastewater and Waste)

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22 pages, 4283 KiB

Open AccessFeature PaperArticle

GIS-Driven Methods for Scouting Sources of Waste Heat for Fifth-Generation District Heating and Cooling (5GDHC) Systems: Railway/Highway Tunnels

by Stanislav Chicherin

Processes 2025, 13(1), 165; https://doi.org/10.3390/pr13010165 - 9 Jan 2025

Viewed by 478

Abstract

This paper explores the innovative application of Geographic Information Systems (GISs) to identify and utilize waste heat sources from railway and highway tunnels for fifth-generation district heating and cooling (5GDHC) systems. Increasing the number of prosumers—entities that produce and consume energy—within 5GDHC networks [...] Read more.

This paper explores the innovative application of Geographic Information Systems (GISs) to identify and utilize waste heat sources from railway and highway tunnels for fifth-generation district heating and cooling (5GDHC) systems. Increasing the number of prosumers—entities that produce and consume energy—within 5GDHC networks enhances their efficiency and sustainability. While potential sources of waste heat vary widely, this study focuses on underground car/railway tunnels, which typically have a temperature range of 20 °C to 40 °C. Using GIS software, we comprehensively analyzed tunnel locations and their potential as heat sources in Belgium. This study incorporates data from various sources, including OpenStreetMap and the European Waste Heat Map, and applies a two-dimensional heat transfer model to estimate the heat recovery potential. The results indicate that railway tunnels, especially in the southern regions of Belgium, show significant promise for waste heat recovery, potentially contributing between 0.8 and 2.9 GWh annually. The integration of blockchain technology for peer-to-peer energy exchange within 5GDHC systems is also discussed, highlighting its potential to enhance energy management and billing. This research contributes to the growing body of knowledge on sustainable energy systems and presents a novel approach to leveraging existing district heating and cooling infrastructure. Full article

(This article belongs to the Special Issue Novel Recovery Technologies from Wastewater and Waste)

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17 pages, 22056 KiB

Open AccessArticle

Heavy Metals Research in the Black Soil Region of Liaoning Province, China: Spatial Patterns, Risk Assessment, and Sources Apportionment

by Fan Gao, Jinhan Zhou, Jie Jiang and Guoxin Sun

Processes 2025, 13(1), 57; https://doi.org/10.3390/pr13010057 - 30 Dec 2024

Viewed by 492

Abstract

Heavy metals are enriched in black soil area and affect human safety through the food chain. In this research, 149 soil samples were collected from the black soil region in Liaoning Province; seven heavy metals (Cu, Zn, Cr, Ni, Pb, As, and Cd) [...] Read more.

Heavy metals are enriched in black soil area and affect human safety through the food chain. In this research, 149 soil samples were collected from the black soil region in Liaoning Province; seven heavy metals (Cu, Zn, Cr, Ni, Pb, As, and Cd) were investigated to determine the status, ecological-health risks, and contamination risks and to identify sources. The method of potential ecological risk assessment, Nemerow index, and geo-accumulation index were used to appraise the heavy-metal contamination. Principal component analysis was combined with an absolute factor score/multiple linear regression model to identify the heavy metals’ sources in the soil. The average concentrations of Cu, Zn, Cr, Ni, Pb, As, and Cd were 0.92, 0.87, 0.84, 0.95, 1.09, 0.97, and 1.86 times of the soil background value, respectively. In the research area, Ni and Cr were basically non-enriched; As, Cu, and Zn were mildly enriched; Pb was moderately enriched; and Cd was seriously enriched. The source analysis identified three primary sources of heavy metals: the first was natural sources, including Cr, Ni, and Cu. The second was industrial sources, including smelting, with a high contribution from Cd and Zn. The third was human activities, such as mining operations, which have a high contribution rate to Pb and As. The research area was not heavily contaminated with heavy metals. This work lays a foundation for the environmental restoration of heavy-metals-polluted black soil, which is vital to restoring the ecology of and fostering sustainable agriculture in Liaoning’s black soil region. Full article

(This article belongs to the Special Issue Novel Recovery Technologies from Wastewater and Waste)

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12 pages, 2871 KiB

Open AccessFeature PaperArticle

Recovery of Cellulose Contained in Mixed Fabrics

by Juan A. Conesa and Viviana N. Córdoba

Processes 2024, 12(12), 2854; https://doi.org/10.3390/pr12122854 - 12 Dec 2024

Viewed by 595

Abstract

The present work focuses on the recovery of cellulose from mixed fabrics containing polyester and cotton through the use of different chemical and hydrothermal treatment methods. Through the application of various analytical techniques, such as thermogravimetry (TG) and infrared spectroscopy (IR), we seek [...] Read more.

The present work focuses on the recovery of cellulose from mixed fabrics containing polyester and cotton through the use of different chemical and hydrothermal treatment methods. Through the application of various analytical techniques, such as thermogravimetry (TG) and infrared spectroscopy (IR), we seek to determine the effectiveness of the methods used. The results indicate that different treatments with NaOH and distilled water at high temperatures and pressures are particularly effective for the extraction of the cellulose fraction. Furthermore, these methods were compared with previous studies to evaluate their feasibility and sustainability. The findings underline the importance of selecting appropriate experimental conditions to maximize the purity of the cellulose obtained and minimize fiber degradation, thus promoting more efficient and sustainable textile recycling processes. These results have significant implications for industrial applications by enabling the development of scalable recycling methods and contribute to reducing the environmental impact of textile waste. Full article

(This article belongs to the Special Issue Novel Recovery Technologies from Wastewater and Waste)

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13 pages, 4244 KiB

Open AccessArticle

Bioleaching of Industrial Metallic Steel Waste by Mixed Cultures of Thermoacidophilic Archaea

by Alma Memic, Artem Mashchenko, Denise Kölbl, Holger Schnideritsch, Dominik Wohlmuth, Gerald Klösch and Tetyana Milojevic

Processes 2024, 12(11), 2327; https://doi.org/10.3390/pr12112327 - 23 Oct 2024

Viewed by 945

Abstract

Different mixed cultures of extremely thermoacidophilic microorganisms were used for bioleaching of metalliferous industrial dust waste derived from the basic oxygen furnace (BOF) steelmaking process. Such mixed cultures can extract various metals from multi-metallic BOF-dust waste, improving the metal dissolution and bioleaching performance [...] Read more.

Different mixed cultures of extremely thermoacidophilic microorganisms were used for bioleaching of metalliferous industrial dust waste derived from the basic oxygen furnace (BOF) steelmaking process. Such mixed cultures can extract various metals from multi-metallic BOF-dust waste, improving the metal dissolution and bioleaching performance in frames of metal recycling processes to assist circular economies and waste management. The results of the investigation showed that mixed cultures of thermoacidophilic archaea of the order Sulfolobales (Acidianus spp., Sulfolobus spp., and Metallosphaera sedula) during their growth in laboratory glass bioreactors provided a superior bioleaching system to Acidianus manzaensis alone. Depending on the composition of mixed thermoacidophilic cultures, extraction of various metals from BOF-dust could be achieved. Among the three different types of mixed cultures tested, the mixed culture system of A. manzaensis, A. brierleyi, and S. acidocaldarius was most effective for extraction of major elements (Fe, Ca, Zn, Mn, and Al). The mixed culture of A. manzaensis, A. brierleyi, and M. sedula showed high performance for bioleaching of most of the minor elements (Cu, Ni, Pb, Co, Mo, and Sr). The efficient ability of mixed cultures to colonise the mineral matrix of the metal waste product was observed via scanning electron microscopy, while their metal extraction capacities were analysed by inductively coupled plasma mass spectrometry. These investigations will promote the further design of microbial consortia in order to break down the solid matrix and efficiently extract metals from metalliferous waste materials. Full article

(This article belongs to the Special Issue Novel Recovery Technologies from Wastewater and Waste)

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11 pages, 1210 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

The Evaluation and Optimization of a Decentralized Incineration Facility for Animal By-Products: Performance, Cost Analysis and Resource Recovery

by Panagiotis J. Charitidis, Alexandros Eftaxias, Evangelos A. Voudrias and Vasileios Diamantis

Processes 2024, 12(9), 1847; https://doi.org/10.3390/pr12091847 - 29 Aug 2024

Cited by 1 | Viewed by 1430

Abstract

In this study, a decentralized incineration facility was evaluated over a three-year period, focusing on performance aspects, such as the burning rate, ash production, fuel and electricity consumption, and ash composition, while processing animal by-products (ABPs). The total cost for ABP incineration was [...] Read more.

In this study, a decentralized incineration facility was evaluated over a three-year period, focusing on performance aspects, such as the burning rate, ash production, fuel and electricity consumption, and ash composition, while processing animal by-products (ABPs). The total cost for ABP incineration was determined to be EUR 159 t⁻¹ ABP, with the major components being capital depreciation (42%), maintenance expenditures (26%), labor (18%), and transportation costs (9%). Liquified petroleum gas consumption ranged from 3 to 7 kg t⁻¹, while electricity use was between 15 and 20 kWh t⁻¹ incinerated ABP. The incineration process generated 7–10% (by weight) ABP ash, which was characterized by high calcium and phosphorus contents and low levels of hazardous trace elements. Leaching tests demonstrated the potential for recovering an alkaline supernatant for flue gas treatment and a phosphorus-rich slurry for fertilizer production. The findings suggest that energy recovery and valorization are crucial for minimizing the operational costs and the environmental impact, emphasizing the benefits of integrating advanced resource recovery techniques in ABP incineration facilities. Full article

(This article belongs to the Special Issue Novel Recovery Technologies from Wastewater and Waste)

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13 pages, 5180 KiB

Open AccessArticle

Application of Corn Straw, an Agro-Waste, to Remove Dyes in an Aqueous Medium, Producing Blue or Red Fibers

by Andressa dos Santos, Anne R. Sotiles and Fauze J. Anaissi

Processes 2024, 12(4), 694; https://doi.org/10.3390/pr12040694 - 29 Mar 2024

Cited by 1 | Viewed by 1142

Abstract

The contaminant dyes that, even at low concentrations, may cause a series of adverse effects in humans and animals, and their removal by adsorption methods using alternative adsorbents as natural fibers, are regarded as a research topic that has become increasingly relevant. In [...] Read more.

The contaminant dyes that, even at low concentrations, may cause a series of adverse effects in humans and animals, and their removal by adsorption methods using alternative adsorbents as natural fibers, are regarded as a research topic that has become increasingly relevant. In this study, corn straw (CS), an agro-industrial residue, was used to remove dyes. The samples were characterized by ATR-FTIR, SEM-EDS, zeta potential, diffuse spectra, and colorimetry, before and after dye removal. The analyses allowed us to differentiate the morphology of CS after the treatment’s fiber on the adsorbent surface. The zeta potential showed a negative surface charge, but the acidic or alkaline treatment affected the surface charge of the sample, influencing the adsorption of cationic or anionic dyes. Adsorption data presented an increased removal when alkaline treatment was applied for the methylene blue (MB; q_max = 16.7 mg g⁻¹), and the acid treatment was more effective for the Congo red (CR; q_max = 2.13 mg g⁻¹). After color stability tests, it was observed that the anionic dye CR was more easily desorbed due to the surface charge of the adsorbent. Due to the chemical treatment, corn straw proved to be a good sustainable adsorbent for removing anionic or cationic dyes from aqueous media, contributing directly to the objective of sustainable development (#6—drinking water and sanitation) and with SDG numbers 3, 11, 12, 14, and 17. Full article

(This article belongs to the Special Issue Novel Recovery Technologies from Wastewater and Waste)

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