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16 pages, 3222 KiB

Open AccessArticle

Changes in Sources and Composition of Beach Waste in Coastal Cities around the Bohai Sea of China during the Tourist Peak and Off-Peak Seasons

by Tianqi Kong, Xuefei Li, Ke Pan, Wanli Zhang and Rundong Li

Int. J. Environ. Res. Public Health 2023, 20(3), 2573; https://doi.org/10.3390/ijerph20032573 - 31 Jan 2023

Cited by 2 | Viewed by 1570

Abstract

Beach waste is an important pollutant in the Bohai Sea and coastal cities around the Bohai Sea and has raised many social and environmental concerns in China. The semi-closed characteristics of the Bohai Sea, the well-developed tourism, the special industrial structure and residents’ [...] Read more.

Beach waste is an important pollutant in the Bohai Sea and coastal cities around the Bohai Sea and has raised many social and environmental concerns in China. The semi-closed characteristics of the Bohai Sea, the well-developed tourism, the special industrial structure and residents’ living habits endow the beach waste around Bohai sea with a unique character that should be explored. This study investigated changes in the sources and composition of beach waste in coastal cities around the Bohai Sea of China during the tourist peak and off-peak seasons. Beach waste from twenty beaches in thirteen coastal cities around the Bohai Sea was sampled and analyzed in March and August 2021, respectively. The results showed that beach waste around the Bohai Sea was characterized by large quantities and small weights and was greatly affected by human coastal activities. The sources and composition of beach waste from different coasts and different seasons varied, whereas the overall trend was consistent. In terms of composition, beach waste in both the tourist peak season and off-peak season was mainly composed of plastics, fabrics and paper, which accounted for more than 70% of the total in weight. Meanwhile, the proportion of plastics in the total quantity of beach waste was greatest (maximum of up to 71%) and exhibited seasonal fluctuations, trending higher in the tourist peak season than in the off-peak season. In contrast, trends in the proportion of paper and fabrics in the total quantity and total weight of beach waste were relatively stable in different seasons. In terms of sources, beach waste mainly derived from human coastal activities, the proportion of which in the total quantity of beach waste in the tourist peak season reached 70.55% and was 11% higher than that in the tourist off-peak season. Shipping/fishing activities were the second largest source of beach waste, and their proportion in the total quantity of beach waste in the tourist peak season was 5% lower than that in the tourist off-peak season, as the tourist peak season around the Bohai Sea coincides exactly with the fishing moratorium. The quantity of smoking-related waste only accounted for 9.35% and 7.73% of beach waste in the tourist peak and off-peak seasons, respectively. The special semi-enclosed structure of the Bohai gulf, surrounded by land on three sides, aggravated the accumulation of beach waste on the coast. Source reduction and classified recovery, collaborative management of marine waste and beach waste, and joint prevention and control mechanisms of three provinces (Liaoning, Hebei and Shandong) and one municipality (Tianjin) were suggested for comprehensive management of beach waste in coastal cities around the Bohai Sea of China. This study provided valuable information for beach waste management in coastal cities around the Bohai Sea of China. Full article

(This article belongs to the Special Issue Air Pollution Control, Solid Waste Treatment, and Environmental Catalysis)

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11 pages, 1691 KiB

Open AccessArticle

Pre-Drying of Chlorine–Organic-Contaminated Soil in a Rotary Dryer for Energy Efficient Thermal Remediation

by Rui Chai, Jinqing Wang, Mingxiu Zhan, Dingkun Yuan, Zuohe Chi, Hailin Gu and Jiani Mao

Int. J. Environ. Res. Public Health 2022, 19(24), 16607; https://doi.org/10.3390/ijerph192416607 - 10 Dec 2022

Cited by 2 | Viewed by 1302

Abstract

In response to the current problem of the high energy consumption of direct thermal desorption systems when treating soils with a high moisture content, we propose using the waste heat of the system to pre-dry soil to reduce its moisture. Taking chlorine–organic-contaminated soil [...] Read more.

In response to the current problem of the high energy consumption of direct thermal desorption systems when treating soils with a high moisture content, we propose using the waste heat of the system to pre-dry soil to reduce its moisture. Taking chlorine–organic-contaminated soil as an object, an experimental study on the drying and pollutant desorption characteristics of soil in an indirect rotary dryer was carried out. The results show that the non-isothermal drying process was divided into warm-up and falling rate periods, and no constant period was observed. The higher the rotation speed, the lower the soil outlet temperature and the higher the drying tail gas temperature. Soil outlet and dry tail gas temperatures were lower for soils with a higher moisture content. Benzene and cis-1,2-dichloroethylene are easily desorbed. Therefore, the disposal of dry tail gas should be determined according to the type and concentration of soil pollutants present. The volumetric heat transfer coefficient was found to be 85–100 W m⁻³ °C⁻¹, which provides a key parameter for the size design of a rotary dryer. Full article

(This article belongs to the Special Issue Air Pollution Control, Solid Waste Treatment, and Environmental Catalysis)

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12 pages, 3266 KiB

Open AccessArticle

The Effect of Iron Content on the Ammonia Selective Catalytic Reduction Reaction (NH₃-SCR) Catalytic Performance of FeO_x/SAPO-34

by Zhaoyang Li, Geng Chen, Zhenghua Shao, Haonan Zhang and Xiujuan Guo

Int. J. Environ. Res. Public Health 2022, 19(22), 14749; https://doi.org/10.3390/ijerph192214749 - 10 Nov 2022

Cited by 2 | Viewed by 1607

Abstract

Iron-based catalysts are regarded as promising candidates for the ammonia selective catalytic reduction reaction (NH₃-SCR) which show good catalytic activity at medium and high temperatures, whereas SAPO-34 molecular sieves have a micro-pore structure and are ideal catalyst carriers. In this paper, [...] Read more.

Iron-based catalysts are regarded as promising candidates for the ammonia selective catalytic reduction reaction (NH₃-SCR) which show good catalytic activity at medium and high temperatures, whereas SAPO-34 molecular sieves have a micro-pore structure and are ideal catalyst carriers. In this paper, four FeO_x/SAPO-34 molecular sieve catalysts with different iron contents (Fe = 1%, 2%, 3%, 4%) were prepared using an impregnation method. The effect of iron content on the surface properties and catalytic activity was investigated by a series of characterization techniques including XRD, SEM, BET, XPS, H₂-TPR and NH₃-TPD. Iron species in the FeO_x/SAPO-34 catalysts exist in the form of isolated iron ions or well-dispersed small crystals and iron oxide species clusters. With the addition of iron content, the integrity of CHA (chabazite) zeolite structure remained, but the crystallinity was affected. The FeO_x/SAPO-34 catalyst with 3% Fe loading showed a relatively flat surface with no large-diameter particles and strong oxidation-reduction ability. Meanwhile, more acidic sites are exposed, which accelerated the process of catalytic reaction. Thus, the FeO_x/SAPO-34 catalyst with 3% Fe showed the best NO conversion performance among the four catalysts prepared and maintained more than 90% NO conversion efficiency in a wide temperature range from 310 °C to 450 °C. Full article

(This article belongs to the Special Issue Air Pollution Control, Solid Waste Treatment, and Environmental Catalysis)

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17 pages, 4473 KiB

Open AccessArticle

Soot Combustion over Cu–Co Spinel Catalysts: The Intrinsic Effects of Precursors on Catalytic Activity

by Chunlin Zhou, Xinbo Zhu, Fei Zhang, Xinbao Li, Geng Chen, Zijian Zhou and Guohua Yang

Int. J. Environ. Res. Public Health 2022, 19(22), 14737; https://doi.org/10.3390/ijerph192214737 - 9 Nov 2022

Cited by 1 | Viewed by 1132

Abstract

In this work, a series of CuCo₂O₄-x (x = N, A and C) catalysts were synthesized using different metal salt precursors by urea hydrothermal method for catalytic soot combustion. The effect of CuCo₂O₄- [...] Read more.

In this work, a series of CuCo₂O₄-x (x = N, A and C) catalysts were synthesized using different metal salt precursors by urea hydrothermal method for catalytic soot combustion. The effect of CuCo₂O₄-x catalysts on soot conversion and CO₂ selectivity in both loose and tight contact mode was investigated. The CuCo₂O₄-N catalyst exhibited outstanding catalytic activity with the characteristic temperatures (T₁₀, T₅₀ and T₉₀) of 451 °C, 520 °C and 558 °C, respectively, while the CO₂ selectivity reached 98.8% during the reaction. With the addition of NO, the soot combustion was further accelerated over all catalysts. Compared with the loose contact mode, the soot conversion was improved in the tight contact mode. The CuCo₂O₄-N catalysts showed better textural properties compared to the CuCo₂O₄-A and CuCo₂O₄-C, such as higher specific surface areas and pore volumes. The XRD results confirmed that the formation of a CuCo₂O₄ crystal phase in all catalysts. However, the CuO crystal phase only presented in CuCo₂O₄-N and CuCo₂O₄-A. The relative contents of Cu²⁺, Co³⁺ and O_ads on the surface of CuCo₂O₄-x (x = N, A and C) catalysts were analyzed by XPS. The CuCo₂O₄-N catalyst displayed the highest relative content of Cu²⁺, Co³⁺ and O_ads. The activity of catalytic soot combustion showed a good correlation with the order of the relative contents of Cu²⁺, Co³⁺ and O_ads. Additionally, the CuCo₂O₄-N catalyst exhibited lower reduction temperature compared to the CuCo₂O₄-A and CuCo₂O₄-C. The cycle tests clarified that the copper–cobalt spinel catalyst obtained good stability. In addition, based on the Mars–van Krevelen mechanism, the process of catalytic soot combustion was described combined with the electron transfer process and the role of oxygen species over CuCo₂O₄ spinel catalysts. Full article

(This article belongs to the Special Issue Air Pollution Control, Solid Waste Treatment, and Environmental Catalysis)

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16 pages, 3114 KiB

Open AccessArticle

Low-Temperature Catalytic Ozonation of Multitype VOCs over Zeolite-Supported Catalysts

by Jiaming Shao, Yunchu Zhai, Luyang Zhang, Li Xiang and Fawei Lin

Int. J. Environ. Res. Public Health 2022, 19(21), 14515; https://doi.org/10.3390/ijerph192114515 - 4 Nov 2022

Cited by 8 | Viewed by 1662

Abstract

Volatile organic compounds (VOCs) are an important source of air pollution, harmful to human health and the environment, and important precursors of secondary organic aerosols, O₃ and photochemical smog. This study focused on the low-temperature catalytic oxidation and degradation of benzene, dichloroethane, [...] Read more.

Volatile organic compounds (VOCs) are an important source of air pollution, harmful to human health and the environment, and important precursors of secondary organic aerosols, O₃ and photochemical smog. This study focused on the low-temperature catalytic oxidation and degradation of benzene, dichloroethane, methanethiol, methanol and methylamine by ozone. Benzene was used as a model compound, and a molecular sieve was selected as a catalyst carrier to prepare a series of supported active metal catalysts by impregnation. The effects of ozone on the catalytic oxidation of VOCs and catalysts’ activity were studied. Taking benzene as a model compound, low-temperature ozone catalytic oxidation was conducted to explore the influence of the catalyst carrier, the active metal and the precious metal Pt on the catalytic degradation of benzene. The optimal catalyst appeared to be 0.75%Pt–10%Fe/HZSM(200). The catalytic activity and formation of the by-products methylamine, methanethiol, methanol, dichloroethane and benzene over 0.75%Pt–10%Fe/HZSM(200) were investigated. The structure, oxygen vacancy, surface properties and surface acidity of the catalysts were investigated. XRD, TEM, XPS, H₂-TPR, EPR, CO₂-TPD, BET, C₆H₆-TPD and Py-IR were combined to establish the correlation between the surface properties of the catalysts and the degradation activity. Full article

(This article belongs to the Special Issue Air Pollution Control, Solid Waste Treatment, and Environmental Catalysis)

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14 pages, 6065 KiB

Open AccessArticle

Study on the Properties and Heavy Metal Solidification Characteristics of Sintered Ceramsites Composed of Magnesite Tailings, Sewage Sludge, and Coal Gangue

by Yanlong Li, Mingyuan Xu, Quan Li, Anjun Gai, Tianhua Yang and Rundong Li

Int. J. Environ. Res. Public Health 2022, 19(17), 11128; https://doi.org/10.3390/ijerph191711128 - 5 Sep 2022

Cited by 6 | Viewed by 1564

Abstract

With the rapid development of industry, the disposal of industrial solid waste needs to be solved urgently in China. Thus, an effective disposal method should be proposed to recycle these solid wastes in an environmentally friendly and sustainable manner. In this paper, ceramsite [...] Read more.

With the rapid development of industry, the disposal of industrial solid waste needs to be solved urgently in China. Thus, an effective disposal method should be proposed to recycle these solid wastes in an environmentally friendly and sustainable manner. In this paper, ceramsite was prepared from sewage sludge (SS), magnesite tailings (MTs), and coal gangue (CG). The influence of the material ratio and sintering temperature on the properties of the ceramsite was investigated. The results show that the ceramsite had better properties when the following parameters were used: a ratio of SS: CG: MT of 4.5:4:1.5; a sintering temperature of 1250 °C; a compressive strength of 11.2 MPa (or it can be rounded to 11; our major remark relates to significant figures, and they should be up to 2–3 figures, according to measurement errors); a water absorption of 3.54%; and apparent and bulk densities of 1.19 and 0.81 g/cm³, respectively. The strength was superior to more than twice the 900-density grade prescribed by the Chinese national standard. After sintering, most of the heavy metals in the ceramsite mainly existed in the form of residue state (FD), meaning that they were highly stable. The leaching concentrations of Zn and Ni from the ceramsite were 0.72 and 0.25 mg/L lower than the prescribed regulatory limits (2.0 and 0.1 mg/L). The overall pollution toxicity index (OPTI) was only 240, less than that of raw pellets, indicating that the environmental risk is low. Not only did the ceramsite, prepared from SS, CG, and MT, exhibit excellent chemical properties, but it also proved to be an environmentally safe material. Therefore, it is an effective approach to realize the collaborative treatment of SS, CG, and MT by preparing ceramsite. Full article

(This article belongs to the Special Issue Air Pollution Control, Solid Waste Treatment, and Environmental Catalysis)

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12 pages, 2865 KiB

Open AccessArticle

Using Stable Sulfur Isotope to Trace Sulfur Oxidation Pathways during the Winter of 2017–2019 in Tianjin, North China

by Shiyuan Ding, Yingying Chen, Qinkai Li and Xiao-Dong Li

Int. J. Environ. Res. Public Health 2022, 19(17), 10966; https://doi.org/10.3390/ijerph191710966 - 2 Sep 2022

Cited by 4 | Viewed by 1340

Abstract

After the implementation of the Coal Replacing Project (CRP) in the northern parts of China in 2017, its effect on PM_2.5 composition is still unclear. In the study, water-soluble ionic components (WSICs) and stable sulfur isotope ratios (δ³⁴S) of SO [...] Read more.

After the implementation of the Coal Replacing Project (CRP) in the northern parts of China in 2017, its effect on PM_2.5 composition is still unclear. In the study, water-soluble ionic components (WSICs) and stable sulfur isotope ratios (δ³⁴S) of SO₄²⁻ in PM_2.5 collected during the domestic heating period before and after the implementation of CRP in Tianjin were analyzed. Results showed that the average concentrations of both PM_2.5 and WSICs have dropped dramatically after the CRP, especially for the SO₄²⁻ (by approximately 57–60%). After the CRP, the range of δ³⁴S_sulfate was significantly narrowed to 4.1–7.5‰ in January 2018 and 1.4–6.1‰ in January 2019, which suggested that the sulfur source was becoming simple. It was interesting that the δ³⁴S_sulfate value in the pollution period before the CRP was higher than that in the clean period, whereas it showed the opposite tendency after the CRP, which implied that the contribution of sea salt was high during the pollution period before the CRP. The MIXSIAR model calculated that the contributions of the transition-metal ion (TMI) oxidation and NO₂ oxidation pathways in the three sampling stages were higher than those of the OH radical oxidation and H₂O₂/O₃ oxidation pathways, indicating that the formation pathway of sulfate was mainly dominated by heterogeneous oxidation. Before the CRP, the NO₂ oxidation pathway was the dominant sulfate oxidation pathway during a haze episode, and the TMI oxidation pathway dominated the formation of sulfates after the CRP. Full article

(This article belongs to the Special Issue Air Pollution Control, Solid Waste Treatment, and Environmental Catalysis)

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15 pages, 5607 KiB

Open AccessArticle

Pollution Levels and Risk Assessment of Heavy Metals in the Soil of a Landfill Site: A Case Study in Lhasa, Tibet

by Peng Zhou, Dan Zeng, Xutong Wang, Lingyu Tai, Wenwu Zhou, Qiongda Zhuoma and Fawei Lin

Int. J. Environ. Res. Public Health 2022, 19(17), 10704; https://doi.org/10.3390/ijerph191710704 - 27 Aug 2022

Cited by 9 | Viewed by 2150

Abstract

As an important ecological security barrier in China, the ecological environment of Tibet has aroused widespread concern domestically and overseas. Landfills are a major solid waste treatment approach in Tibet but also cause severe environmental pollution. To date, there are no studies related [...] Read more.

As an important ecological security barrier in China, the ecological environment of Tibet has aroused widespread concern domestically and overseas. Landfills are a major solid waste treatment approach in Tibet but also cause severe environmental pollution. To date, there are no studies related to the pollution risk of landfills in Tibetan areas. This study investigated the pollution levels, ecological risk, health risk, and possible pollution sources of eight heavy metals in the soils around a landfill site in Lhasa, Tibet. The results indicated that the concentrations of heavy metals in soil were relatively low, only cadmium (Cd), arsenic (As), copper (Cu), chromium (Cr), zinc (Zn), nickel (Ni), and lead (Pb) were 1–2 times higher than the corresponding background value. The values of the single pollution index and geo-accumulation index show that the study area is most seriously polluted by Cd and As. Based on the Nemerow pollution index and the pollution load index, over 83.3% and 8.33% of soil sampling sites had light and moderate contamination levels. According to the results of potential ecological risk evaluation, the potential ecological risk of heavy metals in soil was very low, and only one out of the 72 sampling sites exhibited considerable ecological risk. Cd, As, and mercury (Hg) served as the dominant ecological risk contributors and contributed over 45.0%, 14.1%, and 18% of the ecological risk. The results of the health risk evaluation showed that adults have a higher risk of cancer (1.73 × 10⁻⁵), while the non-carcinogenic risk for adults was low. Waste disposal activities and construction activities have a significant influence on soil heavy metal concentrations, causing a higher pollution level in the southeast part of the landfill site in Lhasa. Full article

(This article belongs to the Special Issue Air Pollution Control, Solid Waste Treatment, and Environmental Catalysis)

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19 pages, 4337 KiB

Open AccessArticle

Spatial Characteristics Analysis for Coupling Strength among Air Pollutants during a Severe Haze Period in Zhengzhou, China

by Linan Sun, Antao Wang and Jiayao Wang

Int. J. Environ. Res. Public Health 2022, 19(14), 8224; https://doi.org/10.3390/ijerph19148224 - 6 Jul 2022

Cited by 1 | Viewed by 1326

Abstract

This paper investigates the multifractal characteristics of six air pollutants using the coupling detrended fluctuation analysis method. The results show that coupling correlations exist among the air pollutants and have multifractal characteristics. The sources of multifractality are identified using the chi square test. [...] Read more.

This paper investigates the multifractal characteristics of six air pollutants using the coupling detrended fluctuation analysis method. The results show that coupling correlations exist among the air pollutants and have multifractal characteristics. The sources of multifractality are identified using the chi square test. The coupling strengths between different pollutants are quantified. In addition, the coupling contribution of a series in the haze system is calculated, and SO₂, as the main pollutant, plays a key role in the pollution system. Moreover, the Kriging interpolation method is used to analyze the spatial characteristic on coupling contribution of SO₂. The spatial analysis of coupling strength for air pollutants will provide an effective approach for pollution control. Full article

(This article belongs to the Special Issue Air Pollution Control, Solid Waste Treatment, and Environmental Catalysis)

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14 pages, 1702 KiB

Open AccessArticle

Magnetic Nanoparticle-Based Dispersive Solid-Phase Microextraction of Three UV Blockers Prior to Their Determination by HPLC-DAD

by Suad E. Abughrin, Usama Alshana and Sezgin Bakirdere

Int. J. Environ. Res. Public Health 2022, 19(10), 6037; https://doi.org/10.3390/ijerph19106037 - 16 May 2022

Cited by 4 | Viewed by 1763

Abstract

The need for proper handling of environmental samples is significant, owing to their environmental effects on both humans and animals, as well as their immediate surroundings. In the current study, magnetic nanoparticle-based dispersive solid-phase microextraction was combined with high-performance liquid chromatography using a [...] Read more.

The need for proper handling of environmental samples is significant, owing to their environmental effects on both humans and animals, as well as their immediate surroundings. In the current study, magnetic nanoparticle-based dispersive solid-phase microextraction was combined with high-performance liquid chromatography using a diode array as the detector (HPLC-DAD) for both the separation and determination of three different UV blockers, namely octocrylene, ethylhexyl methoxycinnamate, and avobenzone. The optimum conditions for the extraction were found to be as follows: Stearic acid magnetic nanoparticles (20 mg) as the sorbent, acetonitrile (100 µL) as the eluent, as well as a sample pH of 2.50, adsorption and desorption time of 1.0 min, with a 3.0 mL sample volume. The limits of detection were as low as 0.05 µg mL⁻¹. The coefficient of determination (R²) was above 0.9950, while the percentages of relative recoveries (%RR) were between 81.2 and 112% for the three UV blockers from the environmental water samples and sunscreen products. Full article

(This article belongs to the Special Issue Air Pollution Control, Solid Waste Treatment, and Environmental Catalysis)

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16 pages, 38498 KiB

Open AccessArticle

Co-Pyrolysis of Sewage Sludge and Wetland Biomass Waste for Biochar Production: Behaviors of Phosphorus and Heavy Metals

by Ilham Gbouri, Fan Yu, Xutong Wang, Junxia Wang, Xiaoqiang Cui, Yanjun Hu, Beibei Yan and Guanyi Chen

Int. J. Environ. Res. Public Health 2022, 19(5), 2818; https://doi.org/10.3390/ijerph19052818 - 28 Feb 2022

Cited by 16 | Viewed by 2903

Abstract

Large amounts of sewage sludge (SS) and wetland plant wastes are generated in the wastewater treatment system worldwide. The conversion of these solid wastes into biochar through co-pyrolysis could be a promising resource utilization scheme. In this study, biochar was prepared by co-pyrolysis [...] Read more.

Large amounts of sewage sludge (SS) and wetland plant wastes are generated in the wastewater treatment system worldwide. The conversion of these solid wastes into biochar through co-pyrolysis could be a promising resource utilization scheme. In this study, biochar was prepared by co-pyrolysis of SS and reed (Phragmites australis, RD) using a modified muffle furnace device under different temperatures (300, 500, and 700 °C) and with different mixing ratios (25, 50, and 75 wt.% RD). The physicochemical properties of biochar and the transformation behaviors of phosphorus (P) and heavy metals during the co-pyrolysis process were studied. Compared with single SS pyrolysis, the biochar derived from SS-RD co-pyrolysis had lower yield and ash content, higher pH, C content, and aromatic structure. The addition of RD could reduce the total P content of biochar and promote the transformation from non-apatite inorganic phosphorus (NAIP) to apatite phosphorus (AP). In addition, co-pyrolysis also reduced the content and toxicity of heavy metals in biochar. Therefore, co-pyrolysis could be a promising strategy to achieve the simultaneous treatment of SS and RD, as well as the production of value-added biochar. Full article

(This article belongs to the Special Issue Air Pollution Control, Solid Waste Treatment, and Environmental Catalysis)

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12 pages, 1684 KiB

Open AccessArticle

Short-Chain Fatty Acids Production from Anaerobic Fermentation of Sewage Sludge: The Effect of Higher Levels Polyaluminium Chloride

by Puli Zhu, Xiaoyun Li, Jing Feng, Rui Zhang, Hui Bai, Duo Bu, Zeng Dan, Wei Li and Xuebin Lu

Int. J. Environ. Res. Public Health 2022, 19(5), 2806; https://doi.org/10.3390/ijerph19052806 - 28 Feb 2022

Cited by 5 | Viewed by 1978

Abstract

With the annual increase in the sludge production in China’s sewage treatment plants, the problem of sewage sludge treatment and disposal is becoming more and more serious. Anaerobic fermentation can convert complex organic matter in sewage sludge into short-chain fatty acid, hydrogen, methane [...] Read more.

With the annual increase in the sludge production in China’s sewage treatment plants, the problem of sewage sludge treatment and disposal is becoming more and more serious. Anaerobic fermentation can convert complex organic matter in sewage sludge into short-chain fatty acid, hydrogen, methane and other resources and is an effective method for sewage sludge treatment and disposal. At the same time, sewage sludge often contains flocculants, which will inevitably affect the effect of anaerobic fermentation. As a high-performance flocculant, polyaluminum chloride (PAC) is widely used in wastewater treatment and sewage sludge dewatering processes. Previous studies indicated that lower levels of PAC inhibit the effect of the anaerobic fermentation process of sewage sludge; on the other hand, it is necessary to understand the effects of higher levels of PAC in anaerobically fermented sewage sludge. The results showed that higher levels (0.2–1 g Al/g total solids (TS)) of PAC could promote acid production from anaerobically fermented sewage sludge. Moreover, mechanism studies suggest that higher levels (0.2–1 g Al/g total solids (TS)) of PAC caused excessive adsorption of the charge on the surface of the sewage sludge colloid and reversed the charge. The sewage sludge colloid was stabilized again, which increases the concentration of soluble proteins, polysaccharides, and soluble extracellular polymers (S-EPS) in the fermentation broth, thereby improving the anaerobically fermented sewage sludge efficiency. The results provided from this study may act as technical reference and guidance for the engineering application of sewage sludge anaerobic fermentation. Full article

(This article belongs to the Special Issue Air Pollution Control, Solid Waste Treatment, and Environmental Catalysis)

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17 pages, 4164 KiB

Open AccessArticle

Pyrolysis Behaviors and Residue Properties of Iron-Rich Rolling Sludge from Steel Smelting

by Hengdi Ye, Qian Li, Hongdi Yu, Li Xiang, Jinchao Wei and Fawei Lin

Int. J. Environ. Res. Public Health 2022, 19(4), 2152; https://doi.org/10.3390/ijerph19042152 - 14 Feb 2022

Cited by 5 | Viewed by 1799

Abstract

Iron-rich rolling sludge (FeRS) represents a kind of typical solid waste produced in the iron and steel industry, containing a certain amount of oil and large amounts of iron-dominant minerals. Pyrolysis under anaerobic environment can effectively eliminate organics at high temperatures without oxidation [...] Read more.

Iron-rich rolling sludge (FeRS) represents a kind of typical solid waste produced in the iron and steel industry, containing a certain amount of oil and large amounts of iron-dominant minerals. Pyrolysis under anaerobic environment can effectively eliminate organics at high temperatures without oxidation of Fe. This paper firstly investigated comprehensively the pyrolysis characteristics of FeRS. The degradation of organics in FeRS mainly occurred before 400 °C. The activation energy for pyrolysis of FeRS was extremely low, ca. 5.44 kJ/mol. The effects of pyrolytic temperature, atmosphere, heating rate, and stirring on pyrolysis characteristics were conducted. Commonly, the yield of solid residues maintained around 85 wt.%, with approximately 13 wt.% oil and 2 wt.% gas. Due to the low yield of oil and gas, their further utilization remains difficult despite CO₂ introduction which could upgrade their quality. The solid residues after pyrolysis exhibited porous properties with co-existence of micropores and mesopores. Combined with the high content of zero-valent iron, magnetic property, hydrophobic characteristic, and low density, the solid residues could be further utilized for water pollution control and soil remediation. Moreover, the solid residues were suitable for sintering to recover valuable iron resources. However, the solid residues also contained certain heavy metals, such as Cd, Cr, Cu, Ni, Pb, and Zn, which might cause secondary pollution during their utilization. In particular, the toxic Cr possessed high content, which should be treated with detoxification and removal. This paper provides fundamental information for pyrolysis of FeRS and utilization of solid residues. Full article

(This article belongs to the Special Issue Air Pollution Control, Solid Waste Treatment, and Environmental Catalysis)

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15 pages, 3893 KiB

Open AccessArticle

Experimental and Numerical Study of the Laminar Burning Velocity and Pollutant Emissions of the Mixture Gas of Methane and Carbon Dioxide

by Yalin Wang, Yu Wang, Xueqian Zhang, Guoping Zhou, Beibei Yan and Rob J. M. Bastiaans

Int. J. Environ. Res. Public Health 2022, 19(4), 2078; https://doi.org/10.3390/ijerph19042078 - 12 Feb 2022

Cited by 1 | Viewed by 2134

Abstract

This paper presents the experimental and numerical study of the laminar burning velocity and pollutant emissions of the mixture gas of methane and carbon dioxide. Compared to previous research, a wider range of experimental conditions was realized in this paper: CO₂ dilution [...] Read more.

This paper presents the experimental and numerical study of the laminar burning velocity and pollutant emissions of the mixture gas of methane and carbon dioxide. Compared to previous research, a wider range of experimental conditions was realized in this paper: CO₂ dilution level up to 60% (volume fraction) and equivalence ratio of 0.7–1.3. The burning velocities were measured using the heat flux method. The CO and NO emissions after premixed combustion were measured by a gas analyzer placed 20 cm downstream of the flame. The one-dimensional free flames were simulated using the in-house laminar flame code CHEM1D. Four chemical kinetic mechanisms, GRI-Mech 3.0, San Diego, Konnov, and USC Mech II were used in Chem1D. The results showed that, for laminar burning velocity, the simulation results are all lower than the experimental results. GRI Mech 3.0 showed the best agreement when the CO₂ content was below 20%. USC Mech II showed the best consistency when the CO₂ content was between 40 and 60%. For CO emission, these four mechanisms all showed a small error compared with the experiments. When CO₂ content is higher than 40%, the deviation between simulation and experiment becomes bigger. When the CO₂ ratio is more than 20%, the proportion of CO₂ does not affect CO emission so much. For NO emission, when the CO₂ content is 40%, the results from simulation and experiment showed a good agreement. As the proportion of CO₂ increases, the difference in NO emissions decreases. Full article

(This article belongs to the Special Issue Air Pollution Control, Solid Waste Treatment, and Environmental Catalysis)

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14 pages, 2997 KiB

Open AccessArticle

Emission Characteristics of NO_x and SO₂ during the Combustion of Antibiotic Mycelial Residue

by Yaxin Ge, Guangyi Zhang, Jianling Zhang, Wennan Zhang and Lijie Cui

Int. J. Environ. Res. Public Health 2022, 19(3), 1581; https://doi.org/10.3390/ijerph19031581 - 29 Jan 2022

Cited by 5 | Viewed by 2378

Abstract

The antibiotic mycelial residue (AMR) generated from cephalosporin C production is a hazardous organic waste, which is usually disposed of by landfilling that causes potential secondary environmental pollution. AMR combustion can be an effective method to treat AMR. In order to develop clean [...] Read more.

The antibiotic mycelial residue (AMR) generated from cephalosporin C production is a hazardous organic waste, which is usually disposed of by landfilling that causes potential secondary environmental pollution. AMR combustion can be an effective method to treat AMR. In order to develop clean combustion technologies for safe disposal and energy recovery from various AMRs, the emission characteristics of NO_x and SO₂ from AMR combustion were studied experimentally in this work. It was found that the fuel-N is constituted by 85% protein nitrogen and 15% inorganic nitrogen, and the fuel-S by 78% inorganic sulfur and 22% organic sulfur. Nitrogen oxide emissions mainly occur at the volatile combustion stage when the temperature rises to 400 °C, while the primary sulfur oxide emission appears at the char combustion stage above 400 °C. Increasing the combustion temperature and airflow cause higher NO_x emissions. High moisture content in AMR can significantly reduce the NO_x emission by lowering the combustion temperature and generating more reducing gases such as CO. For the SO₂ emission, the combustion temperature (700 to 900 °C), airflow and AMR water content do not seem to exhibit obvious effects. The presence of CaO significantly inhibits SO₂ emission, especially for the SO₂ produced during the AMR char combustion because of the good control effect on the direct emission of inorganic SO₂. Employing air/fuel staging technologies in combination with in-situ desulfurization by calcium oxide/salts added in the combustor with operation temperatures lower than 900 °C should be a potential technology for the clean disposal of AMRs. Full article

(This article belongs to the Special Issue Air Pollution Control, Solid Waste Treatment, and Environmental Catalysis)

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17 pages, 4069 KiB

Open AccessArticle

A Comparison of Combustion Properties in Biomass–Coal Blends Using Characteristic and Kinetic Analyses

by Yalin Wang, Beibei Yan, Yu Wang, Jiahao Zhang, Xiaozhong Chen and Rob J. M. Bastiaans

Int. J. Environ. Res. Public Health 2021, 18(24), 12980; https://doi.org/10.3390/ijerph182412980 - 9 Dec 2021

Cited by 4 | Viewed by 1926

Abstract

This paper presents comparative research on the combustion of coal, wheat, corn straw (CS), beet residues after extracting sugar (BR), and their blends, coal–corn straw blends (CCSBs), coal–wheat blends (CWBs), and coal–beet residue blends (CBRBs), using thermogravimetric (TG) analysis under 10, 20, 30, [...] Read more.

This paper presents comparative research on the combustion of coal, wheat, corn straw (CS), beet residues after extracting sugar (BR), and their blends, coal–corn straw blends (CCSBs), coal–wheat blends (CWBs), and coal–beet residue blends (CBRBs), using thermogravimetric (TG) analysis under 10, 20, 30, 40 and 50 °C/min. The test results indicate that CS and wheat show better combustion properties than BR, which are recommended to be used in biomass combustion. Under the heating rate of 20 °C/min, the coal has the longest thermal reaction time when compared with 10 and 30 °C/min. Adding coal to the biomass can improve the burnout level of biomass materials (BM), reduce the burning speed, and make the reaction more thorough. The authors employed the Flynn–Wall–Ozawa (FWO) method and the Kissinger–Akahira–Sunose (KAS) method to calculate kinetics parameters. It was proven that overall, the FWO method is better than the KAS method for coal, BM, and coal–biomass blends (CBBs), as it provides higher correlations in this study. It is shown that adding coal to wheat and BR decreases the activation energy and makes conversion more stable under particular α. The authors selected a wider range of biomass raw materials, made more kinds of CBB, and conducted more studies on different heating rates. This research can provide useful insights into how to choose agricultural residuals and how to use them. Full article

(This article belongs to the Special Issue Air Pollution Control, Solid Waste Treatment, and Environmental Catalysis)

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Review

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32 pages, 9827 KiB

Open AccessReview

Progress in the Preparation and Modification of Zinc Ferrites Used for the Photocatalytic Degradation of Organic Pollutants

by Jinyuan Zhu, Yingying Zhu, Zhen Chen, Sijia Wu, Xiaojian Fang and Yan Yao

Int. J. Environ. Res. Public Health 2022, 19(17), 10710; https://doi.org/10.3390/ijerph191710710 - 28 Aug 2022

Cited by 12 | Viewed by 2982

Abstract

Zinc ferrite is a type of photocatalytic material with high physicochemical stability, narrow band gap, high carrier separation efficiency, high porosity, and paramagnetism, which makes it easy to recover. Thus, zinc ferrite is widely used as a photocatalyst in water treatment. In this [...] Read more.

Zinc ferrite is a type of photocatalytic material with high physicochemical stability, narrow band gap, high carrier separation efficiency, high porosity, and paramagnetism, which makes it easy to recover. Thus, zinc ferrite is widely used as a photocatalyst in water treatment. In this paper, the preparation principles as well as the advantages and disadvantages of typical methods used to prepare zinc ferrite including hydrothermal, co-precipitation, sol-gel, and other novel methods such as biosynthesis have been summarized. Modification methods such as elemental doping, composite formation, and morphological modification have been highlighted. Using these modification methods, the catalytic activity of zinc ferrite toward the photocatalytic degradation of organic pollutants in water has been enhanced. Biosynthesis is regarded as a promising preparation method that uses biological materials instead of chemical materials to achieve the large-scale preparation of zinc ferrite using low cost, energy efficient, and environmentally friendly processes. Meanwhile, the combination of multiple modification techniques to enhance the photocatalytic performance of zinc ferrite will be an important research trend in the future. Full article

(This article belongs to the Special Issue Air Pollution Control, Solid Waste Treatment, and Environmental Catalysis)

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