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For a sustainable ecology, slaughterhouse sludge must be managed effectively in preview of the parasitic or coliforms' spill over to the community. In order to determine the effectiveness of a customized biological decomposer solution in lowering the parasitic eggs and coliform bacteria, three composting units (Unit 1, Unit 2, and Unit 3) were treated with its different amounts. Over a period of 60 days, pH, temperature, humidity, number of the parasitic eggs per gram (EPG) of faecal material, viability of eggs, and coliform counts were evaluated. By the fifth day of the composting process, pH had significantly (P < 0.05) increased across all the treatments and then decreased gradually. Also on the 5th day, all three units entered the thermophilic range (> 45 °C), which persisted for 20 days for Unit 3 and 15 days for Units 1 and 2. Humidity levels initially increased significantly (P < 0.05) in all three units (Unit 3 = 71%, Unit 2 = 64%, and Unit 1 = 55%) but then gradually decreased. On day 5, no decrease in EPG in Unit 1 was detected; however, a non-significant (P > 0.05) 12.5% decline in EPG in Unit 2 and Unit 3 was recorded. After that, a significant (P < 0.05) reduction in EPG was observed in all the three treatments until day 25. By day 5, decreased egg viability was significantly (P < 0.05) recorded in Unit 3 (21.43%); in Unit 1 and Unit 2, the decrease was 6.25% and 14.29%, respectively. Additionally, all units showed a significant (P < 0.05) decrease in total coliforms, meeting minimum allowable limit in Unit 2 and 3 on day 10 and on day 15 in Unit 1. The most substantial reduction in faecal coliforms was observed in Unit 3 (from 2.6 log₁₀ to 1.3 log₁₀), followed by Unit 2 (from 2.6 log₁₀ to 1.5 log₁₀), and then Unit 1 (from 2.6 log₁₀ to 1.6 log₁₀). The results of this study support recommendation of advanced composting techniques to eradicate or reduce the abundance of pathogens (parasites and coliforms). Hence, we endorse the value of careful composting procedures in environment-friendly abattoir waste management and agricultural practices through creating pathogen-free, eco-friendly fertilizers to promote both agricultural and environmental sustainability. [ABSTRACT FROM AUTHOR]

This article presents the results of a pilot study on the treatment of sludge from a water treatment plant in the city of Almaty, Republic of Kazakhstan, to ensure further disposal. The main objective of the study was to compare the efficiency of sludge drying by natural and artificial methods. The qualitative characteristics of the leachate from the dewatering unit, the chemical composition of the dried sludge and the granulometric analysis of the dried sludge were also studied. The greatest reduction in moisture content was recorded for drying in natural conditions (2.1%), but this process required the longest drying time. The leachate obtained from sludge dewatering was characterized by significant contamination (e.g., turbidity—55.65 on average, color—67.7, total Fe—5.15 mg/L, total N—79.6 mg/L, COD—311 mg/L, BOD—336.15 mg/L), which indicates the need for its pretreatment before further management in the technological system of the treatment station. The content of chemical substances contained in the dry residue of the sludge was also determined, of which aluminum was 0.94–13.8 mg/kg, silicon was 50.24–146.3 mg/kg, potassium was 1.72–5.51. mg/kg, calcium was 71.8–79.1 mg/kg, iron was 2.0–7.54 mg/kg and nickel was 0.9–4.4 mg/kg. A particle size analysis of the dried sludge showed that the majority fractions were fine and very fine sand, with a total of 20.2%, and silt and clay, with a total of 78.3%. Such properties justify the rationality of considering the reuse of dried sludge as a raw material for making, for example, construction materials or soil remediation material. [ABSTRACT FROM AUTHOR]

Municipal sewage treatment plants yield lots of sewage sludge, which has complex composition, and improper disposal may cause environmental pollution problem. Therefore, proper sludge treatment is important to solve this problem. Traditional sludge disposal methods such as incineration and landfill have the drawbacks of high energy consumption and soil pollution problem. Anaerobic carbon fixation is a new sludge disposal method, which has good application prospect. This study adopted anaerobic carbon fixation to treat dreed sludge. The thermogravimetric analysis was carried out to assess the effects of process parameters (carbonization temperature and time) on the degree of anaerobic carbon fixation of dreed sludge. The influence of process parameters on the physicochemical properties, nutrient indicators, heavy metal content and seed germination index of sludge were investigated. Taking seed germination index as evaluation indicator, the optimum conditions were determined by extreme difference analyses of orthogonal tests. The results indicated that high carbonization temperature and long carbonization time were crucial to ensure that anaerobic carbon fixation of sludge fully competed. Process parameters had significant effects on the properties of sludge. Various performance indicators of sludge treated by anaerobic carbon fixation could meet the standard of municipal sewage treatment plant sludge disposal for landscaping purpose (GB/T 23486--2009), so the treated sludge could be used as landscaping substrate. The optimum carbonization temperature and time were determined as 600 °C and 1.5 h, respectively. In this condition, sludge anaerobic carbon fixation fully competed and the content of toxic and harmful substances such as soluble salts and water-soluble heavy metals in treated sludge were low, which was conductive to seed germination. Seed germination index reached 138. 79%, far higher than the national production quality standard (70%). As a result, anaerobic carbon fixation treatment and effective process parameters adjustment open up new possibility for sludge resource utilization. [ABSTRACT FROM AUTHOR]

Safe and enduring water, sanitation, and hygiene (WASH) for all is the key target of Sustainable Development Goal 6. Despite progress in global WASH monitoring to support SDG 6, significant data gaps persist, especially in urban informal settlements in the Melanesian Pacific Region. This study aimed to improve understanding of existing sanitation systems, residents' preferences, and climate hazard exposure in these areas. Household surveys were conducted with 393 households in Suva (Fiji) and Port Vila (Vanuatu). Water availability for sanitation was high in Suva (99%) and Port Vila (70%), with noted improvements in sanitation superstructure. However, dry pits without slabs remain significant (15%) in Port Vila. The preference for water-based systems highlights the need for a resilient sanitation service chain, including adequate faecal sludge management, which was problematic in both locations. Reports of climate-driven hazard damage were more frequent in Vanuatu, with one in three respondents reporting impacts on their sanitation services. [ABSTRACT FROM AUTHOR]

Dewatered sludge (DS) is a sewage sludge with a unique property due to extracellular polymeric substances (EPSs) and polymer flocculants. These components form a stable 3D polymer network to increase dewatering efficiency, leaving behind valuable materials such as lipids. This article explored the influences of DS particle size on lipid yield and the effects of extraction on the chemical, morphological, and thermal properties of the residual dewatered sludge (RDS). Lipid yields with unimodal distribution were observed across the particle size ranges (<0.5, 0.5–1.0, 1.0–2.0, 2.0–4.0, and 4.0 mm). The highest lipid yield of 1.95% was extracted from 1.0–2.0 mm after 4 h at 70 °C and 0.1 g/mL sludge-to-solvent ratio. Efficiency was influenced by the DS's morphology, facilitating solvent infiltration and pore diffusion. The extraction process reduced water and organic fractions, resulting in higher thermal stability. Bibliometric analysis of "extraction*" and "sewage sludge" shows increasing research interest from 1973 to 2024. Five research clusters were observed: heavy metal speciation and stabilization, sludge and its bioavailability, extraction techniques and resource recovery, contaminants remediation, as well as phosphorus recovery and agricultural applications. These clusters highlight the diverse approaches to researching DS and RDS while promoting sustainable waste management. [ABSTRACT FROM AUTHOR]

One method of preparing sludge for management and use is solar drying. To intensify the drying process, natural lignocellulosic additives can be used to alter the structure of the sludge and accelerate water evaporation. Light, hard materials with low absorption capacity are best suited for this purpose, e.g., walnut shells, which are unused waste. The aim of the study was to determine the impact of the evaluation of walnut shells on the sludge drying process and to assess the impact of the drying process on the chemical, physical, and fuel properties of the additive. The moisture content, crushing strength, chemical composition, and physical and fuel properties of mixtures were determined. A small addition of walnut shells (25%) was found to accelerate the drying process even in winter and spring (up to 30 days) compared to sludge without additives. Walnut shells retain their chemical composition and strength despite unfavourable conditions and a chemically aggressive environment, indicating they may be reused. The mixture containing sewage sludge and walnut shells has a calorific value of 15.6 MJ/kg, which is similar to wood; it is also fully biodegradable and suitable as a fertiliser to improve soil structure, as it contains approx. 80–90% DM (including approx. 40% carbon, 3% nitrogen, and other elements, such as phosphorus and potassium.) [ABSTRACT FROM AUTHOR]

As a by-product of wastewater treatment, sewage sludge can be used for natural, agricultural, or energy purposes. One method of preparing sludge for management and use is solar drying. To intensify the drying process, natural additives can be used to alter the structure of the sludge and accelerate the evaporation of water. This research aimed to evaluate the influences of different organic additives in sewage sludge mixtures on the physicochemical and energy parameters of briquettes. This research was carried out without thermal boosting in a 4 × 2.5 × 2 m plastic tunnel. The tunnel was equipped with three drying stations and control and measuring equipment. In two test series, sludge additives in the form of straw and lignocellulosic materials, sawdust, bark, woodchips, and walnut shells, were used. Briquettes were made from the resulting mixtures and then subjected to physical and chemical analyses. This research showed high variability in the contents of trace elements, nitrogen, and sulphur in relation to an increase in the amount of sludge in the briquettes, which, for the briquettes made from sewage sludge, was nearly twice as high as for the briquettes made from the mixtures. The results of the flue gas analysis for the briquettes with sawdust and wood chip additives were very similar. The briquettes made from sewage sludge with lignocellulosic materials (bark and wood chips) had fuel properties similar to woody biomass, with a calorific value and heat of combustion of 15–16 MJ/kg. Fibrous additives (straw) significantly increased the strength parameters of the briquettes, by more than 50% of the value. The compositions and properties of the mixtures affected the following briquetting parameters: temperature and compressive force. The briquettes made from sewage sludge and additives can be classified according to ISO 21640 as SRFs (solid recovered fuels). In most of the results, the net calorific value (NCV) was 3 to 4; the chlorine content (CL) was 2 to 1; and the mercury content (Hg) was 1. The sewage sludge mixtures facilitated the agricultural and energy use of the briquettes. [ABSTRACT FROM AUTHOR]

• Advancements in sludge processing to reduce particle and acidification emissions. • Reduced environmental footprint through innovative sludge treatment. • Sludge hydrochar carbon stabilization contributes to climate change mitigation. Proper management of wastewater treatment plant side streams in pulp and paper mills is a matter of great interest. This study evaluates the environmental impact of different strategies in the management of biosludge from pulp and paper mills in Finland through a Life Cycle Assessment methodology. The base industrial standard practice, biosludge incineration for energy recovery and ash landfill disposal (Scenario 1), was compared to the alternative process of hydrothermal carbonization. The hydrochar generated from hydrothermal carbonization was evaluated for energy recovery through incineration (Scenario 2), or for use in composting for nutrient recovery (Scenario 3). The results showed that the hydrothermal process improved the overall environmental performance of the sludge management, particularly in terms of energy consumption and greenhouse gas emissions. The use of hydrochar as a soil amendment in composting also resulted in a significant reduction on the environmental impact compared to the other two scenarios. Overall, this study highlights the potential of hydrothermal carbonization and hydrochar utilization as sustainable options for managing biosludge from pulp mills. [ABSTRACT FROM AUTHOR]

Triclosan (TCS) is an anti-microbial widely used in personal care and medical antibacterial products. Despite the widespread occurrence of TCS in municipal sewage sludge, understanding toward the fate of TCS within sewage treatment and environmental risks in the eventual land application is still limited. This review summarizes the TCS loads and transfer mechanisms in the sewage treatment process, sludge management process, land application, and its potential environmental impacts. TCS transfer from sewage to sludge mainly occurs in the primary sedimentation process, representing 2.50 to 4.58 times more compared to the secondary sedimentation process. This transfer is facilitated through adsorption because of the presence of humic acid-like and protein-like substances in sludge. Both anaerobic digestion and aerobic composting contribute to the degradation of TCS with aerobic composting being more effective, exhibiting TCS degradation rates 1.04–2.87 times higher than those observed in anaerobic digestion. After sludge land application, TCS majorly dissipates in the soil through biodegradation by fungi and bacteria, potentially posing environmental risks, such as inhibiting the seedling growth of plant species. Additionally, the degradation of TCS, coupled with the formation and subsequent degradation of MeTCS, is observed, with MeTCS exhibiting a higher half-life and greater toxicity than its parent compound (TCS). Overall, this research offers vital insights to enhance understanding of TCS's migration and degradation processes in sewage treatment and soil. It also provides guidance in environmental protection and sustainable resource management. [ABSTRACT FROM AUTHOR]

This document discusses the integration of circular economy (CE) principles into the water and wastewater sector to address global challenges related to resource depletion, environmental degradation, and climate change. It highlights the potential for CE practices to transform how water and wastewater are managed, emphasizing the recovery of valuable resources such as water, energy, and raw materials from wastewater. The document includes case studies and research articles that explore various technological aspects of wastewater treatment and resource recovery, including the impact of nano-sized polyethylene terephthalate on wastewater treatment processes, waste heat recovery from commercial kitchen wastewater, the direct reuse of treated wastewater to address water scarcity, and the use of zeolites for ammonium recovery. The document concludes that further research and development of technologies, as well as monitoring of CE applications in wastewater management, are needed to promote sustainable water management practices. [Extracted from the article]

Global sewage sludge production is rapidly increasing, and its safe disposal is becoming an increasingly serious issue. One of the main methods of municipal sewage sludge management is based on its agricultural use. The wastewater and sewage sludge contain numerous antibiotic resistance genes (ARGs), and its microbiome differs significantly from the soil microbial community. The aim of the study was to assess the changes occurring in the soil microbial community and resistome after the addition of sewage sludge from municipal wastewater treatment plant (WWTP) in central Poland, from which the sludge is used for fertilizing agricultural soils on a regular basis. This study used a high-throughput shotgun metagenomics approach to compare the microbial communities and ARGs present in two soils fertilized with sewage sludge. The two soils represented different land uses and different physicochemical and granulometric properties. Both soils were characterized by a similar taxonomic composition of the bacterial community, despite dissimilarities between soils properties. Five phyla predominated, viz. Planctomycetes, Actinobacteria, Proteobacteria, Chloroflexi and Firmicutes, and they were present in comparable proportions in both soils. Network analysis revealed that the application of sewage sludge resulted in substantial qualitative and quantitative changes in bacterial taxonomic profile, with most abundant phyla being considerably depleted and replaced by Proteobacteria and Spirochaetes. In addition, the ratio of oligotrophic to copiotrophic bacteria substantially decreased in both amended soils. Furthermore, fertilized soils demonstrated greater diversity and richness of ARGs compared to control soils. The increased abundance concerned mainly genes of resistance to antibiotics most commonly used in human and animal medicine. The level of heavy metals in sewage sludge was low and did not exceed the standards permitted in Poland for sludge used in agriculture, and their level in fertilized soils was still inconsiderable. [ABSTRACT FROM AUTHOR]

Introduction: Efficient treatment of fecal sludge in densely populated settings is essential as it has a direct impact on public health and the environment. This study presents a comprehensive assessment of fecal sludge treatment technologies in Rohingya camps at Cox’s Bazar, Bangladesh, focusing on removal efficiencies and compliance with regulatory standards. Methods: Seventeen treatment plants of five different technologies were evaluated based on removal efficiency and standard discharge guidelines for various physicochemical and microbiological parameters. Results: Waste Stabilization Pond (WSP) was the top performer compared to four other different treatment technologies evaluated, achieving notable removal rates: 97.3% reduction in E. coli, 100% in helminth eggs, 98.3% for COD, 97.8% for BOD, 98.7% for TSS, 92.1% for TS, 82.8% for phosphate, and 93.3% for total nitrogen. Lime Stabilization Ponds showed lower removal rates, except for E. coli (98.9%), with reductions of 99.7% for helminth eggs, 81.6% for COD, 80.9% for BOD, 86.3% for TSS, 68.6% for TS, and 49.2% for phosphate. Upflow Filters demonstrated good removal efficiencies for E. coli (99.7%), TSS (95.9%), COD (91.7%), BOD (93.5%), and helminth eggs (93.7%). WSP consistently outperformed other technologies across all seasons. Despite these, none of the technologies fully met discharge standards. Discussion: These findings highlight the need for a comprehensive approach, the combination of physicochemical and biological processes, to enhance efficacy. Promoting improved fecal sludge management technologies through awareness campaigns and technical support can mitigate environmental health risks in densely populated humanitarian settings. [ABSTRACT FROM AUTHOR]

This study was conducted to determine the changes in the heavy metal and microelement contents of bean (Phaseolus vulgaris L.) plants with increasing doses of boron and sewage sludge applications. The experiment, which was set up according to the completely randomized design (CRD) in the climate chamber, was carried out with three replications. In the study where Mina, a standard dwarf bean variety, was used, four different boron doses (B0:0 mg/kg, B10:10 mg/kg, B20:20 mg/kg, B40: 40 mg/kg) and four doses of sewage sludge (SS0: %0, SS5: %5, SS10: %10, SS20: %20) were used as trial factors. In the study, sewage sludge treatments were found to be more effective in increasing the content of microelements in beans compared to control, such as aluminum, copper, manganese, zinc, iron, chromium, lead, nickel, arsenic, cadmium, and cobalt. At the same time, it was observed to cause a decrease in the content of boron. The highest microelement and heavy metal contents were measured at 5% and 10% sewage sludge doses. On the other hand, it was determined that boron applications increased the aluminum, copper, boron, zinc, cobalt, manganese, and nickel contents of bean plants compared to control plants, and decreased the iron, arsenic, cadmium, and lead contents. The study showed that the negative effects of increased metal contents as a result of sewage sludge applications can be tolerated with boron applications. It seems that it may be possible to reduce heavy metal pollution in plants with such boron treatments. [ABSTRACT FROM AUTHOR]

The effective management of waste-activated sludge (WAS) presents a significant challenge for wastewater treatment plants (WWTPs), primarily due to the sludge's high content of organic matter, pathogens, and hazardous substances such as heavy metals. As urban populations and industrial activities expand, the increasing volume of WAS has intensified the need for sustainable treatment solutions. Conventional approaches, such as landfilling and anaerobic digestion, are frequently ineffective and resource-intensive, particularly when dealing with the protective extracellular polymeric substances (EPS) that render WAS resistant to biodegradation. Thermal pretreatment methods have gained attention due to their ability to enhance the biodegradability of sludge, improve dewaterability, and facilitate resource recovery. These processes function by breaking down complex organic structures within the sludge, thereby increasing its accessibility for subsequent treatments such as anaerobic digestion. The integration of thermal treatment with chemical methods can further optimize the management process, resulting in higher biogas yields, reduced pathogen content, and lower environmental risks. While thermal disintegration is energy-intensive, advancements in energy recovery and process optimization have made it a more viable and environmentally friendly option. This approach offers a pathway to more sustainable and efficient sludge management practices, which align with the goals of reducing waste and complying with stricter environmental regulations. [ABSTRACT FROM AUTHOR]

The production of value‐added products from sewage sludge is considered to be one of the solutions for the sustainable management of sludge in wastewater treatment plants (WWTPs). The presence of carbon, nitrogen, and phosphorus sources has made the sewage sludge of WWTPs a valuable and low‐cost substrate for the production of fermentative products. In the current study, a process was developed for microbial lipid production from two types of sewage sludge from a WWTP in northern Isfahan: anaerobic digester inlet sludge (DIS) and anaerobic digester outlet sludge (DOS). This process was based on the release of volatile fatty acids (VFAs) from the sludge by combinations of γ‐ray irradiation, anaerobic digestion, and acidogenic fermentation followed by utilization of VFAs in a microbial process by the oleaginous yeast Cryptococcus aureus UIMC65. After γ‐ray irradiation, the acidogenic fermentation of the treated sludge released 72% of the organic matter content of the sludge with acidification efficiency of 12% leading to 0.516 g L−1 VFAs. The oleaginous fermentation of the released VFAs for 7 days was accompanied by production of 1.58 g L−1 dry cell biomass with 40% lipid content. The results of this study indicate that the sewage sludge from urban WWTP has the potential to be used for the production of microbial lipids. [ABSTRACT FROM AUTHOR]

The production of pulp and paper from recycled paper generates significant quantities of deinking paper sludge (DPS). This sludge contains a significant amount of organic matter (36%) as well as heavy metals such as Pb, Zn, and Cr. In this work, the incorporation of DPS (0%, 8%, 10%, and 12%) in the manufacture of clay bricks leads to valorization of this waste by showing that two of its contents considered problematic (organic matter and heavy metals) have several positive effects. It was found that the organic parts were transformed into pores after brick firing (850°C), which improved thermal insulation while keeping mechanical resistance in conformity with usual standards. For the heavy metals, which make DPS a hazardous waste, a leaching test was employed. The results show that these metals were trapped in the ceramic matrix after the firing of bricks at a high temperature, resulting in a final product that was not dangerous. Other tests were carried out on bricks with DPS to evaluate density, water absorption, shrinkage, loss on ignition, porosity, and microstructure in order to characterize this new product. It was concluded that DPS can be used in clay bricks as an asset for the formation of pores to enhance thermal insulation. The addition of DPS can be optimized at 10% to comply with the standard and not exceed the required values for shrinkage, water absorption, and loss on ignition. [ABSTRACT FROM AUTHOR]

Milk-based products are essential to the human diet, with India contributing 23% of global milk production. Dairy industries generate large amounts of waste, including solid and liquid waste, which are treated using wetland, biological, and physico-chemical methods. In India, dairy sludge is effectively managed by converting it into fertilizers. If industrial solid and liquid dairy waste is not managed correctly, it will increase pollution and harm biodiversity. If the sludge is properly managed, there is potential to transform it into various value-added products, including biofuels, biomass, biofertilizers, bricks, struvite, fertilizer, etc. Consequently, this technical review's focal topic includes information on dairy operations' wastewater treatment methods, the viability of microalgal cultures in wastewater, dairy sludge management, the range of biological product recovery, and its impact on the environment. [ABSTRACT FROM AUTHOR]

If adequately treated, sewage sludge can be a safe and sustainable source of nutrients and organic matter for soil enhancement, improving agriculture productivity. To close loops in the sewage treatment-agriculture nexus, it is crucial to compare sludge generation (quantity and location of treatment plants) and possible sites for sludge application on a regional level. This study used spatial multicriteria analysis to assess land suitability for sludge application based on several criteria related to soil, land use characteristics, and environmental legal constraints. The study area comprised two large watersheds (a total area of 52,870 km2) in Minas Gerais state, southeast Brazil. Results indicated a total sludge production of 21,778 t dry solids.year−1, which is currently mainly disposed of in landfills (76%). Even though approximately 52% of the study area presented constraints to sludge application in agricultural fields, suitable areas can receive the total amount of sludge generated. In some cases, the most suitable areas would afford for a capacity 20-fold bigger than the sludge produced. Although other factors should be addressed for effectively applying sludge to agriculture (e.g. social acceptance), this work shows the usefulness of the spatial multicriteria analysis tool to select suitable sites. [ABSTRACT FROM AUTHOR]

The solids in sewage sludge are primarily composed of organic matter and offer new possibilities for sustainable sludge management, if considered as a stable biomass source in terms of quantity and quality. Reducing the volume of sludge with an extremely high moisture content is challenging, and enhanced dewatering through mechanical treatment is crucial from an environmental and sustainability perspective because it alleviates the reliance on thermal treatment. This study employed ultrasonication to enhance the dewatering efficiency of activated sludge. The disruption of sludge induced by ultrasonication notably facilitated the elimination of intracellular water during mechanical expression. Additionally, the ultrasonicated sludge was verified to be re-flocculated by introducing inorganic electrolytes such as Ca2+ (divalent cations), Al3+ (trivalent cations), and polyferric sulfate. Conversely, no re-flocculation of disrupted sludge was observed upon applying organic polymer flocculant. Under optimized conditions, the sludge re-flocculation progressed to form large flocs, leading to a decreased suspended solids (SS) value from 1423 to 73 mg/L and reduction in capillary suction time (CST) from over 2000 to 18 s. Following pretreatment, the moisture content of the mechanically expressed cake at 500 kPa decreased significantly from 76 wt% (untreated sludge) to less than 60 wt% (treated sludge) due to the elimination of intracellular water. [ABSTRACT FROM AUTHOR]

Sludge treatment reed bed planted (STRB) with Phragmites australis (P.australis) and Arundo donax (A.donax) was assessed in the presence of Eisenia fetida under control condition during the dry season. Worm-planted units were fed with mixed sewage sludge (dry and volatile solids of 29.44 g DS.L−1 and 24.23 g VS.L−1). Sludge loading rates (SLR) of 50, 60, and 70 kg DS m−2 year−1 were examined to assess dewatering efficiency. Surface layers in units with P.australis and A.donax achieved DS of 80 and 81% at a loading rate of 50 kg DS m−2 year−1, while their subsurface DS were 41 and 25%, respectively. Units with A.donax experienced plant loss when subjected to SLR exceeding 60 kg DS m−2 year−1. More than 10 cm of residual sludge accumulated on the top of units after a 2-month final rest. Evapotranspiration was greater in the unit with P.australis (5.23 mm day−1) compared to the unit with A.donax (4.24 mm day−1) while both were fed with 70 kg DS m−2 year−1. Water loss contributions from residual sludge layer, drained water, and evapotranspiration were 3, 46, and 51%, respectively. Units with P.australis indicated 20% higher water loss compared to units with A.donax. Although the drained water quality improved over time, it did not meet standard limits. The residual sludge layer contained macro and micronutrients, and heavy metals with a significant elemental order of N > Ca > P > S > mg > K (N:P:K = 31:8:1), Fe > Na > B > Mn > Mo and Zn > Cr > Cu > Pb > Ni > Cd. Overall, STRB could be a sustainable alternative technology to conventional sewage sludge management techniques. [ABSTRACT FROM AUTHOR]

Wastewater treatment plants generate significant amounts of sludge, a residual product that is rich in nutrients, usually considered waste, and traditionally eliminated by storage or incineration, methods that are expensive, environmentally damaging, and often unsustainable. Composting is increasingly recognized as an ecological and durable solution for managing biodegradable waste, including sludge resulting from wastewater treatment. The composting of residual sludge usually requires mixing with bulking agents, such as green waste or agricultural residues, to ensure a well-balanced carbon–nitrogen ratio. This mixture undergoes a controlled aerobic decomposition, sometimes followed by post-treatment, resulting in a stabilized final product that is nutrient-rich and pathogen-free and can be used as soil amendment or fertilizer in different agricultural or landscaping applications. By using composting, communities can reduce elimination costs, reduce greenhouse gas emissions, and minimize the environmental impact of sludge management. This paper reviews recent reported experiences in the laboratory regarding full-scale sludge composting, highlighting the particularities of the processes, the influence factors, the quality of the final product, and the environmental and regulatory constraints. Composting is a sustainable and ecological solution for managing wastewater sludge, contributing to nutrient circularity, and minimizing the environmental impact. [ABSTRACT FROM AUTHOR]

This article presents a study on the daily reliability analysis of a full-scale activated sludge wastewater treatment plant located in Northern Jordan. The coefficient of reliability (COR) is calculated to assess the performance of the plant in regard of wastewater concentrations of COD, BOD5, and TSS. The results indicate that the global effluent performances for COD, BOD5, and TSS comply with Jordanian standards. However, the BOD5 performance is found to be below the quality level due to issues in the ventilation basin and exceeding treatment capacity, while the TSS performance is affected by problems in the grit chamber and variations in influent quality and quantity. The study fills a research gap by focusing on the reliability of wastewater treatment plants using activated sludge technology and utilizes a probabilistic model proposed by Niku et al., (1979) to evaluate the reliability. The findings provide valuable insights into the daily variability of the treatment plant and suggest measures for improving reliability and overall efficiency. [ABSTRACT FROM AUTHOR]

The disposal of municipal sewage sludge (MSS) from wastewater treatment plants poses a major environmental challenge due to the presence of inorganic and organic pollutants. Co-pyrolysis, in which MSS is thermally decomposed in combination with biomass feedstocks, has proven to be a promising method to immobilize inorganic pollutants, reduce the content of organic pollutants, reduce the toxicity of biochar and improve biochar's physical and chemical properties. This part of the review systematically examines the effects of various co-substrates on the physical and chemical properties of MSS biochar. This review also addresses the effects of the pyrolysis conditions (temperature and mixing ratio) on the content and stability of the emerging pollutants in biochar. Finally, this review summarizes the results of recent studies to provide an overview of the current status of the application of MSS biochar from pyrolysis and co-pyrolysis for the remediation of HM-contaminated soils. This includes consideration of the soil and heavy metal types, experimental conditions, and the efficiency of HM immobilization. This review provides a comprehensive analysis of the potential of MSS biochar for environmental sustainability and offers insights into future research directions for optimizing biochar applications in soil remediation. [ABSTRACT FROM AUTHOR]

Diatomite, a natural adsorbent rich in active silica, serves as a valuable precursor for geopolymer synthesis. The safe disposal of diatomite as a failed lead (Pb(II)) adsorbent is critical to prevent secondary contamination. This study investigated the immobilisation efficiency of geopolymerisation for Pb(II)-rich diatomite sludge. Low-grade diatomite with high ignition loss was utilised in the synthesis of alkali-activated geopolymers. It was demonstrated that the geopolymers achieved a compressive strength of 28.3 MPa with a 50% replacement rate of metakaolin by diatomite sludge, which was not a compromise in strength compared to that of the geopolymer with no Pb(II) (26.2 MPa). The leaching behaviour of Pb(II) was evaluated using water and acetic acid, yielding concentrations below 3 mg/L and immobilisation efficiencies of 95% in both scenarios. Analytical techniques including Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) elucidated the mineral composition and chemical environment of the geopolymers. These analyses revealed that Pb(II) migrated from diatomite pores, potentially forming soluble hydroxides under sufficient hydroxide, which then participated in condensation with silicon and aluminium monomers, effectively immobilising Pb(II) within amorphous aluminosilicate gels. Furthermore, the formation of the amorphous gels within diatomite pores hindered Pb(II) leaching, encapsulating Pb(II) effectively. This study presents a novel approach to immobilising heavy metals within building materials, enhancing mineral resource utilisation efficiency while addressing environmental contamination concerns. [ABSTRACT FROM AUTHOR]

This paper investigated the effect of nitrogen loading rates (NLRs) on the stability of aerobic granular sludge (AGS) for treating simulated ionic rare earth mine wastewater with high ammonia nitrogen and extremely low organic content. Mature AGS from a sequencing batch reactor (SBR) was seeded into five identical SBRs (R1, R2, R3, R4 and R5). The five reactors were operated with different NLRs (0.2, 0.4, 0.8, 1.2 and 1.6 kg/m3·d). After 30 days of operation, R1, R2 and R5 were dominated by broken granules, while most of the granules in R3 and R4 still maintained a complete structure. The properties of granules from R1, R2, R3, R4 and R5 deteriorated to varying degrees, while the granules from R3 and R4 showed better stability than that from R1, R2 and R5. In R1, R2, R3 and R4, the steady-state ammonia nitrogen removal efficiencies were all greater than 90%, and the steady-state removal efficiencies of total inorganic nitrogen (TIN) were approximately 30%. In R5, the removal efficiencies of ammonia nitrogen and TIN were both approximately 70%. The dominant nitrifying and denitrifying bacterial genera of the granules from the five reactors were Nitrosomonas and Thauera, respectively, and their relative abundance was much higher in granules from R3 and R4. The results demonstrated that a relative equilibrium between the growth and metabolism of nitrifying/denitrifying bacteria was achieved when NLR was between 0.8 and 1.2 kg/m3·d, which could provide technical support for the stability maintenance of AGS in the treatment of ionic rare earth mine wastewater. [ABSTRACT FROM AUTHOR]

The concept of the circular economy represents the most relevant mainstream approach to reducing the negative environmental impact of waste. Anaerobic digestion has proved to be one of the leading and widely adopted techniques for sewage sludge treatment under the principles of the circular economy. The purpose of this study is to forecast environmental and economic indicators through modeling the extensive utilization of biogas technologies with a case study of an administrative territorial unit. The proposed methodological framework involves the use of averaged specific indicators and is based on the relationship between inhabitants, waste generation rates, biogas yield, greenhouse gas emission mitigation and biogas energy potential. The widespread use of anaerobic digestion techniques according to the proposed methodology in the instant scenario will ensure the biogas yield of 10 million Nm3 within the considered administrative territory unit with a population of 4.2 million P.E., which ultimately can be expressed in electricity and thermal generation potential of 20.8 and 24.8 million kWh*y, respectively, annual greenhouse gas elimination of 119.6 thousand tons of CO2 equivalent and capital investment attraction of EUR 65.18 million. Furthermore, all sewage sludge will be subjected to disinfection and stabilization procedures to ensure its safe utilization. The findings of this study offer an opportunity for a wide range of stakeholders to assess the environmental and economic benefits of the widespread adoption of biogas technologies. The developed methodology can be utilized to inform management decisions through the use of the instant and scenario forecasts. [ABSTRACT FROM AUTHOR]

A novel coupling process to replace the traditional multi-stage anammox process—sulfur autotrophic denitrification (SAD) coupled anaerobic ammonium oxidation (anammox) system was designed, which solved problems of nitrate produced in anammox process and low nitrate conversion rate caused by nitrite accumulation in SAD process. Different filter structures (SAD filter and anammox granular sludge) were investigated to further explore the excellent performance of the novel integrated reactor. The results of sequential batch experiments indicated that nitrite accumulation occurred during SAD, which inhibited the conversion of nitrate to dinitrogen gas. When SAD filter and anammox granular sludge were added to packed bed reactor simultaneously, the nitrate removal rate increased by 37.21% and effluent nitrite concentration decreased by 100% compared to that achieved using SAD. The stratified filter structure solved groove flow. Different proportion influence of SAD filter and anammox granular sludge on the stratified filter structure was evaluated. More suitable ratio of SAD filter to anammox granular sludge was 2:1. Proteobacteria (57.26%), Bacteroidetes (20.12%) and Chloroflexi (9.95%) were the main phyla. The dominant genera of denitrification functional bacteria were Thiobacillus (39.80%), Chlorobaculum (3.99%), norank_f_PHOs-HE36 (2.90%) and Ignavibacterium (2.64%). The dominant genus of anammox bacterium was Candidatus_Kuenenia (3.05%). [ABSTRACT FROM AUTHOR]

• In-situ forming nano Fe 3 O 4 @CaFe-LDH in Fe(II)-catalytic wastewater treatment. • Achieving zero Fe sludge and reusing all Fe resources into Fe 3 O 4 @CaFe-LDH. • Advancing organics removal via in-situ forming Fe 3 O 4 @CaFe-LDH. • Fe 3 O 4 modified by oxidation products benefited CaFe-LDH formation. • The proposed strategy was suitable for many organic wastewaters' treatment. Due to its high efficiency, Fe(II)-based catalytic oxidation has been one of the most popular types of technology for treating growing organic pollutants. A lot of chemical Fe sludge along with various refractory pollutants was concomitantly produced, which may cause secondary environmental problems without proper disposal. We here innovatively proposed an effective method of achieving zero Fe sludge, reusing Fe resources (Fe recovery = 100%) and advancing organics removal (final TOC removal > 70%) simultaneously, based on the in situ formation of magnetic Ca-Fe layered double hydroxide (Fe 3 O 4 @CaFe-LDH) nano-material. Cations (Ca2+ and Fe3+) concentration (≥ 30 mmol/L) and their molar ratio (Ca:Fe ≥ 1.75) were crucial to the success of the method. Extrinsic nano Fe 3 O 4 was designed to be involved in the Fe(II)-catalytic wastewater treatment process, and was modified by oxidation intermediates/products (especially those with COO− structure), which promoted the co-precipitation of Ca2+ (originated from Ca(OH) 2 added after oxidation process) and by-produced Fe3+ cations on its surface to in situ generate core-shell Fe 3 O 4 @CaFe-LDH. The oxidation products were further removed during Fe 3 O 4 @CaFe-LDH material formation via intercalation and adsorption. This method was applicable to many kinds of organic wastewater, such as bisphenol A, methyl orange, humics, and biogas slurry. The prepared magnetic and hierarchical CaFe-LDH nanocomposite material showed comparable application performance to the recently reported CaFe-LDHs. This work provides a new strategy for efficiently enhancing the efficiency and economy of Fe(II)-catalyzed oxidative wastewater treatment by producing high value-added LDHs materials. [Display omitted] [ABSTRACT FROM AUTHOR]

Anaerobic digestion (AD) is widely employed for sludge stabilization and waste reduction. However, the slow hydrolysis process hinders methane production and leads to prolonged sludge issues. In this study, an efficient and eco-friendly lysozyme pre-treatment method was utilized to address these challenges. By optimizing lysozyme dosage, hydrolysis and cell lysis were maximized. Furthermore, lysozyme combined with hydrothermal pretreatment enhanced overall efficiency. Results indicate that: (1) When lysozyme dosage reached 90 mg/g TS after 240 min of pretreatment, SCOD, soluble polysaccharides, and protein content reached their maxima at 855.00, 44.09, and 204.86 mg/L, respectively. This represented an increase of 85.87%, 365.58%, and 259.21% compared to the untreated sludge. Three-dimensional fluorescence spectroscopy revealed the highest fluorescence intensity in the IV region (soluble microbial product), promoting microbial metabolic activity. (2) Lysozyme combined with hydrothermal pretreatment significantly increased SCOD, soluble proteins, and polysaccharide release from sludge, reducing SCOD release time. Orthogonal experiments identified Group 3 as the most effective for SCOD and soluble polysaccharide release, while Group 9 released the most soluble proteins. The significance order of factors influencing SCOD, soluble proteins, and polysaccharide release is hydrothermal temperature > hydrothermal time > enzymatic digestion time.(3) The lysozyme-assisted hydrothermal pretreatment group exhibited the fastest release and the highest SCOD concentration of 8,135.00 mg/L during anaerobic digestion. Maximum SCOD consumption and cumulative gas production increased by 95.89% and 130.58%, respectively, compared to the control group, allowing gas production to conclude 3 days earlier. [Display omitted] [ABSTRACT FROM AUTHOR]

The treatment of sludge is one of the main sources of carbon emissions throughout the entire life cycle of sewage treatment. This study conducted carbon emission analysis on the sludge treatment process of a sewage treatment plant in Guangzhou, China, and offered a carbon accounting boundary calculation process for the sludge called the deep dehydration–drying–incineration process. An international standard method was improved to offer a carbon emissions accounting method for direct carbon emissions, indirect carbon emissions, and carbon sink for the sludge treatment of the effluent treatment plant. Research has found that the amount of sludge treatment is directly proportional to carbon emissions and carbon sinks. When the sludge treatment capacity reaches 600 t or more, almost zero carbon emissions are achieved, and the carbon emissions generated during the incineration stage of sludge treatment are the highest in all process steps. In addition, there is a significant positive correlation between dry sludge treatment capacity and carbon emissions from drying/integration. There is a significant positive correlation between dry sludge treatment capacity and direct emissions caused by incineration, but there is no correlation with carbon emissions generated by the use of electricity/chemicals. This study offered important data support and technical reference for the resource development and low-carbon disposal regulation of sludge, and a basis for the calculation of carbon emissions throughout the entire process of sludge treatment. Practical Applications: The paper explored the carbon emission accounting method for sludge treatment. An international standard method has been improved to offer an accounting method for direct carbon emissions, indirect carbon emissions, and carbon sequestration of sludge treatment in sewage treatment plants, providing possibilities for carbon accounting throughout the entire life cycle of sewage and sludge in sewage treatment plants. The results show that the sludge treatment capacity is directly proportional to carbon emissions and carbon sinks. When the sludge treatment capacity reaches 600 t or more, almost zero carbon emissions are achieved, and the carbon emissions generated during the sludge treatment incineration stage are the highest in all process steps. In addition, there is a significant positive correlation between dry sludge treatment capacity and carbon emissions from drying/integration. There is a significant positive correlation between dry sludge treatment capacity and direct emissions caused by incineration, but there is no correlation with carbon emissions generated by the use of electricity/chemicals. The research results contribute to the resource utilization and low-carbon disposal of sludge. [ABSTRACT FROM AUTHOR]

[Display omitted] • The influence of pre-drying methods on HTC of sewage sludge was evaluated. • Pre-drying affected the composition and pyrolysis/combustion behavior of sludge. • Pre-drying limitedly affected hydrochar yield, composition, and characteristics. • The quality of sludge hydrochar with and without pre-drying is comparable. While pre-drying of sewage sludge prior to hydrothermal carbonization is rarely practiced, various pre-drying methods have been performed in literature at lab-scale for convenient solid-to-liquid ratio adjustment. This has created a barrier for comparing hydrochar quality between different studies. Given pre-drying can destroy the floc structure of sewage sludge, we hypothesize that pre-drying may promote the hydrolysis step during hydrothermal carbonization process, resulting in improved hydrochar quality with low nitrogen content. In the current study, the influence of different pre-drying methods (freeze-dry, air-dry and vacuum-dry at 70 °C and 105 °C) on the subsequent hydrothermal carbonization of sewage sludge at 220 °C was assessed in terms of sewage sludge and hydrochar's chemical composition, fuel properties, pyrolysis and combustion behavior, as well as the characterization of the liquid phase. The results indicate that although pre-drying impacts sewage sludge's chemical composition, pyrolysis and combustion behavior, no significant differences exist in the yield, chemical composition, fuel properties, and pyrolysis and combustion behavior of the hydrochar. Therefore, the use of pre-drying would not affect the hydrothermal carbonization process of sewage sludge, and a comparison can be made on hydrochar quality between different studies with or without pre-drying. [ABSTRACT FROM AUTHOR]

In this research endeavor, the influence of thermal hydrolysis treatment on product distribution obtained through the pyrolysis of hydrolysis treated sludge and raw sewage sludge was investigated. Raw sewage sludge sample was received from a municipal sewage sludge treatment plant, and hydrolysis of sewage sludge was performed at a temperature of 200 °C and a pressure of 0.4 MPa in a fixed-bed furnace. The pore structure of the obtained biochar and non-condensable gas collected at various temperatures was analyzed via Brunauer, Emmett, and Teller and gas chromatography techniques, respectively. The results revealed that thermal hydrolysis treatment had a significant impact on product distribution at varying temperatures (500-800 °C). An increase in temperature led to a decrease in the biochar and biooil yield, while the yield of gas increased for both hydrolysis treated sludge and raw sewage sludge. It was observed that the concentration of H2, CH4, and CO from hydrolysis treated sludge was higher than raw sewage sludge. Furthermore, it was observed that by increasing the temperature, the pore volume and specific surface area of the biochar increased while the average pore width decreased. The maximum Brunauer, Emmett, and Teller surface area was measured from biochar obtained from hydrolysis treated sludge at 800 °C as 50.61 m²/g. The findings suggest that thermal hydrolysis treatment is a viable method for the treatment of sewage sludge as compared to conventional methods. [ABSTRACT FROM AUTHOR]

The effluents from the South African wastewater treatment plant systems have a detrimental effect on the country's water resources and public health. Municipal wastewater services are often considered inadequate when compared to national standards and inter-national benchmarks. The objective of this study was to evaluate the quality of wastewater effluent discharged from multiple sewage treatment facilities throughout the Crocodile River catchment area in the Lowveld. The quality of wastewater effluent was tested at nine wastewater discharge stations along the Crocodile River. Samples were collected monthly during the eight-month duration of 2021. Samples were analyzed by the South African National Accreditation System (SANAS) laboratory and statistical analysis was conducted using the Seaborn program. The results indicated that almost all the sampling sites had very high suspended solid concentrations in their effluent discharges; the highest was recorded at Kanyamazane site with 26,20 mg/L, and the lowest at Kabokweni with 7,2 mg/L. High levels chemical oxygen demand (COD) were recorded, which increased nitrate levels. High COD is an indication of water treatment system inefficiency. In most cases, the levels of E. coli were within the legal required limits, except for Kabokweni (192425)/100 mL) and Hectorspruit (1183/100 mL). R² = 0.83 showed a strong association between suspended particles and ammonia nitrogen (NH3-N). Pollution of the Crocodile River is mostly due to wastewater treatment facility failure; therefore, the South African government should invest in wastewater treatment and sludge management technology. Funds should be utilized efficiently for infrastructure development and maintenance. [ABSTRACT FROM AUTHOR]

To reduce the operating cost of wastewater treatment plants and in situ treatment of sewage sludge and domestic food waste, the current investigation of anaerobic codigestion of domestic food waste and primary bioflocculated sewage sludge was conducted in an anaerobic reactor coupled with a decentralized domestic wastewater treatment plant. The performance of the anaerobic reactor and wastewater treatment system was tested for 30 days. The anaerobic digester was placed after the flocculation chamber in the wastewater treatment plant to transfer the primary bioflocculated sludge using gravity. The 0.5 kg Day−1 of domestic food waste and 29 L Day−1 of bioflocculated sewage sludge were used as feedstock for an anaerobic codigestion and supernatant collected in the flocculation chamber were passed to the water treatment stages. The bioflocculated sludge was collected by adding flocculant in domestic raw wastewater and fed in a digester whereas food waste was added using the separate port in the digester on daily basis. The anaerobic digester was operated in continuous mode at mesophilic temperature conditions at a hydraulic retention time of 7 days. The physiochemical parameters for controlling the anaerobic digester were examined periodically which showed the maximum volatile fatty acid accumulation of 6,500 mg L−1 on the 12th day with the highest biomethane production of 0.35 L CH4 g−1 VSconsumed. The highest energy production potential of biogas was estimated as 0.35 kWh unit. The physical, chemical, organic, inorganic, and biological characteristics of treated water were tested to quantify the treatment efficiency of the process for the reuse of treated water. Results indicated that more than 90% of effluent was collected at the outlet of treatment units and the tested parameters were fulfilling the guidelines set by the different agencies for the reuse of effluent for various purposes. Practical Applications: This paper investigates the performance of anaerobic codigestion of food waste and bioflocculated sewage sludge coupled with a decentralized wastewater treatment plant for the ease of substrate availability. Biomethane production was used to analyze the energy generation potential of domestic sewage sludge and food waste to reduce the operating cost of wastewater treatment systems. The feeding ratio used for operating the anaerobic reactor was decided based on food waste and sewage sludge availability from typical households. The limiting values of VFA with codigestion of food waste and bioflocculated sewage sludge have been reported in the current study and compared with literature values. This work provides insights to make possible the in situ treatment of domestic wastewater along with energy generation from food waste and bioflocculated sewage sludge in an integrated system which is unavailable in the literature. [ABSTRACT FROM AUTHOR]

Microbial fuel cells (MFCs) are green technology capable of generating direct current while simultaneously treating wastewater. Although in most studies, catholytes used in MFC reactors are either phosphate buffer, direct oxygen or air cathodes. In this study, the effect of different organic loads in synthetic wastewater (equivalent to the organic load present in low- and medium-strength wastewater) as anolyte and acidic water as catholyte on cell voltage, current, power generation, and chemical oxygen demand (COD) removal efficiency with a mixed bacterial culture inoculum as biocatalyst have been accessed. Results showed a positive effect of using acidic water (pH 2) as catholyte with increasing organic load in each cycle on cell voltage, current density, and volumetric power density generation. Among all the cycles, Cycle 5 with 5.35 g/L COD load generated highest cell voltage of 205.55 mV, continuous current density, and volumetric power density of 60.45 mA/m2 and 84.50 mW/m3 , respectively, with 93.85% COD removal efficiency and 77.38% Coulombic efficiency (CE). Although none of the cyclic voltammograms (CVs) showed any oxidation peak but reduction peaks were observed in Cycles 3, 4, and 5 with 1.60, 3.21, and 5.35 g/L organic load. Cycle 5 showed two sharp reduction peaks, which can be attributed to growth of mixed bacterial culture, and 16S microbiome profiling confirmed the dominance of two unclassified species, one of Sphingomonas and the other of Burkholderia, which may have contributed to the occurrence of the two sharp reduction peaks in Cycle 5. This study demonstrates that acidic water (pH 2) can be used as an effective catholyte along with species from Sphingomonas and Burkholderia genera in treatment of synthetic wastewater with COD equivalent to low- and medium-strength domestic wastewater and bioelectricity generation. Practical Applications: Conventional wastewater treatment technologies are not sustainable to treat huge quantities of low- and medium-strength wastewater because they are cost-intensive and energy-driven processes that also release a large quantity of sludge, leading to sludge disposal problem. Moreover, they do not yield energy or any other valuable by-product. Results from our study shows that MFC can be effectively used to reduce 68.83% of total dissolved solids (TDS) and 93.85% of COD content of synthetic wastewater equivalent to low- and medium-strength wastewater, thereby efficiently treating the wastewater and also solving the problem of huge amounts of sludge generation and disposal. In the process of wastewater treatment, our study was also able to generate 84.50 mW/m3 of power density, making it an energy-yielding technology. Usage of an inexpensive mixed microbial culture inoculum as a biocatalyst (dominance of Sphingomonas and Burkholderia species) in this work showed that biocatalysts can be used as alternative to expensive metal catalysts in treatment of low- and medium-strength wastewater. During practical application of this study's findings, synthetic wastewater can be replaced with any low- and medium-strength wastewater, be it of kitchen, domestic, or municipal origin, and acidic water as catholyte can be replaced with acidic wastewater effluents of any industry to simultaneously treat two type of wastewaters and generate bioelectricity. [ABSTRACT FROM AUTHOR]

In this manuscript, CH4 emissions from sludge treatment centres are quantified using an unmanned aerial vehicle (UAV) framework, with particular focus on anaerobic digesters and digestate storage tanks. The outcomes are compared to those obtained using the carbon accounting workbook (CAW), which is the most commonly used industry tool by UK and Irish water companies to estimate the annual greenhouse gas emissions from their process operations. Path integrated concentrations are monitored with the use of an open-path tuneable diode laser absorption spectroscopy sensor embedded on a UAV. Measurements are interpolated using geostatistics (Kriging) and coupled with the mass balance approach to estimate emissions. The findings show that the CAW seems to underestimate emissions from digestate storage tanks by up to an order of magnitude. The results also show that CH4 emissions are linked with the residence time in the tank and temperature of the digestate. This study highlights the limitations of assumptions made using current reporting methods based on the carbon accounting workbook. This study proves that the UAV framework, together with the mass balance approach, provides high spatial resolution data; it captures the dynamic nature of emissions compared to the CAW and can be a cost-effective solution to estimate CH4 fluxes compared to other sensor-based systems. [ABSTRACT FROM AUTHOR]

This study partially replaced the clay with sewer sludge (SS) and rice husk (RH-SS) to make fired bricks. The brick samples were examed in terms of shrinkage, water absorption, and compressive strength. Besides, they were analyzed via XRD and metal extraction to determine the heavy metal residuals in the products. The results showed that it was possible to fabricate fired bricks using sewer sludge or rice husk-blended sludge with up to 30% by weight. These brick samples complied with the technical standard for clay brick production, in which the compressive strength was more than 7.5 MPa, water absorption was from 11–16%, and the linear shrinkage was all less than 5%. The rice husk addition helped mitigate the heavy metal residuals in the bricks and leaching liquid, in which all the values were lower than the US-EPA maximum concentration of contaminants for toxicity characteristics. Implications: Previous studies have proved the possibility of mixing sewage sludge from different origins (sewage sludge, river sediment, canal sediment, sewer sediment, etc.) with clay and some wastes to make bricks. In which, mostof the studies used sewage sludge from wastewater treatment plants, very fewdealt with lake/river or sewer sediment. This study shall be the first to study the possibility of employing sewer sediments with the addition of rice husk powder to achieve two targets, including (1) the reuse of biowaste and sludge for brick fabrication and (2) the reduction of heavy metals in final calcined bricks. Different ratios of the rice-husk blended sewer sludge (RH-SS) – clay mixture shall be tested to find the optimized compositions. The results showed that it was possible to fabricate fired bricks using sewer sludge or rice husk-blended sludge with up to 30% by weight, which meant reduce 30% of clay in the brick production. The final products were proved to meet the quality standard in terms of compressive strength (more than 10 MPa), water absorption(from 11–16%), and the linear shrinkage (less than 5%). Larger scale of this study can be an evident to recommend for policy change in the waste reuse in construction field. [ABSTRACT FROM AUTHOR]

The disposal of sewage sludge (SS) is an environmental issue in many large cities worldwide. Due to its high nutrients and organic matter contents, the SS can be used as a substrate to produce tree seedlings. However, few studies evaluate the suitability of SS from different wastewater treatment plants (WWTP) as seedlings' substrates. The present study assessed the chemical and physical properties of three SS from different WWTPs and two commercial substrates (CS), aiming to evaluate how the SSs' properties can affect the production of seedlings from two tree species. SS from Alegria, Ilha, and Sarapuí WWTP were assessed, and CS was composed mainly of peat and pine bark. As chemical properties, heavy metals, macro, and micronutrients total contents were evaluated. Meanwhile, density and porosity were measured as physical properties. The growth in shoot height was measured for seedlings of two Atlantic Forest species (Colubrina glandulosa and Peltophorum dubium). The SS showed higher nutrients (mainly N and P), and the CS had better physical properties. The Ilha and Sarapuí SS are recommended as substrates to produce seedlings of both species. Considering its low macroporosity, the Alegria SS must be mixed or composted with other materials to be used as a substrate for tree species. Although the contents of aluminum, zinc, and other metal were high in the SS, no adverse effects were observed in seedlings. Without chemical fertilizers, SS from Ilha and Sarapuí produced seedlings in a shorter period and with higher growth than those grown with CS plus chemical fertilizers. [ABSTRACT FROM AUTHOR]

Efficiently managing sludge extract from physio-chemical processes in water/wastewater treatment plants is imperative for achieving zero-waste discharge and advancing environmental sustainability. This review critically examines current practices, challenges, and opportunities associated with sludge extract management, with a specific focus on maximizing resource recovery while minimizing environmental impacts. It distinguishes between primary sludge, generated from physico-chemical processes, and secondary sludge from biological treatments, highlighting the unique treatment needs of primary sludge. By evaluating the role of physico-chemical processes in sludge generation and exploring the significance of zero-waste discharge strategies, this review highlights the importance of optimizing sludge extract reuse within waste management bases. Key factors influencing the quality and composition of sludge extract, including chemical characteristics and treatment techniques, are thoroughly assessed. Furthermore, technological approaches for optimizing sludge extract reuse are discussed, including advanced treatment technologies and successful case studies. Challenges and limitations associated with sludge extract reuse are identified, along with recommendations for overcoming these barriers. The implications of optimizing sludge extract reuse for environmental sustainability, resource conservation, and regulatory agreement are discussed, highlighting the potential for significant positive impacts on waste management practices. Future research directions are also delineated, aiming to advance the field of sludge extract management and promote the adoption of zero-waste strategies in waste management. This review serves as a valuable resource for sludge management guiding sustainable waste practices. [ABSTRACT FROM AUTHOR]

This study aims to evaluate the emissions of greenhouse gases (GHGs) stemming from the sludge treatment sector in China and to investigate the feasibility of novel technologies in curtailing these emissions, with the aim of fostering sustainable sludge management methodologies. Employing a life-cycle assessment (LCA) methodology, the research computed the comprehensive GHG emissions resulting from sludge treatment, taking into consideration diverse elements such as treatment techniques (e.g., landfills, incineration, and land application) and the geographical variations among China's 660 municipalities. Findings indicate that the total amount of GHG emissions from sludge treatment amounted to 18.54 Mt CO2-eq in 2017, with incineration registering the highest emissions (10,011.53 kg CO2-eq/t dry sludge (DS)), followed by landfills (717.51 kg CO2-eq/t DS) and land application (276.41 kg CO2-eq/t DS). The geographical dispersion of emissions characteristics reveal notable regional disparities, with the top 1% of cities responsible for 34.2% of the overall emissions. The concentration of emissions in the top 1 percent of cities underscores the necessity for tailored mitigation measures that consider localized sustainable development challenges. Principal component analysis (PCA) demonstrates that economic determinants and treatment scales exert substantial influence on emissions, underscoring the imperative of aligning Sustainable Development Goals (SDGs) with economic advancement. To curtail the carbon footprint associated with sludge treatment and enhance sustainability, the study evaluated the emission mitigation potential and expenses of diverse technologies, encompassing thermal conversion, anaerobic digestion, hydrothermal treatment, and wet oxidation. These technologies have the capacity to slash GHG emissions by 0.09–0.46 t CO2-eq/t DS in comparison to traditional approaches, while concurrently advancing resource recuperation and principles of circular economy. For instance, gasification could diminish GHG emissions by 0.33–0.46 t CO2-eq/t DS, whereas anaerobic digestion could yield reductions of 0.09–0.30 t CO2-eq/t DS. The implementation of these innovative technologies across 660 Chinese municipalities could potentially curtail total GHG emissions from sludge treatment by 15–40%. Nevertheless, further enhancements are imperative to refine their environmental and economic efficiency and guarantee enduring sustainability. By deploying these technologies and embracing optimization tactics, China's sludge treatment sector can make a substantial contribution towards attaining national carbon neutrality objectives and advancing sustainable development. [ABSTRACT FROM AUTHOR]

As the "carbon peaking and carbon neutrality" strategy advances, carbon emissions have gradually become a significant indicator in selecting and evaluating sewage and sludge treatment solutions. This study compared the carbon footprints of different digested sludge post-treatment routes, taking the Lu'an project in China as an example. Considering anaerobic digestion and digested sludge post-treatment options, the carbon footprints are as follows: 347.7 kg CO2 (land application) < 459.7 kg CO2 (composting-involved land application) < 858.4 kg CO2 (brickmaking). In general, land application was superior to brickmaking from the perspective of carbon footprints. The power consumption incurred by aerating and turning and the direct N2O and CH4 emissions during composting increase the composting-involved land application carbon footprint. However, digested sludge that is not subject to high-temperature sterilization and compost is phytotoxic and can be fetid, which is a limitation of its applicability. And the composted sludge has a lower N ratio and water content, so the same N input means more sludge usage, which is conducive to solving the disposal problem of large amounts of sludge. Thus, if possible, composting-involved land application should be a preference, and improvements to the technique are required to minimize energy consumption and direct N2O and CH4 emissions. [ABSTRACT FROM AUTHOR]

[Display omitted] • A broad variety of radionuclides and elements were determined in SSA, APC and DFB. • Mobility of wide spectrum of elements in studied waste was examined. • Relatively high activity of 226Ra in SSA and DFB samples was observed. • The content of majority of elements in samples decrease in samples: SSA > DFB > APC. • High mobility of metalloids and low mobility of metals in SSA and DFB was observed. The research was aimed at providing new knowledge in the field of chemical characteristics of solid waste generated in the process of combustion of sewage sludge in fluidized bed furnaces. The research material consisted of disposed fluidized beds (DFB), sewage sludge ash (SSA) and air pollution control residues (APC) from three Polish installations for the thermal treatment of sewage sludge. Natural radionuclides as well as anthropogenic isotope 137Cs were determined in the tested materials and the migration of a wide spectrum of trace elements to various waste fractions generated in the process of sewage sludge combustion was examined. It was observed that both radioisotopes and most of the trace elements determined accumulate in SSA and DFB, while the APC fraction contains a much smaller amount of them. The exceptions are mercury and selenium, whose volatile compounds migrate to the exhaust gas dedusting system and accumulate in the APC fraction (up to 40 mg/kg and 13 mg/kg, respectively). A potential threat from the 226Ra isotope in SSA is identified in the context of the management of this waste in the production of building materials because the typical activity of 226Ra in SSA collected from areas with very low Ra content in natural environment exceeds 1.5–6 times the activity of this isotope in conventional cement mixtures. When managing SSA and DFB, special attention should be paid to the content of metalloids such as As, B and Se, due to the high content of mobile forms of these elements in the mentioned materials. [ABSTRACT FROM AUTHOR]

Antibiotic resistance genes (ARGs) have emerged as a significant global health threat, contributing to fatalities worldwide. Wastewater treatment plants (WWTPs) and livestock farms serve as primary reservoirs for these genes due to the limited efficacy of existing treatment methods and microbial adaptation to environmental stressors. Anaerobic digestion (AD) stands as a prevalent biological treatment for managing sewage sludge and manure in these settings. Given the agricultural utility of AD digestate as biofertilizers, understanding ARGs' fate within AD processes is essential to devise effective mitigation strategies. However, understanding the impact of various factors on ARGs occurrence, dissemination, and fate remains limited. This review article explores various AD treatment parameters and correlates to various resistance mechanisms and hotspots of ARGs in the environment. It further evaluates the dissemination and occurrence of ARGs in AD feedstocks and provides a comprehensive understanding of the fate of ARGs in AD systems. This review explores the influence of key AD parameters such as feedstock properties, pretreatments, additives, and operational strategies on ARGs. Results show that properties such as high solid content and optimum co-digestion ratios can enhance ARG removal, while the presence of heavy metals, microplastics, and antibiotics could elevate ARG abundance. Also, operational enhancements, such as employing two-stage digestion, have shown promise in improving ARG removal. However, certain pretreatment methods, like thermal hydrolysis, may exhibit a rebounding effect on ARG levels. Overall, this review systematically addresses current challenges and offers future perspectives associated with the fate of ARGs in AD systems. [ABSTRACT FROM AUTHOR]

Wastewater treatment systems produce large volumes of sludge which is not used; its final disposal is in soil or landfill. This sludge represents a biomethane-energy alternative through anaerobic co-digestion, contributing to reducing the environmental impacts caused by their inadequate disposal. Biomethane production by the two-stage production method in batch digesters with pH and temperature control was evaluated by two qualities of waste-activated sludge (SLB50 and SLB90) and with a mixture of two co-substrates: cow manure (CEV50 and CEV90) and residual edible oil (CAV50 and CAV90). Bacteria in good-quality sludge (SLB90) showed a faster adaptation of 2 days than those in low-quality sludge (SLB50), with a 25-day lag phase. The highest CH4 production was for SLB90 (303.99 cm3 d−1) compared to SLB50 (4.33 cm3 d−1). However, the cow manure–sludge mixture (CEV90) contributed to the increased production of CH4 (42,422.8 cm3 d−1) compared to CEV50 (12,881.45 cm3 CH4 d−1); for CAV90 and CAV50, these were 767.32 cm3 d−1 and 211.42 cm3 d−1, respectively. The addition of sludge co-substrates improves the nutrient balance and C/N ratio; consequently, methane production improves. This methodology could be integrated into concepts of the circular economy. [ABSTRACT FROM AUTHOR]

In present times, with increasing emphasis on circular economies, municipal wastewater treatment plants (WWTPs) are considered resource recovery facilities. The targeted resources are water, biogas, and sludge, organic residuals containing nutrients and elements needed by plants (nitrogen and phosphorus). Sludge is a byproduct that constitutes the largest volume of all other byproducts obtained in wastewater treatment plants. Its processing and disposal are challenging for environmental engineers because of its complexity. Thus, quick development and implementation in industrial practice of sludge valorization and utilization technologies is required, where high nutrient content must be taken into account. Also, the occurrence of a variety of pathogens in sewage sludge is a matter of concern, even in the case of developed countries. The use of untreated sludge or wastewater in agricultural activities poses a serious risk of bacterial and parasitic infection in human beings. To overcome such issues, the application of ionizing radiation processing, especially electron beam (EB), can be considered a promising method. Its effectiveness in pathogen removal has been proven by researchers. Water radiolysis products created during irradiation of water are highly reactive and cause some effects such as DNA damage, O H   • radical production, etc. Additionally, ionizing radiation technologies in sewage sludge treatment enhance the efficiency of the methane fermentation process. Depending on specific needs, different types of ionizing radiation sources can be discussed. Based on the review information and our research results, the basic engineering parameters of hybrid installation have been presented as the conclusion of the report. In this technical solution, a notably effective additional step would be the use of EB irradiation, combined with conventional wastewater treatment, to achieve efficient removal of pollutants. [ABSTRACT FROM AUTHOR]

Municipal sewage sludge (MSS) is an inevitable byproduct of wastewater treatment, with increasing amounts year by year worldwide. The development of environmentally and economically acceptable methods for the sustainable management of MSS is a major environmental challenge. Nowadays, sludge management practices, besides the commonly used stabilization methods, focus attention on alternative sludge-disposal pathways, which encompass enhanced energy and valuable-resource recovery. This review presents the recent advances in the recovery of selected value-added products from sludge. Because of the high nitrogen and phosphorus concentrations, waste MSS can be a nutrient source (e.g., struvite). This paper discusses the conditions of and advances in the technology of struvite recovery. As in the extracellular polymeric substances (EPSs) of biological sludge, alginate-like exopolymers (ALEs) are present in MSS systems that treat municipal wastewater. The yields, dynamics in content, and characterization of ALEs and their possible applications were analyzed. MSS is an important source of humic substances. Their occurrence, characterization, and yields in various types of MSS (e.g., untreated, composted, and digested sludge) and main methods of application are presented. The important aspects and trends of MSS pyrolysis, including the thermochemical conversion to biochar, are discussed in this review. The characterization of biochar derived from MSS and the assessment of the environmental risks are also covered. This paper explores the potential use of biochar derived from MSS in various applications, including soil amendment, carbon sequestration, and environmental remediation. [ABSTRACT FROM AUTHOR]

The treatment of sewage sludge has become a global concern. Large amounts of sewage sludge can be disposed of by burning coal-mixed sludge. Thermogravimetric analysis and lab-scale combustion experiments in a drop tube furnace were utilized to study the combustion characteristics, pollutant emissions, and heavy metal migration during the co-combustion of coal and sewage sludge. The results showed that the blended fuels with a sewage sludge content less than 10 weight percent exhibited coal-like combustion characteristics. Additionally, the additional sewage sludge favored the ignition performance of blended fuels. When sewage sludge was added, the SO2 emissions rose to 76 mg/Nm3 under the 10% sludge condition—nearly three times higher than that of coal alone. While NOx emissions stayed mostly unchanged, HCl and HF emissions were very low. Meanwhile, Cr, Cu, and Ni migrated to the bottom ash, and their concentrations were all reduced with an increase in sewage sludge. Pb, Cd, Cr, Cu, Ni, and Hg migrated to the flue gas, mostly in the form of gaseous components. The results provide crucial information in the co-combustion of sewage sludge and coal, with implications in the development and improvement of large-scale, harmless, and resource-recovering techniques for waste sludge. [ABSTRACT FROM AUTHOR]

Copper-containing sludge is a common by-product of industrial activities, particularly electroplating and metal processing. This type of sludge contains high concentrations of heavy metals such as copper, which can pose a potential threat to the environment. Therefore, its treatment and disposal require special attention. Due to its efficient mass and heat transfer characteristics, the suspended state technology has shown significant potential for application in a number of key processes, including the drying, decomposition, and reduction of copper-containing sludge. This paper presents an in-depth analysis of the current status of the application of the suspended state technology in the treatment of copper-containing sludge. Based on this analysis, a device for the treatment of copper-containing sludge in the suspended state was designed, through which the characteristics of copper-containing sludge in the oxidative decomposition and reduction phases are investigated. The research objects were gas concentration, temperature, contact state, and particle size time. Orthogonal experiments were initially employed to investigate the relationship between the influencing factors and the conversion rate of copper oxides. This was followed by a single-factor influence study, which led to the determination of the optimal process parameters for the decomposition experiments of the Cu-containing sludge in an oxidizing atmosphere. The 100 μm Cu-containing sludge was reacted with 10% O2 gas at a flow rate of 1 m/s for 3 min under the condition of 900 °C. The process parameters were then determined as follows: The research objects were gas concentration, temperature, contact state, and particle size time. Orthogonal experiments were employed to investigate the relationship between the influencing factors and the copper conversion rate. This was followed by a single-factor influence study, which determined the optimal process parameters for the copper-containing sludge reduction experiments. The 200 μm copper-containing sludge was reacted for 5 min at a flow rate of 7% carbon monoxide at a flow rate of 1.5 m/s under the condition of 800 °C. [ABSTRACT FROM AUTHOR]

This research demonstrates changes in the behaviors and characteristics of sintered bricks while using industrial sludge ash (ISA) and waste glass (WG) as a replacement for clay in the brick manufacturing procedure. Owing to the limited amount of available land in Taiwan, it is becoming increasingly difficult to locate suitable sites for sanitary landfills, which is a common final disposal method for ash that is produced during thermal treatment in sludge factories. To meet the urgent need for land, the final waste disposal must convert this waste into a new resource. This research investigated the feasibility of using general industrial sludge ash waste, due to its abundance and high potential as a raw material in producing bricks. The result of this study shows that the bricks made from ISA and WG under a certain mixture proportion (ISA50%/WG40%/Clay10%) had excellent industrial potentials, such as compressive strength and water absorption rate. However, owing to the wide variety of components from different sources of ISA, the mixture proportion might vary accordingly. This study also analyzed the incineration index, proportion design, and process improvement, as well as investigating the possibility of increasing the total use of sludge ash as a resource. This study shows the potentials of utilizing wastes as raw materials in industrial manufacturing procedures. Therefore, more wastes can be tested and turned into resources in the future. [ABSTRACT FROM AUTHOR]