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Sewage sludge requires effective dewatering and high nutrients retention before disposal for agricultural application. Pressurized electro-osmotic dewatering (PEOD) process with low energy consumption can effectively remove water from sludge, but the influences of PEOD process on nutrients for agricultural application still lacks in-depth research. In this study, the influences of PEOD process on nutrients for agricultural application were investigated, including organic matter, nitrogen, phosphorus, potassium and silicon contents. Layered experiments were conducted to investigate the layered variation of nutrients in sludge and to understand the potential change mechanisms. The experimental results showed that PEOD process caused small losses (<10%) of organic matter and total phosphorus (TP) in sludge, but caused 11.2−18.4% loss of total nitrogen (TN). PEOD process also caused 18.6−27.0% loss of total potassium (TK) and over 80% loss of available potassium in sludge, and could weaken the potential salt damage during the agricultural application of sludge. Furthermore, the available phosphorus content of sludge in the anode area increased significantly after the PEOD process, indicating that PEOD process could enhance the phosphorus bioavailability of sludge in the anode area. Besides, PEOD process caused a slight loss of silicon components in sludge, but improved the long-term silicon dissolution and release ability of sludge. This work could expand the knowledge about the influences of PEOD process on sludge nutrients and provide scientific guidance for the agricultural application of PEOD sludge. [ABSTRACT FROM AUTHOR]

• Co-pyrolysis Ea was ∼ 50 % lower than with waste textiles alone. • 3D diffusion explained co-pyrolysis devolatilization stages. • Co-pyrolysis increased hydrocarbon yield, lowered emissions. • Co-pyrolysis enhanced sugar and acid decomposition. • Co-pyrolysis char showed more fatty alkyls and branching. Co-pyrolysis is a promising technology for industrial organic waste to utilize their unique resource and energy properties for efficient conversion into valuable products. This study was the first time to characterize the co-pyrolysis of waste textiles with Ca-rich industrial sludge and Fe-rich industrial sludge on a laboratory-scale fixed bed. The properties, mechanisms, gas, oil and carbon production were investigated as a function of temperature and mixing type. Co-pyrolysis increased the total weight loss from 50.05 % to 69.81 % for Ca-rich industrial sludge mixed with 50 % waste textiles and from 49.13 % to 70.01 % for Fe-rich industrial sludge mixed with 50 % waste textiles. The activation energy of co-pyrolysis was approximately 50 % lower compared to the pyrolysis of waste textiles alone. The optimal reaction model for the different reaction stages for all samples was three diffusion (D3). Co-pyrolysis resulted in lower CO and CO 2 emission temperatures of about 25–110 °C and produced more short-chain organic compounds (C < 10). Co-pyrolysis produced more aldehydes and ketones organics. Moreover, co-pyrolysis char exhibited an elevated level of fatty alkyl side chains and bridge branching, as well as higher degrees of aromatization and stability. This study offers valuable insights into the potential application of pyrolysis for the management of Ca/Fe-rich industrial sludge and waste textiles, thereby serving as a basis for future utilization endeavors. [ABSTRACT FROM AUTHOR]

The gasification of sewage sludge (SS) and digestate was investigated in a pilot-scale fluidized bed gasifier with an output of 100 kWt. The treatment of these by-products is an ongoing challenge for sustainable development. SS and digestate are most commonly used as fertilizers. However, regulations restrict their use, mainly because of the content of heavy metals, pathogens and bacteria. Gasification of these by-products instead of application to agricultural land seems to be more efficient, as the syngas can subsequently be used for combined heat and power (CHP) generation. A series of measurements were carried out to get a better understanding of the gasification process of these fuels and to study the effects of gasifying agent on the syngas composition, particulate matter (PM) and tar. The produced syngas and tar were analyzed using a gas chromatograph with mass spectrometry (GC–MS). The results showed that no ash slagging was observed and therefore it is feasible to operate digestate and SS gasification at 750°C. The lower heating value (LHV) of the syngas from digestate and SS with air as the gasifying agent is comparable, 4.06 MJ·Nm−3 for digestate and 4.11 MJ·Nm−3 for SS. The addition of steam had a positive effect on the amount of tar and the tar dew point, which was below 150°C. Tar reduction in digestate was 5037.3 mg·Nm−3 to 3566.3 mg·Nm−3 and in SS 7447.7 mg·Nm−3 to 3390.3 mg·Nm−3. Furthermore, the concentrations of the individual tar compounds were determined and subsequently divided into tar classes. [ABSTRACT FROM AUTHOR]

Among the steelmaking slag, secondary metallurgy slag (SMS) is the most problematic to be recycled. Several attempts to recover such slag as lime replacement, slag flux, pozzolanic materials have been made for long time with pros and cons. However, the amount of recyclable slag is limited and often their employment requires higher energy demand than traditional materials. Nevertheless, the use of SMS in agriculture is poorly or never considered. In this article, the legal and technical evaluation of SMS as raw material for fertilizers production is investigated. Compliance of technical specification, toxic metals concentration, and leaching behavior allows to confirm the technical feasibility of SMS use as a raw material for fertilizers manufacture. Both from the literature data and the experimental results on 16 industrial SMS samples, the requirements for calcium‐magnesium‐sulfur‐based fertilizers, soil correctives and for sanitizing agricultural sewage sludge, appear fully satisfied. The CaO concentration in SMS (35–60 wt%) is abundantly higher than the requirements (≥15 wt%) and CaO is present in most part as water‐soluble complexes such as calcium aluminates (70 wt%), silicates (10 wt%), and sulfide (4 wt%). The pH of the SMS samples leachate is comparable to that of fresh lime (12.35 vs 12.46), highlighting a better behavior for sewage sludge sanitation with respect to limestone (9.98). The measured toxic metals and leachate elements concentration over the corresponding admittable threshold are always lower than 0.5 and 1.0 (mg kg−1/mg kg−1) for liming materials. Finally, these results lead to officially approve the use of SMS as soil corrective according to the Italian Fertilizer Regulation. [ABSTRACT FROM AUTHOR]

The objective was to evaluate the biosolids as an alternative source of nutrients in the production of chrysanthemums by adding increasing doses to the cultivation substrate. The experimental design was in blocks with 6 treatments and 5 replications. The treatments consisted of the mixture (commercial substrate + biosolid) at the concentrations: 20%, 40%, 60% and 80% of biosolid + two controls (100% of biosolid and 100% of substrate). The experiment was conducted in a greenhouse for 90 days. Physiological parameters, number of flower buds, dry biomass and nutrient accumulation were evaluated. Physiological parameters were evaluated using the Infrared Gas Analyzer. The number of flower buds was evaluated by counting. Biomass was determined after drying the structures and then calculated the accumulation of nutrients. A total of 90 plants were evaluated. Concentrations of up to 40% of biosolid promoted a greater number of flower buds, dry biomass and nutrient accumulation. Concentrations above 60% lower number of buds, biomass increment and nutrient accumulation. It is concluded that the biosolid has potential as an alternative source of nutrients in the cultivation of chrysanthemums, indicating concentrations of up to 40% and the nutrient content of each batch generated must be verified. [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]

Hydrothermal liquefaction is a new, sustainable pathway to generate biogenic liquids from organic resources. The technology is compatible with a wide variety of resources such as lignocellulosic resources, organic waste, algae, and sewage sludge. The chemistry is complex and predictions of yields are notoriously difficult. Understanding and modeling of hydrothermal liquefaction is currently mostly based on a simplified biochemical analysis and product yield data. This paper presents a large dataset of 2439 experiments in batch reactors that were extracted from 171 publications in the scientific literature. The data include biochemical composition data such as fiber content and composition, proteins, lipids, carbohydrates, and ash. The experimental conditions are recorded for each experiment as well as the reported yields. The objective of this paper is to make a large database available to the scientific community. This database is analyzed with machine‐learning tools. The results show that there is no consensus on the analysis techniques, experimental procedures, and reported data. There are many inconsistencies across the literature that should be improved by the scientific community. Machine‐learning tools with a large dataset allow the generation of reliable yield production tools with a large application field. Given the accuracy of the data, the overall precision of prediction in an extrapolation to new results can be expected to be around 10%. [ABSTRACT FROM AUTHOR]

One of the most important problems and the main obstacle of this process is the transformation of the complex structure of lignocellulose. One of the ways to break the lignocellulosic structure is to use suitable pretreatment compounds and nanoparticles with appropriate concentration. For this purpose, the synergistic effect of 6%NaOH pretreatment with different magnetite nanoparticle (MNP) concentrations was assessed for maximizing the biogas production. In this study, the optimal mixing ratio of MSW and SS codigestion was determined from our previous studies (MSW:SS 60:40). Application of the 6%NaOH pretreatment alone increased biogas and methane production by 24.6 and 35.4%, respectively, compared to the control. Also, the 6%NaOH pretreatment alone elevated cellulose by 85% while reducing lignin and hemicellulose by 64 and 33%, respectively. The greatest biogas and methane production was obtained in the reactor of 6%NaOH with an MNP concentration of 110 ppm, experiencing an 86 and 162% increase compared to the control. The greatest reduction in total solids and volatile solids was also obtained in this digestor by 76.6 and 79%, respectively, compared to the control reactor. [ABSTRACT FROM AUTHOR]

Pyrolysis is a promising alternative for the removal or immobilization of hazardous elements in sewage sludge (SS) without compromising its biofertilizer features. However, the effects of pyrolysis on SS emerging contaminants have not been fully investigated. Therefore, this study aimed to assess the fate of heavy metals, pesticides, and organic pollutants in SS through pyrolysis, as well as the suitability of SS and its derived biochar (SSB) for soil application. Municipal SS was pyrolyzed at different scales (bench and micro units) and temperatures (400, 500, and 600°C) for comparison. The general properties, surface morphology, and functional groups of SS and SSB were analyzed. Also, a quantitative analysis of heavy metals (Zn, Cu, Cr, Ni, Cd, and Pb) and a qualitative investigation of organic pollutants and pesticides were performed. The results demonstrated that pyrolysis at 400°C increased the stability of SS and strongly affected its surface area, resulting in a high pore structure with a developed surface charge. Simultaneously, the relative content of organic matter and nutrients remained nearly unchanged. All heavy metals analyzed in SS and SSB400 were within limits set by the International Biochar Initiative for soil application. Moreover, organic pollutants and pesticides were detected in the SS but were partially degraded or immobilized after pyrolysis > 400°C. In conclusion, the production of SSB proved to be an effective method for removing toxic elements from SS while enhancing its properties for soil remediation and crop productivity. [ABSTRACT FROM AUTHOR]

Phenol bioremediation was investigated using two bacteria (primarily cocci) Dermacoccus nishinomiyaensis, Kocuria rosea strains and the one actinomycetes Nocardiopsis lucentensis which were isolated from samples of activated sludge from the wastewater treatment plant (WWTP) in Beni‐Suef, Egypt as sole carbon and energy sources. This was applied on real industrial wastewater sample taken from Ul HAWA textile plant, Middle Egypt. Degradation of phenol by microbes adsorbed on natural kaolin clay was studied compared with free microbes. In case of 50 mg/L as starting phenol concentration, the percentage removal using free microbes was 68%, corresponding to 98% in case of microbes adsorbed on kaolin clay after the passage of 48 h under incubation at 30°C and neutral pH at 150 rpm. Also, 300 mg/L of phenol achieved degradation frequency of 80% compared to 38% after ≈48 h without clay addition. High concentrations of an organic pollutant are usually inhibitory for the microorganisms. Kaolin clay has a pronounced effect in accelerating phenol degradation through biofilm formation resulting in decreasing the degradation time, increasing the percentage of removing efficiency under high phenol concentration conditions due to its buffering effects on pH fluctuations of the degradation system. Kaolin clay protects microorganisms against unfavorable environment, resists the adverse effects of substrate inhibition and accelerates the degradation process. The adsorption process was demonstrated by the pseudo‐first‐order, pseudo‐second‐order, Weber–Morris adsorption kinetic models, and four isotherm models namely, Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich have been applied to express the adsorption process. The SEM images of microbes adsorbed on kaolin clay explain their adsorption mode on the clay surface as biofilm (Bio kaolinite). [ABSTRACT FROM AUTHOR]

This study aimed to determine the quantity and quality of dissolved organic carbon (DOC) released from sewage sludge-derived biochar and digestion-derived biochar under different extraction conditions (deionised water, hot water, 0.1 mol·L-1 NaOH) using TOC analyser, UV-vis spectroscopy. Biochars were produced through the pyrolysis process at temperatures of 400, 500, 600, and 800 ℃. The objective of this article was to examine the influence of diverse extraction solutions on the amount of dissolved organic carbon (BDOC) released from biochars and to delineate alterations in the composition and characteristics of DOC contingent on the extraction parameters. The findings demonstrated that elevated pyrolysis temperatures resulted in a notable reduction in DOC concentration, with fractions extracted using NaOH exhibiting the highest DOC concentrations. SUVA254 analysis and the E2/E3 ratio indicated that biochars produced at higher temperatures contained a greater proportion of aromatic and hydrophobic substances. These results indicate that pyrolysis temperature, feedstock type and extraction conditions are of significant importance for the properties of DOC in biochar. This has important implications for their potential applications in soil management and carbon sequestration strategies. [ABSTRACT FROM AUTHOR]

In this work, a techno-economic feasibility and environmental sustainability assessment of the aerobic composting process was conducted assuming that 20,000 tons of sewage sludge are produced annually at the As-Samra plant, Jordan. Three pilot reactors were designed and operated under different conditions by varying the aeration mode, choice of bulking agents, and sludge-mixing ratio. The results demonstrated that the final composting product was found to satisfy Class B requirements as per Jordanian Standard (1145: 2016), while Class A requirements were met in most of the parameters. The estimated capital and annual operating expenditures of the proposed composting facility were 1,084,233.60 JD and 2,008,236.26 JD, respectively. The annual compost production is estimated at 12,000 tons, resulting in 66.6% compositing with an annual revenue of 2,880,000 JD. Based on economic feasibility analysis, the project is economically viable with a 40% internal rate of return (IRR) and a discounted payback period (DPP) of 2.6 years, while the net present value (NPV) of this project was 4,565,963.24 JD. The findings also substantiate that the composting facility would result in a decrease in net greenhouse gas emissions (GHG) by 475,000 t CO2-eq (i.e., an 80% reduction in GHG releases) over the 15 years of the project's lifespan. Overall, this work establishes a viable approach to evaluate the techno-economic and environmental sustainability of the composting process as a feasible strategy for managing sewage sludge in Jordan. [ABSTRACT FROM AUTHOR]

Microplastic (MP) load in urban sewage sludge could vary annually in wastewater treatment plants (WWTPs) depending on seasonal precipitation and human activities. We investigated the seasonal dynamics in abundance and characterization of MP loading in WWTPs located in two cities across River Ganga, India's ecologically sensitive upper stretch. During a 12-month seasonal sampling (pre-monsoon, monsoon, and post-monsoon), sludge samples (n = 36) (primary sludge, PS; drying bed sludge, DBS) were collected and analyzed for load, polymer types, shape, colour, and size (20–1000 µm). Across the three seasons, MP concentrations (particles/kg) were found to be in the ranges of 93.4 ± 5.0 × 103–189.4 ± 11 × 103 in the PS and 39.6 ± 4.0 × 103–152.0 ± 7 × 103 in the DBS. The trend of MP loading was in the following order: monsoon > post-monsoon > pre-monsoon. The dominant MP size was 50–200 µm (36.22%) followed by 20–50 µm (27.65%), 200–500 µm (24.55%) and 500–1000 µm (11.58%). ATR-FTIR results revealed polypropylene, polyethylene terephthalate, polyvinyl chloride, and nylon dominating MP in sludge. This study highlights the importance of long-term monitoring of MP loading in sewage sludge to offer a more accurate estimate of MP contamination in sludge from WWTPs and develop a possible mechanism for its elimination to safeguard the environment. [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]

Due to its nitrogen, phosphorus, and magnesium content, sewage sludge is used, among other things, to grow plants for energy purposes or to intensify biogas production. These processes are always accompanied by odor emissions, which are treated as pollution according to European legislation and are subject to legal regulations in many countries. Therefore, this publication presents the results of a study on the removal of odor from sewage sludge by adsorption on biochars produced from selected biowaste. Beekeeping waste (grain) and coffee brewing residues (spent coffee grounds) were selected for the study. Both materials were pyrolyzed to produce biochar which was applied for adsorption of odors from sewage sludge. Commercial Organosorb 200-1 Wi activated carbon was used as a comparison material. The odors were taken from dried sewage sludge from a municipal wastewater treatment plant. The obtained biochars are suitable for odor adsorption and can be an alternative to commercial adsorbents. The biochar from beekeeping waste showed the highest efficiency, allowing 100% odor removal. Slightly worse results were obtained for biochar from spent coffee grounds. [ABSTRACT FROM AUTHOR]

Vermicomposting utilizes the synergistic effect of earthworms with microorganisms to accelerate the stabilization of organic matter in biowastes. Nevertheless, the exact mechanism behind the maturity of vermicompost and the growth of earthworms exposed to biochar of varying particle sizes remains unclear. This study presents an investigation of the effect of biochar particle size on earthworm (Eisenia fetida) survival, microbial diversity, and the quality of vermicompost products. To address these issues, pelletized dewatered sludge samples from a municipal sewage treatment plant were amended with pine-based biochar with particle sizes of 1–2 mm, 25–75 μm, 200 nm, and 60 nm as the substrate for vermicomposting. This study revealed that the addition of millimeter-scale biochar and micron-scale biochar significantly promoted the degradation of organic matter since the organic matter in the treatment with 1–2 mm biochar at the end of the vermicomposting experiment decreased by 12.6%, which was equivalent to a 1.9-fold increase compared with that of the control. Excessive nanopowdering of nanobiochar significantly affected the survival of earthworms and led to 24.4–33.3% cumulative mortality, while millimeter-scale (mm) biochar and micron-scale (μm) biochar achieved zero mortality. The findings of this study could be used for evaluating the potential impact of nanoscale biochar to earthworms and guiding biochar-augmented vermicomposting. Highlights: The addition of 1–2 mm biochar resulted in a 1.9-fold greater reduction in organic matter compared to the control group. The introduction of 25–75 μm biochar led to a significant 94% increase in earthworm cocoons. The cumulative mortality rates of 200 nm and 60 nm biochar amendment reached peaks of 33.3% and 24.4% at first week, respectively. Earthworms excrete mucus that effectively removes attached nanobiochar. [ABSTRACT FROM AUTHOR]

Qatar's population has been rapidly increasing in recent years, and the country's long-term vision, QNV 2030, aims to sustain this growth by transforming the country into a sustainable state. One aspect of this vision is to convert waste into value-added products, which will reduce the environmental and spatial burden associated with waste in Qatar, while contributing to a circular economy. This study describes methods for producing biochar and activated carbon (AC) from gas-to-liquids derived biosolids, cardboard waste and mixed samples using pyrolysis and activation techniques. The characterisation of products revealed that the yield of biochar samples was higher than AC, and that the pH of the biochar samples was more alkaline than the feed samples due to metals after pyrolysis and reduced acid surface functional groups. Proximate analysis of samples showed lowered moisture and enhanced ash in feeds upon pyrolysis and activation due to increased temperature with reduced volatile content. AC application to water treatment is considered a potential benefit due to the increased surface area, pore volume and magnetic properties based on the Brunauer–Emmett–Teller (BET) and X-ray Powder Diffraction (XRD) analysis. The X-ray photoelectron spectroscopy (XPS) analysis also showed increased –CO3/O–C = O and potassium in the ACs as a result of potassium carbonate activation. The study proposes various applications that can support a circular economy, but future studies should investigate actual applications and potential health and environmental effects and evaluate the feasibility and environmental impact of production methods. [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]

Recycling industrial solid wastes as building materials in the construction field exhibits great environmental benefits. This study designed an eco-friendly non-sintered brick by combining multiple industrial solid wastes, including sewage sludge, fly ash, and phosphorus gypsum. The mechanical properties, microstructure, and environmental impacts of waste-based non-sintered bricks (WNBs) were investigated comprehensively. The results revealed that WNB exhibited excellent mechanical properties. In addition, steam curing could further promote the strength development of WNB. The compressive strength of WNB with 10 wt% of sewage sludge reached 13.5 MPa. Phase assemblage results indicated that the incorporation of sewage sludge promoted the generation of ettringite. Mercury intrusion porosimetry results demonstrated that the pore structure of WNB varies with the dosage of sewage sludge. Life-cycle assessment results revealed that the energy consumption and CO2 emission of WNB were 45% and 17% lower than those of traditional clay bricks. Overall, the development of WNB in this study provided insights into the co-disposal of industrial solid wastes. [ABSTRACT FROM AUTHOR]

Hydrogen-rich gas, characterized by high yield and purity, can be effectively generated through the steam gasification of sewage sludge (SS), offering substantial benefits for organic solid waste treatment and resource conservation. This study evaluated the gasification performance in a horizontal moving-bed reactor employing a wet-mixed CaO-red mud (CaO-RM) composite catalyst. The effects of CaO loading rate (CaO/RM), catalyst-to-SS ratio (CaO-RM/SS), and reaction temperature on the syngas yield, lower heating value (LHV), carbon conversion ratio, H 2 to CO (H 2 /CO) ratio, and H 2 yield were investigated. Results indicated that red mud loaded with a calcium-based catalyst significantly enhanced syngas production, particularly for hydrogen generation, during SS gasification. A maximum hydrogen molar fraction of 50.84% and a yield of 7.07 mol/kg were achieved with a CaO/RM of 40% and a CaO-RM/SS of 30% at 750 °C. With the reaction temperature increase from 700 to 900 °C, the catalytic performance for secondary tar cracking and steam reforming was further enhanced. The total syngas yield, H 2 yield, hydrogen molar fraction, LHV of syngas, and carbon conversion rate peaked at 0.79 m³/kg, 19.30 mol/kg, 54.41%, 10,249.48 kJ/kg, and 65.67%, respectively, at 900 °C. • Study boosts energy conversion of sewage sludge with new CaO-RM composite catalyst. • Examines effects of CaO loading rate, catalyst/SS ratio, temperature on gasification. • Prepared CaO-RM catalyst greatly increase syngas, especially hydrogen production. • Temperature rise from 700 to 900 °C boosts catalytic tar cracking and reforming. [ABSTRACT FROM AUTHOR]

In this study, the co-pyrolysis of sewage sludge (SS), two-component special municipal waste (SMW) and plastic waste (Plastic) was studied using thermogravimetric equipment and a scaled-up tubular reactor. During the experiments, the effects of the raw material composition and pyrolysis temperature on the decomposition processes, the product yields and compositions were investigated. It was found that co-pyrolysis was a series of complex reactions and resulted in more volatile and lower residue yield than the pyrolysis of the individual raw materials. In some cases (e.g., 25%SMW + 75%Plastic, 25%SS + 75%Plastic, 50%SS + 50%Plastic blends), it also caused a higher synthesis gas yield and H2/CO ratio. During the thermogravimetric analysis, the beneficial effects occurred at lower temperatures, but in the scaled-up experiments, these effects only prevailed at 900 °C as a result of the larger amount of raw materials and the worse heat transfer. The produced gases can be characterized by a lower heating value of 17.3–35 MJ/Nm3. Therefore, they can be used for energetic purposes; however, before chemical use, further quality improvement is needed due to the lower H2/CO ratios. [ABSTRACT FROM AUTHOR]

Sewage sludge ash (SSA), obtained by the incineration of sewage sludge, which is a byproduct of water treatment, could be used as a cement replacement material (CSR) to promote sustainability. SSA characteristics differ due to its different sources, compositions, and incineration methods. On the other hand, extensive investigations have highlighted the CSRs' ability to control alkali–silica reaction (ASR) as a destructive phenomenon, threatening durability. Hence, this study was conducted in order to study the ability of SSA with two finenesses, three replacement levels, and also its ternaries with trass or pumice, as natural pozzolans, to control ASR. The utilized SSA did not meet the requirements of a pozzolan at either finenesses. The results revealed that despite the fact that SSA generally reduced ASR expansion significantly, it only managed to control ASR at 50% replacement level. This was true for both finenesses. Furthermore, ternaries improved resistance against ASR expansion significantly, providing the ability to control ASR at lower replacement levels of SSA. The Si/Ca ratio was the key reason of SSA's ability to control ASR as it contained 1.5 and 2.5 times more SiO2 and Al2O3 than Portland cement respectively, and about one third of its CaO. Scanning electron microscopey (SEM), energy dispersive spectroscopy (EDS), and mapping confirmed that the relative amounts of Si, Al, and Ca in the SSA was crucial. [ABSTRACT FROM AUTHOR]

This open-field small-plot long-term experiment was set up between 2011 and 2021 with willow (Salix triandra × S. viminalis 'Inger'), grown as a short rotation coppice energy crop in Nyíregyháza, Hungary. The sandy loam Cambisol was treated with wastewater solids (WS) in the form of municipal sewage sludge compost (MSSC, 2011, 2013, and 2016), municipal sewage sediment (MSS, 2018), and with willow ash (WA, 2011, 2013, 2016, and 2018). Control plots remained untreated since 2011. All soil treatments significantly enhanced the uptake or accumulation of potentially toxic elements (PTEs) in the leaves of willows. During June 2019, 53 weeks after the last soil treatments, MSSC + MSS-, WA-, and MSSC + MSS + WA-treated willows leaves had 14–68% more As, 17–48% more Ba, 31–104% more Cr, 4–12% more Cu, 6–15% more Mn, 18–218% more Pb, and 11–35% more Zn compared to the untreated control. Significantly higher Mn and Zn concentrations were measured in the MSSC + MSS + WA treatments than in the MSSC + MSS treatments. The assumption that WA reduces the accumulation of PTEs in willow leaves when applied together with MSSC and MSS was therefore only partially confirmed. The hypothesis of this study was that PTEs accumulated in the leaves would affect the microanatomical parameters of the leaves. Numerous positive changes were observed with the combined application of WS and WA. MSSC + MSS + WA treatment reduced the thickness of the mesophyll less than MSSC + MSS or WA treatments alone; the size of the cells building the palisade and spongy parenchyma and the extent of the main vein significantly increased. In the case of the combined treatment, the extent of the sclerenchymatous stock was smaller than in the control but larger than in WS- or WA-treated willow. The extent of the collenchymatous stock significantly increased compared to the control. Increases in the thickness of the adaxial epidermis and the number of stomata were statistically significant. However, the extent of the increases did not reach the extent of the increase experienced in the case of WS treatment, as the size of the stomata did not significantly decrease. [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]

The irrigation of soils with reclaimed contaminated wastewater or its amendment with sewage sludge contributes to the uptake of pharmaceuticals by vegetables growing in the soil. A multiresidue method has been devised to determine five pharmaceuticals and nine of their main metabolites in leafy and root vegetables. The method employs ultrasound-assisted extraction, clean-up via dispersive solid-phase extraction, and analysis through liquid chromatography–tandem mass spectrometry. Box–Behnken design was used to refine variables such as extraction solvent volume, time of extraction, number of extraction cycles, and the type and amount of d-SPE sorbent. The method achieved linearity (R2) greater than 0.994, precision (relative standard deviation) under 16% for most compounds, and detection limits ranging from 0.007 to 2.25 ng g−1 dry weight. This method was applied to a leafy vegetable (lettuce) and to a root vegetable (carrot) sourced from a local market. Parent compounds were detected at higher concentrations than their metabolites, with the exception of carbamazepine-10,11-epoxide. [ABSTRACT FROM AUTHOR]

Anaerobic digestion (AD) presents a promising avenue for efficiently reducing sewage sludge and generating renewable energy. The success of AD systems largely relies upon the microbial community composition, which is associated with various process parameters. This review aims to investigate the correlations among the microbiota abundances, digestion performances, and process parameters based on 233 datasets in 69 publications. Statistical analysis of the datasets uncovers significant correlations between process parameters with dominant bacterial phyla and archaeal genera. The evolution of microbial relative abundance (RA) reveals that Chloroflexi are positively correlated with Actinobacteria, Spirochaetes, and Synergistetes, while Firmicutes exhibit negative correlations with Proteobacteria, Chloroflexi, and Spirochaetes. Methanosarcina have negative correlations with Methanothrix, Methanobacterium, and Methanomassiliicoccus. Bacteria and archaea exhibit potential competitive (between syntrophic acetate-oxidizing bacteria and acetoclastic archaea) and syntrophic (between hydrogen-producing bacteria and hydrogenotrophic archaea) relationships. Furthermore, the volatile solids reduction and methane yield are significantly correlated with microbiota RAs and the ratio of Bacteroidetes and Firmicutes. This review sheds light on microbial interactions and thus AD performance by establishing the correlations between process parameters and microbiota composition. Future research directions should emphasize the significance of rare taxa, the necessity for experimental validation, and the potential of advanced modeling approaches to optimize sludge AD systems. [ABSTRACT FROM AUTHOR]

In the frame of bioeconomy and circular economy, wastewater sludge (WS) could be a good candidate for its use in agriculture as fertilizer, due to its high content of organic matter, N and P, but on the other hand, it is full of toxicants such as heavy metal, microplastics, detergent, antibiotics, and so on that can reach groundwater and water bodies in leachate form. In this study, we have investigated different sludge concentrations in the eluate form, combined and not with PVC on two different freshwater organisms Selenastrum capricornutum and Daphnia magna, using ecotoxicity tests. At the endpoint, we have evaluated inhibition growth rate, oxidative stress, and pigments production for S. capricornutum, while in case of D. magna, we have assessed organism immobilization and development. From our results, it emerged that at the higher WS concentration, there was not inhibition growth rate, while at oxidative stress, it was higher in algae treated with WS and PVC. Higher Chl‐a production was shown for algae treated with 0.3 g/L of sludge coupled with PVC, where higher phaeopigments production were recorded for algae treated with 0.3 g/L of WS. D. magna has shown an opposite trend when compared with algae, where at the highest WS concentrations supplied was corresponding to an increased mortality explaned as the highest immobility percentage. Practitioner Points: Wastewater sludge is used in agriculture as fertilizer.PVC microplastic presence and associate ecotoxicity was tested.PVC presence increased oxidative stress in S. capricornutum.D. magna was significantly affected by sludge concentrations supplied. [ABSTRACT FROM AUTHOR]

Biocrusts and plants are the main ground cover and provide multiple ecosystem functions in arid and semiarid areas. As land degradation worsens and waste management is ever more pressing, the use of composted waste appears as a sustainable restoration practice to enhance vegetation reestablishment, but its effects on biocrusts still remain largely understudied. Moreover, developing appropriate methods for the co‐introduction of plants and biocrusts can be an emerging approach to reconstruct the biocrust/plant interaction and their associated functions. We evaluated the effect of different compost types on biocrust and plant cocultivations. We performed a greenhouse mesocosm experiment using urban organic solid waste and sewage sludge composts to grow a moss‐dominated biocrust and seedlings of two pioneer shrubs (Senecio filaginoides and Acaena splendens) in the Patagonian steppe. Both compost types successfully enhanced biocrust cover and chlorophyll a development, with cultured biocrusts being compositionally similar to the natural inoculum. Only the addition of composted sewage sludge enhanced seedling growth, and biocrusts had significant but opposite effects (positive/negative) on the two plant species we used for experimentation. This difference in the biocrust/plant interaction outcome was likely mediated by the significant influence of biocrusts on the relative availability of ammonium and nitrate and possible plant species‐specific preferences for different inorganic nitrogen forms. We conclude that the application of sewage sludge compost effectively improves the success of biocrust and plant cocultures, but species‐specific differences in the performance of seedlings growing in biocrusted soils impose limits on attempts to promote biocrust and plant joint restoration. [ABSTRACT FROM AUTHOR]

Mining activities provide a pathway for the entry and accumulation of heavy metals in soil. Utilization of biochars could remediate such contaminated soils. Therefore, in this study, the impact two percent of different wastes and biochars (prepared at temperature of 600 °C) was investigated on the availability and release kinetics of lead in polluted soil. Sandy loam calcareous soil, which was collected near Bama lead and zinc mine located in Sepahan Shahr city, was treated with residues and biochars and incubated for 120 days. Then the availability and release kinetics of lead were measured in control and treatments extracting with diethylenetriaminepentaacetic acid solutions (DTPA-TEA) during 504 hours. Results showed that treating soils with biochars, decreased the bioavailablaty and release kinetics of Pb significantly in comparison with control. The comparison of the coefficient of explanation (R2 ) and the standard error of estimation (SEE) of equations showed that simple Elovich equations, power function and first order equations had the highest coefficient of explanation and the lowest standard error of estimate for control and treated soils. So, these mathematical equations have been useful in explaining the cumulative release and release rate of Pb. Values of 1/β (derived from the simplified Elovich equation) and b (derived from the power function equation) changed from 161.47 – 237.18 mg kg-1 h-1 and 0.245 – 0.299 mg kg-1 h-1, respectively. Correlation analysis study, between DTPA-Pb with constants illustrated that among the constants, “K1”, “1/β”, “b”, and “a*b” were better parameters to predict the release kinetics of Pb. [ABSTRACT FROM AUTHOR]

Wheat straw (WS) constitutes a considerable biomass resource and can be used to produce the energy carrier methane through anaerobic digestion. Due to the low contents of several nutrient elements and water in harvested WS, the use of sewage sludge (SS), consisting of primary sludge and waste-activated sludge, as a nutrient source in co-digestion with steam-pretreated wheat straw (PWS) was investigated theoretically and practically. WS was steam-pretreated, with acetic acid as the catalyst, at 190 °C for 10 min, ending with a rapid reduction in pressure. Process stability and specific methane production were studied for the mono-digestion and co-digestion of PWS and SS in continuous stirred-tank reactors for 208 days. The HRT was 22 days and the OLR 2.1 gVS L−1 d−1. In co-digestion, the OLR was increased to 2.8 gVS L−1 d−1 for one week. Nutrient elements were added to PWS mono-digestion at two different concentration levels. Co-digestion was stable, with a total concentration of short-chain fatty acids (SCFAs) at a safe level below 0.35 g L−1 at both OLRs. The higher OLR during co-digestion would require an increase in reactor volume of 14%, compared to the mono-digestion of SS, but would increase the annual production of methane by 26%. The specific methane production levels for PWS mono-digestion, SS mono-digestion, and co-digestion were 170, 320, and 260 mL g−1VS, respectively. Co-digestion did not result in a synergistic increase in the methane yield. SCFAs accumulated in the mono-digestion of PWS when using lower levels of nutrient supplements, and the concentrations fluctuated at higher nutrient levels. The main conclusion is that PWS and SS can be co-digested with long-term process stability, without the addition of chemicals other than water and acetic acid. The specific methane production for mono-digestion of PWS was relatively low. The effect of using higher concentrations of micronutrients in PWS mono-digestion should be evaluated in future studies. [ABSTRACT FROM AUTHOR]

A continuous long-term field experiment with maize monoculture was conducted to evaluate the P availability and balance, DM yield, P uptake, and P sorption parameters in chernozem soil after 27 years. A total of 2 doses of nitrogen (120 and 240 kg ha−1) were applied as mineral nitrogen (N120 and N240) and sewage sludge (SS120 and SS240) and compared with unfertilized control (Con). The aboveground biomass (DM) yields significantly increased in the order of Con < SS120 < SS240 < N120 < N240 treatments and the maximum P uptake was recorded for both N240 and SS240 (25.1 kg P ha−1) according to the nutrient application gradient. The N120 and N240 treatments positively influenced the DM yield but negatively influenced the P balance (−648 and −678 kg P ha−1 27 years−1), gradually bringing a risk of P deficiency in the soil. On the other hand, applications of SS120 and SS240 positively influenced the P availability and pseudototal (PAR) content in the soil, which resulted in a buildup of legacy P or an increase in P saturation greater than the environmental threshold value. Aluminum was found to be a major controlling sorption factor for P in our chernozem soil. [ABSTRACT FROM AUTHOR]

Antibiotic resistance genes (ARGs) are widespread in the environment, and soils, specifically, are hotspots for microorganisms with inherent antibiotic resistance. Manure and sludge used as fertilizers in agricultural production have been shown to contain vast amounts of ARGs, and due to continued applications, ARGs accumulate in agricultural soils. Some soils, however, harbor a resilience capacity that could depend on specific soil properties, as well as the presence of predatory bacteria that are able to hydrolyse living bacteria, including bacteria of clinical importance. The objectives of this study were to (i) investigate if the antibiotic resistance profile of the soil microbiota could be differently affected by the addition of cow manure, chicken manure, and sludge, and (ii) investigate if the amendments had an effect on the presence of predatory bacteria. The three organic amendments were mixed separately with a field soil, divided into pots, and incubated in a greenhouse for 28 days. Droplet digital PCR (ddPCR) was used to quantify three ARGs, two predatory bacteria, and total number of bacteria. In this study, we demonstrated that the choice of organic amendment significantly affected the antibiotic resistance profile of soil, and promoted the growth of predatory bacteria, while the total number of bacteria was unaffected. [ABSTRACT FROM AUTHOR]

Over the past 50 years, there has been a concerning decline in male reproductive health and an increase in male infertility which is now recognised as a major health concern globally. While male infertility can be linked to some genetic and lifestyle factors, these do not fully explain the rate of declining male reproductive health. Increasing evidence from human and animal studies suggests that exposure to chemicals found ubiquitously in the environment may in part play a role. Many studies on chemical exposure, however, have assessed the effects of exposure to individual environmental chemicals (ECs), usually at levels not relevant to everyday human exposure. There is a need for study models which reflect the 'real-life' nature of EC exposure. One such model is the biosolids-treated pasture (BTP) sheep model which utilises biosolids application to agricultural land to examine the effects of exposure to lowlevel mixtures of chemicals. Biosolids are the by-product of the treatment of wastewater from industrial and domestic sources and so their composition is reflective of the ECs to which humans are exposed. Over the last 20 years, the BTP sheep model has published multiple effects on offspring physiology including consistent effects on the male reproductive system in fetal, neonatal, juvenile, and adult offspring. This review focuses on the evidence from these studies which strongly suggests that low-level EC exposure during gestation can alter several components of the male reproductive system and highlights the BTP model as a more relevant model to study real-life EC exposure effects. [ABSTRACT FROM AUTHOR]

Anaerobic digestion (AD) relies on the cooperation of specific microbial communities, making it susceptible to process disruptions that could impact biogas production. In this regard, this study presents a technological solution based on the Arduino platform, in the form of a simple online monitoring system that can track the produced biogas profile, named as biogas analyzer module (BAM). The applicability of the BAM focused on monitoring the biogas produced from sugarcane vinasse inoculated with sewage sludge biodigestion processed in mesophilic conditions (38 oC), in a pH range of 6.5–7.5, and following a three-stage operational model: (i) an adaptation (168 h), (ii) complete mixing (168 h), and (iii) bio-stimulation with glycerol (192 h). Then, the lab-made BAM was used to trace the produced biogas profile, which registered a total biogas volume of 8,719.86 cm3 and biomethane concentration of 95.79% (vol.), removing 90.8% (vol) of carbon dioxide (CO2) and 65.2% (vol) of hydrogen sulfide (H2S). In conclusion, the results ensured good accuracy and efficiency to the device created by comparisons with established standards (chromatographic and colorimetric methods), as well as the cost reduction. The developed device would likely be six times cheaper than what is available in the market. [ABSTRACT FROM AUTHOR]

Reports regarding the composition and functions of microorganisms in activated sludge from wastewater treatment plants for treating tuna processing wastewater remains scarce, with prevailing studies focusing on municipal and industrial wastewater. This study delves into the efficiency and biological dynamics of activated sludge from tuna processing wastewater, particularly under conditions of high lipid content, for pollutant removal. Through metagenomic analysis, we dissected the structure of microbial community, and its relevant biological functions as well as pathways of nitrogen and lipid metabolism in activated sludge. The findings revealed the presence of 19 phyla, 1,880 genera, and 7,974 species, with Proteobacteria emerging as the predominant phylum. The study assessed the relative abundance of the core microorganisms involved in nitrogen removal, including Thauera sp. MZ1T and Alicycliphilus denitrificans K601, among others. Moreover, the results also suggested that a diverse array of fatty acid-degrading microbes, such as Thauera aminoaromatica and Cupriavidus necator H16, could thrive under lipid-rich conditions. This research can provide some referable information for insights into optimizing the operations of wastewater treatment and identify some potential microbial agents for nitrogen and fatty acid degradation. [ABSTRACT FROM AUTHOR]

Organic fertilization is a key issue in European Union (EU) regulations, particularly in the context of promoting a circular nutrient economy, maintaining soil quality, and sequestering carbon to face climate change. In a rainfed system in Northeastern Spain, an experiment was set up (split-plot design). It included five pre-sowing N fertilization treatments: control, mineral, pig slurry, and composted sewage sludge (two rates). The average N rates were 0, 30, 141, 176, and 351 kg N ha−1, respectively. They were combined with mineral N topdressings (0, 50, and 100 kg N ha−1). Three crops were grown: barley (nine years), wheat (three years), and rapeseed (one year). In the driest years (c. 350 mm rainfall), the yields averaged 2.5, 2.0, and 1.9 Mg ha−1, respectively. The maximum yields were for barley (6.5 Mg ha−1) and wheat (5.5 Mg ha−1). The avoidance of a significant increase in soil residual NO3−-N, plus the control of soil build up of available P, micronutrients, and Cd, defines the fertilization strategies. (i) With a previous spring drought season, no fertilization is needed in the following year, if devoted to winter cereals. (ii) In rainier seasons, pig slurry or composted sewage sludge (lowest rate) applied at sowing is sufficient; however, 50 kg of mineral-N ha−1 at the topdressing can be applied. The study found that pig slurry favors K, Mg, Cu, and Zn availability, while composted sewage sludge enhances Fe availability. Although it is possible to reduce N inputs from organic fertilizers, organic C build-up will be constrained. [ABSTRACT FROM AUTHOR]

This study aimed to determine the level of immobilization and the mechanism of leaching of heavy metals (Cd, Cr, Cu, Pb and Zn) from self-hardening slurries (SHSs) based on ash from municipal sewage sludge incineration. To mimic the character of the SHS operation in the cut-off wall, the author's leaching method—a filtration leaching test based on the percolation test—was used. In addition, this paper briefly described the factors affecting the level of heavy metal release from cement composites, as well as the chemical mechanisms and physical processes responsible for this phenomenon. This study showed that SHSs immobilized heavy metals at high levels (≥98.18%), and the aqueous extracts from the samples had a high pH (≥12.9%). Statistically significant correlations were obtained between the concentration of some metals and pH (positive correlation for Cr and Zn), test duration (positive correlation for Cd) and the liquid-to-solid ratio (negative correlation for Cd and Cr). For some of the metals tested, it was possible to determine the release mechanisms: dissolution and wash-out for Cd and Pb, and dissolution for Cr and Zn. [ABSTRACT FROM AUTHOR]

Anaerobic wastewater treatment technology has been intensively and extensively investigated in the industry and scientific research. Inspired by the advantages of multi-stage and multi-phase anaerobic reactor technology (SMPA) in recent years, a three-stage anaerobic reactor (3S-AR) was designed and applied to treat poplar chemical–mechanical pulp wastewater, and various operation parameters, including the volume loading rate (VLR), hydraulic retention time (HRT), ascending velocity, reflux ratio, pH and temperature of the 3S-AR, were optimized to evaluate the reactor's removal efficiency for poplar wastewater. The properties of anaerobic granular sludge and the composition of wastewater were also characterized to assess microorganism growth and pollutant migration. Results show that the COD removal rate was over 75% with a volume loading rate range of 15–25 gCOD/(L·d) in the 3S-AR; the hydraulic retention time was also found to be an important factor affecting the performance of the 3S-AR reactor. The volume loading rate and degradation efficiency of the 3S-AR reactor are higher than those of the up-flow anaerobic sludge blanket (UASB) reactor. Microorganism separation can be achieved in the 3S-AR, which is conducive to the growth and methanogenesis activity of bacteria, thereby leading to enhanced removal and buffering efficiency. After treatment in the 3S-AR, the main pollutants of poplar wastewater were benzene aromatic acids and long-chain esters, which do no biodegrade easily; in contrast, most of the fatty acid substances with small molecules were completely degraded. [ABSTRACT FROM AUTHOR]

This study optimized the organic matter solubilization of faecal sludge (FS). FS was treated in a microwave oven at varying microwave power and treatment times. Changes in total solids (TS), volatile solids (VS), total chemical oxygen demand (TCOD), and soluble chemical oxygen demand (sCOD) were measured. A response surface methodology (RSM) optimized organic matter solubilization during microwave treatment. A central composite design was employed, and the observed responses were used to fit a second-order response surface model. Microwave treatment at 14,000 kJ/kg. TS reduced FS volume by 58%. The VS/TS ratios remained similar before and after microwave treatment. The solubilization of organic matter (measured by the sCOD/TCOD ratio) increased after microwave treatment, showing an initial linear increase with specific energy followed by a decrease. The highest solubilization was 38%, achieved at a microwave power level of 630 W for 3 min. Organic matter solubilization was more sensitive to contact time than microwave power. RSM determined the optimized conditions to be 617.7 W and 2.4 min, within the experimental design boundaries. These findings align with similar observations from other studies using wastewater sludge. The results suggest that microwave treatment can achieve multiple FS treatment objectives. Optimal operating conditions should be identified if the aim is to solubilize organic matter in FS. [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]

Industrial wastewater sludge is one of the vital sources of metals, including heavy metals, valuable metals, and precise metals. Apart from metals' necessity and economic value, some are toxic and harmful to the environment. This review explores the technologies currently applied for extracting and recovering heavy metals from industrial wastewater sludge. The technologies have been explained, and the merits and demerits of methods, as reported in past investigations, have been highlighted. The salient findings of this review are that the hydrometallurgical processes using acid leaching (H2SO4, HNO3, HCl, etc.) have been considered for the metal extraction process. Metal dissolution, concentration/purification, and recovery are the main stages of hydrometallurgical processes. The selection of successive metal recovery methods depends on the concentration of metals and chemical characteristics of industrial wastewater sludge. Different metal purification and concentrations were reported, including adsorption, ion exchange solvent extraction, and so forth, while precipitation and electrodeposition were mainly applied for metal recovery from industrial wastewater sludge. In this review, the cost and economic viability of the metal recovery process are also evaluated by previous reported studies. This review may be considered a valuable source of information for environmentally friendly and cost‐effective methods for metal recovery from industrial wastewater sludge. [ABSTRACT FROM AUTHOR]

The anaerobic digestion of aqueous condensate from fast pyrolysis is a promising technology for enhancing carbon and energy recovery from waste. Syngas, another pyrolysis product, could be integrated as a co-substrate to improve process efficiency. However, limited knowledge exists on the co-fermentation of pyrolysis syngas and aqueous condensate by anaerobic cultures and the effects of substrate toxicity. This work investigates the ability of mesophilic and thermophilic anaerobic mixed cultures to co-ferment syngas and the aqueous condensate from either sewage sludge or polyethylene plastics pyrolysis in semi-batch bottle fermentations. It identifies inhibitory concentrations for carboxydotrophic and methanogenic reactions, examines specific component removal and assesses energy recovery potential. The results show successful co-fermentation of syngas and aqueous condensate components like phenols and N-heterocycles. However, the characteristics and load of the aqueous condensates affected process performance and product formation. The toxicity, likely resulting from the synergistic effect of multiple toxicants, depended on the PACs' composition. At 37 °C, concentrations of 15.6 gCOD/gVSS and 7.8 gCOD/gVSS of sewage sludge-derived aqueous condensate inhibited by 50% carboxydotrophic and methanogenic activity, respectively. At 55 °C, loads between 3.9 and 6.8 gCOD/gVSS inhibited by 50% both reactions. Polyethylene plastics condensate showed higher toxicity, with 2.8 gCOD/gVSS and 0.3 gCOD/gVSS at 37 °C decreasing carboxydotrophic and methanogenic rates by 50%. At 55 °C, 0.3 gCOD/gVSS inhibited by 50% CO uptake rates and methanogenesis. Increasing PAC loads reduced methane production and promoted short-chain carboxylates formation. The recalcitrant components in sewage sludge condensate hindered e-mol recovery, while plastics condensate showed high e-mol recoveries despite the stronger toxicity. Even with challenges posed by substrate toxicity and composition variations, the successful conversion of syngas and aqueous condensates highlights the potential of this technology in advancing carbon and energy recovery from anthropogenic waste streams. [ABSTRACT FROM AUTHOR]

To meet global food demands sustainably, it is necessary to safeguard finite natural resources and reduce harmful emissions to the environment. Nutrients in biowastes are often not managed appropriately. Instead, they can be recovered, recycled into bio-based fertilizers (BBFs) and reincorporated into food production systems. This review addresses three critical issues for developing and adopting new BBFs, focusing on the European context: (1) BBFs should match the agronomic efficiency of mineral fertilizers. We propose that the agronomic efficiency of BBFs can be increased through pre-treating the inputs in biowaste transformation processes (e.g., anaerobic digestion), chemical treatments of existing BBFs, organo-mineral combinations, and soil placement strategies. (2) Production and use of new BBFs is not free of environmental impacts, and these are influenced by regional conditions. (3) Public perception and end-user preferences play a significant role in the adoption of BBFs. Therefore, it is vital to address the requirements of end-users of BBFs. Our findings indicate that for widespread adoption, BBFs need sufficient and reliable nutrient amounts and crop-adequate ratios, as well as competitive pricing. A key advantage of BBFs over mineral fertilizers is their ability to improve soil fertility. However, farmers also require fertilizers that can be handled and applied with existing machinery and offer the practicality of commercial products. Another important aspect is the willingness of consumers to buy products fertilized with BBFs. Designing and promoting BBFs requires a careful assessment of environmental impacts and regional conditions, as the sustainability of BBFs depends on factors like energy sources and biowaste transport distances. Ultimately, the goal is to promote a circular economy and not just to substitute mineral fertilizers with new products. This review aims to guide researchers, policymakers, and stakeholders by highlighting key innovations and addressing critical barriers. [ABSTRACT FROM AUTHOR]

This paper presents a study on reducing sewage sludge by an oxic-settling-anaerobic (OSA) pilot plant compared to the conventional activated sludge (CAS) process in view of resource recovery and moving towards plant carbon neutrality. The OSA plant was supplied with real wastewater and the anaerobic reactor was operated under two hydraulic retention times (HRT) (4 and 6 h). Greenhouse gas (GHG) emissions were monitored for the first time to determine the OSA process's production mechanism. The results highlighted that under the lowest HRT (4 h), the removal efficiencies of COD and PO4−P, increased from 75 to 89% and from 39 to 50% for CAS and OSA configurations, respectively. The observed yield coefficient was reduced from 0.58 gTSS gCOD−1 (CAS period) to 0.31 gTSS gCOD−1 (OSA period). A remarkable deterioration of nitrification efficiency under OSA configuration was obtained from 79% (CAS) to 27% (OSA with HRT of 6 h). The huge deterioration of nitrification significantly affected the GHG emissions, with the N2O-N fraction increasing from 1% (CAS) to 1.55% (OSA 4 h HRT) and 3.54% (OSA 6 h HRT) of the overall effluent nitrogen, thus suggesting a relevant environmental implication due to the high global warming potential (GWP) of N2O. [ABSTRACT FROM AUTHOR]

Biochars derived from apple pomace (AP-BC) and industrial wastewater sludge (IS-BC) were used to investigate adsorption performance and mechanism for removing carbendazim from water and compare its performance with commercial biochar (commercial BC). The results showed that the adsorption capacity of AP-BC and IS-BC were 76 mg g−1 and 82 mg g−1 respectively that was comparable with the commercial BC (80 mg g−1). The adsorption kinetics and isotherms were best described by the Pseudo-second-order and Langmuir models. Thermodynamic analysis suggested that higher temperatures can enhance the mobility of molecules, increased mobility facilitates more frequent and stronger interactions between the adsorbate molecules and the surface of the adsorbent material, leading to greater adsorption capacity. Density functional theory (DFT) calculations confirmed carbendazim's weak electrophilic nature, supporting the primary physisorption mechanism. Even after five cycles of recycling, both biochars maintained a consistent carbendazim removal efficiency of around 82%, highlighting their high reusability. In this study, the examination of waste-derived biochar's economic feasibility revealed that using biochars derived from waste biomass for large-scale wastewater treatment applications is an economically viable choice. [ABSTRACT FROM AUTHOR]

Background: Achieving climate neutrality is a goal that calls for action in all sectors. The requirements for improving waste management and reducing carbon emissions from the energy sector present an opportunity for wastewater treatment plants (WWTPs) to introduce sustainable waste treatment practices. A common biotechnological approach for waste valorization is the production of sugars from lignocellulosic waste biomass via biological hydrolysis. WWTPs produce waste streams such as sewage sludge and screenings which have not yet been fully explored as feedstocks for sugar production yet are promising because of their carbohydrate content and the lack of lignin structures. This study aims to explore the enzymatic hydrolysis of various waste streams originating from WWTPs by using a laboratory-made and a commercial cellulolytic enzyme cocktail for the production of sugars. Additionally, the impact of lipid and protein recovery from sewage sludge prior to the hydrolysis was assessed. Results: Treatment with a laboratory-made enzyme cocktail produced by Irpex lacteus (IL) produced 31.2 mg sugar per g dry wastewater screenings. A commercial enzyme formulation released 101 mg sugar per g dry screenings, corresponding to 90% degree of saccharification. There was an increase in sugar levels for all sewage substrates during the hydrolysis with IL enzyme. Lipid and protein recovery from primary and secondary sludge prior to the hydrolysis with IL enzyme was not advantageous in terms of sugar production. Conclusions: The laboratory-made fungal IL enzyme showed its versatility and possible application beyond the typical lignocellulosic biomass. Wastewater screenings are well suited for valorization through sugar production by enzymatic hydrolysis. Saccharification of screenings represents a viable strategy to divert this waste stream from landfill and achieve the waste treatment and renewable energy targets set by the European Union. The investigation of lipid and protein recovery from sewage sludge showed the challenges of integrating resource recovery and saccharification processes. [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]

Per- and polyfluoroalkyl substances (PFAS) are a group of fluorinated synthetic chemicals that are highly recalcitrant, toxic, and bio-accumulative and have been detected in biosolids worldwide, posing potential risks to humans and the environment. Recent studies suggest that the organic C-F bond in PFAS can be destructed and potentially mineralised into inorganic fluorides during thermal treatment. This study focuses on thermodynamic equilibrium investigations and the fate of fluorine compounds post-PFAS destruction during biosolid thermal treatment. The results indicate that gas-phase fluorine compounds are mainly hydrogen fluoride (HF) and alkali fluorides, whereas solid-phase fluorine compounds include alkaline earth fluorides and their spinels. High moisture and oxygen content in the volatiles increased the concentration of HF in the gas phase. However, adding minerals reduced the emission of HF in the gas phase significantly and enhanced the capture of fluorine as CaF2 spinel in the solid phase. This study also investigates the effect of feedstock composition on the fate of fluorine. High ash content and low volatile matter in the feedstock reduced HF gas emissions and increased fluorine capture in the solid product. The findings of this work are useful in designing thermal systems with optimised operating conditions for minimising the release of fluorinated species during the thermal treatment of PFAS-containing biosolids. [ABSTRACT FROM AUTHOR]