Search

Biomass waste energy recovery is a significant method for recycling energy from waste and capturing it for use in renewable energy sources. The abundance of brewing byproducts, such as brewery spent grain (BSG) and brewery wastewater sludge (BWWS), as well as their high carbon concentrations gives these wastes energy potential. With 20% molasses utilized as a binding agent to maximize the high caloric value of the briquette, this study sought to examine the quality of mixed briquettes made from BSG and BWWS. In order to make composite briquettes with a maximum caloric content of 19.94 MJ/kg, the ideal conditions were chosen, which included a temperature of 350°C, a production period of 60 min, and a 75% BSG mixing ratio. It can be compared to sawdust briquettes, which have a calorific value of 22.88 MJ/kg, by looking at the calorific value of densified with pressure 100 bar for mixed carbonized briquettes vs mixed noncarbonized briquettes (21.13 MJ/kg). The value of R2 was 0.9607 and indicated that 96.07% of the total validation in the calorific value correlation between experimental and predicted values. The finding of the study showed that the efficiency of the quadratic model in fitting the data would be higher under the conditions of the experiment. Based on ISO 17225‐6 fuel quality classes and specifications for graded nonwoody pellets, the study concluded that using BSG and BWWS as alternative energy sources meets those requirements. [ABSTRACT FROM AUTHOR]

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]

This study reports the use of deep‐eutectic‐solvent‐ (DES‐) assisted hydrothermal carbonization (HTC) to disrupt the floc structure of sewage sludge (SS) for deep carbonization, with the resulting hydrochars employed in the preparation of formaldehyde‐free plywood bioadhesives. Sewage‐sludge‐based bioadhesive exhibits an excellent wet shear strength, complying with the requirements of Chinese national standard GB/T 9846–2015 (≥0.7 MPa). The molecular weight of proteins and the formation of covalent bonds via dehydration have a notable role in improving adhesive performance (wet shear strength). The Maillard reaction is a key reaction during HTC to destroy the secondary structure of proteins, resulting in the release of more OH and NH2. The main reaction during hot‐press treatment is dehydration. High ash content in bioadhesives improves flame resistance potential, particularly on addition of DES. A plausible mechanism is proposed for this. This work provides a new method for the valorization of SS‐derived hydrochars and contributes to the development of greener formaldehyde‐free wood bioadhesives. [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]

Municipal wastewater may contain toxic substances that have a negative impact on biological treatment processes and receiving waters. This paper presents the wastewater toxicity test results from the Lodz hybrid sewage system. Wastewater is discharged to surface waters through a treatment plant, but also during wet weather, partially without treatment by combined sewer overflows. The research was carried out using the ToxTrakTM method with the use of the microbial community of activated sludge from the wastewater treatment plant in Lodz. The median toxicity, expressed as the degree of inhibition, ranged from 16.0% to 30.7%, but sometimes exceeded 50%. Higher toxicity was observed in wet weather than in dry weather. Seasonal variability was found but typical daily variability was not observed. In the case of sewage samples with the degree of inhibition above 40%, a significant correlation was found with chromium concentration and non-ionic surfactants (Pearson’s coefficient correlation above 0.7). [ABSTRACT FROM AUTHOR]

Background: In this study, individual methanogenic (anaerobic), granular biofilms were used as true community replicates to assess whole-microbial-community responses to environmental cues. The aggregates were sourced from a lab-scale, engineered, biological wastewater treatment system, were size-separated, and the largest granules were individually subjected to controlled environmental cues in micro-batch reactors (μBRs). Results: Individual granules were identical with respect to the structure of the active community based on cDNA analysis. Additionally, it was observed that the active microbial community of individual granules, at the depth of 16S rRNA gene sequencing, produced reproducible responses to environmental changes in pH, temperature, substrate, and trace-metal supplementation. We identified resilient and susceptible taxa associated with each environmental condition tested, as well as selected specialists, whose niche preferences span the entire trophic chain required for the complete anaerobic degradation of organic matter. Conclusions: We found that single anaerobic granules can be considered highly-replicated whole-ecosystems with potential usefulness for the field of microbial ecology. Additionally, they act as the smallest whole-community unit within the meta-community of an engineered bioreactor. When subjected to various environmental cues, anaerobic granules responded reproducibly allowing for rare or unique opportunities for high-throughput studies testing whole-community responses to a wide range of environmental conditions. [ABSTRACT FROM AUTHOR]

N,N-dimethylformamide (DMF) is an organic solvent with stable chemical properties and high boiling point. Based on its good solubility, DMF is widely used in synthetic textile, leather, electronics, pharmaceutical and pesticide industries. However, the DMF pollutes the environment and does harm to human liver function, kidney function, and nerve function. Herein, an efficient DMF-degrading strain, DM175A1-1, was isolated and identified as Paracoccus sulfuroxidans. This strain can use DMF as the sole source of carbon and nitrogen. Whole-genome sequencing of strain DM175A1-1 revealed that it has a 3.99-Mbp chromosome a 120-kbp plasmid1 and a 40-kbp plasmid2. The chromosome specifically harbors the dmfA1 and dmfA2 essential for the initial steps of DMF degradation. And it also carries the some part of genes facilitating subsequent methylotrophic metabolism and glutathione-dependent pathway. Through further DMF tolerance degradation experiments, DM175A1-1 can tolerate DMF concentrations up to 10,000 mg/L, whereas the majority of Paracoccus strains could only show degradation activity below 1,000 mg/L. And the efficiency of organic nitrogen conversion to NH3-N in DMF can reach 99.0% when the hydraulic retention time (HRT) is controlled at 5 days. Meanwhile, it showed a significant degradation effect at a pharmaceutical enterprise in Zhejiang Province with high concentration of DMF wastewater. This study provides a new strain Paracoccus sulfuroxidans DM175A1-1 which shows a significant influence on DMF degradation, and reveals the characterization on its DMF degradation. It lays the foundation for the application of biological method in the efficient degradation of DMF in industrial wastewater. [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]

Pollution caused by heavy metals, due to their toxicity and harmful effects on plant species, is considered one of the fundamental problems. The unique properties of graphene oxide (GO) in adsorbing heavy metals from contaminated soil systems have garnered attention in the past decade. This study evaluates the effects of different doses of graphene oxide (0.5 and 1.5 g kg-1) on the adsorption and distribution of heavy metals, including Cadmium (Cd) and Copper (Cu) fractions, in soil contaminated with two rates (2% and 10%) of sewage sludge (SS) over a 92-day period. Subsamples were collected from the soils at intervals of 5, 15, 29, 57, and 92 days, air-dried, and subjected to metal fractionation. The aim was to evaluate the separation of Cd and Cu by employing a five-stage sequential extraction technique, where each stage involved 2 grams of air-dried soil as a sample. The overall metal quantity in the treatments was determined by utilizing aqua regia digestion. The recovery rate was determined by calculating the percentage of the total metal concentration obtained from acid digestion, involving the summation of the concentrations of the five metal fractions. The results showed that the F1 fraction of heavy metals in the soil with a 2% SS rate decreased with an increase in GO dosage. The calculated mobility factor of the metals at five incubation times (5, 15, 29, 57, and 92 days) was found to be in the range of 28.1-60.9 for Cd and 14.4-25.3 for Cu, indicating a higher mobility of Cd. The findings suggest that the presence of GO as an adsorbent and the incubation time were critical parameters in stabilizing heavy metals in the soil with different rates of SS. Additionally, the nature of the applied SS was found to influence the fractionation of heavy metals in the soil, besides providing elements. [ABSTRACT FROM AUTHOR]

Wastewater treatment plants (WWTPs) contribute to the release of microplastics into the environment. While the removal efficiency of MPs in WWTPs can reach up to 99.9 %, the highest amount of microplastics is retained in the sludge. Anaerobic digestion, one of the most promising and common processes, can help reduce sludge volume and odour, and due to the formation of biogas, mainly consisting of methane (CH4) and carbon dioxide (CO2), can help decrease the operating costs of WWTPs. A test measuring the inhibition of biogas production using the OxiTop® measuring system was employed to determine the effect of added microfibres (MFs) on biogas production. Particles less than 1 mm in size of polyester, polyamide, and polyacrylic, were added to anaerobic sludge at concentrations ranging from 0.05 to 0.10 g l–1 to simulate their effect on biogas production. The yields of CH4 and CO2 produced during anaerobic digestion of the MFs-contaminated sludge were determined. The addition of MFs to sewage sludge affects methane production. The results indicated that the lowest added concentrations of 0.05 g l–1 of MFs promoted methane production, while the presence of 0.1 g l–1 decreased methane production for all types of MFs used. Polyacrylic at 0.1 g l–1 had the most negative effect on methane production (up to 27 %), while polyamide at 0.05 g l–1 reached the highest methane production (up to 25 %). [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]

Sewage sludge odorous gas release is a key barrier to resource utilization, and conditioners can mitigate the release of sulfur-containing gases. The gas release characteristics and sulfur compound distribution in pyrolysis products under both single and composite conditioning strategies of CaO, Fe2O3, and FeCl3 were investigated. This study focused on the inhibition mechanisms of these conditioners on sulfur-containing gas emissions and compared the theoretical and experimental sulfur content in the products to evaluate the potential synergistic effects of the composite conditioners. The findings indicated that at 650 °C, CaO, Fe2O3, and FeCl3 inhibited H2S release by 35.8%, 23.2%, and 9.1%, respectively. Notably, the composite of CaO with FeCl3 at temperatures ranging from 350 to 450 °C and the combination of Fe2O3 with FeCl3 at 650 °C were found to exert synergistic suppression on H2S emissions. The strongly alkaline CaO inhibited the metathesis reaction between HCl, a decomposition product of FeCl3, and the sulfur-containing compounds within the sewage sludge, thereby exerting a synergistic suppression on the emission of H2S. Conversely, at temperatures exceeding 550 °C, the formation of Ca-Fe compounds, such as FeCa2O4, appeared to diminish the sulfur-fixing capacity of the conditioners, resulting in increased H2S emissions. For instance, the combination of CaO and FeCl3 at 450 °C was found to synergistically reduce H2S emissions by 56.3%, while the combination of CaO and Fe2O3 at 650 °C synergistically enhances the release of H2S by 23.6%. The insights gained from this study are instrumental in optimizing the pyrolysis of sewage sludge, aiming to minimize its environmental footprint and enhance the efficiency of resource recovery. [ABSTRACT FROM AUTHOR]

The increasing amount of sewage sludge produced demands new methods of its management to minimize socioeconomic and environmental problems related to its current treatment. An effective solution may be the thermochemical conversion of sewage sludge through gasification. First, the most known sewage sludge gasification processes are presented along with the challenges that they face. Then the detailed characteristics of sewage sludge are discussed from the point of view of its use in the gasification process, as well as research on the kinetics of gasification of sewage sludge char using various models. As scientific reports on sewage sludge gasification focus on the influence of process parameters on gas yield and composition (especially H2 and tar content), the main part of the work is devoted to the discussion on the influence of temperature, type, and amount of the gasifying agent and the presence of a catalyst on these parameters. Moreover, the co-gasification of sewage sludge as well as advanced gasification methods, i.e., supercritical water gasification and plasma gasification, are analyzed. Finally, the possibilities of utilization of sewage sludge gasification process by-products were discussed and the impact of the process on the environment was assessed. The review concludes with indications of directions for further research. [ABSTRACT FROM AUTHOR]

Biomass-to-biofuel conversion represents a critical component of the global transition to renewable energy. One of the most accessible types of biomass is sewage sludge (SS). This by-product from wastewater treatment plants (WWTPs) contains microplastics (MPs) originating from household, industrial and urban runoff sources. Due to their small size (<5 mm) and persistence, MPs present a challenge when they are removed from sewage systems, where they mainly accumulate (~90%). The presence of MPs in SS poses environmental risks when biosolids are applied as fertilizer in agriculture or incinerated for the purpose of energy production. The key problem is the efficient and reliable identification and reduction of MPs in sewage systems, due to the lack of standardized procedures. The reduction methods for MPs might involve physical, chemical, biological, and hydrothermal approaches, including hydrothermal carbonization (HTC). The HTC of SS produces hydrochar (HC), a solid biofuel, and presents a cutting-edge approach that simultaneously addresses secondary microplastic pollution and renewable biomass-derived energy production. In this article, we review briefly the MPs content in biosolids from different countries, and present HTC as a promising method for their removal from SS. In conclusion, HTC (i) effectively reduces the abundance of MPs in biosolids, (ii) produces an improved solid source of energy, and (iii) contributes to circular SS management. [ABSTRACT FROM AUTHOR]

Waste Cooking Oil (WCO), Soy Oil (SO), and Wastewater Sludge (WWS) have great potential to increase reclaimed asphalt pavement (RAP) content for economic and environmental benefits. This study explored the effects of SO and WCO on rutting, fatigue cracking, and low-temperature cracking performance of binders and Hot Mix Asphalt (HMA) with high RAP content. The potential effect of WWS on the performance and compaction efforts of high RAP content mixes at a 10 °C (50 °F) lower compaction temperature than the control compaction temperature was also investigated. The results indicated that 85% of the RAP binders can be incorporated while maintaining similar performance compared to the control by using 15% SO or 12.5% WCO as a rejuvenator with 2.5% virgin binder. Adding 1% WWS by weight of the total binder improved the binder's rheological properties, the mix's cracking performance, and the mix's density at lower compaction temperatures. [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]

This study evaluates the sustainability of spreading wastewater or sewage sludge on agricultural land, balancing benefits with contamination risks. Conventional ecological risk indices often fail to address the long-term accumulation of metals in soils. We investigate the feasibility of spreading based on current knowledge of potentially contaminating metals and their behavior in soil. We analyzed the speciation of metals (Ag, Cd, Co, Cr, Cu, Ni, Pb, Ti, Zn) through sequential extraction in sludge, treated wastewater, and soils after 14 years of application of sewage sludge and treated wastewater issued from an Algerian wastewater treatment plant. We introduce a Time to Critical Content Index (TCCI) that calculates the time required to reach critical levels of potentially mobile metals, considering total metal content and speciation. The TCCI takes into account product knowledge, soil characteristics, metal behavior, ecological/toxicological thresholds, and regulations. Applied to our case study, the TCCI indicates that spreading sewage sludge can continue despite metal contents exceeding regulatory ceiling values. The index serves as a precautionary measure, adaptable to evolving knowledge, providing a comprehensive framework for sustainable agricultural practices. [ABSTRACT FROM AUTHOR]

Application of sewage sludge as fertilizer can be beneficial for sustainable agriculture as it could largely account for nitrogen and phosphorus demand for crops and has lower costs compared to other disposal routes, e.g., incineration, and sanitary landfills. This study evaluates the feasibility of pilot-scale pelletization of sewage sludge for non-food crops (e.g., ornamental plants). The co-pelletization method was designed by mixing sewage sludge and binder (tapioca starch) at a 9:1 sludge-to-starch weight ratio. The amount of nitrogen (N), phosphorus (P), and potassium (K) of the resultant pellets were determined at 5.7%, 4.9%, and 0.2%, respectively. Following Malaysian and US Standards, non-essential elements and pathogenicity of the pelletized sewage sludge were measured below the predetermined limits and hence safe for agricultural application. The planting trial using 50% inorganic fertilizer + 50% sewage sludge pellets exhibited a promising result on the growth of the flowering plant Celosia plumosa, with having better dimension and color, 20% higher in height, 4% more chlorophyll content, 54% more leaf, 43% greater stem growth, and 27% more flowers compared to control. Likewise, the planting trial on Tagetes erecta resulted in 10.5% wider leaf, 10.6% heavier leaf dry weight, and 12.5% more chlorophyll content compared to control with full usage of inorganic fertilizer. By considering liquidities to operate the production facility, the economic analysis estimated that the production cost per ton of pelletized sewage sludge produced was USD 0.98. [ABSTRACT FROM AUTHOR]

Vermicomposting offers an eco-friendly solution to managing the sewage sludge generated in wastewater treatment plants. The objective of this study was to investigate the microbial community composition, structure and functionality during the vermicomposting of sewage sludge. We analyzed samples of sewage sludge, earthworm casts and vermicompost by applying high-throughput sequencing 16S and ITS rRNA. Most of the bacterial (95%) and fungal taxa (99%) were eliminated and subsequently replaced by other microbial taxa originating from earthworms. Further changes resulted in a vermicompost with a more diverse bacterial (but not fungal) community. In addition, the earthworm activity led to an increase in bacterial and a decrease in fungal alpha diversity, resulting in greater differences in beta diversity between sewage sludge, casts and vermicompost. We also found that bacterial pathways associated with amino acid and plant hormone biosynthesis and antibiotic synthesis were enriched. Vermicomposting successfully eliminated most of the 10 human bacterial pathogens found in the sewage sludge. Simultaneously, parasitic and pathogenic fungal taxa were removed. Overall, vermicompost derived from sewage sludge is safer for disposal on land than raw sludge, particularly regarding their respective microbial compositions. This indicates that it could potentially be used as a soil organic amendment and fertilizer. [ABSTRACT FROM AUTHOR]

Advanced 1H Nuclear Magnetic Resonance (NMR) relaxometry and diffusometry methods and VIS-nearIR spectroscopy combined with pH, electrical conductivity (EC) and totally dissolved solids (TDSSs) measurements were used to assess the properties of wastewater collected from a chicken slaughterhouse in each step of the treatment process (wastewater before treatment, biologically treated wastewater, chemically treated wastewater and discharged wastewater) and from sludge. The 1H NMR Carr–Purcell–Meiboom–Gill (CPMG) and Pulsed-Gradient-Stimulated-Echo (PGSE) decay curves recorded for all samples of wastewater were analyzed by inverse Laplace transform (ILT) to obtain the distributions of transverse relaxation times T2 and diffusion coefficient D. The VIS-nearIR total absorbance, T2-values, D-values, pH, EC and TDSS parameters were used for statistical analysis in principal component (PCA). The 1H T2-distributions measured for the slaughterhouse wastewater lie in two main regions reflecting the number of dissolved solids or the distribution of undissolved solids. The PCA analysis successfully differentiates between polluted and less polluted wastewaters and sludge. The wastewater treatment applied by the slaughterhouse is efficient. The recommended methods for wastewater monitoring are the NMR T2- and D-distributions and EC, TDSSs and NMR-D diffusion coefficient. Finally, Machine Learning algorithms are used to provide prediction maps of wastewater treatment stage. [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]

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]

Sewage sludge is an important soil conditioner, and source of nutrients with a potential for use in agriculture. However, such benefit needs to be weighed against the risks due to the presence of heavy metals, and other substances that may endanger human health, plants, soil and the ecosystem. This research had the objective of evaluating the agricultural potential of sewage sludge together with the risks that may be present in use. Samples of sewage sludge from seven wastewater treatment plants in Eswatini were analyzed for selected physical and chemical parameters, and heavy metal concentrations using commonly established laboratory procedures. The analysis results indicated that, sludge samples exhibited high organic matter content, cation exchange capacity, macro nutrients such as nitrogen and phosphorus and micro nutrients (trace metal elements) needed for plant growth. Anaerobically digested sludge samples showed higher carbon to nitrogen ratio because of biomass loss in the form of methane and carbon dioxide. The heavy metal concentrations are all within safe limits except the sludge from Matsapha area that had levels of chromium, and nickel above regulatory limits. With respect to their heavy metal contents, most of the sludge samples would qualify as Class A sludge ready to be used as organic fertilizer for agriculture without regular monitoring of heavy metals in the soil to which they are applied. The study results indicated the importance of sewage sludge for their agricultural potential through supplementation of both micro and macro nutrients needed for plant growth, for improving the soil properties such as water holding capacity and permeability, through the increase of organic matter content, and retention of nutrients due to the high cation exchange capacity. All these benefits are realized with sewage sludge being a lower cost alternative to commercial fertilizers. Moreover, the low concentration of heavy metals present in the sludge presents lower risk that may arise in the course of utilizing the sludge as agricultural supplement. [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]