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Mining activities put the Brazilian savannas, a global biodiversity hotspot, in danger of species and soil carbon losses. Experiments employing biosolids have been applied to rejuvenate this degraded ecosystem, but a lingering question yet to be answered is whether the microbiota that inhabits these impoverished soils can be recovered towards its initial steady state after vegetation recovery. Here, we selected an 18-year-old restoration chronosequence of biosolids-treated, untreated mining and native soils to investigate the soil microbiota recovery based on composition, phylogeny, and diversity, as well as the potential factors responsible for ecosystem recovery. Our results revealed that the soil microbiota holds a considerable recovery potential in the degraded Cerrado biome. Biosolids application not only improved soil health, but also led to 41.7 % recovery of the whole microbial community, featuring significantly higher microbiota diversity and enriched groups (e.g., Firmicutes) that benefit carbon storage compared to untreated mining and native soils. The recovered community showed significant compositional distinctions from the untreated mining or native soils, rather than phylogenetic differences, with physiochemical properties explaining 55 % of the overall community changes. This study advances our understanding of soil microbiota dynamics in response to disturbance and restoration by shedding light on its recovery associated with biosolid application in a degraded biodiverse ecosystem.

Thermochemical conversion of sewage sludge was proven as a useful method for waste management. Moderate temperatures in the absence of oxygen (pyrolysis) and hydrothermal carbonisation (HTC) performed in the presence of water, under autogenous pressures, were selected to treat the same sample of anaerobic-digested sewage sludge (SS). Two hydrochars were prepared by HTC in one high-pressure reactor using SS at 80% humidity content and heating it at 180 and 240 °C for 4 h, leading to H180-4 and H240-4, respectively. Two pyrochars were prepared from a pre-oven-dried SS at 105 °C for 48 h, followed by slow pyrolysis at 300 °C for 1 h, and 400 °C for 1 h leading to P300-1 and P400-1, respectively. HTC and slow pyrolysis significantly increased thermal stability of chars with higher temperatures, only reducing organic matter content (from 68.4 to 46.7–59.2%). Based on the characterisation results, the treatments could be a suitable choice to pre-treat sludge as soil amendment. Higher temperatures of pyrolysis would be attractive to store stable carbon in soil and construction materials, whilst lower temperatures of pyrolysis and HTC would produce a material that could be used as a source of organic matter providing a pool of labile carbon and fixed carbon. Thermochemical conversions generated mesopores (10–50 nm, >40%) and slightly increased surface area from 2 m2/g (SS) to 5–17 m2/g (pyrochars) and to 20 m2/g (hydrochars). Hence, HTC showed the greatest potential to produce a material with higher adsorption capacity (100 cm3/g for H180-4) but all chars should be subjected to an activation process to be able to compete with other kinds of feedstocks. The reduction of the H:C and O:C from the original SS after the treatments indicated a greater carbonisation degree, but a general reduction of the high heating value (HHV) from 17.94 MJ kg−1 in SS to (14.93 MJ kg−1). The torrefied char and hydrochars could be an attractive option to reduce energy of the process and drying stage in the case of HTC. [ABSTRACT FROM AUTHOR]

This study investigates the potential of converting waste biosolids from industrial sources, focusing on economic viability and heavy metal removal efficiency. Traditional management methods like landfilling and incineration are increasingly impractical due to land constraints and environmental concerns, prompting a shift towards thermal and biological conversion technologies including anaerobic digestion, pyrolysis, gasification, and hydrothermal liquefaction. Incorporating a pretreatment for heavy metal removal is essential, as industrial wastes are highly subjected to metal contamination. The study screens a range of metal removal processes, including precipitation, adsorption, ion exchange, and microwave induction. Although a techno-economic analysis can help give a perspective on the economic viability and environmental impact of each technology, it does not account for technical limitations and variations in the treated waste stream. A mixed integer linear programming (MILP) optimization model is developed to fill in this gap and assist in waste stream allocation to the most appropriate technology, taking into account both technology capacities and feed characteristics. This study looked into the optimal treatment route at different feed moisture contents and varying flow rates. The results demonstrate that the model distributes the feed across the different technologies on the basis of maximizing the capacity of the optimal technology while ensuring the moisture and heavy metal content limits are satisfied. Thus, it maximizes profitability and ensures heavy metal removal efficiency. By optimizing industrial biosolids treatment pathways, this study promotes sustainable resource recovery aligning with circular economy principles in waste management. The developed model facilitates informed decision-making in biosolids management and industrial waste treatment practices. [ABSTRACT FROM AUTHOR]

Pyrolysis has been identified as a possible thermal treatment process for reducing perfluoroalkyl and polyfluoroalkyl substances (PFAS) from wastewater solids, though off‐gas from the pyrolysis unit can still be a source of PFAS emissions. In this work, the fate of PFAS through a laboratory‐scale pyrolysis unit coupled with a thermal oxidizer for treatment of off‐gasses is documented. Between 91.5% and >99.9% reduction was observed through the entire system for specific compounds based on targeted analyses. Overall, the pyrolysis and thermal oxidizer system removed 99.4% of the PFAS moles introduced. Furthermore, shorter chain variants comprised the majority of reportable PFAS in the thermal oxidizer flue gas, indicating the longer chain compounds present in the dried biosolids fed to pyrolyzer decompose through the system. Practitioner Points: Thermal oxidation is a promising treatment technology for exhaust systems associated with thermal biosolids treatments.Thermal oxidation demonstrated significant degradation capabilities, with gas phase emissions comprising only 0.200% of initial PFAS concentrations to the system.Short‐chain PFAS made up a higher percent of thermal oxidizer emissions, ranging between 54.4% and 79.5% of PFAS in the exhaust on a molar basis.The possibility of recombinant PFAS formation and partial thermal decomposition of PFAS in thermal oxidation is a needed area of research. [ABSTRACT FROM AUTHOR]

Mine environments in boreal and sub-boreal zones are expected to experience extreme weather events, increases in temperature, and shifts in precipitation patterns. Climate change impacts on geochemical stability of tailings contaminants and reclamation structures have been identified as important climate-related challenges to Canadian mining sector. Adapting current reclamation strategies for climate change will improve long-term efficiency and viability of mine tailings remediation/restoration strategies under a changing climate. Accordingly, mesocosm experiments were conducted to investigate associations of climate-driven shifts in microbial communities and functions with changes in the geochemistry of organic covers and underlying tailings. Our results show that warming appears to significantly reduce C:N of organic cover and promote infiltration of nitrogen into deeper, unoxidized strata of underlying tailings. We also observed an increase in the abundance of some nitrate reducers and sulfide oxidizers in microbial communities in underlying tailings. These results raise the concern that warming might trigger oxidation of sulfide minerals (linked to nitrate reduction) in deeper unoxidized strata where the oxygen has been eliminated. Therefore, it would be necessary to have monitoring programs to track functionality of covers in response to climate change conditions. These findings have implications for development of climate resilient mine tailings remediation/restoration strategies. [ABSTRACT FROM AUTHOR]

The convective drying of spherical biosolids particles from two wastewater treatment plants (Type 1: anaerobic/anoxic treatment with belt filter press dewatering; Type 2: aerobic/anoxic treatment with centrifuge dewatering) was studied under 10 conditions across 44 trials. A wide spectrum of conditions including three drying temperatures (88, 109, and 138 ° C), two gas velocities (1.6 and 2 m s − 1 ), and particle sizes of 2 cm and 4 cm were investigated. Measured variables included particle mass, center/internal temperature, surface temperature, shrinkage, and qualitative observations of morphological changes. Most samples showed two drying periods, a constant rate period followed by a falling rate period. Additionally, it was found that drying rates and morphological changes depended significantly on particle size and drying intensity (i.e., drying gas temperature and gas velocity) with higher intensities resulting in larger, more porous particles. Internal temperature profiles displayed a consistent pattern, an initial heating phase where internal temperatures quickly rose to approximately the wet bulb temperature of the drying gas, a quasi-constant temperature phase at that temperature, and a final sharp increase/spike to reach equilibrium with the drying gas temperature. Moreover, IR images showed that sub-surface temperatures (between the core and surface) were significantly lower than surface temperatures. Surface temperatures showed a more linear increase throughout drying until equilibrium with the drying gas temperature. The consistent temperature difference between the center and surface, as well as the internal temperature profile, suggests the existence of a drying front, moving radially inward as the particle dries. This research contributes to a better understanding of biosolids drying dynamics, offering insights to improve thermal treatment strategies thereby contributing to the broader field of waste management. [ABSTRACT FROM AUTHOR]

Exposure to biosolids in human waste handling occupations is associated with a risk for illness due to microbial infections. Although several years of exposure to biosolids might be hypothesized to be a prophylaxis against infection, the risks associated with infections from antibiotic-resistant organisms can also be a potential concern. Therefore, this study aimed to conduct a screening level risk assessment by deriving occupational exposure limits (OELs) characterizing the risks of adverse health effects among workers in human waste handling occupations with a focus on exposure to two pharmaceuticals commonly found in biosolids: ciprofloxacin (CIP) and azithromycin (AZ). Epidemiological and exposure studies of workers exposed to biosolids were identified through searches of major scientific databases. Screening OELs (sOELs) for these antibiotics were derived using a standardized methodology. The airborne concentrations of CIP and AZ antibiotics were determined using an exposure factors approach. The health-based exposure limits (i.e., sOELs) and the acceptable daily exposure (ADE) values for both of these antibiotics were derived as 80 μg/m3 and 12 μg/kg-day, respectively. An exposure factor approach suggested that inhalation route exposures to CIP and AZ are well below the sOELs and ADE daily doses, and likely too low to cause direct adverse health effects through antibiotic inhalation. A critical review of epidemiological studies on different occupations handling biosolids showed that the workers in industries with potential biosolids exposure have experienced an increased incidence of microbial-exposure-related illness. The health effects seen in the workers have been attributed to bacterial, viral, and protozoan infections. To the extent that bacteria are the pathogen of concern, it is not clear whether these bacteria are resistant to antibiotics commonly found in biosolids. It is also unclear whether the presence of antibiotics or antibiotic-resistant bacteria increases the susceptibility of these workers. Additional studies will provide more definitive estimates of inhalation and dermal exposures to CIP and AZ and could verify the exposure estimates in this study based on the literature and common exposure factors. [ABSTRACT FROM AUTHOR]

Biosolids from stabilized sludge present a high fertilization potential, due to their rich content of nutrients and organic matter. The intrinsic and subtle properties of such fertilizers may greatly influence the fertilization efficiency. In this sense, the utility, advantages and limitations of advanced characterization methods, for the investigation of structural and dynamic properties at the microscopic scale of slightly different formulations of fertilizers were assessed. For that, three formulas of organo-mineral fertilizers based on biosolids (V1, V2 and V3), having at least 2% N, 2% P2O5, and 2% K2O, were characterized by advanced methods, such as 1H NMR relaxometry, 1H MAS and 13C CP-MAS NMR spectroscopy, 1H double-quantum NMR and FT-IR spectroscopy. Advanced structural characterization was performed using SEM, EDX and X-ray diffraction. Four dynamical components were identified in the NMR T2 distribution showing that the rigid component has a percentage larger than 90%, which explains the broad band of NMR spectra confirmed by the distributions of many components in residual dipolar coupling as were revealed by 1H DQ-NMR measurements. SEM and EDX measurements helped the identification of components from crystalline-like X-ray diffraction patterns. To evaluate the release properties of organo-mineral fertilizers, dynamic measurements of classical electric conductivity and pH were performed by placing 0.25 g of the formulas (V1, V2 and V3) in 200 mL of distilled water. The content of N and P were quantified using specific reactants, combined with VIS-nearIR spectroscopy. Two release mechanisms were observed and characterized. It was found that V3 presents the smallest release velocity but releases the largest number of fertilizers. [ABSTRACT FROM AUTHOR]

The present work deals with the “Decision Support System-Computer Program,” a tool that can be used for the reuse of treated wastewater and biosolids in agriculture. It has been developed by the research team of the Hellenic Open University, School of Science and Technology, Laboratory of Sustainable Waste Management. The basic aim of this tool being the following: (a) Exploitation of treated wastewater and biosolid reuse, in agriculture. (b) The safe reuse of treated wastewater and biosolids and optimization of soil fertility and productivity, minimizing human health risk. (c) Improvement of soil physical characteristic by increasing its organic matter content. (d) Rational crop fertilization, suggesting to user the right kind and the optimum levels of fertilizers to be applied to crops and accomplishment of economy in the use of inorganic fertilization of crops. (e) Supply plants with nutrients and irrigation water. (f) Optimize crop fertilization, reducing the fertilizer cost g- forecast and prevent soil pollution with heavy metals. (h) Optimize crop production quantitatively and qualitatively. (j) Protect agricultural soils from over accumulation of biosolids and the surface waters from heavy metals and nutrients. (k) Relieve of the environment from the pressure exerted by the accumulation of heavy metals and toxic substances. (l) Optimize environmental and life quality.

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]

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

Sewage sludge biochar (SSB) exhibits higher phosphorus (P) concentrations than the original sewage sludge (SS) and can be used as a P fertilizer. However, SSB-associated P is strongly retained in chemical compounds, which hinders its release and subsequent plant uptake. The use of organic acids facilitates P solubilization from SSB. Herein, we evaluated the effect of oxalic acid on P release from SSB applied to soil over time. Biochar was produced at 300 °C (SSB300) and 500 °C (SSB500). P release from SSB increased with an increasing concentration of oxalic acid in the SSB incubation solution and in SSB-treated soil. P speciation in SSB showed that P was predominantly inorganic (Pi), which represented 81% and 92% of the total P in SSB300 and SSB500, respectively. Pi in SSB consisted mainly of non-apatite P, accounting for 91% and 96% of all Pi in SSB300 and SSB500, respectively. Because SSB is predominantly insoluble in water, oxalic acid is crucial for the release of P from SSB. Oxalic acid increased P release from SSB300 and SSB500 by 103- and 600-fold, respectively, compared to the control, from which P was extracted with water. Oxalic acid enhancement of P release from SSB increases the possibility of using SSB as a sustainable source of P for agriculture. [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]

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]

The beneficial reuse and recovery of biosolids is an attractive option instead of disposal. However, odour emissions present significant challenges to land application of biosolids, increasing operational costs and reducing community acceptance. This study aimed to assess the influence of conveying and storage conditions in wastewater treatment plants on the sensory impact from biosolids. For sensory assessment, samples of anaerobically digested biosolids were collected after centrifuge and during storage out-loading. The emissions were extracted over 15 days using a dynamic flux chamber and sensory analysis conducted using an ODP coupled to a TD-GC-MS. Odour descriptors and intensities (from 1 - weak to 4 - strong) were evaluated by expert panellists, providing insights into the sensory aspects of odour emissions. The ODP results showed variations in the number of occurrences, intensity and modified frequency of odour events across the stages of wastewater solids processing and laboratory storage. Conveying could potentially impact the release of volatile compounds due to the mechanical agitation that can aerate and disturb the structure and surface of the biosolids. On the other hand, storage can accelerate biological and chemical processes as a result of the development of anaerobic conditions leading to subsequent odour generation. The interplay between wastewater treatment processes and odour emissions is complex and requires targeted strategies. The application of sensorial analysis contributes to valuable insights into understanding and managing odour emissions in wastewater treatment plants, offering potential avenues for optimizing operational parameters to benefit biosolids reuse initiatives. [ABSTRACT FROM AUTHOR]

Biosolids and Dairy Shed Effluent (DSE) can contain high concentrations of plant nutrients, making them potential resources for enhancing forest tree species growth and soil fertility. This study aimed to investigate the effects of biosolids and DSE application on the growth and nutrient uptake of Leptospermum scoparium and Kunzea robusta, while also considering the potential accumulation of contaminants. The results demonstrated that amending low-fertility soil with 2600 kg N ha-1 of biosolids and 200 kg N ha-1 of DSE positively influenced the growth of both L. scoparium and K. robusta. This improvement was evident through increased biomass production and enhanced uptake of essential elements such as calcium (Ca), potassium (K), and sulfur (S). Notably, L. scoparium exhibited superior growth when combined with DSE, while both species showed similar positive responses when combined with biosolids. However, it should be noted that the application of biosolids resulted in elevated concentrations of certain trace elements in the plants, whereas DSE did not. These trace elements included cadmium (Cd), copper (Cu), manganese (Mn), and zinc (Zn). Despite the increase, the levels of these elements did not exceed unacceptable thresholds. Considering the potential influence of biosolids on plant rhizodeposition, it is recommended that future studies investigate the interactions between plant roots and microbes, particularly in relation to plant element uptake. This line of research would further enhance our understanding of the underlying mechanisms involved. In conclusion, the findings suggest that the application of biosolids and DSE can effectively improve forest tree growth and nutrient uptake. However, careful management is necessary to mitigate the potential accumulation of trace elements. These results provide valuable insights for optimizing the use of biosolids and DSE in forestry practices, with potential economic and environmental benefits.

Applying sewage sludge and biosolids to agricultural lands has become an increasingly essential aspect of sustainable waste management and circular economy as it contributes positively to nutrient recycling, soil fertility and environmental health. Due to the widespread presence of per and polyfluoroalkyl substances (PFAS) globally, wastewater treatment plants have become a sink for PFAS. PFAS resist degradation by conventional wastewater treatment processes and are usually adsorbed to sewage sludge and biosolids. However, there have been significant concerns that land application of sewage sludge and biosolids could become a probable pathway for PFAS to enter the food chain. This article assessed the global sewage sludge/biosolids generation and country-to-country management methods through a systematic review. The global occurrence, distribution and prevalence of different classes of PFAS were assessed. We also evaluate the factors influencing PFAS contamination in sewage sludge/biosolids and the existing regulations on the upper limit of PFAS in biosolids before their disposal or application to farmland (or other usages). Additionally, most reports revealed high PFAS concentrations in influent, effluent, sewage sludge and biosolids generated worldwide. Overall, recorded PFAS concentration on a global scale varied from 2.2 to 2,156 ng/L (influents), 1.9-4,800 ng/L (effluents) and 2.1-500,000 ng/g (biosolids). While most studies focused on legacy PFAS detection, recent studies have revealed the prevalence of diPAPs in high concentrations in sewage sludge and biosolids, contributing from 40% to 95% of the total PFAS concentration. Across all PFAS classes, PFAAs and diPAPs were the dominant groups exhibiting elevated detection rates (35%-95%). Due to documented PFAS contamination in agricultural lands, rigorous regulations need to be instituted to govern the application of these biowastes on agricultural lands. However, several countries lack data on the level of PFAS in the sewage sludges they generate, and there are currently few or no regulations guiding their application to farmlands. Notably, the diPAPs class of PFAS was shown to be present in biosolids and sewage sludge; their inclusion in the list of PFAS required in standardized analytical methods and risk assessment becomes imperative. [ABSTRACT FROM AUTHOR]

Disposal of biosolids, the solid fraction of sewage treatment, is a global environmental issue. Biosolids contain valuable organic matter and plant nutrients; however, they also contain contaminants including trace elements, xenobiotics, and pathogens. The quality of the biosolids greatly depends on the source of wastewater (i.e., industrial vs. domestic) and the treatment processes. We aimed to determine the potential of three distinct biosolids and one pond sludge to grow indigenous plants for ecosystem restoration. For each amendment, we tested six indigenous species, Veronica salicifolia, Corokia cheesemanii, Griselinia littoralis, Phormium tenax, Poa cita, and Cordyline australis in bark mixed with biosolids and/or pond sludge at rates of 0–50%. There was a significant positive correlation between plant growth and biosolid addition up to a species-dependent plateau. Growth decreased at the highest rates. At a rate of 10% for fresh biosolids and 30% for aged biosolids provided consistent optimal growth across all species. The pond sludge was unsuitable for the establishment of indigenous seedlings. At the optimal rates, there were significant increases in foliar N, P, K, S, and Zn. None of the trace elements accumulated in the plants at phytotoxic concentrations or levels that presented a risk to ecosystems. Future work should determine how plants raised with biosolids perform once planted out in the field. [ABSTRACT FROM AUTHOR]

The asbestos mining industry has deeply transformed the landscapes of southern Quebec, leaving behind about 800 million tonnes of tailings and waste rock (overburden) in large piles near former mining towns. Some environmental issues arising from these landscapes (e.g., wind and water erosion) have been successfully addressed by covering the piles by mixing by-products to create technosols, which are then seeded with grasses. Yet, no attempt at afforestation had been made thus far because these environments are thought to impose too many constraints on tree establishment and growth. We developed two experimental plantations at a decommissioned asbestos mine in southern Quebec, on waste rocks and on tailings, to test the performance of eight tree species/clones/provenances planted on two types of technosols. Both were constructed from mixtures of municipal biosolids and deinking sludge and configured in small windrows. Soil texture, apparent bulk density, element composition, including carbon, nitrogen and some metals, as well as soil temperature, water potential and volumetric water content were assessed, together with seedling survival and growth (diameter and height). Leaf specific surface area, nutrients, water use efficiency (δ13C) and gas exchange (i.e., net photosynthetic assimilation rate, Anet, and stomatal conductance to water vapour, gsw) were evaluated for three hybrid poplar clones (Populus spp.) during the third growing season. Hybrid poplar clones had significantly higher survival (87–94%) after three years than planted conifers (10–56%) that were tested, although dry planting conditions could have exerted adverse effects on conifers. The conifer species exhibiting the highest survival rates (46–56%) was white spruce (Picea glauca). Average growth rates of hybrid poplar clones were 45 cm y−1, with some tree heights reaching over 300 cm after three years. Clone DN × M-915508 appears to be more drought-tolerant than other clones being tested. Phosphorus and potassium were the most growth-limiting nutrients. Few differences were apparent between technosols; results suggest that the addition of Class B contaminated soils to the main mixture of by-products has benefits with respect to tree survival and growth. Our study demonstrates a promising technology for reclamation through afforestation of asbestos mines in southern Quebec. Some treatments should be added to limit plant competition within the first few years as a means of augmenting survival and growth, whereas limited technosol volume and accompanying low moisture and nutrient availability could compromise mid- to long-term growth of trees. [ABSTRACT FROM AUTHOR]

Biosolids and Dairy Shed Effluent (DSE) can contain high concentrations of plant nutrients, making them potential resources for enhancing forest tree species growth and soil fertility. This study aimed to investigate the effects of biosolids and DSE application on the growth and nutrient uptake of Leptospermum scoparium and Kunzea robusta, while also considering the potential accumulation of contaminants. The results demonstrated that amending low-fertility soil with 2600 kg N ha-1 of biosolids and 200 kg N ha-1 of DSE positively influenced the growth of both L. scoparium and K. robusta. This improvement was evident through increased biomass production and enhanced uptake of essential elements such as calcium (Ca), potassium (K), and sulfur (S). Notably, L. scoparium exhibited superior growth when combined with DSE, while both species showed similar positive responses when combined with biosolids. However, it should be noted that the application of biosolids resulted in elevated concentrations of certain trace elements in the plants, whereas DSE did not. These trace elements included cadmium (Cd), copper (Cu), manganese (Mn), and zinc (Zn). Despite the increase, the levels of these elements did not exceed unacceptable thresholds. Considering the potential influence of biosolids on plant rhizodeposition, it is recommended that future studies investigate the interactions between plant roots and microbes, particularly in relation to plant element uptake. This line of research would further enhance our understanding of the underlying mechanisms involved. In conclusion, the findings suggest that the application of biosolids and DSE can effectively improve forest tree growth and nutrient uptake. However, careful management is necessary to mitigate the potential accumulation of trace elements. These results provide valuable insights for optimizing the use of biosolids and DSE in forestry practices, with potential economic and environmental benefits. [ABSTRACT FROM AUTHOR]

The application of biosolids to agricultural land has been identified as a major pathway of microplastic (MP) pollution to the environment. Very little research, however, has been done on the MP content of biosolids within Canada. Fifteen biosolid samples from different treatment processes (liquid, dewatered, pelletized, and alkali‐stabilized) were collected from 11 sources across southern Ontario to quantify and characterize the MP load within them. All samples exhibited MP concentrations ranging from 188 200 (±24 161) to 512 000 (±28 571) MPs/kg dry weight and from 4122 (±231) to 453 746 (±38 194) MPs/kg wet weight. Field amendment of these biosolids can introduce up to 3.73 × 106 to 4.12 × 108 MP/ha of agricultural soil. There was no significant difference in the MP concentrations of liquid, dewatered, and pelletized samples; but a reduction in MP content was observed in alkali‐stabilized biosolids. Fragments composed 57.6% of the MPs identified, while 36.7% were fibers. In addition, MPs showed an exponential increase in abundance with decreasing size. Characterization of MPs confirmed that polyester was the most abundant, while polyethylene, polypropylene, polyamide, polyacrylamide, and polyurethane were present across the majority of biosolid samples. The results of the present study provide an estimate of the potential extent of MP contamination to agricultural fields through the amendment of biosolids. Environ Toxicol Chem 2024;43:793–806. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. [ABSTRACT FROM AUTHOR]

Agricultural soils are degraded worldwide as result of anthropogenic activities; environmental contamination; and excessive use of chemicals, fertilizers, and pesticides. Scientists are concerned about this problem; during the past few years sewage compost and sludge have been used as alternatives to improve the soil's physical and chemical characteristics. Recycling solid waste residues can be a cost-effective way to reduce landfill material disposal and improve macro and micronutrients' availability in agricultural soils. In this study, two types of biosolids (compost and sludge) were added to tropical soils (coloso and voladora series) to improve the nutritional content in two edible herbs (basil and coriander). Soil mixtures were made by volume percentage; compost was constant, at 25%, and soil and sludge were incorporated in different proportions to complete the 100% (25 comp/75 soil, 25 comp/62.5 soil/12.5 sludge, 25 comp/50 soil/25 sludge and 25 comp/37.5 soil/37.5 sludge). pH and electrical conductivity were measured in soil mixtures. Basil and coriander were cultivated in pots for 30 days at an open greenhouse (5 replicates per soil mixtures). Germination percentage, stems' length, total chlorophyll (SPAD 502), acid digestions of plant tissues and an ICP-OES analysis were performed for both plants cultivated in all the soil mixtures. In voladora soil, the pH increased from 4.55 ± 0.10 to 5.64 ± 0.22 and EC from 0.0563 ± 0.0003 dS/m to 1.39 ± 0.01 dS/m in a 25% comp/37.5% soil/37.5% sludge mixture. In the coloso soil, the pH increased from 6.38 ± 0.13 to 6.82 ± 0.07 and electrical conductivity from 0.117 ± 0.001 to 1.310 ± 0.009 dS/m in 25% compost/37.5% soil/37.5% sludge mixture. Significant differences (p < 0.05) were found in the chlorophyll content and stem length for both plants. The highest chlorophyll value was in basil leaves from a 25% compost/50% soil/25% sludge mixture (43.20 ± 074) compared to the coloso soil (26.99 ± 0.43). In the voladora soil, the highest chlorophyll content was in a 25% compost/37.5% soil/37.5% sludge mixture (39.97 ± 0.83). In coriander leaves, the highest chlorophyll content was 33.01 ± 0.84 in the 25% compost/62.5% coloso/12.5% sludge mixture. In the voladora soil, chlorophyll content in leaves did not show a significant difference between treatments. Larger basil stems were found at 25% compost/75% voladora mixture (17.50 ± 2.39 cm) and in a 25% compost/62.5% coloso/12.5% sludge mixture (9.95 ± 0.71 cm) compared to control plants (3.45 ± 0.18 cm). Greater coriander stems were observed in a 25% compost/50% voladora/25% sludge mixture (2.43 ± 0.11 cm) and in a 25% compost/50% coloso/25% sludge mixture (2.17 ± 0.10 cm) compared to control plants (2.05 ± 0.07 cm). Macro and micronutrient content in plants increased with biosolids' incorporation to soils. Mg content in basil leaves increased from 8.61 ± 0.70 mg/g in the voladora soil to 10.31 ± 0.60 mg/g in a 25% compost/37.5% soil/37.5% sludge mixture. In coriander leaves, Mg increased from 6.91 ± 0.06 mg/g in a 25% compost/75% soil mixture to 9.63 ± 0.02 mg/g in a 25% compost/50% soil/25% sludge mixture. The Mn uptake by basil leaves increased from 0.076 ± 0.005 mg/g in the coloso soil to 0.152 ± 0.019 mg/g in a 25% compost/75% soil mixture. In coriander leaves, Mn increased from 0.357 ± 0.002 mg/g in a 25% compost/75% soil mixture to 0.651 ± 0.006 mg/g in a 25% compost/37.5% soil/37.5% sludge mixture. [ABSTRACT FROM AUTHOR]

The wastewater circular economy promises improved environmental impacts within the food-water-energy nexus. This requires verification as the global sanitation sectors seek to improve environmental impacts and achieve integrated water management. Life cycle assessment (LCA) has been used to compare novel technologies for wastewater treatment and recovery, but research addressing plant-wide improvements of co-product resource recovery using real data from full-scale plants is still needed, particularly in a Latin American context. In Chile, two wastewater treatment plants (WWTPs) have embraced the circular economy configuration, recovering treated effluent, biosolids, and biogas, in addition to implementing advanced nitrogen removal using different technologies. The LCA of these two WWTPs demonstrated that Plant A improved 8 out of 10 impact categories compared to the baseline conventional scenario, while Plant B improved 5 categories out of 10. The analysis of the two plants showed the influence of influent quality on environmental impacts and the trade-off that occurs between the different technologies implemented. Plant B generated larger environmental credits through increased biogas and biosolids recovery due to thermal hydrolysis pre-treatment and anaerobic digestion, combined with cogeneration of heat and power. Plant A implemented water recovery, which provided benefits on a smaller magnitude but to more impact categories. Therefore, both plants improved environmental impacts through the wastewater circular economy, but further improvements in system configurations are recommended in each.

The National Academies of Sciences, Engineering, and Medicine recommends per- and polyfluoroalkyl substance (PFAS) blood testing for patients with risk of elevated exposure, and the Agency for Toxic Substances and Disease Registry (ATSDR) suggests PFAS blood testing based on exposure. Barriers to PFAS blood testing include cost, access to labs, and evolving laboratory methods. We quantify water and serum PFAS levels among a highly-exposed cohort in an area with groundwater contaminated by historical agricultural biosolid application. We compare the gold standard PFAS serum test with a commercial test and results from a one-compartment toxicokinetic model. Participants were adults (n = 30) whose household (n = 19) water had levels of the sum of six PFAS > 500 ng/L. Serum PFAS were measured using liquid chromatography-tandem mass spectrometry. Demographic and water consumption data were collected via telephone. Serum PFAS results from the commercial test were accessed via medical record. Statistical analysis included descriptive statistics and bivariate plots of serum levels. Perfluorohexanoic acid, perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorobutanesulfonic acid, perfluorohexanesulfonic acid (PFHxS), and perfluorooctanesulfonic acid (PFOS) were detected in 19 wells, and PFHpA, PFOA, PFNA, perfluorodecanoic acid, perfluoroundecanoic acid, PFHxS, and PFOS were detected in at least 19 participants’ serum. In well water, PFOA and PFOS levels had geometric means (GMs) of 1749 ng/L (geometric standard deviation [GSD] 2.4) and 887 ng/L (GSD 19.7), respectively. In serum, PFOA and PFOS had GMs of 116.2 µg/L (GSD 13.5) and 58.3 µg/L (GSD 13.8), respectively. Our results are comparable with and had a wider mix of PFAS than other high-exposure cohorts. There was good agreement between the commercial and gold standard tests for PFOA, PFNA, and PFHxS, and mixed agreement between the gold standard test and modeled predictions, suggesting water-based toxicokinetic models of serum PFAS may be inadequate for assessing exposure in this population.

Increasingly stringent limits on nutrient discharges are motivating water resource recovery facilities (WRRFs) to consider the implementation of sidestream nutrient removal or recovery technologies. To further increase biogas production and reduce landfilled waste, WRRFs with excess anaerobic digestion capacity can accept other high-strength organic waste (HSOW) streams. The goal of this study was to characterize and evaluate the life-cycle global warming potential (GWP), eutrophication potential, and economic costs and benefits of sidestream nutrient management and biosolid management strategies following digestion of sewage sludge augmented by HSOW. Five sidestream nutrient management strategies were analyzed using environmental life-cycle assessment (LCA) and life-cycle cost analysis (LCCA) for codigestion of municipal sewage sludge with and without HSOW. As expected, thermal stripping and ammonia stripping were characterized by a much lower eutrophication potential than no sidestream treatment; significantly higher fertilizer prices would be needed for this revenue stream to cover the capital and chemical costs. Composting all biosolids dramatically reduced the GWP relative to the baseline biosolid option but had slightly higher eutrophication potential. These complex environmental and economic tradeoffs require utilities to consider their social, environmental, and economic values in addition to present or upcoming nutrient discharge limits prior to making decisions in sidestream and biosolids management.

Biosolids from stabilized sludge present a high fertilization potential, due to their rich content of nutrients and organic matter. The intrinsic and subtle properties of such fertilizers may greatly influence the fertilization efficiency. In this sense, the utility, advantages and limitations of advanced characterization methods, for the investigation of structural and dynamic properties at the microscopic scale of slightly different formulations of fertilizers were assessed. For that, three formulas of organo-mineral fertilizers based on biosolids (V1, V2 and V3), having at least 2% N, 2% P2O5, and 2% K2O, were characterized by advanced methods, such as 1H NMR relaxometry, 1H MAS and 13C CP-MAS NMR spectroscopy, 1H double-quantum NMR and FT-IR spectroscopy. Advanced structural characterization was performed using SEM, EDX and X-ray diffraction. Four dynamical components were identified in the NMR T2 distribution showing that the rigid component has a percentage larger than 90%, which explains the broad band of NMR spectra confirmed by the distributions of many components in residual dipolar coupling as were revealed by 1H DQ-NMR measurements. SEM and EDX measurements helped the identification of components from crystalline-like X-ray diffraction patterns. To evaluate the release properties of organo-mineral fertilizers, dynamic measurements of classical electric conductivity and pH were performed by placing 0.25 g of the formulas (V1, V2 and V3) in 200 mL of distilled water. The content of N and P were quantified using specific reactants, combined with VIS-nearIR spectroscopy. Two release mechanisms were observed and characterized. It was found that V3 presents the smallest release velocity but releases the largest number of fertilizers.

• Directions for future research of sustainable use of biosolids as a N source. • Global biosolids regulations and common biosolids treatment methods are discussed. • Higher total N content in HDB and reduced N availability from CB are reported. • Key factors in biosolids treatment affecting biosolids properties are identified. • Existing models of soil N dynamics after biosolids application are summarized. Application of biosolids to agricultural land has gained increasing attention due to their rich nutrient content. There are a variety of treatment processes for converting sewage sludge to biosolids. Different treatment processes can change the physicochemical properties of the raw sewage sludge and affect the dynamics of nutrient release in biosolids-amended soils. This paper reviews heat drying, alkaline treatment, and composting as biosolids treatment processes and discusses the effects of these treatments on biosolid nitrogen (N) content and availability. Most N in the biosolids remain in organic forms, regardless of biosolids treatment type but considerable variation exists in the mean values of total N and mineralizable N across different types of biosolids. The highest mean total N content was recorded in heat-dried biosolids (HDB) (4.92%), followed by composted biosolids (CB) (2.25%) and alkaline-treated biosolids (ATB) (2.14%). The mean mineralizable N value was similar between HDB and ATB, with a broader range of mineralizable N in ATB. The lowest N availability was observed in CB. Although many models have been extensively studied for predicting potential N mineralization in soils amended with organic amendments, limited research has attempted to model soil N mineralization following biosolids application. With biosolids being a popular, economical, and eco-friendly alternative to chemical N-fertilizers, understanding biosolids treatment effects on biosolids properties is important for developing a sound biosolids management system. Moreover, modeling N mineralization in biosolids-amended soils is essential for the adoption of sustainable farming practices that maximize the agronomic value of all types of biosolids. [ABSTRACT FROM AUTHOR]

Over recent decades, an extensive array of anthropogenic chemicals have entered the environment and have been implicated in the increased incidence of an array of diseases, including metabolic syndrome. The ubiquitous presence of these environmental chemicals (ECs) necessitates the use of real‐life exposure models to the assess cumulative risk burden to metabolic health. Sheep that graze on biosolids‐treated pastures are exposed to a real‐life mixture of ECs such as phthalates, per‐ and polyfluoroalkyl substances, heavy metals, pharmaceuticals, pesticides, and metabolites thereof, and this EC exposure can result in metabolic disorders in their offspring. Using this model, we evaluated the effects of gestational exposure to a complex EC mixture on plasma triglyceride (TG) concentrations and metabolic and epigenetic regulatory genes in tissues key to energy regulation and storage, including the hypothalamus, liver, and adipose depots of 11‐month‐old male offspring. Our results demonstrated a binary effect of EC exposure on gene expression particularly in the hypothalamus. Principal component analysis revealed two subsets (B‐S1 [n = 6] and B‐S2 [n = 4]) within the biosolids group (B, n = 10), relative to the controls (C, n = 11). Changes in body weight, TG levels, and in gene expression in the hypothalamus, and visceral and subcutaneous fat were apparent between biosolid and control and the two subgroups of biosolids animals. These findings demonstrate that gestational exposure to an EC mixture results in differential regulation of metabolic processes in adult male offspring. Binary effects on hypothalamic gene expression and altered expression of lipid metabolism genes in visceral and subcutaneous fat, coupled with phenotypic outcomes, point to differences in individual susceptibility to EC exposure that could predispose vulnerable individuals to later metabolic dysfunction. [ABSTRACT FROM AUTHOR]

Sewage sludge in natura is rich in nutrients, water, and organic matter and is essential for plant development. However, sewage sludge is diluted with water when composted, which could hamper plant growth. Therefore, supplementation with chemical fertilization may be necessary. This study evaluated the performance of composted sewage sludge (CSS) in producing Peltophorum dubium (Spreng.) Taub. seedlings with and without chemical fertilization via fertigation. The experiment was completely randomized in a 3 × 4 factorial scheme, with four fertigation (Ca(NO3)2(H2O)x: 0.87; (NH4)(H2PO4): 0.21; KCl: 0.47; (NH4)2SO4: 0.11; CH₄N₂O: 0.54; MgSO4: 0.52; Fe (13%): 0.03; B(OH)3: 6.00; CuSO4: 0.60; ZnSO4: 1.40; MnSO4: 6.00; Na2MoO4: 0.16 g L−1) doses: zero, standard, duplicate, and quadruplicate. In addition, three substrates were used: commercial substrate as the control, sewage sludge composted with sugarcane bagasse (LBC), and sewage sludge composted with Eucalyptus bark (LCE). The development of the seedlings was measured through the following variables: height, stem diameter, shoot/root ratio, leaf dry mass, root dry mass, total dry mass, green color index, the Dickson Quality Index, and the accumulation of nutrients in plant tissue. The seedlings produced with LCE that were subjected to the standard dose (1×) and the quadruplicate dose (4×) had the statistically highest mean values for most variables. Nevertheless, supplementation with chemical fertilization was necessary. Composted sewage sludge with eucalyptus bark, at the standard dosage, can be used for the commercial production of P. dubium seedlings, thus preventing the dangerous disposal of waste and strongly decreasing associated environmental hazards. [ABSTRACT FROM AUTHOR]

Biobased residues are local and cost-effective sources of soil amendments that can efficiently provide nutrients to crops, enhance soil health and serve as alternatives to mineral fertilizers. The objective of our study was to comprehensively evaluate the soil health and crop productivity of temperate agroecosystems amended with different types of organic residues (biobased residues), including composted food waste (compost), biosolid slurry (biosolids) and liquid anaerobic digestate (digestate), compared with nitrogen fertilizer. The experiment was conducted on a silt loam soil under maize-soybean rotation in Canada, where a wide range of physical, chemical and biological indicators were measured and integrated into a soil health score. Biobased residues resulted in about 50%-60% increase in soil-exchangeable potassium and 10% soil-exchangeable sodium over levels found in nitrogen fertilizer. Soil microbial biomass and the capacity of soil microbes to utilize carbon substrates differed among growing seasons but not among amendment types (p > .05). Crop productivity was similar among amendment types (p > .05). We found that the soil health score of biosolids was positively correlated with shoot and root biomass and negatively correlated with shoot nitrogen (p < .05), while that of nitrogen fertilizer was positively correlated with shoot carbon (p < .05). This was likely because of a variation in the availability of labile carbon and nitrogen among amendment types. Our research also suggests that temperate silt loam soil amended with biobased residues, especially biosolids, supplied sufficient nitrogen without the need for additional nitrogen fertilizer. [ABSTRACT FROM AUTHOR]

Sewage sludge contains plant nutrients and organic matter in its composition, making it a potential partial substitute for mineral fertilizers if it meets environmental, agronomic, and sanitary standards. The objective was to evaluate the content of nutrients and heavy metals in the sludge generated in four wastewater treatment stations (WWTPs) in Rio de Janeiro state and assess its potential value and usefulness. The samples of 19 batches from the WTTPs Alegria, Barra da Tijuca, Ilha do Governador, and Sarapuí were analyzed. The WWTPs differ in methods and processes used for treating sewage and sludge. The total contents of C, N, P, K, Ca, Mg, Fe, Al, Na, Co, Mn, As, Ba, Cd, Cr, Cu, Ni, Se, Pb, and Zn were evaluated, as well as the ratio C/N, pH, organic matter content, and electrical conductivity. The grouping of sludge samples was assessed using principal components (PCA) and cluster analysis. The economic valuation of sludge was conducted utilizing the substitute goods method, which compared the sludge's N-P-K contents with the prices of consolidated nutrient sources. All the evaluated sludge batches exhibited concentrations of heavy metals below the limits allowed by Brazilian law, along with high levels of nutrients and organic matter. Considering the chemical characteristics, all evaluated materials showed potential for agricultural use, but it is crucial to evaluate the microbiological characteristics of sludge batches before agriculture application. PCA and cluster analysis demonstrated that sludge samples from the same WWTP clustered close to each other, demonstrating higher similarity among themselves than with samples from other WWTPs. The sludge had an average added value of U$ 88.46 per megagram, considering the total contents of N, P, and K in its composition. Land application of sewage sludge can reduce the need to purchase mineral fertilizers, thereby supporting the feasibility of reusing this material in the agricultural sector. [ABSTRACT FROM AUTHOR]

Applying sewage sludge and biosolids to agricultural lands has become an increasingly essential aspect of sustainable waste management and circular economy as it contributes positively to nutrient recycling, soil fertility and environmental health. Due to the widespread presence of per and poly-fluoroalkyl substances (PFAS) globally, wastewater treatment plants have become a sink for PFAS. PFAS resist degradation by conventional wastewater treatment processes and are usually adsorbed to sewage sludge and biosolids. However, there have been significant concerns that land application of sewage sludge and biosolids could become a probable pathway for PFAS to enter the food chain. This article assessed the global sewage sludge/biosolids generation and country-to-country management methods through a systematic review. The global occurrence, distribution and prevalence of different classes of PFAS were assessed. We also evaluate the factors influencing PFAS contamination in sewage sludge/biosolids and the existing regulations on the upper limit of PFAS in biosolids before their disposal or application to farmland (or other usages). Additionally, most reports revealed high PFAS concentrations in influent, effluent, sewage sludge and biosolids generated worldwide. Overall, recorded PFAS concentration on a global scale varied from 2.2 to 2,156 ng/L (influents), 1.9–4,800 ng/L (effluents) and 2.1–500,000 ng/g (biosolids). While most studies focused on legacy PFAS detection, recent studies have revealed the prevalence of diPAPs in high concentrations in sewage sludge and biosolids, contributing from 40% to 95% of the total PFAS concentration. Across all PFAS classes, PFAAs and diPAPs were the dominant groups exhibiting elevated detection rates (35%–95%). Due to documented PFAS contamination in agricultural lands, rigorous regulations need to be instituted to govern the application of these biowastes on agricultural lands. However, several countries lack data on the level of PFAS in the sewage sludges they generate, and there are currently few or no regulations guiding their application to farmlands. Notably, the diPAPs class of PFAS was shown to be present in biosolids and sewage sludge; their inclusion in the list of PFAS required in standardized analytical methods and risk assessment becomes imperative.

Introduction Self-contained sanitation systems such as septic tanks, latrines, and public toilets store faecal sludge, which must be regularly evacuated. If this sludge is not regularly collected, transported, and treated in a wastewater treatment plant, it can cause serious harm to the environment and public health. Purpose This study aimed to show that the biosolids resulting from the treatment of septage collected in Kinshasa in the Democratic Republic of the Congo are uncontaminated and contain nutrients and properties that make them a resource to be valorized. Methods The present study was carried out in Kinshasa between January and March 2022. Samples of fresh faecal sludge were taken at Ndolo/auto service, a site where tanker trucks dump sludge from all over the city into a stream that flows into the Congo River. Pathogen levels were detected by counting bacteria. Helminth eggs were identified following the US Environmental Protection Agency's "Rule 503" recommendations for Class A and B biosolids. Total nitrogen was determined by the Kjeldahl method, while phosphorus and potassium were determined spectrometrically. Statistical analyses were performed using Excel 2021 and SPSS v.21 software. Results The results obtained showed values

Developing land use strategies to optimize carbon sinks and improve carbon footprints involves proposing efficient nature-based solutions that industries and businesses can implement while considering financial and legislative constraints. The pulp and paper industry is associated with significant greenhouse gas (GHG) emissions, primarily due to the substantial carbon dioxide (CO2) footprint of its mills. Also, some forestry operations contribute to the release of carbon to the atmosphere in the form of CO2 and methane (CH4). Conversely, this industry could potentially be a significant ally in the fight against climate change by favoring forestry practices that reduce carbon emissions and increase its sequestration, namely, by adding value to industrial by-products (e.g., biosolids) instead of treating them as wastes and landfilling them. Notably, the pulp and paper industry has been seeking alternative uses of its by-products, such as fertilizers to maximize tree growth. In this paper, we identify opportunities and challenges that exist for the pulp and paper industry in regard to recycling industrial by-products to: 1) lower GHG emissions directly at the mill and 2) improve its GHG budget by increasing carbon sequestration in forests and plantations. We illustrate our analyses by describing a case study of a pulp and paper mill in southern Quebec, Canada, that uses its biosolids and other by-products as fertilizers. This case study highlights that this strategy could not only contribute to the reduction of GHGs but could also create added value and improve economic returns of forest operations.

Purpose: The response of sweet sorghum to biosolids application under different irrigation regimes was studied in a field experiment conducted during 2010 and 2011 in Central Greece. The study assessed the effects of soil application of biosolids on plant height, biomass production, and water use efficiency.Method: The experiment consisted of nine treatments with three replications, including the application of biosolids to the soil, the application of fertilizer, and an untreated control, with three levels of irrigation (100%, 80%, and 60% of the crop water needs).Results: The study found that plant height was similar regardless of whether biosolids or fertilizer was applied. Under reduced irrigation, the application of biosolids at a rate of 5 Mg/ha resulted in a 9.2-11.5% increase in dry biomass production of sweet sorghum compared to dry biomass production from inorganic fertilizer application. When biosolids were applied with reduced irrigation, the dry biomass yield was similar to that produced by inorganic fertilizer application under full irrigation. Additionally, this was achieved while using 31.4% less irrigation water. Biosolids application to soil improved water use efficiency by up to 34% compared to fertilizer application.Conclusion: The findings of this research suggest that substituting inorganic fertilizers with biosolids application can lead to significant water savings.

Cadmium (Cd) is a highly toxic metal, occurring in municipal wastewater and stormwater as well as in wastewater from various industries. Char derived from the pyrolysis of municipal sewage sludge has the potential to be a low-cost sorption media for the removal of Cd. However, the balance between possible local char production and demand has not been assessed previously. In this study, the Cd sorption capacities of chars derived from primary (PSC) and secondary sludge (DSC), as well as the feasibility of char production for Cd sorbent purposes, and the pyrolysis energy balance were evaluated. Results showed that the sorption capacity of PSC (9.1 mg/g; 800 °C, 70 min) was superior to that of DSC (6.0 mg/g; 800 °C, 70 min), and increased with a higher pyrolysis temperature. Pyrolysis of primary sludge had a more favourable energy balance compared with the pyrolysis of digested sludge; however, when accounting for loss of biogas production the energy balance of primary sludge pyrolysis was negative. Assessment of the regional demand (Västerås, Sweden) indicated that PSC or DSC may cover the local Cd sorbent demand. However, it was estimated that large char volumes would be required, thus making the use of DSC/PSC less feasible. HIGHLIGHTS Char derived from the pyrolysis of municipal sewage sludge is a potential low-cost technology for Cd removal.; Char derived from primary sludge showed superior sorption capacity compared to char derived from mixed digested sludge.; Theoretical calculations indicated a potentially positive energy balance of digested sludge pyrolysis.; Locally, sludge pyrolysis may not be motivated by Cd sorbent production alone.;

One of the issues facing modern society, regardless of the socio-economic level of the communities involved, is the development of sustainable strategies for the management of sludge/biosolids. Nowadays, it is imperative to replace solutions aimed at simply “disposing of” with those oriented toward “maximizing recovery benefits”. It is desirable that agricultural use remains the main option in sludge/biosolids management; however, to ensure effective and safe agronomic benefits, correctly fulfill the legal requirements, and build stakeholder and public confidence, rigorous and sustainable procedures need to be established. The development of realistic and enforceable regulations is crucial, as they represent the right balance between the different aspects of coordinated and effective management. Furthermore, it is important to recognize that regulations must be supported by standardized characterization procedures and good practice guidelines because well-defined procedures allow the legal requirements to be correctly and uniformly met, as well as to reliably compare the results obtained under different conditions and their wide application in different regulatory contexts. In this article, the main aspects for (i) the sustainable application of sludge/biosolids in agriculture and (ii) the development of standardized characterization methods and procedures, thus ensuring effective agronomic benefits and guaranteeing quality/safety of agricultural products, are discussed. Some pieces on the evolution of European legislation in this field are also provided. Details and results of the research activities behind the development of these methods/procedures can be found in the referenced documents.

Sludge is a by-product of urban wastewater treatment plants using a biological method, which needs to be properly processed and managed in order to avoid environmental pollution and maintain the health of society. The main goal of the current research is to analyze the amounts of sludge disposal and energy recovery in the wastewater treatment plant in south of Tehran, emphasizing the nexus between carbon and energy footprints. Biogas and electricity produced in the wastewater treatment plant were carefully examined. Their impact on reducing direct and indirect emissions and carbon footprint was calculated using relevant international coefficients based on the amount of methane gas and electricity produced. Also, the amount of waste sludge was analyzed during the period of eight years (2014 to 2021). During the investigated period, at least 2414 tons, maximum 22850 tons and an average of 7265.4 tons of sewage sludge were produced per month. The amount of waste sludge produced per million cubic meters of treated wastewater is 24.4, 99.8 and 57.1 tons, respectively. On average, 9.5 million m3 of methane are produced every year, which is equivalent to 146347.54 tons of CO2/ year. On average, 1.1 MW/hr is produced in the power plant of the treatment plant, which is equivalent to preventing the emission of 3612 to 6472 tons of CO2/ year. The total direct and indirect emissions prevented are equal to 149,960 to 152,820 tons of CO2 equivalent. The production of biogas and its consumption to produce electricity in the investigated wastewater treatment plant has a significant effect on reducing greenhouse gas emissions.

Sewage sludge biochar (SSB) exhibits higher phosphorus (P) concentrations than the original sewage sludge (SS) and can be used as a P fertilizer. However, SSB-associated P is strongly retained in chemical compounds, which hinders its release and subsequent plant uptake. The use of organic acids facilitates P solubilization from SSB. Herein, we evaluated the effect of oxalic acid on P release from SSB applied to soil over time. Biochar was produced at 300 °C (SSB300) and 500 °C (SSB500). P release from SSB increased with an increasing concentration of oxalic acid in the SSB incubation solution and in SSB-treated soil. P speciation in SSB showed that P was predominantly inorganic (Pi), which represented 81% and 92% of the total P in SSB300 and SSB500, respectively. Pi in SSB consisted mainly of non-apatite P, accounting for 91% and 96% of all Pi in SSB300 and SSB500, respectively. Because SSB is predominantly insoluble in water, oxalic acid is crucial for the release of P from SSB. Oxalic acid increased P release from SSB300 and SSB500 by 103- and 600-fold, respectively, compared to the control, from which P was extracted with water. Oxalic acid enhancement of P release from SSB increases the possibility of using SSB as a sustainable source of P for agriculture.

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 Background Over 40% of the six million dry metric tons of sewage sludge, often referred to as biosolids, produced annually in the United States is land applied. Biosolids serve as a sink for emerging pollutants which can be toxic and persist in the environment, yet their fate after land application and their impacts on human health have not been well studied. These gaps in our understanding are exacerbated by the absence of systematic monitoring programs and defined standards for human health protection. Methods The purpose of this paper is to call critical attention to the knowledge gaps that currently exist regarding emerging pollutants in biosolids and to underscore the need for evidence-based testing standards and regulatory frameworks for human health protection when biosolids are land applied. A scoping review methodology was used to identify research conducted within the last decade, current regulatory standards, and government publications regarding emerging pollutants in land applied biosolids. Results Current research indicates that persistent organic compounds, or emerging pollutants, found in pharmaceuticals and personal care products, microplastics, and per- and polyfluoroalkyl substances (PFAS) have the potential to contaminate ground and surface water, and the uptake of these substances from soil amended by the land application of biosolids can result in contamination of food sources. Advanced technologies to remove these contaminants from wastewater treatment plant influent, effluent, and biosolids destined for land application along with tools to detect and quantify emerging pollutants are critical for human health protection. Conclusions To address these current risks, there needs to be a significant investment in ongoing research and infrastructure support for advancements in wastewater treatment; expanded manufacture and use of sustainable products; increased public communication of the risks associated with overuse of pharmaceuticals and plastics; and development and implementation of regulations that are protective of health and the environment.

The purpose of this investigation was to verify the effectiveness of composting in the sanitization of sludge from urban sewage (SS). The treatments (T) used consisted of SS mixed with sugarcane bagasse (SB), tree pruning residues (TP), poultry litter (PL) or grass clipping (GC) at a carbon/nitrogen ratio of approximately 30/1 and ratios of T1 (SS+SB), T2 (SS+SB+TP), T3 (SS+SB+GC), T4 (SS+SB+PL) or T5 (SS+SB+TP+GC). Temperature was measured daily for over 280 days of composting. Every two weeks, the compounds were analyzed for thermotolerant coliforms and viable helminth eggs using the multiple-tube and Yanko techniques; and once each month to identify Cryptosporidium spp. and Giardia spp. (oo)cysts using the sucrose and zinc sulfate centrifugal flotation technique and nested PCR followed by sequencing. The maximum temperatures measured in the thermophilic phase of the compounds ranged from 55°C to 64.8°C, and at day 280, weight reductions of 27% (T1), 48% (T2), 63% (T3), 66% (T4) and 64% (T5) were observed. The absence of fecal coliforms was observed from day 98 (T4), day 126 (T1), day 196 (T3 and T5) and day 210 (T2). All treatments resulted in helminth egg inviability and the absence of protozoan (oo)cysts. Only T4 and T5 were positive for G. duodenalis according to the sequencing analysis. In conclusion, high temperatures during the composting thermophilic phase made the use of pathogens required by legislation unfeasible; therefore, it is important to investigate the viability of protozoa in compounds to ensure a safe final product for human and animal health.

Background: Sewage sludge is rich in fecal coliforms, Salmonella, parasite eggs, and heavy metals that can cause disease in humans. The aim of this study was to evaluate the quality of outlet biosolids and sludge heavy metals in the wastewater treatment plants (WWTP) in Mazandaran province and to compare them with the Environmental Protection Agency (EPA) standards. Methods: This study was carried out on the sludge of the treatment plants of Sari, Joybar, Babol, Babolsar, Nowshahr, and Nowshahr-Chalus sludge compost plants. In this study, physical, chemical, and biological properties of sludge samples including retention time, pH, total solids (TS), color, heavy metals (copper, zinc, nickel, cadmium, and chromium) as well as the density of fecal coliform, Salmonella and parasite eggs were determined and reported. Results: Biosolids of Joybar, Babol, Babolsar, and Nowshahr-Chalus WWTP in terms of parasite eggs were in class A. Biosolids of Sari WWTP in summer after drying off naturally were located in Class A, and in summer and spring, were located in Class B based on the US EPA criteria. The average concentration of heavy metals (copper, zinc, nickel, cadmium, and chromium) was lower than the EPA standard. Conclusion: The results showed that mostly the treated sewage sludge in Mazandaran WWTPs were in Class B of the EPA guideline. The concentration of heavy metals in the biosolids of these WWTPs is lower than the EPA regulation and the use of these biosolids in agriculture is not limited for these metals.