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The land application of sewage sludge can cause different environmental problems due to the high content of potentially toxic elements (PTEs). The objective of this study was to compare the effect of urban biological sewage sludge (i.e. the waste of activated sludge process) and its derived biochar as the soil amendments on the bioavailability of PTEs and their bioaccumulation by corn (Zea mays L.) under two months of greenhouse conditions. The soil was treated by adding biochar samples at 0 (control), 1, 3, 5% w/w. The diethylenetriamine pentaacetic acid (DTPA)-extractable concentrations of PTEs including Zn, Pb, Cd, Cr, Ni, Fe, and Cu in soil and their accumulation by plant shoot and root were measured. Conversion of the biological sewage sludge into the biochar led to decrease the PTEs bioavailability and consequently decreased their contents in plant tissues. The DTPA extractable metal concentrations of produced biochar in comparison to the biological sewage sludge reduced 75% (Cd), 65% (Cr), 79% (Ni and Pb), 76% (Zn), 91% (Cu) and 88% (Fe). Therefore, the content of Ni, Fe, Zn and Cd in corn shoot was decreased 61, 32, 18 and 17% respectively in application of 5% biochar than of raw sewage sludge. Furthermore, the application of 5% biochar enhanced the physiological parameters of the plants including shoot dry weight (twice) and wet weight (2.25 times), stem diameter (1.70 times), chlorophyll content (1.03 times) in comparison to using 5% raw sewage sludge. The results of the study highlight that application of the biochar derived from urban biological sewage sludge in soil could decrease the risk of PTEs to the plant. [ABSTRACT FROM AUTHOR]

Organophosphate ester flame retardants (OPFRs) are ubiquitous organic pollutants in the environment and present an important preoccupation due to their potential toxicity to humans and biota. They can be found in various sources, including consumer products, building materials, transportation industry, electronic devices, textiles and clothing, and recycling and waste management. This paper presents the first survey of its kind in Romania, investigating the composition, distribution, possible sources, and environmental risks of OPFRs in five wastewater treatment plants (WWTPs) and the rivers receiving their effluents. Samples from WWTPs and surface waters were collected and subjected to extraction processes to determine the OPFRs using liquid chromatography with mass spectrometric detection. All the target OPFRs were found in all the matrices, with the average concentrations ranging from 0.6 to 1422 ng/L in wastewater, 0.88 to 1851 ng/g dry weight (d.w.) in sewage sludge, and 0.73 to 1036 ng/L in surface waters. The dominant compound in all the cases was tri(2-chloroisopropyl) phosphate (TCPP). This study observed that the wastewater treatment process was inefficient, with removal efficiencies below 50% for all five WWTPs. The environmental risk assessment indicated that almost all the targeted OPFRs pose a low risk, while TDCPP, TCPP, and TMPP could pose a moderate risk to certain aquatic species. These findings provide valuable information for international pollution research and enable the development of pollution control strategies. [ABSTRACT FROM AUTHOR]

An innovative process layout for sludge waste management based on chemical looping combustion and flue gas methanation is analyzed in this work. The technical performance of the system was assessed by considering that the flue gas is first purified and then mixed with a pure hydrogen stream sourced from an array of electrolysis cells to produce methane. The life cycle assessment (LCA) and life cycle cost (LCC) methodologies were applied to quantify the environmental and economic performances of the proposed process, and a hotspot analysis was carried out to recognize its most critical steps. The proposed system was then compared with a reference system that includes both the conventional waste management pathways for the Italian context and methane production. Finally, to account for the variability in the future economic climate, the effects of changes in landfill storage costs on sewage end-of-life costs for both the proposed and reference systems were evaluated. With respect to 1 kg/h of sewage sludge with 10%wt of humidity, the analysis shows that the proposed system (i) reduces landfill wastes by about 68%, (ii) has an end-of-life cost of 1.75 EUR × kg−1, and (iii) is environmentally preferable to conventional sewage sludge treatment technologies with respect to several impact categories. [ABSTRACT FROM AUTHOR]

This study evaluated the levels of heavy metals in the soil and castor bean plant after fertilization with sewage sludge (SS) subjected to different stabilization processes. The study was conducted in a Haplic Cambisol with the following treatments: control (CO), fertilization with solarized sewage sludge (SSS), composted sewage sludge (CSS), vermi composted sewage sludge (VSS), limed sewage sludge (LSS), and mineral fertilizer (MF). The experimental design included a subdivided plot scheme with fertilization being the primary factor and soil layers or leaf parts being the secondary factor. The data obtained were analyzed using analysis of variance and the Scott-Knott test with 5% significance. Fertilization with SSS, CSS, and LSS led to the highest increase in Zn in the soil, mainly in the surface layer. In the leaf tissues, Zn and Cu levels were higher with the CO and SSS treatments, whereas the Ni level was higher with SSS, CSS, VSS, and MF treatments. In general, Zn and Cu levels were higher in the leaf limb than in the petiole, whereas Ni, Pb, and Cr levels were higher in the petiole than in the leaf limb. In any case, no symptoms of toxicity in the plants and no risk of soil contamination were observed with any of the fertilization treatments. [ABSTRACT FROM AUTHOR]

Waste management practices are vital for human health and the environment in a world where natural resources stress is expected to increase with the growth of population. Our study aimed to evaluate the potential use of crop-livestock residue as a bulking agent associated with the ideal level of hydrated lime for the stabilization and sanitization of urban sewage sludge through the alkalization-composting process. Therefore, we determined the alkalization efficiency on the heavy metal concentration in urban sewage sludge, quantified the viable eggs of helminths in pure and alkalized sludge, and measured the rate of earthworms (Eisenia fetida) surviving in the vermicomposting process using different levels of alkalized urban sewage sludge associated with crop-livestock residue. Four sequential trials were carried out in a completely randomized design with three replicates. The lime alkalization reduced the levels of Ba, As, Pb, Cu, Cr, Mo, Ni, and Zn compared to the pure urban sewage sludge. Using 30% w/w of lime in the urban sewage sludge (SS-30) for composting process reduced the viable helminth eggs by 71, 72, and 69% for sugarcane bagasse (Saccharum officinarum; SB), fresh chopped Napier-grass (Pennisetum purpureum; NG), and bovine ruminal content (BR), respectively. The ideal level of hydrated lime for stabilization and sanitization of urban sewage sludge was found to be 30%, which was able to reduce the heavy metals. The residues have the potential as a bulking agent for the composting of urban sewage sludge when associated with alkalization. The lime alkalization decreases the total number of helminth eggs and the number of viable eggs. The possibility of starting a vermicomposting using the mixtures is promising, evidenced by the earthworm survival in composting urban sewage sludge mixed with crop-livestock residues after 45 days of composting. The earthworm survival is maintained by an association of at least 80% of the crop-livestock residues. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the capacity of different inoculum sources and their bacterial diversity to generate hydrogen (H 2). The highest Simpson (0.7901) and Shannon (1.581) diversity indexes for H 2 -producing bacterial isolates were estimated for sewage inocula. The maximum cumulative H 2 production (H max) was 639.6 ± 5.49 mL/L recorded for the sewage inoculum (SS30) after 72 h. The highest H 2 -producing isolates were recovered from SS30 and identified as Clostridium saccharobutylicum MH206 and Lactobacillus brevis MH223. The H max of C. saccharobutylicum , L. brevis , and synergistic coculture was 415.00 ± 24.68, 491.67 ± 15.90, and 617.67 ± 3.93 mL/L, respectively. The optimization process showed that the H max (1571.66 ± 33.71 mL/L) with a production rate of 58.02 mL/L/h and lag phase of 19.33 h was achieved by the synergistic coculture grown on 3% molasses at 40 °C, pH 7, and an inoculum size of 25% (v/v). This study revealed the economic feasibility of the synergistic effects of coculture on waste management and biohydrogen production technology. [Display omitted] • Screening of H 2 production by different microbial communities was investigated. • Diversity of H 2 producing bacteria in sewage, rumen and wastewater was achieved. • H 2 yield from sugarcane molasses was improved using bacterial synergism. • Maximum H 2 yield of 1571.66 mL/L obtained through an optimization strategy. [ABSTRACT FROM AUTHOR]

Growing concern over mineral resources supply forces us to search for alternative sources of Phosphorus. The possibility to recover phosphorus from incinerated sewage sludge ashes appears to be an important aspect in anthropogenic phosphorus cycle and sustainable economy. To make phosphorus recovery efficient it is important to learn the chemical and mineral composition of ash and phosphorus speciation. The phosphorus content in the ash was over 7%, what corresponds to medium rich phosphorus ores. The main phosphorus rich mineral phases were phosphate minerals. The most widespread was tri-calcium phosphate Whitlockite with various Fe, Mg and Ca proportions. In minority Fe–PO4 and Mg–PO4 were detected. Whitlockite commonly overgrown with hematite, influences negatively mineral solubility and thus recovery potential and indicates low bioavailability of phosphorus. Considerable amount of phosphorus was found in the low crystalline matrix where phosphorus content was around 10 wt% however low crystallinity and dispersed phosphorus also does not strengthen the potential to recover this element. [ABSTRACT FROM AUTHOR]

One of the greatest challenges humankind currently faces is global warming, mainly caused by greenhouse gas emissions. Here we have attempted to show how thermal conversion products, specifically from the pyrolysis of biomass wastes such as sewage sludge, can be used effectively and equivalently to sequester CO2 in brownfield and degraded areas. Scenarios were devised that showed the significant potential for CO2 sequestration in the form of biochar from sewage sludge deposited on degraded and brownfield areas. With the current amount of sludge production, such sludge could even be used in its entirety as a raw material in pyrolysis processes, where, in addition to the biochar, the heat necessary for drying the sludge could be generated and high-energy gas and liquid fractions could be obtained, which could be used to produce alternative fuels. It is therefore important to consider both the potential for CO2 sequestration on degraded and brownfield sites and the potential for sludge disposal in Europe as viable options for reducing greenhouse gas emissions and promoting sustainable waste management practices. [ABSTRACT FROM AUTHOR]

The waste management sector is transitioning from a dirty and undesirable industry towards a green and sustainable future where energy and materials are recycled. Recycling has potential in sewage sludge treatment, where energy and highly valuable nutrients can be recovered through innovative and sustainable sludge management. Although there are many technologies and techniques already used for sewage sludge, the indicators for their sustainability are not developed. In terms of sustainable and innovative sewage sludge treatment, usually, only techno-economic aspects of existing and current technologies are considered. We explore the existing indicators and propose new indicators for sustainable and innovative sewage sludge treatment technologies. The indicators are differentiated into four main categories: technical, social, environmental and economic, where specific indicators are explained, followed by a description of their impact on sustainability. We also consider a case study using the LEAP tool, which considered GHG emissions when utilizing sewage sludge as an energy feedstock to replace existing fossil fuels in the energy mix in several scenarios. The results showed a significant emissions reduction when sludge is used—37.6% and 90.9% in 2030 and 2050, respectively. [ABSTRACT FROM AUTHOR]

Municipal sewage sludge is the residual material produced as a waste of municipal wastewater purification. It is a sophisticated multi-component material, hard to handle. For many years, it has been landfilled, incinerated, and widely used in agriculture practice. When unproperly discharged, it is very polluting and unhealthy. The rapidly increasing global amount of municipal sewage sludge produced annually depends on urbanization, degree of development, and lifestyle. Some diffused traditional practices were banned or became economically unfeasible or unacceptable by the communities. In contrast, it has been established that MSS contains valuable resources, which can be utilized as energy and fertilizer. The objective of the review was to prove that resource recovery is beneficially affordable using modern approaches and proper technologies and to estimate the required resources and time. The open sources of information were deeply mined, critically examined, and selected to derive the necessary information regarding each network segment, from the source to the final point, where the municipal sewage sludge is produced and disposed of. We found that developed and some developing countries are involved with ambitious and costly plans for remediation, the modernization of regulations, collecting and purification systems, and beneficial waste management using a modern approach. We also found that the activated sludge process is the leading technology for wastewater purification, and anaerobic digestion is the leading technology for downstream waste. However, biological technologies appear inadequate and hydrothermal carbonization, already applicable at full scale, is the best candidate for playing a significant role in managing municipal sewage sludge produced by big towns and small villages. [ABSTRACT FROM AUTHOR]

Concrete is currently the most widely used man-made composite material and second only to water in the entire range of materials used. It is a material with a high potential to adapt to specific operating conditions and can be made from local raw materials (aggregate, cement, water, and mineral additives), which can be selected to minimize the carbon footprint. The use of fly ash from the thermal conversion of sewage sludge in concrete is in accord with the advice on waste management proposed in the European Union. This paper presents the results of research on the effect of the partial replacement of Portland cement with this material on the strength parameters, frost resistance, and carbonation of concrete compared to reference concrete and to concrete containing a conventional additive - siliceous fly ash. In addition, the potential environmental impact of the use of sewage sludge ash was investigated by determining the leachability of heavy metals. Concrete mixtures of C20/25 ordinary concrete, based on CEM I 42.5R Portland cement, with varying ash contents comprising 0-20% of the cement mass, were produced for the experimental work. The obtained test results confirmed the possibility of producing plain concrete modified with fly ash from the thermal treatment of sewage sludge and the concrete's compliance with the environmental requirements relating to the leaching of heavy metals. [ABSTRACT FROM AUTHOR]

The production of added-value bio-products and energy from waste streams while minimizing environmental impacts is a crucial aspect within the circular economy's principles. The biorefinery can be an exit to the constant increasing of organic food waste and sewage sludge to solve the issues of waste disposal. This work deals with the production of volatile fatty acids (VFA) as added-value products from food waste and sewage sludge mixture in a pilot scale acidogenic fermentation process. Moreover, due to the lack of information about safety aspects in the literature, the explosive risk of the fermenter has been assessed by means of the quantification of lower flammability limit (LFL) of the generated flammable gases. Different temperature and feedstock's composition were tested, as well as the effect of thermal hydrolysis. Mesophilic fermentation (37 °C) on thermally hydrolysed feedstock (48 h at 72 °C) ensured stability in terms of VFA production at high concentration (30 ± 2 gCOD VFA /L) and COD VFA /COD SOL ratio (0.86 ± 0.09). Such condition also showed high LFL (28.9%), corresponding to a less hazardous condition compared to the other investigated, especially the thermophilic ones where LFL changed between 18% and 26%. • Thermal hydrolysis and mesophilic temperature enhance VFA production. • VFA profile affected by feedstock composition. • Assessment of explosive risk from the gas composition of fermentation reactor. • Lower risk conditions correspond to a parallel higher VFA production and yield. [ABSTRACT FROM AUTHOR]

Wastewater treatment plants are facilities where wastewater is treated by technological processes. A byproduct of a wastewater treatment plant is sewage sludge, which can be both a good soil conditioner and a source of nutrients for the crops to which it is applied. Energy crops are non-food plants that can cleanse the soil of heavy metals through their ability to phytoremediate. The purpose of this study is to determine the effects of different amounts of sewage sludge on soil and plants. In the experiment Virginia mallow (Sida hermaphrodita L.) was used and the influence of stabilized sewage sludge in the amounts of 1.66, 3.32 and 6.64 t/ha dry matter on the energy composition and biomass yield was observed.The obtained results showed a yield of 8.85 t/ha at the maximum amount of sewage sludge used. Hemicellulose content was 20.20% in the application of 6.64 t/ha of sewage sludge and 19.70% in the control, while lignin content was 17.97% in the control and 16.77% in the maximum amount of sewage sludge. The heavy metals molybdenum and nickel did not differ significantly under the influence of larger amounts of sewage sludge, while manganese increased from 23.66 to 35.82 mg/kg. [ABSTRACT FROM AUTHOR]

The conversion of sludge from sewage treatment plants (STPs) into bioenergy is a promising approach to sustainable energy generation and effective waste management. This process occurs through anaerobic digestion in the biodigesters, resulting in biogas production. However, given that the sludge comes from various STPs in different cities, identifying the ideal locations requires careful selection due to the complexity of sludge management, associated costs, and transportation logistics. In this context, this work aims to formulate a mathematical optimization model to determine the best locations for the installation of sludge processing centers, considering the minimization of the economic, environmental, and social costs. The model is implemented in MATLAB software, and geospatial analysis of the regions of interest is performed using QGIS software. For model validation, three distinct instances are considered. The results obtained demonstrate significant potential in terms of biogas and electricity production, with the highest values for the third instance being 61,997,501 Nm³/year and 149,275 MWh/year, respectively. The proposed methodology represents a crucial step toward sustainability, as it promotes the generation and use of bioenergy from STP sludge and contributes to improved waste management and the prevention of air, soil, and water pollution. • A mixed NLP model is proposed to assist in the process of utilizing sewage sludge. • A genetic algorithm is proposed as a metaheuristic for optimization model solution. • Focus is given to minimizing economic, social, and environmental costs. • Computational experiments with real instances are conducted. [ABSTRACT FROM AUTHOR]

Biosolids, derived from wastewater treatment processes, have garnered increasing attention as a valuable resource due to their rich organic and inorganic constituents, which can be beneficially utilized in multiple sectors, including agriculture, civil engineering, and energy recovery. The present review article begins by providing an overview of biosolids, including their production methods and classification based on treatment processes. Subsequently, the chemical composition of biosolids is explored, highlighting the diverse array of organic and inorganic components present. The characterization techniques employed for analyzing biosolids, such as spectroscopy, chromatography, and microscopy, are thoroughly discussed, emphasizing their role in determining the quality and suitability of biosolids for different applications. Furthermore, the environmental impacts associated with biosolids disposal are extensively examined. This includes the potential risks posed by heavy metals, pathogens, and emerging contaminants, as well as strategies for mitigating these risks through proper treatment and management practices. In addition to environmental considerations, the article explores the various products that can be derived from biosolids. These include organic matter-rich soil amendments for agricultural applications, inorganic nutrient supplements for enhancing plant growth, and the potential for energy recovery through anaerobic digestion and thermal conversion technologies. The utilization of biosolids in civil engineering projects, such as landfill capping and construction materials, is promising. Land application of biosolids also can have economic and waste management benefits (e.g., conservation of landfill space; reduced demand on non-renewable resources like phosphorus; and a reduced demand for synthetic fertilizers). [Display omitted] • The utilization of biosolids and their environmental impacts and disposal was reviewed. • The nutrient content of biosolids provides insight into their agronomic utility. • Methane and biogas production is an emerging technique for recovering energy from biosolids. • The conversion of biosolids into useful materials is significant. [ABSTRACT FROM AUTHOR]

Chain elongation (CE) is a promising technology that can produce medium-chain fatty acids (MCFAs) from sewage sludge, reaching the dual benefits of waste management and clean energy production. The feasibility of using biochar to enhance CE efficiency was examined in this study, where the underlying promoting mechanisms and optimal biochar dosage were also simultaneously explored. Biochar improved the carbon conversion and electron transfer efficiency of CE. The highest caproate concentration (3347.95 mg/L) occurred in the group with 10 g/L biochar addition, and caprylate was most accumulated (612.36 mg/L) when biochar dosage was 20 g/L. The electroactive genera positively related to MCFAs (e.g., norank_f__JG3 0-KF -CM45 and Acetobacterium) were noticeably enriched by low dosage, but the acidification genera proliferated better under excessive dosage. The different MCFAs production induced by varied biochar dosages was closely related to the genera Dysgonomonadaceae. The strengthened dominant CE pathways, FAB, might account for the promoted MCFAs production. [Display omitted] • Biochar accelerated substrate utilization and MCFAs production from sewage sludge. • Low biochar dosage enriched CE bacteria and enhanced their syntrophic metabolism. • Acidification bacteria proliferated better than CE bacteria under excessive biochar. • Dysgonomonadaceae was tightly related to varied MCFAs caused by biochar dosage. • Biochar reinforced the dominant status of the FAB metabolic pathway. [ABSTRACT FROM AUTHOR]

Sewage sludge management for fertilizer purposes can be a step in the circular phosphorus (P) economy. Using microbial solubilization in manufacturing fertilizers from recycled materials is an innovative approach with the potential to increase P compounds' bioavailability, and fertilizers from sewage sludge ash and P-solubilizing bacteria are promising products of this technology. In addition to P and a range of macronutrients, these fertilizers contain small amounts of micronutrients and potentially toxic elements. This paper discusses the effects of fertilizer on iron (Fe) and aluminum (Al) content in soil, test plants (spring or winter wheat; grain and straw), weeds and post-harvest residues, based on field experiments. Treatments with conventional P fertilizers (superphosphate, phosphorite) and without P fertilization provided references. The tested biofertilizers containing the Bacillus megaterium or Acidithiobacillus ferrooxidans strain had no effect on total Fe and Al content in the soil or on the concentration of these elements in plant biomass when applied at P doses up to 35.2 kg ha–1. Fe and Al levels in grain did not suggest a potential risk to consumers. [ABSTRACT FROM AUTHOR]

Biological sludge is waste generated in wastewater treatment plants, as a consequence of the sedimentation of suspended material and by the growth of biomass in the biological treatment. This sludge represents a generation that for some countries, reaches figures of 1,400 t / day in Canada, 2,000 t / day in the United States of North America, 1,753 t / day in Mexico, 1,232 t / day in Brazil, among others, with growth 60% expected by 2050. Historically, this type of solids has been disposed of in sanitary landfills, contributing to the environmental, social and economic impacts related to waste management; However, in recent decades and globally, the application of anaerobic digestion has been proposed as an alternative for the treatment of solids, given its easy operation, economic value and the possibility of obtaining by-products such as biogas and compost. In Latin American countries this situation is not particularly different, where some researches have focused their efforts on studying the different variables that are related to anaerobic digestion. In this bibliographic review article, 56 research works related to anaerobic co-digestion processes, pretreatment, mathematical models, microorganisms, operating parameters and economic evaluation were analyzed; where, although there is an important advance in relation to the subject, greater efforts are required to allow the understanding and adjustment of the different parameters, especially in pilot and real scales, enabling their implementation in waste management. [ABSTRACT FROM AUTHOR]

Contextualization: Population growth and environmental problems at the local, national and international levels related to pollution from untreated sludge, due to the increasing volumes of such waste generated by wastewater treatment plants (WWTPs), increase environmental degradation. Knowledge gap: There are deficiencies in the management of sewage sludge, attributable to a lack of knowledge of conventional and sustainable stabilization alternatives, which means that the sludge is not used, because of its characteristics, and is placed at final disposal points, which can generate severe contamination problems. Purpose: Evaluate the scientific literature on the alternatives implemented in the stabilization of sewage sludge generated in WWTPs, through a documentary review and a bibliometric analysis based on the construction of strategic diagrams and a cooccurrence map, to identify research trends in the subject. Methodology: Searching of scientific literature was carried out using a searching algorithm with Boolean connectors, in the specialized database Scopus®. Then, it was analysed making use of bibliometric networks and strategic diagrams. Later, a data base with the relevant information for the conceptual analysis of the subject was organized. Results and conclusions: A total of 1,693 documents about biosolids stabilization alternatives from WWTPs were found, pointing out that countries such as the United States, China, Brazil, and Spain, have the highest scientific production on the subject. The generation of biosolids is a problem that has originated researches about the proper management of this waste to avoid pollution problems, since the most used alternatives are anaerobic digestion, thickening, dehydration and incineration, which are efficient in management, but do not take advantage of the potential exploitation of these wastes. Alternatives such as composting and vermiculture generate byproducts that could be used to achieve an adequate final disposal, reducing operational costs and obtaining economic benefits. [ABSTRACT FROM AUTHOR]

As regulatory frameworks for per- and polyfluoroalkyl substances (PFAS) evolve, the solid waste community seeks to manage PFAS risks effectively. Despite extensive research on PFAS in municipal solid waste (MSW) and wastewater sludge, there is limited information on a major global waste stream which seldom gleans regulatory oversight — construction and demolition debris (CDD). This study sampled a CDD processing facility to provide material-specific information on the PFAS profile within CDD. The bulk CDD accepted by this facility was separated into major categories, representatively sampled, then characterized for total available PFAS (∑ 92 PFAS). As reprocessed CDD is ultimately recycled or landfilled, often unencapsulated or in unlined landfills, the PFAS leaching potential was also examined using two leaching procedures. Among the categories assessed for total PFAS, carpeting, carpet padding, and gypsum drywall showed elevated concentrations compared to other components, with most of the PFAS mass contributed by precursor species. However, materials with the highest total PFAS, such as carpeting, did not necessarily exhibit the highest leaching, and leachate was predominantly composed of terminal species rather than precursors. Extrapolating these findings with national CDD generation and management data inventories suggests that despite MSW having higher total available PFAS concentrations, the leachability of PFAS from landfilled CDD is comparable, raising legitimate concerns with CDD disposal practices, particularly in unlined CDD landfills. [Display omitted] • Various PFAS levels detected in CDD components. • Majority of total available PFAS was from precursor species. • Leachable PFAS consisted mainly of PFCAs. • Data were extrapolated to estimate US CDD waste PFAS mass. • CDD may pose similar or greater leaching risk compared to MSW. [ABSTRACT FROM AUTHOR]

The waste management and water purification are daunting environmental challenges. Biochar, a carbonaceous material prepared from diverse organic waste (agricultural, household residues and municipal sewage sludge) has garnered substantial attention due to its excellent attributes, including carbon content, cation exchange efficacy, ample specific surface area, and structural robustness. Thus, the present review comprehensively analyzes bio waste-derived biochar with a particular emphasis on water remediation applications. This article primarily delves into various strategies for modifying biochar, elucidating the underlying mechanisms behind these modifications and their potential for bolstering pollutant removal efficiency. Furthermore, it addresses the impact of functionalization on both biochar stability and cost for commercialization. Lastly, the article outlines key developments, SWOT analysis, and future prospects, offering insights into the practical execution of biochar applications at a larger scale. Therefore, this article paves the way for future research to deepen the understanding of modified biochar with mechanisms for exploring water remediation applications in a more sustainable manner. • Biochar's distinct properties make it a promising material environmental solution. • The review article primarily emphasizes the significance of modified biochar in water remediation. • The article delves into the mechanisms underlying modifying biochar, and enhancing its pollutant removal efficiency. • Impact of functionalization on biochar, both in terms of stability and cost also discussed. • Lastly, the review outlines challenges and prospects, offering valuable insights for larger-scale applications. [ABSTRACT FROM AUTHOR]

This study deals with energy and agronomic valorisation by anaerobic co-digestion with temperature and microorganism phase separation of sewage sludge, vinasse and poultry manure, with the aim of achieving an integral waste management, obtaining bioenergy and biofertilizer that returns nutrients to the soil in a natural way. The yields obtained were 40 mL H 2 /gVS and 391 mLCH 4 /gVS. The resulting effluent showed more than 98 % removal of E. coli and Total Coliforms , as well as total removal of Salmonella. The results obtained in the phytotoxicity tests showed that all the proportions studied had phytostimulant and phytonutrient properties, with 20 % having the highest germination index (GI) with mean values of 145.30 %. Finally, the agronomic trial carried out with strawberry crops (Fragaria sp.) showed that the addition of this biosolid has fertilising properties and can be used as an agronomic amendment, with an increase of 145 % in fresh weight and 102.5 % in dry weight, and fruit production doubled with respect to the control. The ANOVA statistical study corroborated that there were significant differences in crop growth when applying different proportions of biofertilizer in the fertilizer. Therefore, these results show that this technology is promising and would contribute environmentally, socially and economically to the transfer towards a circular economy model. [Display omitted] • Energy and agronomic valorisation of sewage sludge, vinasse and poultry manure. • Anaerobic co-digestion with phase separation of temperature and micro-organisms. • Removal of 98 % of pathogens in the effluent for class A bisolids classification. • Phytotoxin-free and phytonutrient properties with biofertiliser concentration of 20 %. • 145 % increase in fresh biomass in strawberries for a 100 % concentrated fertiliser. [ABSTRACT FROM AUTHOR]

Biomass pyrolysis is the anoxic thermal conversion of biomass into a carbon rich, porous solid, often called biochar. This could be a better waste management alternative for contaminated organic wastes than incineration, due to the useful properties of biochar and potential for carbon sequestration. There are, however, concerns about the potential formation/destruction of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs). Six organic wastes, including digested sewage sludges, wood wastes, and food waste reject, were pyrolyzed (500–800°C) in a full-scale relevant unit (1–5 kg biochar hr−1). Removal efficiencies for PCBs and PCDD/Fs were > 99% in the produced biochars. Biochar PAH-content (2.7–118 mgkg−1) was not significantly correlated to feedstock or temperature. PAHs (2563–8285 mgkg−1), PCBs (22–113 µgkg−1), and PCDD/Fs (1.8–50 ngTEQ kg−1) accumulated in the pyrolysis condensate, making this a hazardous waste best handled as a fuel for high temperature combustion. Emission concentrations for PAHs (0.22–421 µgNm−3) and PCDD/Fs (≤2.7 pgTEQ Nm−3) were mainly associated with particles and were below the European Union's waste incineration thresholds. Emission factors ranged from 0.0002 to 78 mg tonne−1 biochar for PAHs and 0.002–0.45 µgTEQ tonne−1 biochar for PCDD/Fs. PCDD/F-formation was negligible during high temperature (≥500 °C) biomass pyrolysis (69–90% net loss) [Display omitted] • Organic waste with legacy contaminants pyrolyzed in full-scale relevant system. • Distribution of PAHs, PCBs and PCDD/Fs across pyrolysis products documented. • Emission factors for PAHs and PCDD/Fs in waste organic waste pyrolysis derived. • Net loss of PCBs and PCDD/Fs during pyrolysis observed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Anaerobic digestion with mesophilic, low C/N ratio was carried out in batch system. • Performance of mono and co-digestion of okra waste and sewage sludge was compared. • Biogas and methane production increased by up to 66% and 112%, respectively with AnCoD. • Anaerobic digestion efficiency on different soluble matters was identified. • Kinetic modeling, energy potential, and financial profit data were examined. Lignocellulosic substrates, including wastes generated from agro-industrial activities, are bio-residues evaluated to put an end to the energy needs and sustainable waste disposal problems that the world is trying to deal with today. However, the slow rate of hydrolysis of such lignocellulosic wastes limits the biogas production efficiency with the mono-anaerobic digestion (AD) process. Therefore, anaerobic co-digestion (AnCoD) of such wastes with secondary raw materials rich in microorganisms and various nutrients, such as sewage sludge, is an economical and useful method for both enhancing biogas production and disposal of more waste. In this study, AD and AnCoD processes for biogas and methane production were investigated on okra waste (OW) and municipal sewage sludge (MSS) by using cattle manure as inoculation, which constitutes only 8% of the total working volume. Five different substrate mixing ratios (100%OW, 75%OW-25%MSS, 50%OW-50%MSS, 25%OW-75%MSS, and 100MSS%) were prepared to observe the effect of C/N ratio, maximum biogas production potential, methane content, and organic matter removal efficiency on AD and AnCoD processes. All bioreactors were operated in a batch process with 8% TS in mesophilic temperature for 25 days. The amount of biogas produced in the 100%OW experimental set for the AD process was 44% more than 100%MSS. However, the AnCoD process was more efficient than AD, and biogas and methane production increased by up to 66% and 112%, respectively, compared to the mono-substrate experimental set. The highest biogas production value was 1060 mL (375 mL/gVS removed) with 60% methane content in the bioreactor consisting of 25%OW-75%MSS. As a result of AD and AnCoD process, soluble carbohydrate, protein and COD removal for all bioreactors were between 62% and 79%, 28%-68% and 54%-70%, respectively. The FT-IR peaks seen in digestates were consistent with the presence of functional groups formed as a result of AnCoD. Monod, Cone, Transference function, and Logistic function kinetic models were used for the estimation of cumulative biogas production efficiency. In addition, the energy potential of the methane produced as a result of the AD and AnCoD processes and the financial gain that can be obtained from its direct sale were evaluated. [ABSTRACT FROM AUTHOR]

Compared to noncalcareous soils, data on the soil-to-plant transfer of heavy metals and their response to sewage sludge (SS) in calcareous soils with diverse properties are limited. Cadmium (Cd), cobalt (Co), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) transfer from soil to cabbage (Brassica oleracea L. var. capitata) under greenhouse conditions in 30 diverse soils amended with two types of sewage sludge (non-spiked and spiked with heavy metals) were investigated. Three transfer factors were calculated for heavy metals in three treated soils including control soils (CS), soils treated with non-spiked SS (NSS), and soils treated with spiked SS (PSS). The bio-concentration factor of heavy metals from soil to root (BCFRoots) in cabbage in three treatments was as follows: CS: Pb > Cu > Co > Zn > Ni; NSS: Pb > Co > Cu ≥ Zn > Ni; and PSS: Pb > Cd > Zn > Co > Cu > Ni. The same order was found for the bio-concentration factor of heavy metals from soil to shoots (BCFShoots) in PSS, and in CS and NSS treatments except that the position of Co, Cu, and Zn was changed. Based on the heavy metals translocation from plant roots to shoots, Cd, Cu, and Zn were the heavy metals that posed the highest risk due to the higher shoot content in all treatments, whereas Ni and Pb posed relatively lesser risk. Generally, the percentage of sand and silt in BCFRoots and BCFShoots was quite effective for Co, Ni, and Zn and it seems that soil texture is an important variable in heavy metals bioavailability. In conclusion, our findings highlight the significance of using SS to increase cabbage growth in soils contaminated with heavy metals. Furthermore, cabbage may be a good choice for phytoremediation of heavy metal-contaminated calcareous soils in terms of soil remediation. Novelty statement In recent years, sewage sludge production has increased as well as related waste disposal strategies because of the increasing population and growing demand for agricultural products. Sewage sludge utilization as a low-cost fertilizer has spread in some parts of Iran and the world. On the other hand, unnecessary and unproductive use of sewage sludge results in the accumulation of heavy metals in soils, adding them to food and the potential risk to human health. Currently, work on the transfer of heavy metals from soil to plant after soil treated with sewage sludge has focused on the bioavailability of heavy metals using specific extractants. The assessment of the transfer of heavy metals from soil to different parts of plants using sewage sludge has been less studied. In this study, the transfer of heavy metals (Cd, Co, Cu, Ni, Pb, and Zn) from several soils (30 soils samples) having diverse physical and chemical properties to the tissues of the cabbage plant in control soils, and two types of sewage sludge (nonspiked and spiked with heavy metals) were investigated. The novelty of this study is that the measured bio-concentration factor of heavy metals from soil to root and from soil to shoot and translocation of heavy metals from plant roots to shoots and correlations between these parameters and soil properties are reported for the first time in diverse calcareous soils. [ABSTRACT FROM AUTHOR]

Volatile methylsiloxanes are wastewater organic pollutants originating from industrial and personal care products. They accumulate in sewage sludge and hamper biogas production through the formation of silicon dioxide on the surfaces of gas engines and turbines, yet there is few knowledge on their fate in sludge treatment systems. Here we studied the occurrence and removal of seven volatile methylsiloxanes along the solid treatment line of an urban wastewater treatment plant. We analyzed 75 sludge samples from seven locations using ultrasound-assisted solid–liquid extraction followed by gas chromatography-mass spectrometry. Results show that volatile methylsiloxanes occur in all samples with a predominance of cyclic homologues, particularly decamethylcyclopentasiloxane. Total siloxane levels reach 6087 ng/g dry weight in the secondary sludge, average at 3575 ng/g in digested sludge, and 5703 ng/g in the dewatered sludge, the latter being likely due to the addition of a polyelectrolyte. Overall, these levels call for measures to reduce methylsiloxane levels before the biogas production step. [ABSTRACT FROM AUTHOR]

Waste management is a crucial issue facing modern society. The generation of sewage sludge is increasing annually due to the urbanization and improvement of sanitation systems of cities. The construction sector has emerged as a solution for the elimination of waste due to the enormous volume of materials that this sector can absorb. This paper evaluates the pozzolanic activity of sewage sludge ash (USSA) obtained following an uncontrolled-combustion process, a simple and economic procedure. Compressive strength of Portland cement/USSA mortars with 5%–25% by weight USSA were evaluated. Calcium hydroxide/USSA and Portland cement/USSA pastes were chemically and physically characterized through thermogravimetric/differential-thermogravimetric (TG/DTG), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) analyses. The increase in the replacement of Portland cement by USSA is associated with an increase in the compressive strength of mortars. These values for USSA containing mortars cured for 90 days were in the range of 49.6–55.4 MPa , higher than the one reached by the reference mortar. According to the microstructural analysis, the increment on the compressive strength can be attributed to the formation of hydrated products (C─ S─ H, C─ A─ S─ H, and C─ A─ H) by the pozzolanic reaction of USSA. [ABSTRACT FROM AUTHOR]

• Biogas industry is an important part of Polish bioeconomy. • Anaerobic digestion of sewage sludges enables new added-value bioproducts to be obtained. • Eco-innovative fertilizers developed and produced from valorized sludges. • Optimized bio-treatment of eutrophic digester liquors is necessary and advantageous. • Elaborated novel biotechnologies ensure closing the organic waste management cycles. Bio-based solutions are expected to ensure technological circularity in priority areas such as agriculture, biotechnology, ecology, green industry or energy. Although Poland, unlike the other EU member states, has not yet adopted a precise political strategy to promote bioeconomy, it has taken several actions to enable smart, sustainable and inclusive growth. This goal can be achieved by developing selected bioeconomy-related areas such as the biogas industry together with novel technologies implemented to optimize treatment of municipal sewage and management of organic solid waste. Here, the relatively strong status of the Polish biogas sector is presented. The widely used practice of sewage sludge biomethanation has led to construction of numerous complex installations combining biological wastewater treatment plants with anaerobic digesters. Based on physico-chemical processing of biostabilized sludges, a novel method for efficient granulated soil fertilizer production is elaborated, in line with the concept of circular economy and the notion of "waste-to-product". It is also shown that anaerobic fermentation of sewage sludges can be optimized by co-digestion with properly selected co-substrates to increase bioprocess yield and improve the resultant digestate fertilizer quality. The problem of post-fermentation eutrophic sludge liquors, environmentally hazardous waste effluents requiring proper treatment prior to discharge or field application, is addressed. Attempts to optimize biological treatment of digestate liquors with complex microbial consortia are presented. The Polish innovations described show that the "zero waste" path in circular bioeconomy may bring advantageous results in terms of transformation of waste materials into commercial, added-value products together with recovery of water resources. [ABSTRACT FROM AUTHOR]

Waste disposal is a challenging environmental concern worldwide. Carbon-rich waste materials can be transformed into adsorbent and/or catalyst support to reduce treatment costs and promote waste recycling. In the present study, three waste materials—sewage sludge, black liquor (from pulp and paper mills), and sugar mill press mud—were converted into activated carbons which were used as support for the iron-impregnated heterogeneous Fenton-type photo catalysts. These materials were characterized and tested on synthetic wastewater containing 4-chlorophenol (4-CP) as the model compound and simulated pulp-bleaching effluent. The oxidation runs were performed at an initial reaction pH of 4.4 with stoichiometric H2O2 dose and catalyst mass loading of 1 g/L for 2 h duration. The maximum total organic carbon removal of 69% and 32% was observed for 4-CP and simulated bleaching effluent, respectively, during photocatalytic oxidation with black liquor–derived catalyst. Thus, the use of black liquor–derived catalyst for bleaching effluent can help paper mill operators handle liquid as well as solid waste in a very efficient manner. [ABSTRACT FROM AUTHOR]

Objective: This research aimed to assay the dehydration and stabilization of surplus biosolids from a wastewater activated sludge treatment plant, with sludge-treatment wetlands, at the Iguazú National Park (Misiones, Argentina). Materials and Methods: A 12-cell sludge-treatment reed beds (STRB) system was built and operated for four years. Afterwards, the accumulated sediments were analyzed for total solids (TS) concentration, volatile solids (VS) reduction, specific oxygen-uptake rate (SOUR), and heavy metals and pathogens concentrations. Results and Discussion: TS concentration increased from 0.55 % to 14.3 %, VS were reduced by 33.3 %, and SOUR lowered to 1.09 mg O2gTS-1 h-1. These figures and the final concentrations of heavy metals and pathogenic microorganisms (102 MPN E.coli.gTS-1) indicated a degree of stabilization and sanitation that allowed classifying these biosolids as Class A, according to the Argentine guidelines, National Resolution 410/18, and enabled their reuse for soil amendment in landscapes and other agronomic purposes. Conclusion: The technology tested showed good results applied under a tropical climate, with annual temperatures between 17 and 27 °C, rainfall of 1870 mm y-1, and planted with autochthonous vegetation. Furthermore, it allowed the reuse of 221 t (144 m3 ) of a harmless product in an environmentally sustainable way. [ABSTRACT FROM AUTHOR]

Sustainable and eco-friendly sewage sludge treatment and disposal are crucial for pollution prevention, resource utilization, and control. This study used solid sewage sludge and Pistia stratiotes to produce high-performance biochar through modification and high-temperature pyrolysis. The resulting biochar was used to adsorb ammonia nitrogen and phosphate in wastewater, leading to the development of a green and safe value-added fertilizer. Results showed that the combination of Pistia stratiotes and chemical modification optimized the biochar's pore structure, enhanced chemical functional groups, and immobilized heavy metals. The pseudo-second-order kinetic model and Langmuir isotherm model provided better fitting for the adsorption process. The combination of magnesium chloride and Pistia stratiotes treatment exhibited the highest adsorption performance for ammonia nitrogen and phosphate, with maximum theoretical saturation capacities of 62.47 mg g−1 and 33.56 mg g−1. BET, FTIR, and SEM-EDS analysis revealed that surface functional groups, ion exchange, chemical co-precipitation, electrostatic adsorption, and physical adsorption were the main adsorption mechanisms. Regarding desorption, the ammonia nitrogen and phosphate release rates of the value-added fertilizer were remarkably low during the rapid release stage (0–40 min), with only 20.34% and 33.97%, respectively. Moreover, in a pot experiment, the showed greater potential for lettuce growth compared to raw biochar, especially when modified with magnesium chloride, resulting in a 53.78% increase in lettuce biomass. In conclusion, the proposed approach for sewage sludge treatment and disposal offers significant environmental and agricultural benefits through solid waste resource utilization ammonia nitrogen-phosphate recovery from wastewater. [Display omitted] • High-Performed biochar was prepared from Sewage Sludge and Pistia stratiotes • Sludge-biochar emhanced nitrogen-phosphorus recovery from wastewater. • Modified biochar exhibits a slow-release effect for nitrogen and phosphorus. • Sludge-biochar value-added fertilizer has greater potential for lettuce growth. • Proposed approach provides sustainable waste management and nutrient recovery model. [ABSTRACT FROM AUTHOR]

Both manganese-slag and sewage sludge are typical solid wastes, but their utilization is limited. Based on the soil properties, the abovementioned pollutants were combined with Broussonetia papyrifera to treat soil cadmium (Cd) pollution. Three materials (sewage sludge-derived biochar (SSB), Mn-SSB, and Mn-slag (Slag)) were prepared using oxygen-limited pyrolysis technology with Slag and sewage sludge, and the effects of the three materials on the phytoremediation of Cd-polluted soil were investigated. All three materials had distinct morphological characteristics, good functional group structure, specific surface area, and porosity. The adsorption and leaching experiments in the solution indicated that the three materials could not only directly absorb Cd2+ but also release nutrients, such as nitrogen and phosphorus. The soil pH increased significantly (p < 0.05) with the addition of the above environmental remediation materials. Furthermore, the contents of soil organic carbon, available nitrogen, and available phosphorus in soil increased significantly, whereas the electrical conductivity of the soil decreased significantly (p < 0.05). During remediation of Cd-polluted soil by integrating the above materials with B. papyrifera , Slag significantly increased the B. papyrifera biomass, but the effects of SSB and Mn-SSB were not significant. SSB, Mn-SSB, and Slag significantly increased the protein content of B. papyrifera leaves, with Mn-SSB having the most significant effect (p < 0.05). The applications of SSB, Mn-SSB, and Slag reduced the malondialdehyde content and increased the activities of superoxide dismutase and peroxidase, reducing the damage to B. papyrifera. Mn-SSB significantly reduced the Cd content in the roots, stems, and leaves of B. papyrifera , and SSB and Slag promoted Cd enrichment in B. papyrifera. This study realized the comprehensive utilization of Mn-slag and sewage sludge and established a recycling system from solid waste to the treatment of waste soil. [Display omitted] • Environmental remediation materials based on manganese-slag and sewage sludge can not only improve soil properties, but also directly absorb Cd. • The environmental remediation materials can promote the growth of Broussonetia papyrifera , especially the root system. • The prepared environmental remediation materials also can enhance the resistance of Broussonetia papyrifera to Cd stress. [ABSTRACT FROM AUTHOR]

Hydrothermal liquefaction (HTL) is a rapidly developing technology that converts waste biomass, such as municipal sludge, into a petroleum-like biofuel known as biocrude. At the HTL temperature/pressure of 350 °C/170 bar that simulates an HTL unit designed for a wastewater treatment plant (WWTP), this study found that >64% of energy could be recovered as biocrude from mixed primary and secondary sludge. HTL process also generates two waste streams, hydrochar and HTL aqueous. Heavy metals tend to accumulate in hydrochar, which raises concerns about its valorization. Hydrochar had concerning amounts of Cd, Mo, and Zn for land application, while it was non-hazardous for landfilling. Hydrochar had the most P distribution, resulting in a high concentration (4.6% by weight). Almost all P could be recovered by acidic extraction from hydrochar. The impacts of returning HTL aqueous to wastewater treatment processes were evaluated for the first time. HTL aqueous could be aerobically treated. However, its return increased the final effluent COD by 16.3% and 20.5% and decreased UV disinfection performance by 4% and 8% for average flow and low flow (dry season) conditions, respectively. In conclusion, this study yielded significant information in guiding the development of wastewater biorefinery by incorporating HTL into WWTPs. • HTL achieves >64% energy recovery as biocrude but its quality requires upgrade. • Hydrochar is non-hazardous for landfill but restricted for direct land application. • Hydrochar is enriched with minerals and promising for phosphorus recovery. • HTL aqueous has a BOD/COD of 0.58, meaning easily biodegradable for aerobic treatment. • HTL aqueous requires pretreatment before returning to wastewater treatment plants. [ABSTRACT FROM AUTHOR]

The utilization of organic solid waste (OSW) for preparing standardized seedling substrates is a main challenge due to its temporal and spatial variability. This study aims to form models based on data from the literature and validate them through experiments to explore a standardized seedling substrate. The typical OSW in Hainan Province, including municipal sewage sludge (MSS), coconut bran (CB), seaweed mud (SM), and municipal sewage sludge biochar (MSSB), was used as raw material. A series of six mixing ratios was tested, namely: T1 (0% MSS: 90% CB), T2 (10% MSS: 80% CB), T3 (30% MSS: 60% CB), T4 (50% MSS: 40% CB), T5 (70% MSS: 20% CB), and T6 (90% MSS: 0% CB). SM and MSSB were added as amendment materials at 5% (w/w) for each treatment. The physicochemical properties of substrates, agronomic traits of rice seedlings and microbial diversity were analyzed. The results showed that the four kinds of OSW played an active role in providing rich sources of nutrients. The dry weight of the above-ground part was 2.98 times greater in T3 than that of the commercial substrate. Furthermore, the microbial analysis showed a higher abundance of Actinobacteria in T3, representing the stability of the composted products. Finally, the successful fitting of the results with the linear regression models could establish relationship equations between the physicochemical properties of the substrate and the growth characteristics of seedlings. The relevant parameters suitable for the growth of rice seedlings were as follows: pH (6.46–7.01), EC (less than 2.12 mS cm−1), DD (0.13–0.16 g cm−3), and TPS (65.68–82.73%). This study proposed relevant parameters and models for standardization of seedling substrate, which would contribute to ensuring the quality of seedlings and OSW resource utilization. [Display omitted] • The developed standardized seedling substrate is a practical product based on models. • Municipal sewage sludge (MSS) and coconut bran have potential as growing media. • Substrates with high proportions of MSS showed saline-alkaline properties. • Substrate with 30% MSS increased above-ground biomass. • The highest Actinobacteria level was observed in the substrate with 30% MSS. [ABSTRACT FROM AUTHOR]

• Landfilling was the worst-case scenario in both impact categories in six scenarios. • Alternate methods can treat 60% of total FW and reduce GHG emissions by 70%. • Treating FW with sewage and/or sludge can reduce net GHG emissions of WWTP by ∼50%. • Greater treatment capacity can reach net-zero emissions and net energy recovery. Food waste (FW) being a major solid waste component and of degradable nature is the most challenging to manage and mitigate greenhouse gas emissions (GHEs). Policymakers seek innovative approaches to achieve net zero objectives and recover resources from the FW which requires a comparative and holistic investigation of contemporary treatment methods. This study assessed the lifecycle of six alternative scenarios for reducing net GHEs and energy use potential from FW management in a metropolis, taking Hong Kong as a reference. In both impact categories, the business-as-usual (landfilling) was the worst-case scenario. The combined anaerobic digestion and composting (ADC) technique was ranked best in the global warming impact but was more energy intensive than anaerobic digestion with sludge landfilling (ADL). Incineration ranked second in net GHEs but less favourable for energy recovery from FW alone. The proposed integration of FW and biological wastewater treatment represented an enticing alternative. Integration by co-disposal and treatment with wastewater (CoDT-WW) performed above average in both categories, while anaerobic co-digestion with sewage sludge (AnCoD-SS) ranked fourth. The sensitivity analysis further identified critical parameters inherent to individual scenarios along with biogenic carbon emission and sequestration, revealing their significance on the magnitude of GHEs and scenarios' ranking. Capacity assessment of the studied treatment facilities showed a FW diversion potential of ∼60% while reducing the net GHEs by ∼70% compared to the base-case, indicating potential of net zero carbon emissions and energy footprint by increasing treatment capacity. From this study, policymakers can gain insights and guidelines for low-carbon urban infrastructure development worldwide. [Display omitted] [ABSTRACT FROM AUTHOR]

Acid mine drainage (AMD) is a persistent and extensive source of water pollution and ecological degradation. Cotreating municipal wastewater (MWW) with AMD using existing infrastructure at conventional wastewater treatment plants (WWTPs) may serve as a potential option for AMD abatement. However, commonly elevated iron and aluminum concentrations and low pH of AMD could negatively impact various processes at a WWTP. The focus of this mini review was on determining how cotreating MWW with AMD could impact the solids handling processes at a WWTP. While no studies have explored the solids that could be generated during cotreatment in a WWTP, numerous articles separately discuss the solids generated during AMD or MWW treatment. Reviewing this literature revealed that iron and aluminum, common metals in AMD, are already present in MWW sludge and typically benefit most solids handling processes. The addition of AMD would elevate iron and aluminum concentration but would likely result in improved sludge dewatering, removal of odor-causing compounds during processing, and a decreased bioavailability of trace metals and water-soluble P in land applications. This review concludes that cotreating MWW with moderate to low volumes (<50%) of AMD at WWTPs will have minimal impact on, and likely improve, solids handling processes. [ABSTRACT FROM AUTHOR]

• Inventory of sewage sludge ashes (SSA) generated in Polish plants is presented. • Increasing amount of SSA generated Poland is observed. • SSA contains significant amount of nutrients, as phosphorus (~13%), calcium (~14%) • SSA should be used as secondary source in fertilizer production. This paper presents an inventory of sewage sludge ashes (SSA) generated in the mono-incineration plants for municipal sewage sludge in Poland. This research focused on the detailed study of mass flows, chemical composition, and phosphorus recovery potential. There are currently 11 sludge mono-incineration plants operated with a total capacity of 160,300 Mg dry weight (d.w.) of sludge annually. Recently, a significant increase in the amount of SSA generated in these plants has been observed, reaching 26,756 Mg in 2018. Chemical composition of SSA showed significant amounts of the main nutrients: calcium (~14%), phosphorus (~13%), magnesium (~3%), and potassium (~1%). Additional main elements were iron (~14.5%), silicon (~13%), and aluminium (~6%). The main trace elements in the SSA were zinc (~3750 mg/kg) and copper (~899 mg/kg). Pollutants, according to fertilizer regulations of different countries, present in Polish SSA were chromium (~703 mg/kg), nickel (~260 mg/kg), lead (~94 mg/kg), and cadmium (~9 mg/kg). The radionuclides, uranium, and thorium often present in higher amounts in commercial phosphate rock-based fertilizers, were only detected in SSA at low levels of 4–9 mg/kg and 2–3 mg/kg, respectively. Theoretical phosphorus recovery potential from the SSA (from plants in Cracow, Lodz, Gdansk, Gdynia, Szczecin, and Kielce) was estimated at 1613.8 Mg, of which 33.9% is bioavailable. Currently, in Poland, the recommended approach is the production of fertilizers as a result of the extraction of phosphorus from the SSA with its use in the production of secondary mineral fertilizers. Further research in this area is required considering Polish conditions and legislation. [ABSTRACT FROM AUTHOR]

• Co-digestion of sewage sludge and organic waste for VFA production was studied. • Acetic acid dominated in short-term operation in batch mode. • An increasing proportion of organic waste increased valeric and caproic acid. • Caproic acid dominated during long-term operation in semi-continuous mode. • VFA-rich liquid achieved higher denitrification rate than acetate and methanol. Volatile fatty acids (VFAs) are intermediates of anaerobic digestion with high value and wide range of usage. Co-digestion of sewage sludge and external organic waste (OW) for VFA production can help achieve both resource recovery and ensure sustainable and innovative waste management. In view of this, the effect of substrate proportions on VFA production from co-digestion of primary sewage sludge and OW is studied. Long-term operation in a semi-continuous reactor was performed to assess the resilience of such a system and the VFA-rich effluent was tested for its ability to be used as carbon source for denitrification. Co-digestion was initially carried out in batch reactors with OW proportion of 0%, 25%, 50%, 75%, 100% in terms of COD and scaled up in a semi-continuous reactor operation with 50% OW. In the short-term operation in the batch mode, acetic acid dominated, however, increasing OW fraction resulted in increased valeric and caproic acid production. Moreover, in the long-term semi-continuous operation, caproic acid dominated, accounting for ≈55% of VFAs. The VFA-rich effluent from the semi-continuous reactor achieved the highest denitrification rate as a carbon source when compared with acetic acid and methanol. The results demonstrate that co-fermentation can increase VFA yield and shift products from acetic acid to caproic acid in long-term operation and the VFAs can be used within wastewater treatment plants to close the loop. [ABSTRACT FROM AUTHOR]

• Biosolids add tonnes of microplastics (MPs) and pollutants to farmlands annually. • Approximately 0.5–3% by weight of biosolids applied to farmlands is MPs. • During biosolid treatment, virgin MPs attract heavy metals absorbable by plants. • Degradation of MPs over time creates nanoplastics (NPs) absorbable by plants. • A proposal to recycle all biosolids sustainably by incorporating 7% in fired bricks. Treated waste-water sludge (biosolids) are frequently recycled in agricultural lands; however, this practice has polluted soils with microplastics (MPs), nanoplastics (NPs), synthetics, heavy metals, pharmaceuticals and engineered nanoparticles. This study analyses many of the significant research outcomes in this area and proposes the urgent reduction of biosolids recycling in farmlands, aiming to eliminate their use altogether as soon as practicable, and instead, to utilise this material as a source of brick firing energy in the manufacturing of fired clay bricks and as a replacement for virgin brick soil. Based on a comprehensive data analysis, this study has calculated that in the European Union, the United States, China, Canada and Australia, approximately 26,042, 21,249, 13,660, 1,518 and 1,241 tonnes of microplastics, respectively, are added to farmlands annually as a result of biosolids application. The accumulation of microplastics produces detrimental effects on soil organisms and increases the accumulation of other micropollutants, such as heavy metals. The degradation of MPs over time is a source for the creation of nanoplastics, which pose a greater threat to ecosystems and human and animal health, as their size allows for their absorption into plant cells. On the other hand, the results of a comprehensive study at RMIT, including a comprehensive Life-Cycle Assessment, confirm that recycling biosolids in fired clay bricks (Bio-Bricks) is a promising sustainable alternative. This study proposes the mandatory addition of 7% biosolids in all brick manufacturing worldwide to utilize all biosolids production in fired clay bricks. This will reduce brick firing energy by over 12.5%. [ABSTRACT FROM AUTHOR]

• OFMSW co-digestion with sewage sludge digestate an effective strategy for low OLR. • Energy analysis shows 48% increase in electricity for export, 22% in heat. • Mesophilic digestion at low OLR unstable due to low N concentration. • Digestate addition limited by N input in thermophilic conditions. • Process integration offers a promising route for contaminated feedstocks. Changing waste management practice, introduction of new technologies, and population demographics and behaviour will impact on both quantity and composition of future waste streams. Laboratory-scale anaerobic digestion of the mechanically-separated organic fraction of municipal solid waste (ms-OFMSW) was carried out at relatively low organic loading rates (OLR), and results analysed using an energy modelling tool. Thermophilic operation with water addition and liquor recycle was compared to co-digestion with dilution water replaced by sewage sludge digestate (SSD); thermophilic and mesophilic mono-digestion were also tested at low OLR. All thermophilic conditions showed stable operation, with specific methane production (SMP) from 0.203 to 0.296 m3 CH 4 kg−1 volatile solids (VS). SSD addition increased biogas production by ~20% and there was evidence of further hydrolysis and degradation of the SSD. Long-term operation at 1 kg VS m−3 day−1 had no adverse effect except in mesophilic conditions where SMP was lower at 0.256 m3 CH 4 kg−1 VS and stability was reduced, especially during OLR increases. This was probably due to low total ammonia nitrogen, which stabilised at ~0.2 g N kg−1 and limited the buffering capacity. Energy analysis showed thermophilic operation at OLR 2 g VS L−1 day−1 gave 42% of the theoretical methane potential and 38% of the higher heating value, reducing to 37% and 34% respectively in mesophilic conditions. Scenario modelling indicated that under low ms-OFMSW load even an energy-depleted co-substrate such as SSD could contribute to the energy balance, and would be a better diluent than water due to its nutrient and buffering capacity. [ABSTRACT FROM AUTHOR]

Sewage sludge is an important type of organic wastes among the various categories of solid waste. Organic matter resources in soils are relatively low and frequently require replenishment. Therefore, the use of sewage sludge in agricultural soils is a desirable method of their utilisation. The addition of sewage sludge to soils may be an inexpensive and effective alternative to the methods applied currently (mineral fertilisation, manure etc.). In spite of the undisputable advantages resulting from the application of sewage sludge in agriculture, it also involves some serious threats. Among those we should mention the presence of pathogens, heavy metals, and organic pollutants. In the current scenario of increasing global population, the generation of solid wastes like biosolids is bound to increase remarkably. Improper and unscientific disposal of biosolids results in several environmental issues such as surface and groundwater contamination, degradation of land, and food chain contamination. According to the principles of waste management hierarchy, agricultural recycling of biosolids will be a more environmentally preferred option over the traditional disposal methods. Utilizing the potential of biosolids to recycle valuable plant nutrients and as an effective soil amendment will not only help in sustainable management of this waste but also in minimizing the negatives associated with its traditional disposal. Every country must obey their regulations and legislations for managing their sewage sludge as a basic solution for use of sewage sludge in agricultural soil. [ABSTRACT FROM AUTHOR]

The anionic detergent sodium dodecyl benzene sulfonate (SDBS) inhibits anaerobic solid waste fermentation process in mesophilic anaerobic digesters. In this study, the effect SDBS on the performance of anaerobic digestion (AD) of mixture of sewage sludge, food waste, and green waste serving as substrate was investigated. The batch experiments were conducted with five SDBS concentrations namely 0, 0.01, 0.02, 0.05, 0.1, and 0.2 g/g (SDBS/dry sludge) under mesophilic condition (37 ± 1 °C) and lasted for 63 days. The results showed that the presence of SDBS remarkably increased the release of protein and carbohydrate, and resulting in the serious accumulation of volatile fatty acids (VFAs), especially for propionate accumulation. Likewise, the observed variations in enzyme activities associated with different stage of AD revealed that methanogenesis was quite sensitive to SDBS and inhibited by the increase of SDBS addition. Meanwhile, the presence of SDBS decreased the pH value and the concentration of free ammonia, but increased the concentration of NH4+-N. Furthermore, the production of biogas was reduced by SDBS. In conclusion, SDBS addition has a negative impact on anaerobic co-digestion. On the one hand, methanogens were severely inhibited and biogas yield decreased remarkably, on the other hand, the accumulation of VFAs was excessive. Thus, the presence of surfactant (SDBS) in the municipal organic waste should be concerned during the waste disposal via anaerobic digestion process. [ABSTRACT FROM AUTHOR]

Waste generation, waste management, sustainable energy production, and global warming are interrelated environmental issues to be considered together. Wastewater treatment sludge is an organic substance rich waste which causes significant environmental problems. However, these wastes can be used as raw material in biofuel generation. This study was designed to investigate the possible utilization of waste sludge in biohydrogen production by taking these facts into consideration. For this purpose, the sludge was first pre-treated with acid and then, the solid (sludge) and liquid (filtrate) phases of acid pre-treated sludge were used as the substrates for biohydrogen generation dark fermentation. Two-factor factorial experimental design method was used in acid hydrolysis of sludge to determine the effect of pH (pH = 2–6) and reaction period (time, min) elution of chemical oxygen demand (COD), total organic carbon (TOC) and total sugar (TS), NH 4 N and PO 4 P. Statistical evaluation of the results indicated that pH significantly affects the elution of organic carbon and nutrient content of sludge while the reaction time is significant for only organic carbon content. The optimum pretreatment conditions for maximum organic and nutrient elution were determined as pH = 2 and t = 1440 min. The pretreated products, named as filtrate sludge and sludge, conducted to dark fermentation under mesophilic conditions for biohydrogen generation showed that pretreatment of waste sludge at pH = 6 is the best condition giving the maximum yields (Y H2) as Y H2 = 24 mmol g−1 Total Sugar consumed and Y H2 = 41 mmol g−1 Total sugar consumed, for filtrate and sludge, respectively. • Over 90% carbon and nutrient recovery were achieved by acid hydrolysis of sludge. • The maximum nutrient and carbon recoveries were obtained at pH = 2 and t = 1440 min. • Production rate and yield of hydrolyzed sludge were higher than that of raw sludge. • Filtrate provided 16 times higher production rate than solid phase of sludge. • The yield from filtrate was 10 times higher than that of solid phase of sludge. [ABSTRACT FROM AUTHOR]

In order to reduce sewage sludge of concentrated natural rubber latex (CNRL) and transform it into a valuable material for efficient removal of Al3+ and Cu2+ ions from wastewater, magnetic biochar was prepared. In this work, sewage sludge from CNRL was pyrolyzed at various temperatures (300–700 °C) to assess the effects of pyrolysis temperature on the efficiency of magnetic biochar in removing Al3+ and Cu2+ ions from an aqueous medium. Effect of the chemical composition of sewage sludge on the biochar characteristic was evaluated. Sewage sludge is mainly organic matter. The mineral elements silicon (Si), phosphorus (P), sulfur (S) and calcium (Ca) were also observed in the sewage sludge. With increasing pyrolysis temperature, the contents of P and potassium (K) increased. The inorganic metals chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni) and lead (Pb) were present in small quantities. Pyrolysis temperatures 400–500 °C provided good quality magnetic biochar, while with the higher 700 °C pyrolysis temperature, specific surface area and pore volume decreased. The prepared biochar had combined meso- and macro-porous structure. Isotherms of Type II were indicating multilayer adsorption on porous biochar. The pseudo-second-order kinetic models described well Al3+ and Cu2+ adsorption onto magnetic biochar. The leaching test of magnetic biochar shows the releasing of K and Zinc (Zn) which can effect on the sorption of Al3+ and Cu2+. The binding mechanism between magnetic biochar and Al3+/Cu2+ involved surface complexation, ion exchange and cation‒π interaction. [ABSTRACT FROM AUTHOR]

Municipal solid waste, described as household waste, and sewage sludge, arising from wastewater treatment, are produced in large quantities around the world. Incineration plays a key role in the management of these materials, although the process leaves behind residual ashes: municipal incinerated bottom ash and sewage sludge ash, respectively. This paper examines the use of these ashes as aggregate in concrete, focusing specifically on developing a model to estimate the compressive strength of the concrete. The data used in this work have been obtained from a comprehensive search of the globally published literature. The strength model, focusing on 28 d results, has been developed using a regression analysis approach, with the renowned Abram's law as the foundation. The validated model demonstrated that, with favourable ash properties and mix design parameters, compressive strength results close to the control can be targeted with the use of the ashes as a low content aggregate component. [ABSTRACT FROM AUTHOR]

• Increased loading was possible both with and without thermal hydrolysis treatment. • The pre-treatment had more pronounced effect on sewage sludge than on food waste. • Dewatering and pre-treatment were effective ways to increase retention time. • Pre-treatment increased the proportion of Clostridia in industrial-scale digesters. • Firmicutes:Bacteriodetes ratio positively correlated with methane yield. This study examined the impact of thermal hydrolysis process (THP) pre-treatment on anaerobic co-digestion of wastewater sludge and household waste and assessed whether THP was vital to achieve higher process capacity. Performance data were collected for both industrial- and laboratory-scale digesters and response in microbial community structure was evaluated by Illumina sequencing. Implementation of THP at the industrial-scale plant increased methane yield by 15% and enhanced substrate degradability. Possibility to extend the sludge retention time due to a higher solid content of the substrate, sanitisation of the digestate and improved fertiliser quality of the digestate were other industrial-scale benefits of THP installation. Continuously-fed laboratory-scale digesters were fed THP-treated or untreated substrate at an organic loading rate (OLR) of 5 g volatile solid (VS)/L/day, a feeding rate necessary at the corresponding industrial-scale plant to meet the estimated population increase within the municipality. The results indicated that the plant could have increased the capacity with unimpaired stability independently of THP installation, even though the retention time was significantly shortened during operation with untreated substrate. Microbial community analyses revealed increased contribution of the Clostridia class after THP installation in industrial-scale digesters and positive correlation between Firmicutes:Bacteriodetes and methane yield in all digesters. Differentiated profiles in laboratory-scale digesters indicated that a temperature increase from 37 to 42 °C in association with THP installation and altered substrate composition were strong determining factors shaping the microbial community. Overall, these findings can assist industrial-scale plants in choosing management strategies aimed at improving the efficiency of anaerobic digestion processes. [ABSTRACT FROM AUTHOR]

The contribution of supporting tools developed for logistic optimization and processing infrastructure planning is highly dependent on the quality of input data. Databases containing reports on waste production and treatment are often used for waste management case studies and in the aggregated form at the national level provide sufficient information with negligible errors. On the other hand, analysis in greater detail at the smallest administrative unit usually reveals significant inconsistencies, especially in the case of mass balance control. This often results in the impossibility to track waste flows in the system and evaluate final treatment. This paper aims to present a tool for database verification in order to satisfy mass balances at all levels of the investigated system. As part of the mathematical modelling, the database is first subjected to a statistical analysis where selected inconsistencies between records can be removed. Subsequently, data reconciliation is applied with appropriate weights assigned to each entity in the system. The weights represent credibility and reflect various errors, which are identified in the previous stage of the approach. The correction of mass balances enables an evaluation of quality or composition in greater detail of individual entities and also determines the feasible interval of monitored properties. The tool is applied to the treatment evaluation of dry matter in wastewater sludge in the Czech Republic. Thanks to the developed tool, disposal and material or energy recovery can be quantified at micro-regional. [Display omitted] • National waste management database controlling in the detail of single entities. • Mass balance correction in every level of monitored territory. • Combination of statistics, data reconciliation and network flow problem. • Point and interval estimates of waste flow properties within the system. • Application of the developed approach to a case of wastewater sludge treatment. [ABSTRACT FROM AUTHOR]

Abstract Sewage sludge is a phosphorus (P) source alternative to P fertiliser derived from rock phosphate, but its impact on soil processes driving P cycling in agroecosystems requires further study. In order to optimise the use of sludge for sustainable P fertilisation, we need to elucidate the drivers of P dynamics. The present study aims at determining how different sludges (heated sludge, HS and composted sludge, CS) affect soil P pools and dynamics. A field experiment was established and soil was amended either with sludge or with inorganic P (triple superphosphate, TSP). Soil samples were collected five times during a vegetation period, and analysed for Hedley P fractions, microbial P and phosphatase activity. Phosphorus dynamics in soil was strongly influenced by P concentrations in sludge. About one year after application, sludge with the highest P concentration (HS) was as effective as TSP to improve soil P availability. The P source of TSP was immediately available for plant uptake, but the high phosphatase activity of the HS treatment evidenced that soil microorganisms released phosphatases which can hydrolyse HS-derived organic P compounds. In addition, the high content of microbial P in the HS treatment suggests that soil microorganisms assimilate P into their own biomass. By contrast, sludge with the lowest P concentration (CS) enriched primarily the weakly-soluble soil P fractions, resulting in lower P availability compared with that in the TSP treatment. Our findings suggest that both high P concentration and slow, but continuous microbial breakdown of organic P substrates derived from HS allow using this resource as an important source for plant mineral nutrition. This study stresses the need to both characterise P concentrations and P forms in sludge, prior to their application in the field. Graphical abstract Unlabelled Image Highlights • Sludge with a high P concentration increased labile soil P concentration. • Addition of organic P to the soil increased phosphatase activity and the microbial P pool. • Sludge with a low P concentration had no effect on soil P forms. • Sludge can be considered a slow-release fertiliser. [ABSTRACT FROM AUTHOR]

• Poultry slaughterhouse was valorized by large scale composting process. • Thermophilic phase of 65 °C for 20 days enhanced a significant reduction of pathogens. • Produced compost showed a suitable agronomic quality with GI of 90%. • Compost amendment of 8 t ha−1 improved all physiological growth parameters of maize. This work investigated the potential of composting treatment for hygienization and material recycling from poultry slaughtering by-products and wastes in the context of management aspects and the agricultural value of the final product. A large scale composting cycle of 300 m3 was performed for 90 days, in which poultry slaughterhouse waste (59.65%) was mixed with sewage sludge (4.83%), agricultural waste, cardboard (4.83%), and wood dust (19.35%) and activated compost (11.29%). During the composting progress, physical chemical parameters, FTIR analysis and biological indicators reflecting stability of the compost were analysed for the assessment of the product quality. The composted mixture showed a high microbial activity with a succession of microbial populations depending on the temperature reached during different degradation phases. The thermophilic phase lasted 20 days with temperature exceeding 65 °C allowing pathogens reduction. Fecal coliforms, Streptococci and Escherichia coli were reduced and remained less than values recommended by international guideline. Whilst Salmonella has disappeared at the end of the process. The Composting poultry slaughterhouse waste allowed obtaining hygienic compost with sufficient agronomic quality characterized by a relatively high organic matter content (49.12%), a C/N ratio (13.92%), an alkaline pH (7.7) and a high level of nutrients. The germination indexes reached 91% in the end of process that proved to be good maturity indicators. The compost application in peat amended at ratios equal to 8 t.ha−1, improved the growth of stem length (63.8%), leaf length (57.9%), fresh biomass (65.1%) and dry biomass (66.6%) of maize plants showing that the final slaughterhouse compost presented high level of maturity and it was not phytotoxic. [ABSTRACT FROM AUTHOR]