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A comparative analysis was conducted on raw and treated wastewater and the concentrations of heavy metals in sewage sludge from a wastewater treatment plant (WWTP). The research aimed to demonstrate improved efficiency in reducing heavy metal levels as a part of municipal and industrial waste management, with a specific emphasis on minimising the overall environmental impact. In this study, we presented the results of a repeated measures analysis of variance and assessed compliance with heavy metal content standards in sewage sludge from municipal treatment using a one-sample t-test against a reference norm. The analysis included measurements conducted between 2004 and 2015. We conducted an analysis of heavy metals, including zinc (Zn), lead (Pb), cadmium (Cd), copper (Cu), chromium (Cr), and nickel (Ni), manganese (Mn) and mercury (Hg). High Zn concentration that we observed in pre-treatment wastewater raised important questions. Leakages in sewage networks can result in contaminants infiltrating the wastewater, thereby increasing pollutant concentrations. Elevated concentrations can stem from industrial activities, where Zn and pollutants are discharged into wastewater as byproducts of industrial operations. The study illustrated the attainment of the highest sanitary standards, ensuring that treatment processes effectively eliminate harmful toxic substances, ultimately guaranteeing that the final product is safe for further reclamation processes.

Abstract Production of liquid fertilizers containing nitrogenous nutrients and biostimulants from sewage sludge (SS-NB) has been attracting increasing attention due to its excellent fertilization effect and resource recycling attributes. To better understand the functional effects of nutrients and biostimulants in SS-NB on soil, the adsorption capacity and mechanism of straw biochar (SB) and wood chip biochar (WCB) for alkaline and neutral SS-NB components were investigated. The adsorption of total organic carbon (TOC) from alkaline and neutral SS-NB by WCB was 61.14% and 89.73%, respectively, higher than that by SB, which was 56.25% and 83.36%. Moreover, TOC from neutral SS-NB was more readily adsorbed, especially for fulvic and humic acids. SB had a strong adsorption capacity for calcium ions and nitrogen (TKN, nitrate N, protein, amino acid) and released large amounts of P. In addition, WCB and SB showed a strong affinity for macromolecules (proteins) and reducing substances (lignin and lipids) and excellent fixation ability for phytohormones and allelochemicals. However, WCB adsorbed more types of molecular substances than SB while maintaining a high immobilization rate. Analysis of the adsorption mechanism showed that surface amino groups of the biochar were involved in adsorption, while WCB had additionally high adsorption efficiencies through pore adsorption, hydrogen bonding adsorption and pore size-exclusion effects. The study revealed that biochar can be used as an efficient adsorption carrier for SS-NB to improve soil fertility management. Graphical Abstract

The co-pyrolysis (at 300°C and 600°C) of municipal sewage sludge (SS) with zero-valent iron (Fe0: 1.5% and 3%) was investigated to reduce the toxicity of arsenic (As) and zinc (Zn) in SS. The BCR sequential extraction method, desorption kinetic analysis, and material characterization techniques (Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, X-ray diffraction) were used to evaluate the effects of the treatments on Zn and As behavior. The results showed that co-pyrolysis significantly reduced the acid-soluble fraction (18–43% for Zn; 83–95% for As) and mobility factor (45–85% for Zn; 86–96% for As) of Zn and As compared to untreated SS. Desorption experiments indicated a significant reduction in Zn and As release in treated samples, particularly in the co-pyrolysis sample at 600°C and Fe0 3% (67% for Zn; 88% for As) in comparison with untreated SS. Co-pyrolysis of Fe0 and SS led to the formation of new functional groups (Si–O, aromatic), a more porous surface morphology, and highly stable chemical crystals (ferric arsenate, zinc arsenide), which played a crucial role in Zn and As stabilization. The findings of this study suggest that co-pyrolysis is a promising approach for mitigating As and Zn toxicity in SS. However, additional field testing with plant-based systems is necessary for confirmation.

Abstract Background Wastewater treatment plant outlets are a major source of microplastics, with more than 90% retained in sewage sludge. No standardised method for the extraction, quantification, and characterisation of microplastics in sewage sludge or soil exists, and direct comparison of studies is often impossible. Our aim was to validate oil extraction efficiency with and without pre-treatment with Fenton’s reagent of selected microplastics in various types of environmental samples (sewage sludge and organic-rich substrates). Results Oxidation with Fenton’s reagent removed up to 90% of organic material, which improves the recovery rate and made quantification and characterisation easier and more reliable, regardless of type, shape, size, or density of the selected microplastic particles used in this study. Pre-treatment, as a pre-step of the oil extraction method, was shown to be important in reducing organic matter in all environmental samples, including sewage sludge and organic-rich substrates. It also improved the reliability of the selected method, shortened its duration, and, by reducing organic matter, made extracted microplastics more visible. The recovery rate was better for particles 1–5 mm and lower for particles 0.1

Abstract Pyrolysis is one method for treating sewage sludge, particularly in remote areas or decentralised systems. The end product of pyrolysis, sludge-char, can serve as a soil improver. However, there is a lack of comprehensive data on the organic pollutants’ behaviour in sludge-char. In our work, we focused on the behaviour of per- and polyfluoroalkyl substances (PFASs). Sludge was pyrolyzed at 200–700 °C to determine the minimum safe temperature for effective PFASs removal. It is important to note that PFASs may not only be mineralized but also cleaved to unanalyzed PFASs and other organofluorinated substances. To address this issue, we incorporated additional measurements of organic fluorine in the experiment using combustion ion chromatography (CIC). Due to the inherent heterogeneity of sludge, containing a variety of pollutants and their precursors, we conducted pyrolysis on artificially contaminated sand. This allowed us to assess and compare the behaviour of PFASs in a homogeneous matrix. Based on our analyses, we determined that a temperature greater than 400 °C is imperative for effective PFASs and organic fluorine removal. The results were verified by analyzing samples from a commercial sludge pyrolysis unit at the Bohuslavice-Trutnov WWTP, which confirmed our measurements. In light of these results, it becomes evident that sludge pyrolysis below 400 °C is unsuitable for PFAS removal from sewage sludge. Graphical Abstract

Abstract Background Massive amounts of sewage sludge are generated during biological sewage treatment and are commonly subjected to anaerobic digestion, land application, and landfill disposal. Concurrently, persistent organic pollutants (POPs) are frequently found in sludge treatment and disposal systems, posing significant risks to both human health and wildlife. Metabolically versatile microorganisms originating from sewage sludge are inevitably introduced to sludge treatment and disposal systems, potentially affecting the fate of POPs. However, there is currently a dearth of comprehensive assessments regarding the capability of sewage sludge microbiota from geographically disparate regions to attenuate POPs and the underpinning microbiomes. Results Here we report the global prevalence of organohalide-respiring bacteria (OHRB) known for their capacity to attenuate POPs in sewage sludge, with an occurrence frequency of ~50% in the investigated samples (605 of 1186). Subsequent laboratory tests revealed microbial reductive dechlorination of polychlorinated biphenyls (PCBs), one of the most notorious categories of POPs, in 80 out of 84 sludge microcosms via various pathways. Most chlorines were removed from the para- and meta-positions of PCBs; nevertheless, ortho-dechlorination of PCBs also occurred widely, although to lower extents. Abundances of several well-characterized OHRB genera (Dehalococcoides, Dehalogenimonas, and Dehalobacter) and uncultivated Dehalococcoidia lineages increased during incubation and were positively correlated with PCB dechlorination, suggesting their involvement in dechlorinating PCBs. The previously identified PCB reductive dehalogenase (RDase) genes pcbA4 and pcbA5 tended to coexist in most sludge microcosms, but the low ratios of these RDase genes to OHRB abundance also indicated the existence of currently undescribed RDases in sewage sludge. Microbial community analyses revealed a positive correlation between biodiversity and PCB dechlorination activity although there was an apparent threshold of community co-occurrence network complexity beyond which dechlorination activity decreased. Conclusions Our findings that sludge microbiota exhibited nearly ubiquitous dechlorination of PCBs indicate widespread and nonnegligible impacts of sludge microbiota on the fate of POPs in sludge treatment and disposal systems. The existence of diverse OHRB also suggests sewage sludge as an alternative source to obtain POP-attenuating consortia and calls for further exploration of OHRB populations in sewage sludge. Video Abstract

[Display omitted] • The release of Zn and Pb were mitigated by the synergistic effect. • Bioavailable fractions of HMs were reduced by SiO 2 and Al 2 O 3 from the sludge. • Bioavailable phosphorus was increased from 18.79 to 49.69 mg/g by co-pyrolysis. Phosphate tailings (PT) was used to reduce the release of heavy metals (HMs) during pyrolysis and the leachable rate of residual HMs, and simultaneously improve the bioavailability of phosphorus in the sludge-based biochar. The concentration of heavy metals and the fractions determined by BCR method was used to investigate the release and the transformation of Zn, Pb, Mn, Ni and Cu during pyrolysis involved with the effects of temperature and the addition of PT. The respective pyrolysis experiments shows that the release of Zn and Pb increases with temperature for both sewage sludge (SS) and PT, and the bioavailable fractions (F1 + F2) of Mn, Ni, and Cu increases with temperature for PT. During co-pyrolysis, blended samples released lower quantities of Zn and Pb and presented lower bioavailability of HMs than the individual SS or PT. A synergistic effect of co-pyrolysis was evident for volatile Zn and Pb. The decomposition of CaMg (CO 3) 2 from PT produced CaO, by which the volatile ZnCl 2 and PbCl 2 were transformed into ZnO and PbO with less volatility and higher reactivity with SiO 2 and Al 2 O 3 than the chlorides. Then SiO 2 and Al 2 O 3 from SS acted as the final stabilizer to immobilize the oxides. The final product combined with SiO 2 and Al 2 O 3 , such as ZnSiO 4 and ZnAl 2 O 4 , were detected. The addition of PT also introduced more Ca and P into sludge to produce biochar with higher concentration of apatite phosphorus with higher bioavailability. [ABSTRACT FROM AUTHOR]

The objective of this study is to evaluate the economic feasibility of leveraging H 2 generated from biogas for 28 sanitary landfill consortia in the state of Minas Gerais, Brazil. Two processes were analyzed: steam methane reforming (SMR) and pyrolysis reforming. Both were assessed via the economic analyses of Net Present Value (NPV), Levelized Cost of Hydrogen (LCOH) and Internal Rate of Return (IRR). Potential biogas production from sanitary landfills was estimated along with the production of hydrogen and ammonia. Installation (CAPEX) along with operation and maintenance (OPEX) costs were estimated for the biogas purification processes and attainment of H 2. The sales rate for H 2 as a fuel source was derived for each consortium. The capacity for ammonia attainment from H 2 was determined as well as the Levelized Cost of Ammonia (LCOA). The installed capacity of the consortia varied from 18,332.05 to 2,470,525.30 kg H 2 /year. The LCOH varied from 7.01 US$/kg to 44.45 US$/kg. Comparing the three scenarios, the Steam Methane Reforming (SMR) without CO 2 capture obtained the best economic results; however, this scenario leads to the emission of CO 2. The novelty of this research resides in the use of biogas to obtain H 2 and ammonia, as well as in comparing SMR with pyrolysis. The consortium CIDES showed the best economic results. The reformation processes of CH 4 in H 2 with zero CO 2 emissions obtained the best LCOH values, thus making it less competitive in relation to fossil fuels. Public policy changes are necessary to incentivize the production and use of H 2 and ammonia from biogas. • Economic feasibility of leveraging H 2 from biogas for sanitary landfill in Brazil. • Two processes were analyzed: steam methane reforming and pyrolysis reforming. • Biogas production was estimated along with the production of hydrogen and ammonia. • Ammonia attainment from H 2 and the Levelized Cost of Ammonia were determined. • Installed capacity of consortia varied from 12,738.08 to 1,716,651.77 kgH 2 /year. [ABSTRACT FROM AUTHOR]

In recent centuries, micronutrient deficiencies are considered a major challenge for human health. Biofortification of principal crops has been broadly accepted as a sustainable scenario to overcome this limitation. The experiment was carried out in a completely randomized factorial design with three replications during the 2007–2008 and 2008–2009 growing seasons. Four fertilizers and two doses of humic acid were used in the experiment. Analysis of variance indicated that humic acid, fertilizer type, and growing season caused statistically significant differences in macro and micronutrient content and heavy metal concentrations of shoot and seed in plants. Results also denoted that organic material amendment improved macro and micronutrient content of barley plants compared with IF in which SS treatment increased Ca, Mg, Mn, Fe, Zn, and Ni concentrations in shoot/seed while SM treatment enhanced N, P, and K concentration of plants. Moreover, IF-treated plants increased heavy metal accumulation in shoot and seed tissues whereas organic amendments reduced heavy metal uptake such that the lowest Pb and Cd were determined in SM-treated plants, and the lowest Ni content was measured in W-treated samples. HA application promoted Zn, Mg, and Cu accumulation in plants, however, individual or combined with fertilizers reduced other micro and macronutrient uptake. In conclusion, the amendment of 40 tons ha−1 of sheep manure and sewage sludge is an improving and beneficial practice in barley cultivation for the biofortification of crops. However, HA treatment did not form a meaningful whole in the experiment but promoted Zn, Mg, and Cu concentrations in plant tissues. [ABSTRACT FROM AUTHOR]

Dewatering is a crucial stage in the treatment of sludge since it directly increases capacity and lowers the cost of subsequent handling. Enhanced dewatering of printing and dyeing sludge was experimentally investigated with combined conditioners of sludge-derived biochar and ferric chloride (FeCl3) in this study. Results showed that the optimal conditioner dosages were: FeCl3 of 3% dry sludge (DS) and biochar of 60% DS. Compared with raw sludge, the sludge specific resistance to filtration (SRF) decreased by 77.14%, and the moisture content of sludge decreased from 85.38% to 67.08%. In addition, the chemical oxygen demand (COD), turbidity and chromaticity of supernatant decreased by 32.50%, 89.20% and 77.50%, respectively. It was found that the synergistic effect existed between the two conditioners. The possible mechanism was that FeCl3 aggregated small sludge particles to form large flocs and improved the dewatering performance of sludge, while biochar helped to build an incompressible and permeable sludge cake to further improve the sludge dewaterability due to its relatively hydrophobicity and large specific surface area. Therefore, combined addition of FeCl3 and biochar might be a promising conditioning method to enhance textile sludge dewaterability. [ABSTRACT FROM AUTHOR]

In this paper, we compared the sorption of copper and zinc on three adsorbents - bentonite, zeolite, and dewatered digested sludge from a wastewater treatment plant. Sorption was carried out at 27℃ and subsequently at a reduced temperature of 10℃ and the results were compared. The reduced temperature positively affected the sorption efficiency and increased the adsorption capacity of the monolayer of each sorbent. Regardless of the temperature, the sorption progression was not linear. In the initial phase, the sorption proceeded rapidly, but after about 90 min the system reached equilibrium and the concentrations of metals in solution did not change significantly. The size of the specific surface area of the sorbents did not directly correlate with the removal efficiency of Cu2+ and Zn2+. Copper sorption by bentonite reached a level of almost 100% at reduced temperature and 80% at room temperature. The efficiency of zinc removal by bentonite was found to be 40% at reduced temperature. The efficiency of copper removal using zeolite was approximately 90% at both laboratory and reduced temperature. For bentonite and zeolite, we confirmed their good sorption properties. The sludge showed low Cu2+ sorption efficiency, but Zn2+ removal efficiency was higher than bentonite and zeolite. In both cases, the reduced temperature had a positive effect on the sorption capacity of the sludge. Sludge as a waste material could be used for heavy metal removal by modifying the sorption conditions or its modifying, which should be further investigated. [ABSTRACT FROM AUTHOR]

Experiments of co-gasification of spirit-based distillers' grains (SDG) and sewage sludge (SS) were carried out with red mud (RM) by using a self-designed fixed-bed gasifier. The effects of RM addition, gasification reaction temperature, SS and SDG blending ratio and other factors on the gasification reaction characteristics and synergism were investigated. The results are as follow: RM had catalytic effect on SS and SDG co-gasification, which can enhance the gasification reaction and H2 yield; increasing the temperature can enhance the gasification reaction and reduce the syngas H2/CO; with the increase of SDG, the H2 yield gradually grew; with the rise of SS, the gasification reaction gradually augmented. The catalytic mechanism was mainly due to the redox cycle of Fe2O3 in RM, which can promote the water transfer reaction. At the same time, the eutectic mixture of K, Na, Ca, Fe and other metal elements at high temperatures was the main reason for the synergistic effect. [ABSTRACT FROM AUTHOR]

Over the recent years, ever-increasing population growth and higher wastewater production has been a challenge for decentralized wastewater treatment plants (WWTPs). In addition, sludge treatment due to high cost for equipment and place make authorities to find a sustainable approach in both of economical and technical perspectives. One of the proposed solutions is transferring the sludge produced from decentralized WWTP to centralized WWTP. However, the appropriate proportional ratio of raw sludge to raw sewage is a challenge, otherwise, it make anaerobic conditions and sewage rotting along the sewer network based on permissible limit of dihydrogen sulfide (H2S) gas (5 ppm). In the present study, seven reactors with different ratios of sludge to raw sewage (0, 15, 20, 25, 50, 75, 100) were used to stimulate the feasibility of transferring Shahrake Gharb WWTP sludge along the wastewater transfer pipe to the centralized sewage treatment south Tehran WWTP plant in Tehran, Iran. The septic situation and H2S emission of different reactors within 7 h (Time to reach the compound in the south treatment plant) was analyzed by gas meter. The results indicated that the optimum ratio of sludge to raw sewage was 15% without H2S production during 7 h. In addition, due to the high volume of sludge produced by the Shahrake Gharb WWTP, the optimal ratio of lime to total solids (TS) in sludge (gr/gr) (0.6) increased the sludge loading rate from 15 to 30% without any H2S emission during the stimulation study period. Therefore, the lime stabilization and transfer of sludge from a decentralized WWTP to a centralized WWTP is a feasible way to manage the sludge and enhance the treatment capacity in local WWTP. [ABSTRACT FROM AUTHOR]

The mushroom agroindustry generates a huge amount of waste from mushroom production (WMP). The composition of WMP is not standardized but differs mainly in terms of organic matter (OM) content and OM biodegradability. This makes WMP management, including anaerobic digestion (AD), a significant challenge. A potential solution could be co-digestion of WMP with municipal sewage sludge (SS), especially SS generated in small rural wastewater treatment plants (WWTPs). Therefore, this study investigated mesophilic methane production (MP) from WMP, SS, and mixtures of SS and WMP at ratios of 70:30, 50:50, and 30:70 (w/w OM). Even though the maximum cumulative MP from WMP was relatively low (approx. 60 NL/kg OM), co-digesting WMP with SS increased both MP and the methane content of the biogas: with 30%, 50%, and 70% shares of SS, MP increased almost 2, 2.5, and 3.3 times, and the methane content increased to 61%, 62%, and 64%, respectively. As the SS content was increased, the kinetic coefficients of MP and OM removal decreased (from 0.211 to 0.146 d−1 and from 0.215 to 0.152 d−1), whereas the initial rate of MP and of OM removal increased (from 12.5 to 36.8 NL/(kg OM·d) and from 0.51 kg OM/(m3·d) to 0.59 kg OM/(m3·d), respectively). The effectiveness of OM removal (EOMrem) was lowest with WMP only, at 46.6%. When the SS content of the mixtures was increased to 30%, 50%, and 70%, EOMrem also increased to 55.3%, 60.1%, and 64.9%, respectively. The relationship between maximal MP and the overall OM removed was such that both increased simultaneously. The higher values of EOMrem and, consequently, the lower final contents of OM with more effective MP indicate that the organics were degraded more efficiently. These results suggest that co-digestion may be a profitable solution for simultaneously utilizing both of these waste products, increasing the efficiency of biogas production to such an extent that it would be profitable to conduct AD on mushroom farms. This is a flexible approach that allows varying proportions of WMP and SS to be used, depending on the availability of both substrates and the energy needs of the mushroom farm. However, it should be borne in mind that a higher share of WMP results in lower gas productivity. [ABSTRACT FROM AUTHOR]

Sewage sludge has long been applied to soils as a fertilizer yet may be enriched with leachable metal(loid)s and other pollutants. Sulfidated nanoscale zerovalent iron (S-nZVI) has proven effective at metal sorption; however, risks associated with the use of engineered nanoparticles cannot be neglected. This study investigated the effects of the co-application of composted sewage sludge with S-nZVI for the stabilization of Cd, Pb, Fe, Zn. Five treatments (control, Fe grit, composted sludge, S-nZVI, composted sludge and S-nZVI), two leaching fluids; synthetic precipitation leaching procedure (SPLP) and toxicity characteristic leaching procedure (TCLP) fluid were used, samples were incubated at different time intervals of 1 week, 1, 3, and 6 months. Fe grit proved most efficient in reducing the concentration of extractable metals in the batch experiment; the mixture of composted sludge and S-nZVI was the most effective in reducing the leachability of metals in the column systems, while S-nZVI was the most efficient for reducing about 80% of Zn concentration in soil solution. Thus, the combination of two amendments, S-nZVI incorporated with composted sewage sludge and Fe grit proved most effective at reducing metal leaching and possibly lowering the associated risks. Future work should investigate the longer-term efficiency of this combination. [ABSTRACT FROM AUTHOR]

AbstractTo realize the safe disposal of solid waste containing heavy metals, sewage sludge jointly with slag and metakaolin was used to prepare alkali-activated materials (AAMs), and the effect mechanism of polycarboxylate acid superplasticizer (PCE), naphthalene superplasticizer (NS) and aliphatic superplasticizer (AS) in AAMs were studied. The results showed that both the fluidity and strength of AAMs decreased with the addition of sludge. For the NaOH + Na2SiO3 activated mortar specimen, the incorporation of sludge can reduce their fluidity and strength from 206 mm and 80.25 MPa to 193 mm and 42.43 MPa, respectively. However, the addition of superplasticizers into sludge-containing AAMs leads to a reduction of 3–9% of the fluidity. Interestingly, it can enhance the strength of the AAMs, especially the NS and AS, which increase the strength by approximately 25%. This is attributed to the increase of particle dispersion by superplasticizers. However, the free water released in the process is reabsorbed by the sludge, which increases the local alkali concentration and promotes the activation of the activity. The dispersed sludge particles can play the role of physical filling, making the structure denser. HIGHLIGHTSSludge is adverse effects on both the fluidity and strength of alkali-activated materials (AAMs).The addition of superplasticizers (SPs) increases the strength of AAM with sludge.SPs do not affect improving the fluidity of AAMs with sludge, even slightly bad.The dispersion effect of SPs on the sludge is beneficial to promote its activity in AAMs.Sludge is adverse effects on both the fluidity and strength of alkali-activated materials (AAMs).The addition of superplasticizers (SPs) increases the strength of AAM with sludge.SPs do not affect improving the fluidity of AAMs with sludge, even slightly bad.The dispersion effect of SPs on the sludge is beneficial to promote its activity in AAMs. [ABSTRACT FROM AUTHOR]

Low‐carbon alkaline thermal hydrolysis of sewage sludge for the production of high‐quality plant‐growth‐promoting nutrients and biostimulants is a growing concern for sludge resource utilization in agriculture. Thus, this study aims to investigate functional characteristics and soil biochemical effects of sewage sludge‐derived nutrients and biostimulants (SS‐NB). The content of heavy metals in SS‐NB decreased by 47.39–100%, and an increase in soil protease, invertase, and soil nutrient utilization rates are observed in SS‐NB groups. SS‐NB substituted for chemical fertilizer increased the diversity and evenness of microbial community and reduced the abundance of the soil‐borne bacterial genus Arthrobacter. The dominant community of SS‐NB100 group is mainly enriched in Microvirga, Ensifer, Novosphingobium, Bosea and Ellin6055, which are principally beneficial symbiotic bacteria of plants and participated in C and N cycles. Moreover, SS‐NB reduced the accumulation of Ktedonobacteria and Nitrosospira, which are involved in the production of CO2 and N2O, and also enhanced the coordination of soil microorganisms with enzyme activities and nutrient utilization rate. In conclusion, the results suggest that SS‐NB exerts a positive effect on reducing greenhouse gas emissions and preventing soil‐borne diseases, and can further enhance collaboration with soil enzyme activity and soil nutrient utilization by stimulating soil microorganisms. [ABSTRACT FROM AUTHOR]

Prescribed burning is a management tool commonly used in forested ecosystems in the southeastern United States, but the influence of this method on grassland vegetation and wildlife in this geographic region is unknown. During 2009–2015, we conducted a study to determine if the application of prescribed burning and/or long-term biosolid applications alter plant communities and/or wildlife use of grassland areas at Marine Corps Air Station Cherry Point, Havelock, NC. We monitored vegetation growth, measured plant community composition, and documented wildlife activity in four study plots for 3 years after the implementation of annual winter prescribed burns. Prescribed burning reduced the amount of litter, increased bare ground during spring, and altered the plant community composition relative to areas that were not burned. Overall, prescribed burning did not alter (F1,803 = 0.37, p = 0.54) bird use of the airfield grasslands, while the long-term application of biosolids resulted in higher (F1,803 = 17.61, p < 0.01) bird use. Few species-specific differences in avian use of prescribed burned and unburned grasslands were found. In contrast, white-tailed deer (Odocoileus virginianus) use of areas that were burned in winter, as well as the adjacent unburned areas, was drastically reduced. Winter prescribed burning appeared to remove forage plants at the time of year deer would use them the most. Our findings suggest that prescribed burning and biosolid applications, used alone and in combination, might be viable grassland management tools for altering wildlife use of grassland areas, specifically white-tailed deer; however, similar research at additional locations should be conducted. [ABSTRACT FROM AUTHOR]

The recent SARS‐CoV‐2 outbreak yielded substantial data regarding virus fate and prevalence at water reclamation facilities (WRFs), identifying influential factors as natural decay, adsorption, light, pH, salinity, and antagonistic microorganisms. However, no studies have quantified the impact of these factors in full scale WRFs. Utilizing a mass balance approach, we assessed the impact of natural decay and other fate mechanisms on genetic marker removal during water reclamation, through the use of sludge and wastewater genetic marker loading estimates. Results indicated negligible removal of genetic markers during P/PT (primary effluent (PE) p value: 0.267; preliminary and primary treatment (P/PT) accumulation p value: 0.904; and thickened primary sludge (TPS) p value: 0.076) indicating no contribution of natural decay and other fate mechanisms toward removal in P/PT. Comparably, adsorption and decomposition was found to be the dominant pathway for genetic marker removal (thickened waste activated sludge (TWAS) log loading 9.75 log10 GC/day); however, no estimation of log genetic marker accumulation could be carried out due to high detections in TWAS. Practitioner Points: The mass balance approach suggested that the contribution of natural decay and other fate mechanisms to virus removal during wastewater treatment are negligible compared with adsorption and decomposition in P/PT (p value: 0.904).During (P/PT), a higher viral load remained in the (PE) (14.16 log10 GC/day) compared with TPS (13.83 log10 GC/day); however, no statistical difference was observed (p value: 0.280) indicting that adsorption/decomposition most probably did not occur.In secondary treatment (ST), viral genetic markers in TWAS were consistently detected (13.41 log10 GC/day) compared with secondary effluent (SE), indicating that longer HRT and the potential presence of extracellular polymeric substance‐containing enriched biomass enabled adsorption/decomposition.Estimations of total solids and volatile solids for TPS and TWAS indicated that adsorption affinity was different between solids sampling locations (p value: <0.0001). [ABSTRACT FROM AUTHOR]

It is desirable to recycle sewage sludge as fertilizer for agricultural fields. The application of sludge to agricultural soils is a measure that replaces chemical fertilizers and plays an important role in improving soil's physicochemical and biological properties. However, there are concerns that the pollutants in sewage sludge will cause negative impacts on soil health. To closely monitor the soil–sludge interactions, a field study was conducted over a 20-year period in the North China Plain. In this study, the long-term effects of sewage sludge on the soil properties and soil microbial diversity were investigated. We examined the effects of various fertilization methods (control, chemical fertilizer, uncomposted sludge fertilizer, composted sludge fertilizer) on wheat production and several soil health indicators, such as the soil's enzymatic activities, microbial biomass, microbial diversity, and crop yield. This long-term experiment supports that the composted sludge fertilizer increased crop production by 124.2% compared to the control treatment. The soil's biological quality (e.g., the concentration of soil microbial biomass carbon) was also improved under the composted sludge fertilizer treatment. The concentrations of soil microbial biomass carbon under the uncomposted sludge fertilizer and composted sludge fertilizer treatments were 560.07 mg/kg and 551.07 mg/kg, respectively. The effect of the composted sludge fertilizer was greater than that of the uncomposted sludge fertilizer. The content of heavy metals did not exceed the national standard. The highest soil health index was 0.79 with the composted sludge fertilizer. Therefore, these results suggest that the application of composted sludge fertilizer has the potential to enhance long-term soil health and promote sustainable agricultural practices. [ABSTRACT FROM AUTHOR]

The concentration of viruses in sewage sludge is significantly higher (10–1000-fold) than that found in natural environments, posing a potential risk for human and animal health. However, the composition of these viruses and their role in the transfer of pathogenic factors, as well as their role in the carbon, nitrogen, and phosphorus cycles remain poorly understood. In this study, we employed a shotgun metagenomic approach to investigate the pathogenic bacteria and viral composition and function in two wastewater treatment plants located on a campus. Our analysis revealed the presence of 1334 amplicon sequence variants (ASVs) across six sludge samples, with 242 ASVs (41.22% of total reads) identified as pathogenic bacteria. Arcobacter was found to be the most dominant pathogen accounting for 6.79% of total reads. The virome analysis identified 613 viral genera with Aorunvirus being the most abundant genus at 41.85%. Approximately 0.66% of these viruses were associated with human and animal diseases. More than 60% of the virome consisted of lytic phages. Host prediction analysis revealed that the phages primarily infected Lactobacillus (37.11%), Streptococcus (21.11%), and Staphylococcus (7.11%). Furthermore, our investigation revealed an abundance of auxiliary metabolic genes (AMGs) involved in carbon, nitrogen, and phosphorus cycling within the virome. We also detected a total of 113 antibiotic resistance genes (ARGs), covering major classes of antibiotics across all samples analyzed. Additionally, our findings indicated the presence of virulence factors including the clpP gene accounting for approximately 4.78%, along with toxin genes such as the RecT gene representing approximately 73.48% of all detected virulence factors and toxin genes among all samples analyzed. This study expands our understanding regarding both pathogenic bacteria and viruses present within sewage sludge while providing valuable insights into their ecological functions. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) are widely present in the environment, causing increasing concern because of their impact on soil health, food safety and potential health risks. Four bioremediation strategies were examined to assess the dissipation of PAHs in agricultural soil amended with sewage sludge over a period of 120 days: soil-sludge natural attenuation (SS); phytoremediation using maize (Zea mays L.) (PSS); mycoremediation (MR) separately using three white-rot fungi (Pleurotus ostreatus , Phanerochaete chrysosporium and Irpex lacteus) ; and plant-assisted mycoremediation (PMR) using a combination of maize and fungi. In the time frame of the experiment, mycoremediation using P. chrysosporium (MR-PH) exhibited a significantly higher (P < 0.05) degradation of total PAHs compared to the SS and PSS treatments, achieving a degradation rate of 52 %. Both the SS and PSS treatments demonstrated a lower degradation rate of total PAHs, with removal rates of 18 % and 32 %, respectively. The PMR treatments showed the highest removal rates of total PAHs at the end of the study, with degradation rates of 48–60 %. In the shoots of maize, only low- and medium-molecular-weight PAHs were found in both the PSS and PMR treatments. The calculated translocation and bioconversion factors always showed values < 1. The analysed enzymatic activities were higher in the PMR treatments compared to other treatments, which can be positively related to the higher degradation of PAHs in the soil. [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]

Extreme thermophiles Calditerricola satsumensis DD2 and D3 were isolated from mesothermal municipal sludge, a material used for hyperthermal composting. To understand the ecologically anomalous findings, their behavior at various temperatures, membrane fatty acid composition, and draft genome sequences were compared with those of C. satsumensis YMO81T and Calditerricola yamamurae YMO722T, already isolated from hyperthermal compost. All four strains grew between 56 and 83 °C. However, strains DD2 and D3 were stable for ≥48 h at a wide range of temperatures (20–75 °C), while strains YMO81T and YMO722T were highly labile at lower temperatures. The former strains maintained their colony-forming ability for >180 days at 20 °C, while the latter strains lost it within 1 d. All four strains showed similar composition of membrane fatty acid, which were not affected by 20 °C treatment. Comparative draft genome analyses showed that 13 candidate genes were present only in strains DD2 and D3, and the specific expression of six gene homologs was confirmed. A DNA chaperone, site-specific recombinase XerD homolog, had tetra adenine sequence at its upper gene region, and was up-regulated by 20 °C treatment in DD2 and D3, suggesting a possible role in the cold tolerance of sludge-derived strains. In addition, the lack of another possible DNA chaperone, a homolog of the ATP-dependent DNA helicase, in the compost-derived strains may accelerate their sensitivity to cold shock. In conclusion, we speculate that the specific phenotypic and genotypic characteristics of sludge-derived strains are responsible for their unusual ecological distribution at ambient temperatures. [ABSTRACT FROM AUTHOR]

Liquid biofuels like biodiesel and bioethanol are crucial in the transition to low-carbon and high-energy alternatives to fossil fuels. One significant by-product of biodiesel production is glycerol, which accounts for about 10% of the total conversion output. While waste glycerol poses challenges due to its impurities and contaminants, it also holds potential as a metabolic resource for essential cellular components in microorganisms. Crude glycerol production is reviewed, highlighting relevance in current biodiesel technologies and its biochemical composition. To efficiently utilize waste glycerol, co-valorization with low-cost substrates through biocircular platforms using various microorganisms or insects for second and third-generation oxy-biofuels has been explored. Among these, the black soldier fly larvae have demonstrated higher competitiveness for lipid contents (35–43%), making them a promising organism for recycling waste glycerol into biodiesel production, alongside microalgae and oleaginous yeast. The microbial biodiesel productivity from oleaginous yeast is notably higher (3546 kg ha−1 y−1) than soybean biodiesel (562 kg ha−1 y−1), while microalgal biodiesel productivity surpasses palm biodiesel by more than 25 times. Remarkably, black soldier fly larvae biodiesel productivity was reported to be ~ 1.7 times higher than microalgae and an impressive ~ 43 times higher than palm biodiesel. Despite their potential for biodiesel production, waste glycerol from biodiesel industry still represents a challenge because of high impurities, high viscosity, and limited direct applications in existing processes. To further enhance energy sustainability and address the challenge of waste glycerol, biocircular platforms are discussed for waste glycerol utilization with domestic wastewater sludge, lignocellulosic biomass, and protein-rich wastes. These platforms offer opportunities to create other sustainable agricultural products while minimizing their environmental footprint. [ABSTRACT FROM AUTHOR]

[Display omitted] • Carbon-rich and low-ash hydrochars is prepared innovatively from sewage sludge. • Hydrochar produced from sludge alkaline hydrolysate showed nanoparticle structure. • Multilayer microsphere structure was formed from sludge alkali-thermal hydrolysate. • Hydrochar with carbon content over 70% and ash content less than 5% was realized. • Hydrolysis temperature is an important factor to influence the hydrochar formation. The production of carbon-rich and low-ash hydrochar from sewage sludge is attracting interest due to its great application prospect in high value-added carbon materials fields, but which is impossible through direct hydrothermal carbonization. In this study, alkali-thermal hydrolysis followed by acid-assisted hydrothermal carbonization was thus proposed. Thermal hydrolysis at strong alkaline environment was more effective than acid one to promote the dissolution of organic matters and restrain the release of inorganic matters from sludge, which created a favorable condition for hydrochar formation in a carbon-rich and low-ash way. Alkali-thermal hydrolysis began to show a positive effect on the dissolution of organics in sludge when temperature exceeded the threshold of 90 °C, and an increase of 9.77 % was found at 150 °C when compared to 30 °C. Acid-assisted hydrothermal carbonization of alkali-thermal hydrolysate (ATH) at pH 1.0 strongly promoted condensation polymerization of dissolved organics to form hydrochar and meanwhile inhibited introduction of dissolved inorganics. The nanosized microparticulate hydrochar derived from ATH-30 had a carbon and ash content of 50.98–61.31 % and 10.76–12.09 %, while the micro-sized microspheric hydrochar with multiple deposition layers formed from ATH-150 showed a better performance in carbon-rich and low-ash aspect where a carbon and ash content of 58.24–70.07 % and 0.40–3.24 % was realized, both of which were obviously superior to the direct hydrochar (carbon 34.86 % and ash 46.11 %). The condensation of dissolved organics during alkali-thermal hydrolysis stage is important to the carbonization degree of hydrochar. This study provides a new perspective in sludge disposal and production of advanced carbon materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • Co-incineration biodried products in cement kilns were researched. • Combustion performance of biodried products was better than that of sewage sludge. • Heat efficiency of biodried products during co-incineration was 93.7%. • Co-incineration leads to increased SO 2 and NO X emission concentrations. • Biodried product as fuels have greater potential to reduce carbon emissions. The biodrying technology as a pretreatment technology can overcome the limitations of cement kilns co-incineration sewage sludge (SS) on energy consumption. But the impact of SS biodried products on cement kilns and the route carbon reduction potential of biodrying + cement kilns have not been studied. In this study, SS biodrying and cement kiln co-incineration biodried product trials were conducted to highlight the matrix combustion characteristics, and the impact of biodried products on cement kilns (clinker capacity, coal consumption, and pollutant discharge). The carbon emissions of the four scenarios were assessed based on these results. The results showed that water removal rate reached 65.5 % after 11-day biodrying, and the wet-based lower heating value of the biodried product increased by 76.0 % compared with the initial matrix. Comprehensive combustibility index of the biodried product (0.745 × 10−7 %2℃−3min−2) was better than that of SS (0.433 × 10−7 %2℃−3min−2) although a portion of the organic matter was degraded. Cement kiln co-incineration of biodried products (150 t/d) resulted in per tonne of clinker saved 5.61 kg of coal due to the heat utilization efficiency of biodried products reached to 93.7 %. However, it led to an increase in the emission concentrations of NO X and SO 2. Assessment results indicated that the biodrying + cement kiln pathway reduced CO 2 emissions by 385.7 kg/t SS. Biodried products have greater potential to reduce emissions as alternative fuels than as fertilizers. This study indicated the advantages of SS biodrying + cement kiln co-incineration route. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel combination of X-ray tomography with elemental and crystalline composition. • 3D view of microstructure and phosphate distribution based on the X-ray attenuation. • Phosphates comprised 7–17 vol% of slag particle volume. • Porosity of 15–35 vol% for slag particles from combustion of sewage sludge mixtures. The purpose of this study was to provide detailed knowledge of the morphological properties of ash particles, including the volumetric fractions and 3D distributions of phosphates that lay within them. The ash particles came from digested sewage sludge co-combusted with K- and Si-rich wheat straw or K-rich sunflower husks. X-ray micro-tomography were combined with elemental composition and crystalline phase information to analyse the ash particles in 3D. Analyses of differences in the X-ray attenuation enabled calculation of 3D phosphate distributions that showed high heterogeneity in the slag particles. This is underscored by a distinct absence of phosphates in iron-rich and silicon-rich parts. The slag from silicate-based wheat straw mixtures had lower average attenuation than that from sunflower husks mixtures, which contained more calcium. Calculated shares of phosphates between 7 and 17 vol% were obtained, where the highest value for a single assigned phosphate was observed in hard slag from wheat straw with 10 % sewage sludge. The porosity was notably higher for particles from pure wheat straw combustion (62 vol%), compared to the other samples (15–35 vol%). A high open pore volume fraction (60–97 vol%) indicates that a large part of the pores can be accessed by the surroundings. For all samples, more than 60 % of the discrete (closed) pores had an equivalent diameter < 30 μm, while the largest volume fraction consisted of pores with an equivalent diameter > 75 μm. Slag from sunflower husk mixtures had larger pore volumes and a greater relative number of discrete pores >75 µm compared to wheat straw mixtures. [ABSTRACT FROM AUTHOR]

Straw pretreatment enhances the cellulose accessibility and increases the methane yield from anaerobic digestion. This study investigated the effects of alkali pretreatments with different chemical agents (NaOH, KOH, and Na2CO3) on the physicochemical and thermal characteristics of barley straw, as well as methane production from codigestion with sewage sludge. Artificial neural network modeling with a feedforward neural network (FFNN) and slime mold optimization (SMO) techniques were used to predict methane production. NaOH pretreatment was shown to be the best pretreatment for removing hemicellulose and lignin and for increasing the cellulose accessibility. Moreover, there was a 2.57-fold higher level of methane production compared to that from codigestion with untreated straw. The removal ratios for the total solids, volatile solids, and chemical oxygen demand reached 59.3, 67.2, and 73.4%, respectively. The modeling results showed that the FFNN-SMO method can be an effective tool for simulating the methane generation process, since training, validating, and testing produced very high correlation coefficients. The FFNN-SMO accurately predicted the amount of methane produced, with an R² of 0.998 and a 3.1x10-5 root mean square error (RMSE). [ABSTRACT FROM AUTHOR]

Pyrolysis is one method for treating sewage sludge, particularly in remote areas or decentralised systems. The end product of pyrolysis, sludge-char, can serve as a soil improver. However, there is a lack of comprehensive data on the organic pollutants' behaviour in sludge-char. In our work, we focused on the behaviour of per- and polyfluoroalkyl substances (PFASs). Sludge was pyrolyzed at 200–700 °C to determine the minimum safe temperature for effective PFASs removal. It is important to note that PFASs may not only be mineralized but also cleaved to unanalyzed PFASs and other organofluorinated substances. To address this issue, we incorporated additional measurements of organic fluorine in the experiment using combustion ion chromatography (CIC). Due to the inherent heterogeneity of sludge, containing a variety of pollutants and their precursors, we conducted pyrolysis on artificially contaminated sand. This allowed us to assess and compare the behaviour of PFASs in a homogeneous matrix. Based on our analyses, we determined that a temperature greater than 400 °C is imperative for effective PFASs and organic fluorine removal. The results were verified by analyzing samples from a commercial sludge pyrolysis unit at the Bohuslavice-Trutnov WWTP, which confirmed our measurements. In light of these results, it becomes evident that sludge pyrolysis below 400 °C is unsuitable for PFAS removal from sewage sludge. Highlights: The minimum temperature for significant PFASs and organic fluorine removal was 400 °C. PFASs were part of primary pyrolysis gas: purification or combustion is necessary. Contamination by PFASs and their congeners could be monitored with organic fluorine. [ABSTRACT FROM AUTHOR]

The continuous tightening of legislation regulating the agricultural usage of sewage sludge in the province of Catalonia (Spain) leads us to propose its gasification to produce hydrogen-rich syngas. A thermodynamic equilibrium model was developed using Aspen Plus® to simulate the air and steam gasification of sewage sludge from a wastewater treatment plant in Catalonia. The syngas generated is analyzed in terms of composition and lower heating value (LHV), as a function of equivalence ratio (ER), gasification temperature (Tgas), steam-to-biomass ratio (SBR), and moisture content (MC). Results show that air-blown gasification finds the highest LHV of 7.48 MJ/m3 at 1200 °C, ER of 0.2, and MC of 5%. Using steam as the gasifying agent, an LHV of 10.30 MJ/m3 is obtained at SBR of 0.2, MC of 5%, and 1200 °C. A maximum of 69.7% hydrogen molar fraction is obtained at 600 °C, MC of 25%, and SBR of 1.2. This study suggests using steam as a gasifying agent instead of air since it provides a higher LHV of the syngas as well as a hydrogen-richer syngas for the implementation of gasification as an alternative method to sewage sludge treatment in the region of Catalonia. Since the economic aspect should also be considered, in this regard, our sensitivity analysis provided important data demonstrating that it is possible to reduce the gasification temperature without significantly decreasing the LHV. [ABSTRACT FROM AUTHOR]

The aim of the present work was to investigate ash formation and associated interactions during the pulverized fuel co-combustion of biomass fuels. Combustion experiments were carried out with narrowly sized wheat straw (WS), sewage sludge (SS), and their blends in a drop tube furnace at 1100 °C and 1300 °C. The resulting residual ash and fine particulate matter (PM10) were characterized with various analyses. It was observed that co-combustion influences size distributions of the residual ash particles and generally generates larger residual ash particles close to those of SS combustion. The interaction of K capture by minerals enhances the melting and consequently increases the production of large and melting ash particles during co-combustion. It was found that blending SS with WS has not only the positive interaction of K capture by minerals from SS ash to significantly reduce submicron ash formation, but also the positive interaction of transforming alkali chlorides into alkali sulfates to reduce the corrosiveness of submicron ash particles. Co-combustion of SS with WS can also reduce the presence of alkali chloride at PM1–10, lowering the propensities of deposition and corrosion of the fine residual ash particles. [ABSTRACT FROM AUTHOR]

The valorisation of sewage sludge for sustainable agricultural use and biofuel production proposes an effective and beneficial management of sewage sludge in a closed-loop cycle. The management of sewage sludge biowaste is a rising problem due to increasing waste storage expenses. In this sense, the use of circular economy principles in sewage sludge management creates opportunities to develop new technologies for processing. The biorefinery model allows the application of wasteless technologies via sewage sludge valorisation in terms of agricultural use and biofuel production, especially with the hydrothermal carbonisation method. Applying hydrothermal carbonisation in the treatment of biosolid sewage sludge has numerous benefits due to processing highly hydrated organic waste into carbon hydro char, a high-quality solid biofuel. The direct use of sewage sludge in the soil does not allow for full use of its functional properties. However, the hydrothermal carbonisation of sewage sludge results in biocarbon pellets, making it a viable approach. This work also discusses the barriers (legal, chemical, biological, and technical) and possibilities related to sewage sludge biorefining processes. [ABSTRACT FROM AUTHOR]

Utilizing waste, such as sewage sludge, into biochar fits the circular economy concept. It maximizes the reuse and recycling of waste materials in the wastewater treatment plant. The experiments were conducted to assess: (1) the impact of the temperature on the properties of biochar from sewage sludge (400 °C, 500 °C, 600 °C, 700 °C); (2) how the physical activation (CO2, hot water) or chemical modification using (MgCl2, KOH) could affect the removal of ammonia nitrogen and phosphorus from filtrate collected from sludge dewatering filter belts or synthetic solution, wherein the concentration of ammonium nitrogen and phosphorus were similar to the filtrate. Based on the Brunner–Emmett–Teller (BET) surface and the type and concentration of surface functional groups for the second stage, biochar was selected and produced at 500 °C. The modification of biochar had a statistically significant effect on removing nitrogen and phosphorus from the media. The best results were obtained for biochar modified with potassium hydroxide. For this trial, 15%/17% (filtrate/synthetic model solution) and 72%/86% nitrogen and phosphorus removal, respectively, were achieved. [ABSTRACT FROM AUTHOR]

Wastewater treatment plants (WWTPs) are considered to be hotspots for the spread of antibiotic resistance genes (ARGs). We performed a metagenomic analysis of the raw wastewater, activated sludge and treated wastewater from two large WWTPs responsible for the treatment of urban wastewater in Moscow, Russia. In untreated wastewater, several hundred ARGs that could confer resistance to most commonly used classes of antibiotics were found. WWTPs employed a nitrification/denitrification or an anaerobic/anoxic/oxic process and enabled efficient removal of organic matter, nitrogen and phosphorus, as well as fecal microbiota. The resistome constituted about 0.05% of the whole metagenome, and after water treatment its share decreased by 3–4 times. The resistomes were dominated by ARGs encoding resistance to beta-lactams, macrolides, aminoglycosides, tetracyclines, quaternary ammonium compounds, and sulfonamides. ARGs for macrolides and tetracyclines were removed more efficiently than beta-lactamases, especially ampC, the most abundant ARG in the treated effluent. The removal efficiency of particular ARGs was impacted by the treatment technology. Metagenome-assembled genomes of multidrug-resistant strains were assembled both for the influent and the treated effluent. Ccomparison of resistomes from WWTPs in Moscow and around the world suggested that the abundance and content of ARGs depend on social, economic, medical, and environmental factors. [ABSTRACT FROM AUTHOR]

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]

Soil application of treated sewage sludge is considered a beneficial management option for agriculture and environment. Sludge treated with clay minerals or biochar was evaluated as soil amendment, in comparison with limed or untreated sludge. Bentonite, vermiculite, biochar or lime was added to dewatered sewage sludge at 0 and 15% rates, in three replications and air-dried. Then, the treated and untreated sludge were added to two soils, one acid and one alkaline, at 0 (control), 1 and 3% rates, in three replications. The results showed that the pH of acid soil significantly increased compared to control upon addition of treated and untreated sludge at both rates, but remained acidic (<6.0) in all cases except for limed sludge. Upon addition of 3% treated or untreated sludge to both soils, organic carbon (OC) significantly increased compared to control. The same stands for soil available ammonium nitrogen (NH4-N), phosphorus (P), potassium (K), copper (Cu), zinc (Zn) and boron (B) for both soils and rates. Soil total heavy metals, which regulate sludge's agronomic use, were below the legislative limits. However, the 3% addition rate of all kinds of sludge, especially of untreated, to both soils increased the electrical conductivity of saturation extract (ECse >2 dS m−1) at unacceptable levels for sensitive crops and available P, B and Zn 2–3, 2–4 and 6–12 times above the initial, respectively. Consequently, sewage sludge treated with bentonite, vermiculite or biochar could be used as a soil amendment but at rates lower than 3% (≈120 Mg ha−1). [ABSTRACT FROM AUTHOR]

[Display omitted] • The effect of thermal hydrolysis on sludge hydrochar properties was investigated. • The nitrogen and sulfur content in hydrochars decreased significantly. • Hydrochar thermal decomposition stability was improved. • The driving mechanism of thermal hydrolysis was elucidated. Hydrothermal carbonization of waste activated sludge suffers from a low degree of carbonization caused by limited hydrolysis of carbohydrates and proteins, resulting in a high nitrogen content in hydrochar. Thus, it is hypothesized that thermal hydrolysis could destroy the stable floc structure of waste activated sludge, leading to higher degree of carbonization and high quality hydrochar with low nitrogen content by improving the solubilization and hydrolysis of organic matter. In the current study, thermal hydrolysis at 90 °C, 125 °C, and 155 °C was performed prior to hydrothermal carbonization to obtain low-nitrogen-content hydrochar. Thermal hydrolysis greatly improved the hydrolysis of sewage sludge. The nitrogen and sulfur content in hydrochars obtained after thermal hydrolysis decreased to 1.5–1.6 % from 1.7 %, and to 0.4 % from 0.5 %, respectively, depending on the hydrolysis conditions. Thermal decomposition stability of hydrochars obtained after thermal hydrolysis were also improved. Thermal hydrolysis at 90 °C and 125 °C promoted hydrolysis, dehydration, and the Diels-Alder reaction during hydrothermal carbonization, resulting in lower hydrochar yield but higher H/C and O/C atomic ratio. The Maillard reaction occurred during thermal hydrolysis at 155 °C, leading to the formation of large molecular refractory compounds that were retained in the hydrochar and increased the hydrochar yield. Furthermore, thermal hydrolysis can accelerate pyrolysis reaction of hydrochars, resulting in reduced energy consumption. The newly established thermal hydrolysis-hydrothermal carbonization process using sewage sludge as the feedstock has the potential to contribute to the development of the hydrothermal carbonization industry. [ABSTRACT FROM AUTHOR]

• 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]

To date, only a few studies focused on the carbon monoxide (CO) production during waste composting; all targeted on CO inside piles. Here, the CO net emissions from compost piles and the assessment of worker's occupational risk of exposure to CO at large-scale composting plants are shown for the first time. CO net emissions were measured at two plants processing green waste, sewage sludge, or undersize fraction of municipal solid waste. Effects of the location of piles (hermetised hall vs. open yard) and turning (before vs. after) were studied. Higher CO net emission rates were observed from piles located in a closed hall. The average CO flux before turning was 23.25 and 0.60 mg‧m-2‧h-1 for hermetised and open piles, respectively, while after– 69.38 and 5.11 mg‧m-2‧h-1. The maximum CO net emissions occurred after the compost was turned (1.7x to 13.7x higher than before turning). The top sections of hermetised piles had greater CO emissions compared to sides. Additionally, 5% of measurement points of hermetised piles switched to 'CO sinks'. The 1-h concentration in hermetised composting hall can reach max. ~50 mg CO∙m-3 before turning, and >115 mg CO∙m-3 after, exceeding the WHO thresholds for a 1-h and 15-min exposures, respectively. [ABSTRACT FROM AUTHOR]

This paper aims to study the feasibility of municipal sewage sludge utilization as an energy source in a polygeneration system. This system offers distinctive benefits such as contribution to the principled removal of sewage sludge, simultaneous utilization of raw and digested sludge in different parts of the system, and production of renewable hydrogen from bio-waste. 4E (energy, exergy, exergoeconomic, and environmental) analyses, are performed to understand the system performance comprehensively. Then, parametric studies are examined the impact of changing the values of main parameters on the system operation. Afterward, a multi-objective optimization based on a genetic algorithm is carried out to achieve optimal values, considering a trade-off between the exergy efficiency and the total cost rate. Meanwhile, this work harnesses the potential of artificial neural networks to expedite complex and time-consuming optimization processes. According to the results, the gasifier exhibits the highest rate of exergy destruction, and the primary cost of consumption is attributed to its heat supply. The multi-objective optimization findings show that the optimum point has an exergy efficiency of 38.26 % and a total cost rate of 58.17 M$/year. The hydrogen production rate, energy efficiency, and net power generation rate for the optimal case are determined as 1692 kg/h, 35.24 %, and 4269 kW, respectively. Also, the unit cost of hydrogen in the optimal case is obtained 1.49 $/kg which offers a cost-effective solution for hydrogen production. [Display omitted] • 4E analysis and optimization performed on a bio-waste driven polygeneration system. • Plant optimized using artificial neural network and multi-objective genetic algorithm. • The feasibility of integrating a membrane for hydrogen separation investigated. • The optimum exergy efficiency and total cost rate obtained 38.26 % and 58.17 M$/year. • Hydrogen and electricity cost of 1.49 $/kg and 0.0145 $/kWh achieved for optimal case. [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]

In order to promote the yield and calorific value of combustible gas products in the pyrolysis, a CaO-based biochar (CSC) derived from waste crab shell was used as a low-cost sorption-enhanced catalyst to enhance oil-fried sludge (OS) pyrolysis. The effects of CSC addition and pyrolysis temperature on OS pyrolysis characteristics were analyzed in detail. The results indicated that adding CSC significantly enhanced OS pyrolysis and produced more combustible gas products with CO2 removal. At 700 °C, adding CSC promoted the combustible gas yields and greatly reduced CO2 by 96.9 %. And the corresponding LHV of pyrolysis gas products increased by 26.8 % and reached up to 33.7 MJ/N m3. Additionally, TG-FTIR analysis revealed that adding CSC reduced the formation temperature of CH4. Importantly, although there was only 35.5 wt% of Ca in CSC, CSC exhibited almost the same sorption-catalysis-enhanced effects compared to pure CaO. These findings suggest that biochar derived from crab shell has the potential to replace CaO for enhancing sludge pyrolysis into value-added fuel products. [ABSTRACT FROM AUTHOR]