Search

For a sustainable ecology, slaughterhouse sludge must be managed effectively in preview of the parasitic or coliforms' spill over to the community. In order to determine the effectiveness of a customized biological decomposer solution in lowering the parasitic eggs and coliform bacteria, three composting units (Unit 1, Unit 2, and Unit 3) were treated with its different amounts. Over a period of 60 days, pH, temperature, humidity, number of the parasitic eggs per gram (EPG) of faecal material, viability of eggs, and coliform counts were evaluated. By the fifth day of the composting process, pH had significantly (P < 0.05) increased across all the treatments and then decreased gradually. Also on the 5th day, all three units entered the thermophilic range (> 45 °C), which persisted for 20 days for Unit 3 and 15 days for Units 1 and 2. Humidity levels initially increased significantly (P < 0.05) in all three units (Unit 3 = 71%, Unit 2 = 64%, and Unit 1 = 55%) but then gradually decreased. On day 5, no decrease in EPG in Unit 1 was detected; however, a non-significant (P > 0.05) 12.5% decline in EPG in Unit 2 and Unit 3 was recorded. After that, a significant (P < 0.05) reduction in EPG was observed in all the three treatments until day 25. By day 5, decreased egg viability was significantly (P < 0.05) recorded in Unit 3 (21.43%); in Unit 1 and Unit 2, the decrease was 6.25% and 14.29%, respectively. Additionally, all units showed a significant (P < 0.05) decrease in total coliforms, meeting minimum allowable limit in Unit 2 and 3 on day 10 and on day 15 in Unit 1. The most substantial reduction in faecal coliforms was observed in Unit 3 (from 2.6 log₁₀ to 1.3 log₁₀), followed by Unit 2 (from 2.6 log₁₀ to 1.5 log₁₀), and then Unit 1 (from 2.6 log₁₀ to 1.6 log₁₀). The results of this study support recommendation of advanced composting techniques to eradicate or reduce the abundance of pathogens (parasites and coliforms). Hence, we endorse the value of careful composting procedures in environment-friendly abattoir waste management and agricultural practices through creating pathogen-free, eco-friendly fertilizers to promote both agricultural and environmental sustainability. [ABSTRACT FROM AUTHOR]

Although maintaining/improving soil organic matter (SOM) quantity through utilizing organic amendments (OAs) is a productive practice, information on OA components contributing to long-term SOM accumulation in agricultural soils remains meager. Hence, we examined soil samples from a long-term experiment with different fertilizer managements, including no fertilizer (NF), chemical fertilizer (CF) only (CF), bark compost plus CF (BC + CF), coffee residue compost plus CF (CRC + CF), cattle manure compost plus CF (CMC + CF), and cattle manure compost (CMC) or sewage sludge compost (SSC) alone at a higher application rate. SOM in those samples was physically fractionated into free particulate form (fSOM), free form occluded in aggregates (oSOM), weakly bound form (wSOM), and strongly bound form (sSOM). Analysis of structural components in OAs and SOM fractions using thermally assisted hydrolysis and methylation combined with gas chromatography/mass spectrometry (THM-GC/MS) revealed OA components that have contributed to long-term SOM accumulation in each treatment. The SSC was characterized by higher proportions of short-chain fatty acids (FAs; 50%) and other aliphatic compounds (22%). Correlation analysis suggested that these characteristics may be effective for greater C accumulation in the bulk soil and wSOM fraction. The proportion of lignin-derived phenols, e.g., 3,4-dimethoxybenzaldehyde (Vh) and 1,2-dimethoxy-4-(1,2,3-trimethoxypropyl)benzene, was high in CMC (43%), presumably vital for promoting C accumulations in the oSOM, wSOM, and sSOM fractions in the CMC treatment. The short-chain FAs in CRC and aromatic components in BC are likely important for contributing fSOM accumulation. [ABSTRACT FROM AUTHOR]

• Inoculation increase the temperature, reduce the pH value and improve the GI. • Inoculants reduce the release of NH 3 and H 2 S. • Inoculants reduces the content of nitrogen compounds and increases the content of sulfur compounds. • There is correlation between physicochemical indexes and nitrogen and sulfur compounds in SS. In this study, high temperature thermotolerant nitrifying bacteria (TNB) and high temperature thermotolerant sulfide oxidizing bacteria (TSOB) were obtained from compost samples and inoculated into sewage sludge (SS) compost. The effects of inoculation on physical and chemical parameters, ammonia and hydrogen sulfide release, nitrogen form and sulfur compound content change and physical-chemical properties during nitrogen and sulfur conversion were studied. The results showed that inoculation of TNB and TSOB increased the temperature, pH, OM degradation, C/N ratio and germination index (GI) of compost. Compared with the control treatment (CK), the addition of inoculants reduced the release of NH 3 and H 2 S, and transformed them into nitrogen and sulfur compounds, the hydrolysis of polymeric ferrous sulfate was promoted, resulting in relatively high content of sulfite and sulfate. At the same time, the physical and chemical properties of SS have a strong correlation with nitrogen and sulfur compounds. [Display omitted] [ABSTRACT FROM AUTHOR]

This study investigated the effects of adding earthworm mucus on the changes in sludge compost bacterial community structure and its response to environmental factors. The results showed that adding earthworm mucus improved the composting effect of sludge, reducing nitrogen loss and increasing nutrients; nitrogen loss decreased by 5.55%, and potassium and phosphorus increased by 10.23 and 16.28%, respectively. Firmicutes, Chloroflexi, Actinobacteria, and Proteobacteria were the main bacterial phyla in the sludge, with a combined relative abundance of over 60%. The addition of earthworm mucus significantly impacted bacterial community structure and composting activity, increasing the relative abundance of dominant bacteria during the process. Redundancy analysis showed that environmental factors significantly impacted the changes in bacterial community structure during composting. The results indicate that the addition of earthworm mucus increases the relative abundance of advantageous bacteria playing essential roles in sludge composting, enhancing the fertility and maturity of sludge composting products by significantly reducing nitrogen loss and increasing potassium and phosphorus. Based on the response relationship between environmental factors and bacterial communities, the bacterial community structure in sludge composting can be improved by regulating environmental factors (such as pH and moisture content), enhancing the effectiveness of sludge composting. [ABSTRACT FROM AUTHOR]

Wastewater treatment plants generate significant amounts of sludge, a residual product that is rich in nutrients, usually considered waste, and traditionally eliminated by storage or incineration, methods that are expensive, environmentally damaging, and often unsustainable. Composting is increasingly recognized as an ecological and durable solution for managing biodegradable waste, including sludge resulting from wastewater treatment. The composting of residual sludge usually requires mixing with bulking agents, such as green waste or agricultural residues, to ensure a well-balanced carbon–nitrogen ratio. This mixture undergoes a controlled aerobic decomposition, sometimes followed by post-treatment, resulting in a stabilized final product that is nutrient-rich and pathogen-free and can be used as soil amendment or fertilizer in different agricultural or landscaping applications. By using composting, communities can reduce elimination costs, reduce greenhouse gas emissions, and minimize the environmental impact of sludge management. This paper reviews recent reported experiences in the laboratory regarding full-scale sludge composting, highlighting the particularities of the processes, the influence factors, the quality of the final product, and the environmental and regulatory constraints. Composting is a sustainable and ecological solution for managing wastewater sludge, contributing to nutrient circularity, and minimizing the environmental impact. [ABSTRACT FROM AUTHOR]

Landscape utilization is a green and environment-friendly way of disposing of compost sludge. Garden plants can extract heavy metals from the sludge of land use, but the effect is not enough to be widely used. Chelating agents have been found to facilitate the extraction of heavy metals from plants and are expected to be popularized if they are also environmentally friendly. In this study, the effects of methylglycinediacetic acid trisodium salt (MGDA), tetrasodium glutamate diacetate (GLDA), and ethylene diamine tetraacetate (EDTA) on the extraction of Ni and Cd from compost sludge by Symphytum officinale L. were studied through the pot experiment. Compared with the control group, the application of 5–10 mmol kg−1 MGDA and 1–9 mmol kg−1 GLDA promoted plant growth, while the application of 3–4 mmol kg−1 EDTA inhibited plant growth. The highest Ni content in shoots appeared in 4 mmol kg−1 GLDA treatment, which was 4.2 times that of the CK group. The highest shoot Cd concentration appeared in 4 mmol kg−1 EDTA treatment, 6.5 times that of CK. The promotion effects of the three reagents on the acid-extractable state of Cd were similar, while that of GLDA on the acid-extractable state of Ni was outstanding. The results of this study suggested that S. officinale could be a potential phytoextraction plant for Cd and Ni, and GLDA could friendly promote the Ni phytoextraction ability of the plant. The study provides a new and efficient method for phytoremediation of heavy metals in soil. [ABSTRACT FROM AUTHOR]

The system of fertilizing agricultural soils with sludge or compost from wastewater treatment processes, as one of the principles of the circular economy, can lead to microplastic (MP) contamination. The existing technical standards for fertilization are very recent and do not consider this problem, although there is scientific evidence of their existence. Therefore, this study, on the one hand, evaluates the presence of MPs in agricultural soils, previously treated with sludge or compost from wastewater treatment plants for fertilization, and on the second hand, it studies the effect of these MPs on earthworms in three different locations in the south of Spain. For the study, selected composts deriving from the different stages of the composting process and three fertilized soils with increasing MP doses were followed. Samples were taken from different sections in depth (0–5, 5–10, and 10–20 cm) to study the shape, size, type, and abundance of MPs using infrared spectroscopy (FTIR). The results showed that the most abundant shape was fiber, followed by fragment and finally bulk, for both composts and soils. Regarding size distribution, 100 µm was the predominant size in composts (64.3% ± 9.8), while in the case of soils, the predominant range was from 100 to 500 µm. The prevalent polymers in both, composts and soils, were PTFE, TPE, PP, and PET, with four times higher amounts in composts than in soils. Ingestion of common MPs were also verified in two earthworm species, which ingested concentrations higher than 2.1% w/w. PP was the most ingested MP and Eisenia fetida was more voracious compared with Lumbricus terrestris. Therefore, it can be considered a suitable bioindicator for monitoring microplastic contamination in agricultural soil. [ABSTRACT FROM AUTHOR]

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

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

The composting of sewage sludge (SS) with structure-forming additives is a popular and inexpensive method for the management of biodegradable waste. During this process, a number of transformations of organic matter and nutrients occur. This study presents the rates and directions of quantitative changes in Cu, Zn, and Ni during the composting of various mixtures. The following substances were used for preparing compost mixtures: SS, sawdust, straw, and bark. These substances were mixed together in appropriate proportions as follows: C1: 45% SS + 50% sawdust + 5% straw; C2: 45% SS + 50% bark+ 5% straw; and C3: 45% SS + 35% bark + 15% sawdust + 5% straw. Single (DTPA solution) and sequential extraction methods (BCR protocol) were used for microelement mobility assessment. Compost valorization was performed in each individual composting phase. The chain relative increment analysis was used for such assessment. Additionally, the potential metal pollution in the composts was evaluated by applying the following indices: the pollutant accumulation index (PAI), heavy metal enrichment index (HMEI), and heavy metal pollution load index (HMPLI). During composting, generally, the amounts of Ni, Cu, and Zn increased in the various extracted combinations, which was independent of their susceptibility to decomposition. Despite of this, the tested composts should be considered as a source of slowly available microelements for plants. The most intense quantitative changes in metals occurred in the thermophilic phase, and the weakest changes occurred in the cooling phase. At the same time, the calculated indices indicated a lack of contamination of the composts with the analyzed metals, emphasizing their environmental safety and lack of negative impact. The bulking agents used for composting with SS did not significantly influence the intensity of the quantitative changes in the tested metals. [ABSTRACT FROM AUTHOR]

It is difficult to utilize steel mill sludge because of the high concentration of heavy metals included therein. To passivate the activity of heavy metals, reduce their toxicity, and create a new valuable product, in this study, 4 kg sludge was composted with a combination of earthworms and different ratios (2%, 4%, and 8%) of bamboo charcoal. The effects of bamboo charcoal and the combination of bamboo charcoal and earthworms on the changes of heavy metals in industrial sludge were examined. The results showed that under the 8% bamboo charcoal ratio, addition of bamboo charcoal alone increased the concentrations of heavy metals, while the addition of bamboo charcoal combined with earthworms reduced it in sludge. The application of bamboo charcoal transformed the available state to iron-manganese bound and residue fraction in the sludge, thus reducing the bioavailability of heavy metals. Addition of bamboo charcoal and earthworms promoted the transformation percentage of heavy metals in exchangeable, carbonate, organic matter, and iron-manganese fractions to the residue fraction in sludge, which further decreased the bioavailability of heavy metals. Vermicomposting with 8% bamboo charcoal achieved maximal heavy metal passivation. Correlation and redundancy analyses showed that composting with a combination of bamboo charcoal and earthworms mainly altered the total phosphorus content, which affected the bioavailability of heavy metals. Addition of earthworms and bamboo charcoal to sludge significantly reduced the total contents of heavy metals and their bioavailability, promoted the conversion of heavy metals to the residue fraction, and improved sludge availability. [ABSTRACT FROM AUTHOR]

The aim of the research was to assess the quality of organic matter contained in sewage sludge composting products and their co-composting with fly ash and mineral wool. The object of the research were composts produced using stabilized sewage sludge from the municipal sewage treatment plant (SS_1C) and sewage sludge with the addition of 20% (SSF_2C) and 30% (SSF_3C) of fly ash and 5% (SSW_4C) and 10% (SSW_5C) of mineral wool. Selected physicochemical properties, fractional composition of humic compounds, and the degree and rate of humification were determined in compost samples taken after 180 days of composting. The reaction of the evaluated composts was close to optimal for mature composts. Co-composting of sewage sludge with mineral wool and ash increased the sorption capacity in composts compared to SS_1C. Due to the content of available P and Mg, the discussed composts formed the SS_1C>SSF_2C and SSF_3C>SSW_4C and SSW_5C series. However, in terms of available K content: SSF_2C and SSF_3C>SSW_4C and SSW_5C>SS_1C. In the SS_1C compost the organic carbon (TOC) content was slightly higher, but no statistically significant effect of the addition of fly ash and mineral wool on the TOC content in mature composts was confirmed. The addition of ash and mineral wool significantly increased the total nitrogen content. Due to the humification index, the composts formed the series: SSW_4C > SSW_5C > SSF_2C > SS_1C > SSF_3C. The values of the C-KH/C-KF ratio in SS_1C were typical for good quality soils, while in the remaining composts the C-KH/C-KF values were slightly lower. The degree of humification of the assessed composts was characterized by poorly humified organic materials, with the highest values of this indicator found in composts with the addition of mineral wool. The assessed quality indicators of organic matter indicate that the organic matter of composts from sewage sludge with the addition of mineral wool and 100% sludge was of the highest quality. [ABSTRACT FROM AUTHOR]

[Display omitted] • Culturable enterococci decreased at the thermophilic phase of sludge compost. • The proportion of VBNC enterococci increased at the thermophilic phase. • Extending the cooling phase of sludge compost reduced VBNC enterococci ratio. • Antibiotic-resistant enterococci were residual in the compost product. • Sludge compost products should be considered as a significant reservoir for ARGs. Sludge composting is a sludge resource utilization method that can reduce pollutants, such as pathogens. Enterococci are regarded as more reliable and conservative indicators of pathogen inactivation than fecal coliforms, which are typically used as indicators of fecal pollution. Non-spore pathogenic bacteria may enter a viable but non-culturable (VBNC) state during composting, leading to residual risk. The VBNC status of bacteria is related to their survival during composting. However, the survival mechanisms of enterococci during sludge composting remain unclear. Therefore, this study aimed to investigate the VBNC state of enterococci in different phases of simulated sludge composting and the fate of antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) during the composting process. This study is expected to provide a basis for subsequent exploration of possible methods to completely inactivate enterococci and reduce ARGs during sludge composting. Culturable enterococci were reduced in the thermophilic phase of sludge composting, but the proportion of VBNC subpopulation increased. It was reported for the first time that most VBNC enterococci were killed by extending the cooling phase of sludge compost, and by prolonging the cooling phase the types of ARG were reduced. However, there was a certain quantity (approximately 104/g dry weight) of culturable and VBNC enterococci in the compost products. In addition, MGEs and ARGs exist in both bacteria and compost products, leading to the risk of spreading antibiotic-resistant bacteria and antibiotic resistance when sludge compost products are used. [ABSTRACT FROM AUTHOR]

[Display omitted] • A comprehensive database was established and conducted a series of meta -analysis. • Aerobic composting can substantially reduce ARGs and MGEs (74.3%, 78.8%). • The 3rd to the 6th week is a stable and high reduction composting period. • Nano-iron as an additive improve 75.0% ARGs mitigation compared with the control. • The significance of composting duration has been overlooked in ARGs mitigation. The significant increase in antibiotic resistance genes (ARGs) in organic solid wastes (OSWs) has emerged as a major threat to the food chain. Aerobic composting is a widely used technology for OSW management, with the potential to influence the fate of AGRs. However, the variability of the ARG elimination effects reported in different studies has highlighted the uncertainty regarding the effects of composting on ARGs. To identify the potential of composting in reducing ARG and the factors (e.g., composting technologies and physiochemical properties) influence ARG changes, a meta -analysis was conducted with a database including 4,232 observations. The abundances of ARGs and mobile genetic elements (MGEs) can be substantially reduced by 74.3% and 78.8%, respectively, via aerobic composting. During composting, the ARG levels in chicken and swine manure tended to be reduced more significantly (81.7% and 78.0%) compared to those in cattle manure (52.3%) and sewage sludge (32.6%). The reduction rate of sulfonamide resistant genes was only 35.3%, which was much lower than those of other types. MGEs and composting duration (CD) were identified as the most important factors driving ARG changes during composting. These findings provide a comprehensive insight into the effects of composting on ARG reduction, which may help prevent the transmission in food systems. [ABSTRACT FROM AUTHOR]

Nitrogen loss is an unavoidable problem during composting processes, and the ammonia oxidation process significantly affects nitrogen transformation. The objective of this study was to evaluate nitrogen transformation when garbage enzyme (GE), biochar (BC), pelelith (PL) and combinations thereof were added during sewage sludge composting. Meanwhile, the succession of ammonia-oxidizing bacteria (AOB) and archaea (AOA) were also explored via quantitative polymerase chain reaction and high-throughput sequencing. The results showed that GE + BC and GE + PL treatments decreased ammonia (NH3) formation by 23.8% and 8.3%, and that of nitrous oxide (N2O) by 25.7% and 26.3% relative to the control, respectively. Simultaneously, the GE, GE + BC, and GE + PL treatments boosted the succession of AOA and AOB, and increased the activities of ammonia monooxygenase (AMO) and hydroxylamine oxidoreductase (HAO) activities and the gene copies of AOA and AOB. The AMO activities, NH4-N, NO3-N, and C/N, significantly affect AOA and AOB community structures. The network analysis predicted that the AMO and HAO were secreted mainly by the unclassified_Archaea and norank_Crenarchaeota, whereas it also showed that the GE + BC improved microbial associations with AOA, enzymatic activity, and environmental factors. Thus, the addition of garbage enzyme and biochar appears to be a promising mitigation strategy to reduce nitrogen losses during the composting process. [ABSTRACT FROM AUTHOR]

Iron–manganese solid waste was used to enhance the efficacy of sludge composting, and the humification process and physicochemical properties of the compost were systematically investigated. Iron–manganese slag was added to the composting reactor, the temperature was increased to 69.5°C, and the thermophilic phase was extended to 110 h. Meanwhile, the composting products maintained relatively higher dissolved organic carbon, NH4+-N, protein, and polysaccharide. After composting for 15 days, the humic and fulvic acid ratios in the system with the addition of iron–manganese smelting slag (named as R2) were at least 25% higher than those in the control group, the seed germination index increased to 108%, and the nutrient composition of the composting product reached 8.2%, which was higher than the 6.8% in the raw sludge. Except for arsenic, other heavy metal contents in the R2 system were lower than the Class A limits stipulated by the Chinese Agricultural Sludge Pollutant Control Standard. When iron–manganese slag was added to the sludge piles, microbial metabolism facilitated the release of mineral elements, which enhanced the activities of enzymes such as polyphenol oxidase and alkaline protease, and abundant organic matter was released due to cell lysis and extracellular polymeric substance disruption. Some of the substrates were converted into small-molecule products by microbial actions; meanwhile, precursors such as polysaccharides and proteins were maintained at high levels in the sludge compost, facilitating the formation of humic substances. [ABSTRACT FROM AUTHOR]

Composting is a common treatment for the high amounts of sewage sludge produced in wastewater treatment plants, and the product is used in agriculture. Composting reduces the levels of biodegradable organic pollutants, although other compounds present in wastewater and not eliminated previously by conventional physical–chemical and chemical treatments, such as polychorodibenzo-p-dioxins/furans (PCDD/Fs) and polychlorinated biphenyls (PCBs), have been found in the final compost at higher levels than those observed in the initial sludge. Their formation was studied during composting under unfavorable aeration conditions and paying attention to different stages of the process. Experiments were carried out in small vessels inside a controlled oven for three types of sewage sludge. Pentachlorophenol was previously added as a dioxin precursor. A clear formation of PCDD/Fs was found, especially during the maturation stage for two experiments. Mainly octachlorodibenzo-p-dioxin (OCDD) and 1234678-heptachlorodibenzo-p-dioxin (1234678-HpCDD) to a lesser extent were formed. OCDD levels in the final samples were around 10 times higher than those of the initial mixture after removing the concentration effect. No clear formation nor degradation of PCBs was observed. The toxicity values due to PCDD/Fs and PCBs found in the initial mixtures were 1.20–2.46 ng WHO-TEQ/kg, and those from the final samples were 2.30–7.86 ng WHO-TEQ/kg. Although the toxicity values are below the most restrictive limits found in Europe in this case, toxicity could increase considerably with the presence and concentration of other precursors. Compost from sewage sludge is an ecological product, but the operating conditions must be controlled to avoid PCDD/F formation and facilitate degradation of persistent organic pollutants. [ABSTRACT FROM AUTHOR]

[Display omitted] • Successful thermophilic composting of shrimp sludge through self-heating. • Clean nitrogen (ammonia) recovered used for high-value microalgae cultivation. • Shrimp sludge compost application as soil conditioner for enhanced mango growth. Due to the rapid growth of the aquaculture industry, large amounts of organic waste are released into nature and polluted the environment. Traditional organic waste treatment such as composting is a time-consuming process that retains the ammonia (NH 3) in the compost, and the compost produced has little economic value as organic fertilizer. Illegal direct discharge into the environment is therefore widespread. This study investigates the recovery of NH 3 through thermophilic composting of shrimp aquaculture sludge (SAS) and its application as a soil conditioner for the growth of mango plants. A maximum composting temperature of 57.10 °C was achieved through self-heating in a 200 L bench-scale reactor, resulting in NH 3 recovery of 224.04 mol/ton-ds after 14 days. The addition of calcium hydroxide and increased aeration have been shown to increase NH 3 volatilization. The recovered NH 3 up to 3 kg-N can be used as a source of clean nitrogen for high-value microalgae cultivation, with a theoretical yield of up to 34.85 kg-algae of microalgae biomass from 1 ton-ds of SAS composting. Despite the high salinity, SAS compost improved mango plant growth and disease resistance. These results highlight the potential of SAS compost as a sustainable source of clean nitrogen for microalgae cultivation and soil conditioner, contributing to a waste-free circular economy through nutrient recycling and sustainable agriculture. [ABSTRACT FROM AUTHOR]

The use of lignocellulosic residues, originating from sawdust, in composting sewage sludge for organic fertilizer production, is a practice of growing interest. However, few studies have explored the effect of the proportion of sawdust and sewage sludge raw materials on composting performance in the humification process. This study assessed the addition of sawdust in the sewage sludge composting process, regarding carbon content, presence of heavy metals, and humification of the organic compost. The experimental design employed was a randomized complete block design with five treatments featuring different proportions of organic residues to achieve C/N ratios between 30–1 (T1: 100% sewage sludge and 0% sawdust, T2: 86% sewage sludge and 14.0% sawdust, T3: 67% sewage sludge and 33% sawdust, T4: 55% sewage sludge and 45% sawdust, and T5: 46.5% sewage sludge and 53.5% sawdust) and five replications, totaling 25 experimental units. The addition of lignocellulosic residue in sewage sludge composting increased the levels of TOC and the C/N ratio, reduced the levels of pH, P, N, Na, Ba, and Cr, and did not interfere with the levels of K, Ca, Mg, S, CEC, labile carbon, and metals Fe, Zn, Cu, Mn, Ni, and Pb. The increase in the proportion of sawdust residue favored the degradation of aliphatic groups, increasing the presence of aromatic structures and reducing humification at the end of composting. The use of sawdust as a lignocellulosic residue in sewage sludge composting is a viable and efficient alternative to produce high-quality organomineral fertilizers. [ABSTRACT FROM AUTHOR]

The effects of the initial C/N ratio on the composting of sewage sludge and cotton residues are not reported in the literature. Understanding the main composting control parameters is essential for the good stabilization of these wastes. Therefore, this study sought to evaluate different initial C/N ratios for the composting of sewage sludge and cotton waste, aiming to find the ranges with the best performance for the process and quality of the final organic compost. In this sense, five mixtures of sewage sludge (S) and cotton residues (C) were prepared and composted with three replications for each treatment in a completely randomized design. Physicochemical parameters were evaluated during composting and in the final organic compounds. A Multivariate Principal Component Analysis (PCA) was applied to evaluate the agronomic quality of organic compounds. The thermal behaviour of the mixtures presented differences. The treatments 90C10S, 80C20S and 67C33S showed the highest EXI² index (3566.64, 3448.39 and 2738.89), longer duration of thermophilic phase (12 and 13 days) and better potential for maximum degradation (A) of organic matter (67.5, 61.2 and 65.6%C). The final compounds of 90C10S and 80C20S showed higher pH values (7.9 and 7.5) and higher CEC (123.6 and 114.0 meq/100 g OM). PCA showed similarity in the agronomic quality of organic compounds for 90C10S, 80C20S and 67C33S. The treatment 28C72S (initial C/N ratio of 16.6) presented final pH of 5.3 and did not meet the minimum limit required by Brazilian regulations. Initial C/N relations between 24.9 and 35.2 showed better stabilization of waste and final organic compound with better agronomic quality. [ABSTRACT FROM AUTHOR]

Harmful algal blooms in eutrophic lakes pose significant challenges to the aquatic environment. Aerobic composting is an effectively method for processing and reusing dewatered algal sludge. The fungal communities are the main driver of composting. However, their relationship with carbon loss and the humification process during algal sludge composting remains unclear. In this study, the succession of fungal communities in algal sludge composting was investigated via internal transcribed spacer (ITS) rRNA amplicon sequencing analysis. Overall, no significant differences were observed with the α-diversity of fungal communities at different stages. The composition of the fungal communities changed significantly before and after compost maturation and became more stable after the compost maturation. Redundancy analysis showed that the fungal communities were significantly correlated with physicochemical properties, including humic acid (HA)/fulvic acid (FA), temperature, pH, humic acid, microcystins, and CO2. The co-occurrence network showed that different fungal community modules had different relationships with physicochemical properties. Structural equation modeling further revealed that different metabolic or transformation processes may be mainly driven by different fungi modules. The microcystin degradation, carbon loss, and humification during composting were mainly mediated by fungal communities which were mainly influenced by temperature. Humification was influenced not only by fungal communities but also by the microcystin levels. These results show that changes in the fungal community composition and interaction and their relationship with physicochemical properties could represent a useful guide for optimizing the composting process. [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]

Water-based paint sludge generated from the automotive industry is considered a hazardous waste due to its high carbon content and is challenging and costly to manage. This study investigates the management of water-based paint sludge through the composting process, considering its high carbon content. The water-based paint sludge was composted in five separate reactors with the addition of treatment sludge from the same industry as co-substrate and inoculum, as well as sunflower stalks as a bulking agent. The ratio of paint sludge added to the compost mixtures varied between 40% and 80%. The highest temperature was achieved in reactors where industrial sludge was added, and the bulking agent was used at a rate of 20% (R3 and R5). The most efficient composting process was conducted with the addition of 60% water-based paint sludge, 20% treatment sludge, and 20% sunflower stalks (w/w, wet weight basis) (R3). During this process, reductions in organic matter content were observed due to organic matter mineralization, resulting in a decrease in moisture during the maturation phase and consequently reducing waste volumes. The composting process can be a useful tool in addressing the challenges of paint sludge management. Utilizing the composting process not only reduces waste volumes, thereby minimizing environmental impacts, but also offers a sustainable approach to paint sludge management by lowering disposal costs. It is also possible to achieve more effective results by composting paint sludge with different recipes and the use of various bulking agents. Implications: Composting is a method that can be used to achieve stabilization, reduce the quantity, and enable biodrying of water-based paint sludge generated from the automotive industry. In this study, different ratios of paint sludge were mixed with treatment sludge from the same industry as co-substrate and inoculum, while sunflower stalks were added as a bulking agent, and a composting process was conducted. The addition of industrial wastewater treatment sludge and sunflower stalks has increased the efficiency of the paint sludge composting process. In the management of paint sludge, the composting process has emerged as a significant alternative that reduces disposal costs and environmental impacts. [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]

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

Aeration is an important factor to regulate composting efficiency and nitrogen loss. This study is aimed to compare the effects of different aeration modes (continuous and intermittent) and aeration rate on nitrogen conversion and bacterial community in composting from dehydrated sludge and corn straw. Results showed that the intermittent aeration mode at same aeration volume was superior to the continuous aeration mode in terms of NH3 emission reduction, nitrogen conversion and germination index (GI) improvement. Intermittent aeration mode with 1200 L/h (aeration 5 min, stop 15 min) [K5T15 (V1200)] and 300 L/h of continuous aeration helped to the conservation of nitrogen fractions and accelerate the composting process. However, it was most advantageous to use 150 L/h of continuous aeration to reduce NH3 emission and ensure the effective composting process. The aeration mode K5T15 (V1200) showed the fastest temperature rise, the longer duration of thermophilic stage and the highest GI (95%) in composting. The cumulative NH3 emission of intermittent aeration mode was higher than continuous aeration mode. The cumulative NH3 emission of V300 was 23.1% lower than that of K5T15 (V1200). The dominant phyla in dehydrated sludge and corn straw composting were Firmicutes, Proteobacteria, Actinobacteria, and Bacteroidetes. The dominant phylum in the thermophilic stage was Firmicutes (49.39%-63.13%), and the dominant genus was Thermobifida (18.62%-30.16%). The relative abundance of Firmicutes was greater in the intermittent aeration mode (63.13%) than that in the continuous aeration mode (57.62%), and Pseudomonas was dominant in composting with lower aeration rate and the lowest NH3 emission. This study suggested that adjustment to the aeration mode and rate could affect core bacteria to reduce the nitrogen loss and accelerate composting process. [ABSTRACT FROM AUTHOR]

A pilot-scale experiment was implemented in a waste bioreactor with an inner capacity of 1 m3 in order to simulate a real-scale composting process. The waste underwent composting conditions that are typical of the initial bio-oxidation phase, characterised by a high production of volatile organic compounds (VOCs), hydrogen sulphide (H2S) and odorants. The waste bioreactor was fed with an intermittent airflow rate of 6 Nm3/h. The target of this study was to investigate the air treatment performance of three biofilters with the same size, but filled with different filtering media: (1) wood chips, (2) a two-layer combination of lava rock (50%) and peat (50%), and (3) peat only. The analyses on air samples taken upstream and downstream of the biofilters showed that the combination of lava rock and peat presents the best performance in terms of mean removal efficiency of odour (96%), total VOCs (95%) and H2S (77%) concentrations. Wood chips showed the worst abatement performance, with respective mean removal efficiencies of 90%, 88% and 62%. From the results obtained, it is possible to conclude that the combination of lava rock and peat can be considered as a promising choice for air pollution control in waste composting facilities. [ABSTRACT FROM AUTHOR]

Biochar was derived from rice straw pyrolyzed at 400°C, and biochar was added to the excess sludge at the ratio of 10% DS, 25% DS, and 50% DS as a supplementary skeleton for sludge Fenton pre-treatment. Rice husk biochar mixed with fungus residue as compost conditioner. In this study, we explored the effects of seven groups of composting materials on the composting effect and fertilizer quality under different pre-treatment methods of Fenton-pretreated sludge cake and conventional dewatered sludge cake, and different biochar additions. Specifically, we conducted a 22-day composting experiment using a composting reactor to investigate the effect of rice husk biochar combined with Fenton oxidation on the physicochemical properties of sludge composting. The results of this study showed that the FB50 group significantly increased the composting rate. Nutrient analysis showed that the FB50 group was rich in fertilizer nutrients, such as available phosphorus, and alkali-hydrolyzable nitrogen content increased. Heavy metals (Cu, Cd, Cr, Pb, Zn, Ni) met China's 'Agricultural Sludge Pollutant Control Standard' GB 4284-2018 Grade A standard, with obvious passivation and significantly reduced bioavailability. All these results suggested that biochar coupled with Fenton oxidation was more beneficial to sludge composting. [ABSTRACT FROM AUTHOR]

Dewatered sludges from twenty-two sewage treatment facilities were characterized to develop the quality control indices in India. This study used fertilizer index (FI) and clean index (CI) as a tool for categorizing sludge utilization into different classes (A, B, C and limited use classes LU-1, LU-2, LU-3) by their fertilizing potential, toxicity level, pathogen presence, and vector attraction reduction criteria. The findings revealed that total P (as P2O5), total N, and K (as K2O) in the sludge samples ranged from 0.9 to 5.7%, 1.2 to 3.8%, and 0.1 to 1.5%, respectively. Moreover, all sludges belong to Class C and lower category due to the presence of toxic metals and pathogens. The helminth eggs were found in the range of 25–1450 Numbers/4gTS in sludge samples. The highest number of helminth eggs of 1450/4 g of TS was found in the fecal sludge. The specific oxygen uptake rate (SOUR) values in the sludge samples varied from 0.3 to 4.9, with a median value of 1.3 and an RSD of 86% is way too high. It indicates that the sludge samples need further treatment to be less attractive as a food source for vectors and rodents. However, sludge samples have fertilizing potential and FI values ranges from 4.1 to 4.9, and CI value ranges from 2.5 to 5.0. It indicates that compost is best in quality and has high-fertilizer potential and low heavy-metal content, which is suitable for high-value crops such as organic farming. Further sludge treatment using typical composting, aerobic or anaerobic digestion, and solar or thermal drying could bring the sludges into the Class A and B categories. [ABSTRACT FROM AUTHOR]

Iron-manganese industrial wastes are used to improve the humification degree of sludge composting and realize the synergetic treatment and resource utilization. After iron-manganese smelting residuals or iron-manganese tailings were added to sludge compost mixture, the process and characteristics of sludge humification were studied by composting experiments for 15 days. Adding iron-manganese slags increased the heating rate of the sludge pile, and the period of thermophilic composting (≥50 °C) reached 96 h. After 15 days, the ratio of HA/FA was not less than 1.0, and the seed germination index GI were more than 100%. Except for As, the contents of other metals such as Cr and Ni were lower than the limits of the Grade A stipulated by the Agricultural Sludge Pollutant Control Standard (GB 4284-2018), and then the obtained compost products were suitable for garden, pasture, and cultivated land where crops are not planted. The highest activities of polyphenol oxidase and dehydrogenase in the compost products with the addition of iron-manganese smelting slags were 2.2 µmol/(h • g) and 13.5 mg/(d • g), respectively, and water-soluble organic carbon increased significantly. Iron-manganese smelting slags was more conducive to the conversion of soluble organic carbon into macromolecular substances such as humic acid, and it improved compost stability and maturity while retaining carbon and nitrogen. [ABSTRACT FROM AUTHOR]

The generation of solid dye waste during wastewater purification, especially in coagulation/precipitation steps, and its detoxification, is a major issue because it can leach into the ground water from the landfills during rains. The semisolid textile waste (sludge) showed 99 and 97% decolourization at flask and reactor scale within 72 h, respectively, when treated with consortium containing Azotobacter vinelandii MTCC 1241, Rhodobacter erythropholis MTCC 4688, Bacillus megaterium NCIM 2054 and Rhizobium meliloti NCIM 2757. The decolourization rate of textile sludge majorly affected by the pH, temperature and moisture content of the sludge. At the optimum conditions of pH (6), temperature (30 °C) and moisture content (90%), the consortium showed maximum decolourization of 81, 84 and 97%, respectively. A significant increase in the activities of oxidoreductase enzymes such as lignin peroxidase (5 fold), laccase (2.6 fold), veratryl alcohol oxidase (4.7 fold) and tyrosinase (2.9 fold) was observed, while azo reductase (− 1.3 fold) showed a decrease in the activity during sludge treatment. In addition, a noteworthy reduction in the concentration of macromolecules N (45%), P (70%), K (50%) and C (63%), and microelements B (59%), Cu (50%), Fe (59%) and Mn (75%) were also observed after treatment with sludge bed reactor. Bio-transformed sludge showed less toxic effects on plants. The outcome from the sludge bed bioreactor (solid-state bioreactor) was found to be more effective and can be used using sugar industry waste like sugarcane bagasse for composting. [ABSTRACT FROM AUTHOR]

Multidrug-resistant bacteria and multi-resistance genes in sludge have become a serious issue for public health. It is imperative to develop feasible and environmentally friendly methods of sludge composting to alleviate multidrug resistance genes. Plant-derived essential oil is an effective natural and eco-friendly antibacterial, which has great utilization in inhibiting pathogens in the agricultural industry. Nevertheless, the application of plant-derived essential oil to control pathogenic bacteria and antibiotic resistance in composting has not been reported. This study conducted a composting system by adding plant-derived essential oil i.e., oregano essential oil (OEO), to sludge composting. The findings indicated that multidrug resistance genes and priority pathogens (critical, high, and medium categories) were reduced by (17.0 ± 2.2)% and (26.5 ± 3.0)% in the addition of OEO (OH treatment) compared to control. Besides, the OH treatment changed the bacterial community and enhanced the gene sequences related to carbohydrate metabolism in compost microorganisms. Mantel test and variation partitioning analysis revealed that the target virulence factors (VFs), target mobile genetic elements (MGEs), and priority pathogens were the most important factors affecting multidrug resistance in composting. The OH treatment could significantly inhibit the target VFs, target MGEs, and priority pathogens, which were helpful for the suppression and elimination of multidrug resistance genes. These findings provide new insights into the regulation of multidrug resistance genes during sludge composting and a novel way to diminish the environmental risk of antibiotic resistance.

Rapid urbanisation has led to a dramatic increase in sewage sludge production. There are limited methods of managing sewage sludge along with high energy and monetary investment. A cost-effective, environment-friendly, and sustainable solution needs to be developed for the management of sewage sludge. In the current study, sludge from the Jagjeetpur sewage treatment plant (STP) had been collected, composted, and characterized during January and February 2022. A comparison of STP sludge compost and compost made from farmyard manure showed the presence of essential agricultural nutrients in them, due to which they find application for plant growth. Two products, Jaivik Poshak and Jaivik Prom, containing farmyard compost, were compared with the amended version of the same, containing compost from STP sludge instead of normal compost. The results showed that the modified Jaivik Poshak was the best for maintaining pH and increasing electrical conductivity. The available nitrogen in the soil upon its application increased by 1.6 times (p < 0.001) with respect to control, and it brought about 100% tomato seed germination within sixteen days. The above finding has been validated by goodness of fit value, factor analysis, and hierarchical analysis. The product, modified Jaivik Prom increased organic carbon content and brought about 5.81 and 8 times the enhancement in available phosphorous (p < 0.001) and potassium (p < 0.001) content in soil, respectively, with respect to the control set. The heavy metal content in the soil as a result of all types of treatment was within the permissible limit. This study thus proves that sludge from STP may be used for agricultural uses after proper fortification and testing to convert waste to wealth along with environmental sustenance. [ABSTRACT FROM AUTHOR]

Sewage sludge treatment and disposal remains a challenging problem. Composting of sewage sludges is gaining increasing attention due to its cost-effectiveness, operation convenience, advantages in lifecycle management, and low greenhouse gas emissions. Disadvantages, such as long reaction time, significant land area occupation requirement, potential risks of residual heavy metals, and emerging contaminants, have restricted wider application. Here we review applications of hyperthermophiles in composting , focusing on the unique improvements provided by hyperthermophiles in composing temperatures, product safety, nitrogen preservation and humification. Inoculation of hyperthermophiles allows temperature of composting to reach over 80°C. Specific metabolic strategies are critical in hyperthermophiles-inoculated composting. High-temperature resistance in the metabolism of hyperthermophiles and their roles in temperature rising during composting is often overlooked. This review discusses both aspects, allowing for a deeper understanding of the functions and influences of hyperthermophiles in sludge composting. Additionally, this review highlights the policy challenges associated with the hyperthermophiles-inoculated sludge composing technique and provides potential directions for future research in this field. [ABSTRACT FROM AUTHOR]

Sulfur-containing gases are main sources of landfill odors, which has become a big issue for pollution to environment and human health. Biocover is promising for treating landfill odors, with advantages of durability and environmental friendliness. In this study, charcoal sludge compost was utilized as the main effective component of a novel alternative landfill cover and the in situ control of sulfur-containing odors from municipal solid waste landfilling process was simulated under nine different operating conditions. Results showed that five sulfur-containing odors (hydrogen sulfide, H2S; methyl mercaptan, CH3SH; dimethyl sulfide, CH3SCH3; ethylmercaptan, CH3CH2SH; carbon disulfide, CS2) were monitored and removed by the biocover, with the highest removal efficiencies of 77.18% for H2S, 87.36% for CH3SH, and 92.19% for CH3SCH3 in reactor 8#, and 95.94% for CH3CH2SH and 94.44% for CS2 in reactor 3#. The orthogonal experiment showed that the factors influencing the removal efficiencies of sulfur-containing odors were ranked from high to low as follows: temperature > weight ratio > humidity content. The combination of parameters of 20% weight ratio, 25°C temperature, and 30% water content was more recommended based on the consideration of the removal efficiencies and economic benefits. The mechanisms of sulfur conversion inside biocover were analyzed. Most organic sulfur was firstly degraded to reduced sulfides or element sulfur, and then oxidized to sulfate which could be stable in the layer as the final state. In this process, sulfur-oxidizing bacteria play a great role, and the distribution of them in reactor 1#, 5#, and 8# was specifically monitored. Bradyrhizobiaceae and Rhodospirillaceae were the dominant species which can utilize sulfide as substance to produce sulfate and element sulfur, respectively. Based on the results of OUTs, the biodiversity of these sulfur-oxidizing bacteria, these microorganisms, was demonstrated to be affected by the different parameters. These results indicate that the novel alternative landfill cover modified with bamboo charcoal compost is effective in removing sulfur odors from landfills. Meanwhile, the findings have direct implications for addressing landfill odor problems through parameter adjustment. [ABSTRACT FROM AUTHOR]

Dissolved organic matter (DOM) plays an important role in heavy metal passivation and organic pollutant degradation owing to its redox ability. The structure and composition of DOM are determinants of redox ability changes during composting. Electric field-assisted aerobic composting (EAAC) has been shown to promote the degradation and humification of organic matter in compost. However, how EAAC affects the redox ability of DOM remains unclear. Hence, electron transfer capacity (ETC) of DOM extracted from EAAC was studied using the electrochemical method. Various spectral methods, such as excitation–emission matrix and ultraviolet and visible spectrophotometry were used to study the relationship of ETC with the compositional and structural changes of DOM. Results indicated that EAAC enhanced ETC of DOM at the later stage of composting, and ETC of DOM extracted from the final EAAC product was 10.4% higher than that of the control group. Spectral and correlation analyses showed that EAAC resulted in structural and compositional changes of DOM, and humification degree, aromatic compounds, molecular weight, and fulvic- and humic-like substance contents were improved in EAAC. This conversion increased ETC of DOM. Results of this study will contribute to the understanding of the redox of DOM and in expanding the application of EAAC products. [ABSTRACT FROM AUTHOR]

The remediation of mixed contaminated soil is challenging as it often requires actions to minimize metal-induced risks while degrading organic contaminants. Here, the effectiveness of different bioremediation strategies, namely, rhizoremediation with native plant species, mycoremediation with Pleurotus ostreatus spent mushroom substrate, and biostimulation with organic by-products (i.e., composted sewage sludge and spent mushroom substrate), for the recovery of a mixed contaminated soil from an abandoned gravel pit was studied. The combination of biostimulation and rhizoremediation led to the most significant increase in soil health, according to microbial indicator values. The application of composted sewage sludge led to the highest reduction in anthracene and polychlorinated biphenyls concentrations. None of the strategies managed to decrease contamination levels below regulatory limits, but they did enhance soil health. It was concluded that the biological remediation treatments improved soil functioning in a short time, before the concentration of soil contaminants was significantly reduced. [ABSTRACT FROM AUTHOR]

Purpose: There is an increasing trend of using sewage sludge co-composting to produce bio-fertilizers for use in agriculture. However, existing studies on the quality of the produced compost came out with contradicting results, which hinder its sustainable utilization. Hence, this study aimed at assessing the quality of sludge based compost for agricultural use. Method: Four treatments, T1 (70% sludge, 15.3% wheat straw and 14.7% cattle manure), T2 (50% sludge, 14.8% wheat straw and 35.2% cattle manure), T3 (30% sludge, 20% wheat straw and 50% cattle manure) and T4 (20% sludge, 14.2% wheat straw and 65.8% cattle manure) having three replications were arranged in a randomized complete design. Matured compost samples, composted for 90 days, were analyzed for nutrient contents, pathogens and heavy metals concentration. Results: The nitrogen content of the produced compost was in the range of 1.74-2.0%, which is higher than the recommended 0.3%. It was significantly higher in the T1 treatment, a 0.24% increase compared to the T4 treatment. However, the phosphorous (202-222 ppm) and potassium (1801-2357 ppm) contents were classified into the very low category. Both elements were higher in the T4 treatment, a 9.9% and 31% increase, respectively as compared to that of T1. Furthermore, all treatments were free of the major disease causing bacteria and characterized by a very low heavy metal concentration. Conclusion: Overall, municipal sludge co-composting has yielded a bio-fertilizer with both pathogen-free and safe levels of heavy metal concentrations. However, further research is required to enhance the poor phosphorous and potassium contents. [ABSTRACT FROM AUTHOR]

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

Sewage sludge (SS) is an organic waste that may potentially be used as a slow-release source of phosphorus (P), despite the necessity for pre-treatment and its lower P content compared to soluble mineral fertilizers. For these reasons, composted sewage sludge was used to manufacture pelletized organomineral fertilizers, by mixing it with the inorganic sources monoammonium phosphate (MAP) and AshDec® (ASD) (thermochemically incinerated SS). The fertilizers were physiochemically characterized and evaluated for their P solubilization dynamics and lability in the soil. The sources tested were as follows: organic compost of sewage sludge powder (SSC) and its pelletized form (SCP), pelletized organomineral SSC + MAP (S + MAP) and SSC + ASD (S + ASD), ASD alone, compared conventional MAP and a control (nil-P). These fertilizers were applied to columns containing 50 g of soil at the dose of 100 mg P column−1 and were leached daily with 30 mL of water or 2% citric acid for 30 days. We analyzed the leachates for pH and P content. Pelletizing process resulted in denser products and promoted more gradual P release. The organomineral S + MAP was the most water-soluble recycled source, solubilizing about 70% of the total P, while the others presented much lower solubilization (<20%). In contrast, all fertilizers showed high solubility in 2% citric acid (except for S + ASD). After leaching, soil P fractionation disclosed that the P leftover in the soil remained mostly in the labile and moderately labile pools. Composting and the ASD process produced materials with slow P solubilization, being favored in acidic soils and in plant's rhizosphere. In turn, S + MAP resulted in a promising product with intermediate P solubility, better synchronized with crop demand, potentially increasing P-use efficiency. Our results shed light in the physico-chemical properties and on the solubilization dynamics of novel organomineral products in tropical soil conditions. [ABSTRACT FROM AUTHOR]

Feacal sludge (FS) management is a growing concern in the Global South. Research has shown that FS has a potential for reuse in agriculture due to its high nutrient content. However, it contains many pathogens which present a public health and environmental risks when it is applied to land without proper treatment. Composting is one of the viable options for sanitizing FS biosolids before reuse in agriculture as a soil conditioner. However, pathogen die-off during FS composting and factors responsible for pathogen survival in compost are not well understood. Therefore, we conducted a systematic review to better understand pathogen inactivation during FS composting. The results revealed that although most pathogens are inactivated by the temperature generated during composting, spore-forming bacteria, helminths, and viruses are likely to survive the process. The findings indicated that although temperature-time is the major factor responsible for pathogen inactivation during composting, other factors (change in pH, moisture content, turning frequency, nutrient depletion, toxic by-products) and mechanisms (indigenous microbial activities, microbial antagonistic effect, antibiotic action) also have an influence. In addition, most studies on pathogen inactivation during FS composting are usually based on the use of indicator microorganisms and there are limited studies on specific pathogens. Hence, further research on virus, protozoa and antimicrobial resistance inactivation during FS composting as well as the role of factors and mechanisms involved in the composting process is needed. This research will generate vital formation to inform the design, operation, and optimization of FS composting facilities to produce pathogen-free compost. [ABSTRACT FROM AUTHOR]

In this paper, a method is proposed for the determination of antibiotics classified by the World Health Organization as critically important (four macrolides and three quinolones) and highly important (one tetracycline, one diaminopyridine, and three sulfonamides) and eight of their metabolites. The method is based on ultrasound-assisted extraction, dispersive solid-phase extraction clean-up, and analytical determination by liquid chromatography–tandem mass spectrometry. Variables affecting each stage of the analytical method were thoroughly optimised. The method was validated for its application to sewage sludge from different treatment stages (non-treated sludge: primary and secondary sludge; and treated sludge: digested sludge and compost) and to agricultural soil. Limits of quantification were in the range of 0.03–7.50 ng g−1 dry weight (dw) for most of the compounds. Accuracy values were in the range of 70–102%. Precision was below 17%. The application of the method to real samples revealed that macrolides and fluoroquinolones were the antibiotic classes at the highest concentrations in all types of samples. The lowest concentrations of antibiotics were measured in compost (highest concentration: 27 ng g−1 dw, corresponding to norfloxacin) and soil samples (highest concentration: 93 ng g−1 dw, corresponding to a metabolite of clarithromycin). The proposed method is the first developed to date for the determination of multiclass antibiotics and their main metabolites in sludge from different treatment stages. The method can provide a useful tool for obtaining information about antibiotics in sewage sludge prior to its application to agricultural soils and in agricultural soils. [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]

Bromopsis inermis and Phalaroides arundinacea are increasingly grown not only for feed but also for other purposes, such as obtaining energy. Composting sewage sludge and using such compost to fertilize various plants is also becoming more popular. Therefore, the aim of our study was to investigate how the fertilization of the mentioned plants with sewage sludge compost (SSC) affects the biomass yield and biomass quality of these plants. It was also important to determine whether fertilization with SSC is possible in low-yielding soils of light texture without harming these soils There are no similar studies in Lithuania, and there are very few in Europe and the world. It was found that investigated grasses formed a small biomass DM yield (6.6 t/ha within three years). The biomass of B. inermis and Ph. arundinacea had a very high ash content and concentrations of nitrogen and potassium. This greatly reduced the quality of the biomass of these grasses as a solid biofuel. SSC performed poorly as a fertilizer. Fertilization with 125 t/ha SSC significantly increased the total biomass yield of Ph. arundinacea only. At the same time, using SSC as a fertilizer significantly increased the concentration of Cu, Zn, and Cd in the soil. [ABSTRACT FROM AUTHOR]

The aim of this paper is to analyse sewage sludge production at the level of Medimurje and Varazdin counties with economic analysis of acceptable technical/technological solutions for sludge management routes. The topic is very broad, so the focus was placed on four variants of sludge disposal, which were determined by preliminary analysis to be the most applicable for the area in question. These are: 1) disposal of sewage sludge in agriculture, 2) incineration of sludge in a central mono-incinerator, 3) composting for the area of Varazdin County and at the same time use of sludge reed beds for the area of Medimurje County, and 4) export of sludge outside the state borders. Based on the analysis carried out for the described four variants, sludge incineration in a regional mono-incinerator turned out as the economically most advantageous solution, while the variant that includes disposal of sludge in agriculture has showed as the most expensive one. The last one also showed the largest range of costs uncertainties, but the mentioned facts are greatly influenced by unfavourable legislation, the changes of which in a more rational direction would greatly contribute to the greater competitiveness of this variant. Overall, taking into account the lowest cost and uncertainties in the predicted unit costs, the sludge composting in the Varazdin County and the construction of a reed beds for the Medimurje County, turned out to be the optimal variant. This solution is also the one that was ultimately adopted in practice. [ABSTRACT FROM AUTHOR]

Wastewater treatment plants generate significant amounts of sludge, a residual product that is rich in nutrients, usually considered waste, and traditionally eliminated by storage or incineration, methods that are expensive, environmentally damaging, and often unsustainable. Composting is increasingly recognized as an ecological and durable solution for managing biodegradable waste, including sludge resulting from wastewater treatment. The composting of residual sludge usually requires mixing with bulking agents, such as green waste or agricultural residues, to ensure a well-balanced carbon–nitrogen ratio. This mixture undergoes a controlled aerobic decomposition, sometimes followed by post-treatment, resulting in a stabilized final product that is nutrient-rich and pathogen-free and can be used as soil amendment or fertilizer in different agricultural or landscaping applications. By using composting, communities can reduce elimination costs, reduce greenhouse gas emissions, and minimize the environmental impact of sludge management. This paper reviews recent reported experiences in the laboratory regarding full-scale sludge composting, highlighting the particularities of the processes, the influence factors, the quality of the final product, and the environmental and regulatory constraints. Composting is a sustainable and ecological solution for managing wastewater sludge, contributing to nutrient circularity, and minimizing the environmental impact.

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purpose: The combined contamination of As, Pb, and Cd in soil has caused serious environmental problems. In order to find a more suitable remediation method, this study used the combination of amendment materials and microorganisms to synchronously stabilize As, Pb, and Cd in compound contaminated soil. Materials and methods: The metallogenic characteristics of Lysinibacillus fusiformis were verified by SEM, XRD, FTIR, and other characterization methods; four kinds of amendment materials and microbial agent were used to carry out the comparative experiments of unitary and binary remediation respectively to stabilization soil potentially toxic element(s) (PTEs). By changing the addition amount of materials, the effects on soil physical and chemical properties, speciation transformation, and content of As, Pb, and Cd were discussed. Results: The results of comparative experiments show that the stabilization effects of loess combined with microbial agent on As and Pb are significantly improved, reaching 43.86% and 83.52%, respectively. The combination of compost sludge and microbial agent can effectively improve the stabilization effect of As, reaching 44.53%. Compost sludge can effectively reduce the content of exchangeable fraction of Pb whether used alone or combined with microorganisms. In the experiments of different addition amounts, there was no significant relationship between the addition amount and the stabilization efficiency of three PTEs when loess was added alone, but after combined with microbial agent, the stabilization efficiency of As, Pb, and Cd increased with the increase of the addition amount of loess. Conclusions: The combination of loess and MICP may be an effective method to synchronously stabilize As, Pb, and Cd in soil. Loess, attapulgite clay 1, and attapulgite clay 2 are suitable for As stabilization. Compost sludge and attapulgite clay 1 are more favorable for Pb stabilization. Loess, compost sludge, and attapulgite clay 1 promote Cd stabilization effect. Loess and compost sludge are more suitable for combination with microorganisms. [ABSTRACT FROM AUTHOR]

In the cultivation of extensive green roofs (EGRs), substrate composition is a key aspect together with the evaluation of suitable recycled materials. Recycling materials as amendments can improve the establishment of a self-sustainable EGR, thus providing ecosystem services and benefits from a circular economy and climate change perspective. This study investigates the effects of compost and paper sludge on water retention, substrate temperature attenuation and plant diversity in an EGR experiment. The substrates were composed of tephra (V), compost (C) and paper sludge (P) as follows: VC, as control, VPC and VP. Herbaceous species with different ecological functionality (succulents, annuals, perennials, legumes, geophytes) were sown and/or transplanted with no cultivation inputs. Plant community composition -abundance- and diversity-richness-, substrate water retention and temperature were analyzed. The VPC and VC had the same average substrate temperature, with values lower than VP. The water retention capacity was higher in VC, thanks to the presence of compost. The substrate with paper sludge (VPC and VP) showed the highest species diversity. The VPC substrate was the best compromise for EGR temperature mitigation and plant diversity improvement. Plant functional types in EGRs can be increased, and thus the biodiversity, by modulating the quality and percentage of amendments. The substrate composition can also affect water retention and substrate temperature. In addition, the use of recycling paper sludge in growing media is a winning strategy to reduce waste. [ABSTRACT FROM AUTHOR]