Bioremediation and detoxification of industrial wastes by earthworms: Vermicompost as powerful crop nutrient in sustainable agriculture

Vermi-remediation impacts on growth and metals bioaccumulation in tomato irrigated with wastewater

Due to their persistence in the environment, and their highly toxic and bioaccumulative nature, heavy metals are well known to the environment. Vermicompost has gained popularity because it improves soil properties and, most importantly, remediates and immobilizes heavy metals. The present study assessed vermicompost effects on heavy metal bioaccumulation in tomato plants irrigated with wastewater. A plastic bag experiment was carried out with 5 kg of growing media in each bag. Growing media contain garden soil with four levels of vermicompost mixed at 0%, 5%, 15%, and 25%. The pots were irrigated with wastewater from different industries and tap water, which was taken as control. Wastewater was collected from the pharmaceutical industry, plastic industry, and sewage water of Hayatabad Industrial Estate, Peshawar. Vermicompost application significantly affected all tomatoes' growth attributes and heavy metals concentration. Results revealed that minimum Cd (2.48 mg kg-1), Cr (1.27 mg kg-1), Cu (4.10 mg kg-1), and Pb (0.62 mg kg-1) concentrations were recorded in tomatoes cultivated in 25 % vermicompost amended soil, while, maximum Cd (5.23 mg kg-1), Cr (2.29 mg kg-1), Cu (8.84 mg kg-1) and Pb (2.18 mg kg-1) concentrations were reported in sewage water irrigated plants., Overall, vermicompost applied at 25% significantly enhanced plant growth and yield, reducing the bioavailability and bioaccumulation of heavy metals. From the finding of this study, it is observed that wastewater irrigation of plants should be avoided because of the high level of heavy metals; in contrast, the application of vermicompost is highly recommended as compost reduces heavy metals bioaccumulation and enhances productivity.

First Clarification of the Mechanism of Action of the Apple Glycosyltransferase MdUGT91AJ2 Involved in the Detoxification Metabolism of the Triketone Herbicide Sulcotrione

Sulcotrione is a member of triketone herbicides, a class of HPPD (4-hydroxyphenylpyruvate dioxygenase) inhibitors with broad-spectrum herbicidal activity. Modifications of glycosylation mediated by glycosyltransferases (GT) are involved in plant detoxification. In this study, we analyzed chip data published online and found that eight glycosyltransferases from group A of the apple glycosyltransferase family 1 may be involved in the metabolic mechanism of detoxification of triketone herbicides. To verify this prediction, we induced apple seedlings with six types of triketone herbicides, and then detected the expression levels of eight glycosyltransferase genes through real-time PCR. We found that triketone herbicides induced up-regulation of eight glycosyltransferase genes to varying degrees, with MdUGT91AJ2 being the most significantly up-regulated by sulcotrione-induced glycosyltransferase gene expression. Then, through in vitro enzymatic reactions and HPLC identification of glycoside substrates, it was found that the glycosyltransferase MdUGT91AJ2 had the highest specific enzyme activity against the triketone herbicide sulcotrione. Furthermore, the in vivo mechanism of the glycosyltransferase MdUGT91AJ2 in the detoxification metabolism of sulcotrione was further validated by overexpressing the strain in the plant. HPLC analysis showed that the content of sulcotrione glycosides in the overexpressing strain of MdUGT91AJ2 was significantly higher than that in the wild type. This result indicated that the apple glycosyltransferase MdUGT91AJ2 can still glycosylate and modify sulfotrione in plants, and participate in its detoxification metabolism. In summary, this study identified for the first time a novel apple glycosyltransferase MdUGT91AJ2 and elucidated its mechanism of action in the detoxification and metabolism of the triketone herbicide sulfotriene.

Vermicompost Supply Enhances Fragrant-Rice Yield by Improving Soil Fertility and Eukaryotic Microbial Community Composition under Environmental Stress Conditions

Heavy-metal contamination in agricultural soil, particularly of cadmium (Cd), poses serious threats to soil biodiversity, rice production, and food safety. Soil microbes improve soil fertility by regulating soil organic matter production, plant nutrient accumulation, and pollutant transformation. Addressing the impact of Cd toxicity on soil fungal community composition, soil health, and rice yield is urgently required for sustainable rice production. Vermicompost (VC) is an organic fertilizer that alleviates the toxic effects of Cd on soil microbial biodiversity and functionality and improves crop productivity sustainably. In the present study, we examined the effects of different doses of VC (i.e., 0, 3, and 6 tons ha-1) and levels of Cd stress (i.e., 0 and 25 mg Cd kg-1) on soil biochemical attributes, soil fungal community composition, and fragrant-rice grain yield. The results showed that the Cd toxicity significantly reduced soil fertility, eukaryotic microbial community composition and rice grain yield. However, the VC addition alleviated the Cd toxicity and significantly improved the soil fungal community; additionally, it enhanced the relative abundance of Ascomycota, Chlorophyta, Ciliophora, Basidiomycota, and Glomeromycta in Cd-contaminated soils. Moreover, the VC addition enhanced the soil's chemical attributes, including soil pH, soil organic carbon (SOC), available nitrogen (AN), total nitrogen (TN), and microbial biomass C and N, compared to non-VC treated soil under Cd toxicity conditions. Similarly, the VC application significantly increased rice grain yield and decreased the Cd uptake in rice. One possible explanation for the reduced Cd uptake in plants is that VC amendments influence the soil's biological properties, which ultimately reduces soil Cd bioavailability and subsequently influences the Cd uptake and accumulation in rice plants. RDA analysis determined that the leading fungal species were highly related to soil environmental attributes and microbial biomass C and N production. However, the relative abundance levels of Ascomycota, Basidiomycota, and Glomeromycta were strongly associated with soil environmental variables. Thus, the outcomes of this study reveal that the use of VC in Cd-contaminated soils could be useful for sustainable rice production and safe utilization of Cd-polluted soil.

Effect of conventional and biodegradable microplastics on earthworms during vermicomposting process

The potential effect of microplastics is an increasingly growing environmental issue. However, very little is known regarding the impact of microplastics on the vermicomposting process. The present study explored the effect of non-biodegradable (low density polyethylene; LDPE) and biodegradable (polybutylene succinate-co-adipate; PBSA) microplastics on earthworm Eisenia fetida during vermicomposting of cow dung. For this, earthworms were exposed to different concentrations (0, 0.5, 1 and 2%) of LDPE and PBSA of 2 mm size. The cow dung supported the growth and hatchlings of earthworms, and the toxicity effect of both LDPE and PBSA microplastics on Eisenia fetida was analyzed. Microplastics decreased the body weight of earthworms and there was no impact on hatchlings. The body weight of earthworm decreased from 0 to 60th day by 18.18% in 0.5% of LDPE treatment, 5.42% in 1% of LDPE, 20.58% in 2% of LDPE, 19.99% in 0.5% of PBSA, 15.09% in 1% of PBSA and 16.36% in 2% of PBSA. The physico-chemical parameters [pH (8.55-8.66), electrical conductivity (0.93-1.02 (S/m), organic matter (77.6-75.8%), total nitrogen (3.95-4.25 mg/kg) and total phosphorus (1.16-1.22 mg/kg)] do not show much significant changes with varying microplastics concentrations. Results of SEM and FTIR-ATR analysis observed the surface damage of earthworms, morphological and biochemical changes at higher concentrations of both LDPE and PBSA. The findings of the present study contribute to a better understanding of microplastics in vermicomposting system.

Synergistic effects of vermicompost and mycorrhizal inoculation on arsenic tolerance and phytostabilization in safflower (Carthamus tinctorius L.)

Arsenic (As) is a hazardous metalloid, and mycorrhizal inoculation and vermicompost amendment can influence As bioremediation. However, the studies concerning the sole and joint effects of arbuscular mycorrhizal fungi (AMF) and vermicompost on the phytoremediation efficacy are limited. In the present study at first, the impact of various levels of vermicompost (0, 2, 4, and 8% w/w) was investigated on As mobility in soil and safflower (Carthamus tinctorius L.) plants grown in soils of spiked with 0, 40, and 80 mg kg-1 As. Results revealed that with increasing dose of vermicompost, bioavailable As in soil decreased which resulted in a lower bioaccumulation factor and translocation factor (TF) and led to a significant increase of tolerance index (TI) and total chlorophyll content in plants. The highest effect on TI and total As accumulation per plant was obtained in the dosage of 8% vermicompost. Therefore, in the second experiment, the sole and joint effects of 8% vermicompost and inoculation with Rhizophagus intraradices were assessed on the tolerance and accumulation of As in safflower. The addition of vermicompost aggravated mycorrhizal colonization but did not significantly influence mycorrhizal dependency under As stress. The joint effects of AMF and vermicompost improved the dry weight of roots and shoots, increased P concentration and P:As ratio in shoots, reduced malondialdehyde content, and moderated ascorbate peroxidase activity in leaves of As-stressed plants. Interestingly, co-application of AMF and vermicompost more than their sole usage decreased As concentration in shoots and TF and more strongly increased total As accumulation per plant. These findings suggest that mycorrhizal inoculation and vermicompost have a synergistic effect on As tolerance and phytostabilization efficacy of safflower plants, and their combined application may be a new option to remediate As-contaminated soils.

Vermitechnology transforms hazardous red mud into benign organic input for agriculture: Insights on earthworm-microbe interaction, metal removal, and soil-crop improvement

Bioremediation of hazardous bauxite residues, red mud (RM), through vermicomposting has yet to be attempted. Therefore, the valorization potential of Eisenia fetida in various RM and cow dung (CD) mixtures was compared to aerobic composting. Earthworm fecundity and biomass growth were hindered in RM + CD (1:1) feedstock but enhanced in RM + CD (1:3). The pH of highly alkaline RM-feedstocks sharply reduced (>17%) due to vermicomposting. N, P, and K availability increased dramatically with Ca and Na reduction under vermicomposting. Additionally, ∼40-60% bioavailable metal fractions were transformed to obstinate (organic matter and residual bound) forms upon vermicomposting. Consequently, the total metal concentrations were significantly reduced with considerably high earthworm bioaccumulation. Microbial growth and enzyme activity were more significant under vermicomposting than composting. Correlation statistics revealed that microbial augmentation significantly facilitated a metal reduction in RM-vermibeds. Eventually, RM-vermicompost stimulated sesame growth and improved soil health with the least heavy metal contamination to soil and crop.

Emerging technology effects on combined agricultural and eco-vermicompost

This study focused on the waste management of livestock manure and wetland plant residues and their increasing effect on terrestrial and aquatic ecosystems. The benefits of nutrient-rich plants and manures are often overlooked. By conducting a soil column experiment with a fully factorial design, this work found that adding the vermicompost amendments of wetland plants [combination of Canna indica (CiV), Cyperus alternifollius (CaV), Acorus calamus (AcV), and Hydrocotyle vulgaris (HvV) vermicompost] to agricultural wastes affected maize growth throughout its growing season. The results demonstrated that the use of combined AcV and HvV wetland plant-based vermicompost as an organic fertilizer increased the plant total nitrogen (TN: 92% increase) and soil organic matter (SOM: 192% increase) compared with those in control CK. Meanwhile, the combination of CaV with HvV increased the shoot biomass by 3.4 and 4.6 folds compared with that in NPK and CK, respectively. Overall, a new approach for transforming ecological wastes into organic fertilizers was proposed.

A review on the fate of micro and nano plastics (MNPs) and their implication in regulating nutrient cycling in constructed wetland systems

This review discusses the micro-nano plastics (MNPs) and their interaction with physical, chemical and biological processes in a constructed wetland (CW) system that is typically used as a nature-based tertiary wastewater treatment for municipal as well as industrial applications. Individual components of the CW system such as substrate, microorganisms and plants were considered to assess how MNPs influence the CW processes. One of the main functions of a CW system is removal of nutrients like nitrogen (N) and phosphorus (P) and here we highlight the pathways through which the MNPs influence CW's efficacy of nutrient removal. The presence of morphologically (size and shape) and chemically different MNPs influence the growth rate of microorganisms important in N and P cycling, invertebrates, decomposers, and the plants which affect the overall efficiency of a CW treatment system. Certain plant species take up the MNPs, and some toxicity has been observed. This review focuses on two significant aspects: (1) the presence of MNPs in a significant concentration affects the efficiency of N and P removal, and (2) the removal of MNPs. Because MNPs reduce the enzyme activities in abundance and overproduction of ROS oxidizes the enzyme active sites, resulting in the depletion of proteins, ultimately inhibiting nitrogen and phosphorus removal within the substrate layer. The review found that the majority of the studies used sand-activated carbon (SAC), granular-activated carbon (GAC), rice straw, granular limestone, and calcium carbonate, as a substrate for CW treatment systems. Common plant species used in the CW include Phragmites, Arabidopsis thaliana, Lepidium sativum, Thalia dealbata, and Canna indica, which were also found to be dominant in the uptake of the MNPs in the CWs. The MNPs were found to affect earthworms such as Eisenia fetida, Caenorhabditis elegans, and, Enchytraeus crypticus, whereas Metaphire vulgaris were found unaffected. Though various mechanisms take place during the removal process, adsorption and uptake mechanism effectively emphasize the removal of MNPs and nitrogen and phosphorus in CW. The MNPs characteristics (type, size, and concentration) play a crucial role in the removal efficiency of nano-plastics (NPs) and micro-plastics (MPs). The enhanced removal efficiency of NPs compared to MPs can be attributed to their smaller size, resulting in a faster reaction rate. However, NPs dose variation showed fluctuating removal efficiency, whereas MPs dose increment reduces removal efficiency. MP and NPs dose variation also affected toxicity to plants and earthworms as observed from data. Understanding the fate and removal of microplastics in wetland systems will help determine the reuse potential of wastewater and restrict the release of microplastics. This study provides information on various aspects and highlights future gaps and needs for MNP fate study in CW systems.

Adsorption-desorption characteristics of atrazine on soil and vermicompost prepared with different ratios of raw materials

In this work, vermicompost was prepared with maize stover and cattle dung in ratios of 60:40 (VC1), 50:50 (VC2) and 40:60 (VC3), and the physicochemical properties of the vermicompost were related to the ratio of the raw materials used. The effect of the vermicomposts on the adsorption kinetics, adsorption isotherms and desorption of atrazine were investigated in unamended soil (S) and soil amended with 4% (w/w) of VC1(S-VC1), VC2(S-VC2) and VC3(S-VC3). The total organic carbon (TOC) content of VC1, VC2 and VC3 was 38.46, 37.33 and 34.47%, the HA content was 43.50, 42.22 and 39.28 g/kg, and the HA/FA ratios was 1.47, 0.44 and 0.83, respectively. The adsorption of atrazine on the soil, on the vermicompost and on soils amended with vermicompost followed a pseudo-second-order kinetic model. The Freundlich equation better fitted the adsorption isotherm of atrazine. The vermicomposts enhanced atrazine adsorption and decreased atrazine desorption. Correlation analysis showed that the TOC and HA were significantly positively correlated with Kf, which indicated that TOC and HA of the vermicomposts contributed significantly to the adsorption and desorption of atrazine. This study demonstrated that vermicomposts have great potential in the bioremediation of atrazine pollution and that their role is related to the raw materials used to prepare them.

A Critical Review on the Vermicomposting of Organic Wastes as a Strategy in Circular Bioeconomy: Mechanism, Performance, and Future Perspectives

AbstractTo meet the current need for sustainable development, vermicomposting (VC), a natural, eco-friendly, and cost-effective technology, can be a wise selection for the bioconversion of organic wastes into value-added by-products. However, no one has tried to establish the VC technology as an economically sustainable technology by exploring its linkage to circular bioeconomy. Even, no researcher has made any effort to explore the usability of the earthworms (EWs) as a protein supplement while assessing the economic perspectives of VC technology. Very few studies are available on the greenhouse gas (GHG) emission potential of VC technology. Still, the contribution of VC technology towards the non-carbon waste management policy is not yet explored. In the current review, a genuine effort has been made to inspect the contribution of VC technology towards the circular bioeconomy, along with evaluating its capability to bioremediate the organic wastes generated from domestic, industrial, and agricultural premises. The potential of the EWs as a protein source has also been explored to strengthen the contribution of VC technology towards the circular bioeconomy. Moreover, the linkage of the VC technology to the non-carbon waste management policy has been comprehensively demonstrated by highlighting its carbon sequestration and GHG emission potentials during the treatment of organic wastes. It has been observed that the cost of food production was reduced by 60--70% by replacing chemical fertilizers with vermicompost. The implication of the vermicompost significantly lessened the harvesting period of the crops, thereby helping the farmers attain higher profits by cultivating more crops in a single calendar year on the same plot. Furthermore, the vermicompost could hold the soil moisture for a long time, lessening the water demand up to 30-40%, which, in turn, reduced the frequency of irrigation. Also, the replacement of the chemical fertilizers with vermicompost resulted in a 23% increment in the grapes' yield, engendering an extra profit of up to 110000 rupees/ha. In Nepal, vermicompost has been produced at a cost of 15.68 rupees/kg, whereas it has been sold to the local market at a rate of 25 rupees/kg as organic manure, ensuring a net profit of 9.32 rupees/kg of vermicompost. EWs embraced 63% crude protein, 5-21% carbohydrates, 6-11% fat, 1476 kJ/100 g of metabolizable energy, and a wide range of minerals and vitamins. EWs also contained 4.11, 2.04, 4.43, 2.83, 1.47, and 6.26  g/kg (on protein basis) of leucine, isoleucine, tryptophan, arginine, histidine, and phenylalanine, respectively, enhancing the acceptability of the EW meal (EWM) as the protein supplement. The inclusion of 3 and 5% EWM in the diet of broiler pullets resulted in a 12.6 and 22.5% increase in their feed conversion ratio (FCR), respectively after one month. Similarly, when a 100% fish meal was substituted by 50% EWM and 50% fish meal, the FCR and growth rate of Parachanna obscura were increased substantially. The VC of maize crop residues mixed with pig manure, cow dung, and biochar, in the presence of Eisenia fetida EWs, yielded only 0.003-0.081, 0-0.17, and 130.40-189.10 g CO₂-eq.kg^-1 emissions of CO₂, CH₄, and N₂O, respectively. Similarly, the VC of tomato stems and cow dung ensured 2.28 and 5.76 g CO₂-eq.kg^-1 CO₂ emissions of CH₄ and N₂O, respectively. Additionally, the application of vermicompost at a rate of 5 t/ha improved the soil organic carbon proportion and aggravated carbon sequestration. The land application of vermicompost improved micro-aggregation and cut down the tillage, reducing GHG emissions and triggering carbon sequestration. The significant findings of the current review suggest that VC technology potentially contributes to the concept of circular bioeconomy, substantially negotiates potential GHG emissions, and complies with the non-carbon waste management policy, reinforcing its acceptability as an economically sound and environmentally benevolent organic waste bioremediation alternative.

Effect of NaCl and EDDS on Heavy Metal Accumulation in Kosteletzkya pentacarpos in Polymetallic Polluted Soil

The ability of plants to accumulate heavy metals is a crucial factor in phytoremediation. This study investigated the effect of NaCl and S,S-ethylenediaminesuccinic acid (EDDS) on heavy metal accumulation in Kosteletzkya pentacarpos in soil polluted with arsenic, cadmium, lead, and zinc. The addition of NaCl reduced the bioavailability of arsenic and cadmium, while EDDS increased the bioavailability of arsenic and zinc. The toxicity of the polymetallic pollutants inhibited plant growth and reproduction, but NaCl and EDDS had no significant positive effects. NaCl reduced the accumulation of all heavy metals in the roots, except for arsenic. In contrast, EDDS increased the accumulation of all heavy metals. NaCl reduced the accumulation of arsenic in both the main stem (MS) and lateral branch (LB), along with a decrease in cadmium in the leaves of the main stem (LMS) and zinc in the leaves of the lateral branch (LLB). Conversely, EDDS increased the accumulation of all four heavy metals in the LB, along with an increase in arsenic and cadmium in the LMS and LLB. Salinity significantly decreased the bioaccumulation factor (BF) of all four heavy metals, while EDDS significantly increased it. NaCl had different effects on heavy metals in terms of the translocation factor (TFc), increasing it for cadmium and decreasing it for arsenic and lead, with or without EDDS. EDDS reduced the accumulation of all heavy metals, except for zinc, in the presence of NaCl in polluted soil. The polymetallic pollutants also modified the cell wall constituents. NaCl increased the cellulose content in the MS and LB, whereas EDDS had little impact. In conclusion, salinity and EDDS have different effects on heavy metal bioaccumulation in K. pentacarpos, and this species has the potential to be a candidate for phytoremediation in saline environments.

Potential of vermicomposting with mixtures of animal manure and vegetable leaves in the development of Eisenia foetida, microbial biomass, and enzymatic activity under semi-arid conditions

Vermicomposting is the bio-oxidation and stabilization of organic matter involving relationships between the action of earthworms and microorganisms and the activation and dynamics of several enzyme activities. Semi-arid farmers to make (extra) money and organic production, produce their vermicompost using plant residues and animal manure, but there is no information about the final product generated. Thus, this study aimed to analyze the potential of vermicomposting with mixtures of animal manure and vegetable leaves in the development of Eisenia foetida, microbial biomass, and enzymatic activity in the semi-arid region, Brazil. The experimental design applied was randomized block in a 6 × 4 factorial scheme with four replicates, with six treatments (mixtures of cattle manure, goat manure, cashew leaves, and catanduva leaves) and evaluated at four-time intervals (30, 60, 90, and 120 days of vermicomposting). The treatments were placed in polyethylene pots in the same site, environmental conditions, and residues proportions as used by farmers. The characteristics analyzed were the number of earthworms (NE), total earthworm biomass (TEB) and earthworm multiplication index (MI), microbial biomass carbon (MBC), and activities of enzymes β-glucosidase, dehydrogenase, alkaline and acid phosphatases. The cattle manure vermicomposted shows the highest average values observed for NE, MI, TEB, MBC, and enzymatic activity, regardless of the plant leaves mix. In general, the enzymes activities were found in the descending order of β-glucosidase > alkaline phosphatase > dehydrogenase > acid phosphatase. The maturation dynamics of vermicompost were characterized by a decline in the microbial population and number and biomass of earthworms in the substrate and consequently a decrease in new enzyme synthesis and degradation of the remaining enzyme pool. Microbial biomass and enzymatic activity were indicators for changes in the quality of vermicompost.

Ecological adaptation of earthworms for coping with plant polyphenols, heavy metals, and microplastics in the soil: A review

In recent years, soil pollution by massive accumulation of heavy metals (HMs), microplastics, and refractory hydrocarbon chemicals has become an emerging and global concern, drawing worldwide attention. These pollutants influence soil diversity by hindering the reproduction, abundance, thereby affecting aboveground productivity. The scientific community has recently emphasized the contribution of earthworms to heavy metal accumulation, microplastic degradation, and the decomposition of organic matter in the soil, which helps maintain the soil structure. This review paper aimed to compile scientific facts on how earthworms cope with the effect of HMs, microplastics, and plant polyphenols so that vermiremediation could be widely applied for well-being of the soil ecosystem by environmentalists. Earthworms have special surface-active metabolites in their guts called drilodefensins that help them defend themselves against the oxidative action of plant polyphenols. They also combat the effects of toxic microplastics, and other oxidative compounds by elevating the antioxidant activities of their enzymes and converting them into harmless compounds or useful nutrients. Moreover, earthworms also act as biofilters, bioindicators, bioaccumulators, and transformers of oxidative polyphenols, microplastics, toxic HMs, and other pollutant hydrocarbons. Microorganisms (fungi and bacteria) in earthworms' gut of also assist in the fixation, accumulation, and transformation of these toxicants to prevent their effects. As a potential organism for application in ecotoxicology, it is recommended to propagate earthworms in agricultural fields; isolate, and culture enormously in industry, and inoculate earthworms in the polluted soil, thereby abate toxicity and minimizing the health effect caused by these pollutants as well enhance the productivity of crops.

Production and characterization of enriched vermicompost from banana leaf biomass waste activated by biochar integration

Vermicomposting uses less energy and requires fewer infrastructures, and it is capable of restoring soil nutrition and carbon. Banana cultivation produces lots of trash in a single crop season, with 30 tonnes of waste generated per acre. The biodegradable fraction of banana leaf waste is thrown out in large quantities from temples, markets place wedding halls, hotels, and residential areas. Vermicomposting can be used for recovering lignin, cellulose, pectin, and hemicellulose from banana leaves. Earthworm digests organic materials with the enzymes produced in gut microflora. Biochar adds bulk to vermicomposting, increases its value as fertilizer. The goal of this study was to amend biochar (0, 2, 4 and 6%) with banana leaf waste (BLW) + cow dung (CD) in three different combinations (1:1, 2:1 and 3:1) using Eisenia fetida to produce enriched vermicompost. In the vermicompost with biochar groups, there were higher levels of physicochemical parameters, as well as macro- and micronutrient contents. The growth and reproduction of earthworms were higher in groups with biochar. A maximum of 1.82, 1.18 and 1.67% of total nitrogen, total phosphorus and total potassium was found in the final vermicompost recovered from BLW + CD (1:1) amended with 4% biochar; while the other treatments showed lower levels of nutrients. A lower C/N ratio of 18.14 was observed in BLW + CD (1:1) + 4% biochar followed by BLW + CD (1:1) + 2% biochar amendment (19.92). The FTIR and humification index studies show that degradation of organic matter has occurred in the final vermicompost and the substrates with 4% biochar in 1:1 combination showed better degradation and this combination can be used for nutrient rich vermicompost production.

Co-composting of faecal sludge and carbon-rich wastes in the earthworm's synergistic cooperation system: Performance, global warming potential and key microbiome

Composting is an effective alternative for recycling faecal sludge into organic fertilisers. A microflora-earthworm (Eisenia fetida) synergistic cooperation system was constructed to enhance the composting efficiency of faecal sludge. The impact of earthworms and carbon-rich wastes (rice straw (RS) and sawdust (S)) on compost properties, greenhouse gas emissions, and key microbial species of composting were evaluated. The addition of RS or S promoted earthworm growth and reproduction. The earthworm-based system reduced the volatile solid of the final substrate by 13.19-16.24 % and faecal Escherichia coli concentrations by 1.89-3.66 log10 cfu/g dry mass compared with the earthworm-free system. The earthworm-based system increased electrical conductivity by 0.322-1.402 mS/cm and reduced C/N by 56.16-64.73 %. The NH₄⁺:NO₃^- ratio of the final faecal sludge and carbon-rich waste was <0.16. The seed germination index was higher than 80 %. These results indicate that earthworms contribute to faecal sludge maturation. Earthworm addition reduced CO₂ production. The simultaneous addition of earthworms and RS system (FRS2) resulted in the lowest global warming potential (GWP). The microbial diversity increased significantly over time in the RS-only system, whereas it initially increased and later decreased in the FRS2 system. Cluster analysis revealed that earthworms had a more significant impact on the microbial community than the addition of carbon-rich waste. Co-occurrence networks for earthworm-based systems were simple than those for earthworm-free systems, but the major bacterial genera were more complicated. Highly abundant key species (norank_f_Chitinophagaceae and norank_f_Gemmatimonadaceae) are closely related. Microbes may be more cooperative than competitive, facilitating the conversion of carbon and nitrogen in earthworm-based systems. This work has demonstrated that using earthworms is an effective approach for promoting the efficiency of faecal sludge composting and reducing GWP.

Microbial influence and dynamics of metallurgical waste dissolution in a landfill and recovery context: A multi-phase experimental approach and geochemical model

The effects of abiotic and biotic dissolution on metallurgical wastes (slag and matte) were examined combining a multi-phase experimental approach with a solution renewal and geochemical model. The conditions studied included the exposure of solid wastes to water, a growth medium, and heterotrophic siderophore-producing bacterium Pseudomonas fluorescens. Quantification of the dissolution was performed by tracking the element release, whereas immobilization processes were predicted by applying a geochemical model and scanning electron microscopic observations. The results demonstrated that the phase composition of these wastes subjected to (bio)dissolution was linked to the behavior of Pseudomonas fluorescens, with the deteriorative dissolution effects varying between slag and matte. The contribution level of the bacteria to the mobilization of the elements exhibited the following order: Cu > Pb > Zn; however, the entrapment of these elements in biomass affected the amount of metals released. Copper-bearing sulfides and metallic lead-bearing phases were specifically found to be highly susceptible to (bio)dissolution. Moreover, the bacteria contribution to the Zn release from sphalerite played less of an important role compared to its abiotic mobilization. Overall, this study underlines the important role of bacteria at the interface where wastes are exposed to weathering, resulting in accelerated dissolution. The application of bacteria to Co and Mo recovery is an important approach to the detoxification of landfilled wastes.

Removal of sulfamethoxazole and antibiotic resistance genes in paddy soil by earthworms (Pheretima guillelmi): Intestinal detoxification and stimulation of indigenous soil bacteria

Vermiremediation, which use earthworms to remove contaminants from soil, has been proven to be an alternative, low-cost technology. However, the effects of earthworm activity, especially the degraders in earthworm intestines, on the fate of sulfamethoxazole (SMX), and the effects of intestinal bacteria on degrading bacteria in soil are unclear. In this study, the effects of earthworms on the fate of SMX and related antibiotic resistance genes (ARGs) were investigated. Special attention was paid to the impact of earthworms on SMX degradation efficiency, degradation products, related ARGs, and degraders in both soil and earthworm intestines; the effect of intestinal bacteria on soil bacteria associated with SMX was also studied. Earthworms significantly accelerated SMX degradation by both intestinal detoxification and the stimulation of indigenous soil bacteria. Compared with the treatment without earthworms, the treatment with earthworms reduced SMX residues by 25.1 %, 49.2 %, 35.7 %, 34.2 %, and 35.7 % on the 10th, 20th, 30th, 60th, and 90th days, respectively. Compared with those in soil (treated with earthworms), the SMX residues in wormcasts were further reduced by 12.2-29.0 % from the 2nd to the 20th day, producing some unique anaerobic degradation products that were distinct from those in the soil. In earthworm intestines, SMX degradation was enhanced by bacteria of the genera Microvirga, Sphingomonas, Methylobacterium, Bacillus, and Tumebacillus. All of these bacteria (except Bacillus spp.) entered and colonised the soil with wormcasts, further promoting SMX degradation. Additionally, earthworms removed a significant number of ARGs by increasing the fraction of potential SMX degraders and inhibiting the potential hosts of ARGs and int1. This study demonstrated that earthworms could remediate SMX-contaminated soil by enhancing the removal of SMX and ARGs.

Different ratios of Canna indica and maize-vermicompost as biofertilizers to improve soil fertility and plant growth: A case study from southwest China

Vermicomposting is recommended as an eco-friendly technology for an organic amendment to avoid the excessive use of inorganic fertilizers, which are causing environmental pollution. Here, this study evaluated soil fertility and plant growth after vermicompost amendment using reclaimed wetland plants and manure. A pot experiment was conducted to assess the seven treatments for nutrient recovery and plant growth: a control group without any fertilization (CK); four groups with vermicompost prepared from different ratios of ecological wetland plant residues, maize, and pig manure (V1, 4:6; V2, 5:5; V3, 6:6; and V4, 7:3); one group with only Canna indica (V5, Ci), and a group with synthetic fertilizers (NPK). The results showed the remarkable impacts of Ci-vermicompost and different ratios of organic fertilizer on soil fertility and plant height (28.8%) as major outcomes. In addition, vermicompost substantially increased soil total nitrogen (60.5%), soil organic matter (60.9%) including dissolved organic carbon (52.2%), and shoot biomass (V4, three-fold increase) compared with NPK and CK. Overall, the findings of this study suggest that vermicomposting combined with wetland plants is a feasible method for organic amendments and offers an innovative approach for recycling ecological waste to produce nutrient-rich organic fertilizers, reduce environmental damage, and improve crop production.

Vermiremediation of allopathic pharmaceutical industry sludge amended with cattle dung employing Eisenia fetida

The present study aims to vermiremediate allopathic pharmaceutical industry sludge (AS) amended with cattle dung (CD), in different feed mixtures (AS:CD) i.e (AS₀) 0:100 [Positive control], (AS₂₅) 25:75, (AS₅₀) 50:50, (AS₇₅) 75:25 and (AS₁₀₀) 100:0 [Negative Control] for 180 days using earthworm Eisenia fetida. The earthworms could thrive and grow well up to the AS₇₅ feed mixture. In the final vermicompost, there were significant decreases in electrical conductivity (29.18-18.70%), total organic carbon (47.48-22.39%), total organic matter (47.47-22.36%), and C: N ratio (78.15-54.59%). While, significant increases in pH (9.06-16.47%), total Kjeldahl nitrogen (69.57-139.58%), total available phosphorus (30.30-81.56%), total potassium (8.92-22.22%), and total sodium (50.56-62.12%). The heavy metals like Cr (50-18.60%), Cd (100-75%), Pb (57.14-40%), and Ni (100-50%) were decreased, whereas Zn (8.37-53.77%), Fe (199.03-254.27%), and Cu (12.90-100%) increased significantly. The toxicity of the final vermicompost was shown to be lower in the Genotoxicity analysis, with values ranging between (76-42.33%). The germination index (GI) of Mung bean (Vigna radiata) showed a value ranging between 155.02 and 175.90%. Scanning electron microscopy (SEM) analysis showed irregularities with high porosity of texture in the final vermicompost than in initial mixtures. Fourier Transform-Infrared Spectroscopy (FT-IR) spectra of final vermicompost had low peak intensities than the initial samples. The AS₅₀ feed mixture was the most favorable for the growth and fecundity of Eisenia fetida, emphasizing the role of cattle dung in the vermicomposting process. Thus, it can be inferred that a cost-effective and eco-friendly method (vermicomposting) with the proper amendment of cattle dung and employing Eisenia fetida could transform allopathic sludge into a nutrient-rich, detoxified, stable, and mature vermicompost for agricultural purposes and further could serve as a stepping stone in the allopathic pharmaceutical industry sludge management strategies in the future.

Vermicomposting leads to more abundant microplastics in the municipal excess sludge

Municipal excess activated sludge is not only an important reservoir of microplastics particles, but is also a vehicle of entry of microplastics into the environments as soil amendments or organic fertilizer. Vermicomposting is a cost-effective technology for sludge valorization. However, it is not clear whether vermicomposting affects the occurrence of microplastics in residual sludge. Here, the variation of microplastics (0.05-5 mm) in sludge, including the abundance, type, size, and morphology, before and after vermicomposting by epigeic earthworms under different temperature conditions (15 °C, 20 °C and 25 °C) were investigated by micro Fourier Transform Infrared Spectroscopy (μ-FTIR) and Scanning Electronic Microscopy (SEM). More abundant (over 10⁴ particles ∙kg^-1 (dry weight)), and smaller microplastics (over 60% in total with 0.05-0.5 mm) in the treated sludge via earthworms were observed compared to the raw sludge. The increment of vermicomposting temperature was more obvious (p < 0.05) for the enrichment of the microplastics, especially for polyethylene particle. Gizzard grinding and microbial digestion in the gut of earthworms may contribute to the fragment of microplastics. The present study suggests that the sludge-sourced vermicompost is still an important hotspot of microplastics, posing a potential threat to the receiving environments.

Treatment of heavy metal-polluted sewage sludge using biochar amendments and vermistabilization

Heavy metal contamination of sewage sludge hampers its recycling. Contaminated sewage sludge was amended with different proportions of biochar and vermistabilized. Biochar produced from wheat straw was added at four proportions (0%, 2%, 4%, and 6%). Ten earthworms Eisenia fetida were added, and the sludge was vermistabilized for 60 days. Heavy metal and nutrient concentrations and the accumulation of metals to E. fetida were measured. The treatment with 4% biochar was the most efficient in reducing the concentrations of heavy metals. The concentration of Cd decreased 55%, Cr 28%, Cu 30%, and Pb 21%. The concentrations of plant nutrients increased: total N 43%, total P 92%, and total K 60%. E. fetida accumulated all heavy metals in their internal tissues. The survival and reproductive rate of E. fetida improved during the vermistabilization process. We interpret that the biochar alone did not improve the decomposition process, but the main actors were the earthworms E. fetida. The most efficient proportion of biochar was 4%, not the highest tested (6%). We recommend 4% biochar to be used in the vermistabilization of heavy metal-contaminated municipal sewage sludge. The study benefits both the management of heavy metal-contaminated sewage sludge and agriculture where the final vermistabilization product can be used to improve crop production.

Black soldier fly (Hermetia illucens L.) as a high-potential agent for bioconversion of municipal primary sewage sludge

The treatment of municipal wastewater produces clean water and sewage sludge (MSS), the management of which has become a serious problem in Europe. The typical destination of MSS is to spread it on land, but the presence of heavy metals and pollutants raises environmental and health concerns. Bioconversion mediated by larvae of black soldier fly (BSFL) Hermetia illucens (Diptera, Stratiomyidae: Hermetiinae) may be a strategy for managing MSS. The process adds value by generating larvae which contain proteins and lipids that are suitable for feed and/or for industrial or energy applications, and a residue as soil conditioner. MSS from the treatment plant of Ladispoli (Rome province) was mixed with an artificial fly diet at 50% and 75% (fresh weight basis) to feed BSFL. Larval performance, substrate reduction, and the concentrations of 12 metals in the initial and residual substrates and in larval bodies at the end of the experiments were assessed. Larval survival (> 96%) was not affected. Larval weight, larval development, larval protein and lipid content, and waste reduction increased in proportion the increase of the co-substrate (fly diet). The concentration of most of the 12 elements in the residue was reduced and, in the cases of Cu and Zn, the quantities dropped under the Italian national maximum permissible content for fertilizers. The content of metals in mature larvae did not exceed the maximum allowed concentration in raw material for feed for the European Directive. This study contributes to highlight the potential of BSF for MSS recovery and its valorization. The proportion of fly diet in the mixture influenced the process, and the one with the highest co-substrate percentage performed best. Future research using other wastes or by-products as co-substrate of MSS should be explored to determine their suitability.

Reaction Kinetics in the Vermicomposting Process of Peach Waste

Peach is a fruit cultivated in temperate regions and its use generates waste composed of seeds and skin. Inadequate disposal of this waste generates an environmental impact; therefore, an alternative is to apply a vermicomposting degradation process. In this research, these four laboratory-scale reactors were used: RC (no earthworms), R1, R2, and R3 (50 earthworms each) to get mixtures in the following proportions of peach waste and load material (vegetable waste and eggshell): RC (50%-50%), R1 (50%-50%), R2 (60%-40%), and R3 (40%-60%). In addition, during this process, physicochemical parameters were analyzed (temperature, pH, humidity, total organic carbon (TOC), total nitrogen (TN), and carbon/nitrogen ratio (C/N)). For each mixture, the reaction order and rate constants were determined using mathematical models. After analysis of the reaction kinetics, the results showed that zero- and first-order reactions were best suited for the degradation of this waste in the vermicomposting process. The highest rates of degradation in the mixtures were for RC and R1, which means faster completion of the process, and consequently, smaller dimensions of the facilities necessary for vermicomposting. Thus, this research provides important information for the design of reactors that use similar substrates.

Influence of chromium and sodium on development, physiology, and anatomy of Conilon coffee seedlings

Some components found in the composition of the tannery sludge are nutrients for the plants; it can be considered an alternative source of fertilization as they have favorable agronomic characteristics. However, it is reported in some studies that the presence of chromium and sodium in this residue causes physiological and anatomical disturbances that inhibit the development of the plants. The objective of this study was to evaluate the influence of chromium and sodium on the physiology, anatomy, and development of Conilon coffee seedlings grown on substrates produced with tannery sludge and equivalent doses of chromium and sodium. The experiment was carried out in nursery using randomized block design, containing 5 treatments and 7 repetitions. The treatments consisted of the application of a 40% tannery sludge dose and equivalent doses of chromium and sodium mixed with a conventional substrate. Notably, the presence of sodium in the substrate caused greater damage to the plants, negatively influencing the physiology, anatomy, and, consequently, development of the plants, while the presence of chromium suggests that it does not influence much the evaluated characteristics. The treatment with tannery sludge, on the other hand, despite containing the same chromium and sodium contents, revealed a more pronounced negative influence on the physiology, anatomy, and development patterns of the seedlings. This shows that sodium and chromium alone are not the only factors responsible for the lowest growth indicators studied.

Detection and identification of hazardous organic pollutants from distillery wastewater by GC-MS analysis and its phytotoxicity and genotoxicity evaluation by using Allium cepa and Cicer arietinum L

Distillery industry generates a huge amount of wastewater, which contains a high strength of organic and inorganic load. Accordingly, this study aims to analyze the physico-chemical pollution parameters and the occurrence of phytotoxic, cytotoxic and genotoxic pollutants in wastewater. The result revealed that values of wastewater parameters were recorded as 13268 mg l^-1 (BOD), 25144 mg l^-1 (COD), 25144 mg l^-1 (TS), and 6634 mg l^-1 (phosphate), while pH was alkaline. The organic compounds detected by GC-MS were quercetin 7,3',4'-trimethoxy, octadecadienoic acid, propanoic acid, glycocholic acid methyl ester, cantaxanthin, etc. The Allium cepa was used for the toxicity test with different concentrations of wastewater showed a significant level of reduction in root growth and length after exposure and the maximum reduction was at 25% and 20%. Phytotoxicity studies were performed using Cicer arietinum L. with different concentrations of wastewater, which showed adverse effects on seed germination, root length, and the effect was associated with the increasing concentration of wastewater. A. cepa root tips were used for the analysis of mitotic index (MI), nuclear abnormalities (NA), and chromosomal aberrations (CA). MI was decreasing significantly from 72% (control) to 33%, 22%, 23%, 21%, and 18% at 5%, 10%, 15%, 20%, and 25% wastewater concentration, respectively. The A. cepa root tip cells showed chromosomal aberrations and nuclear abnormalities like vagrant, stickiness, chromosomal loss, c-mitosis, binucleated, micronuclei, and aberrant cell. This study concluded that the wastewater treatment process is insufficient and the discharged waste needs a proper assessment to know the associated health risk.

Recent advances in the treatment of lignin in papermaking wastewater

More than 695.7 million m³ of papermaking wastewater is discharged globally. It contains a mixture of complex pollutants, of which lignin is the major constituent (600-1000 mg/L) of papermaking black liquor, making it the second-largest energy-containing biomass globally and accounting for 47.4% and 59.4% of chemical oxygen demand (16,400 ± 120 mg/L) and chroma (3100 ± 22.32 mg/L) of papermaking wastewater. The complex process and dissolved pollutants are responsible for high pH, biochemical oxygen demand, chemical oxygen demand, total suspended solids, dark color, and toxicity. Papermaking wastewater has emerged as a substantial source of environmental pollution as the conventional wastewater treatment processes are high cost and seldom efficacious. This work introduces the shortcomings of the common treatment methods for papermaking wastewater and lignin, focusing on lignin biodegradation and discussing the metabolic pathways and application prospects of lignin-degrading microbial species. A comprehensive review of the existing lignin treatment methods has proposed that the reasonable amalgamation of biodegradation and various physicochemical techniques are environmentally friendly, sustainable, and economical. Lignin extraction from papermaking wastewater by technology combination is an effective approach to recover valuable organic materials and detoxify wastewater. This review focuses on recent breakthroughs and future trends in papermaking wastewater treatment and lignin removal, with special emphasis on biodegradation, recovery, and utilization of lignin, providing guidance for the mechanism exploration of lignin-degrading microorganisms and the optimization of high-value chemical production.

Influence of biochar remediation on Eisenia fetida in Pb-contaminated soils

In this study, the remediation influence of maize straw biochar on earthworms (Eisenia fetida) in contaminated soils (with Pb at 0, 300, 700, and 1000 mg kg^-1) amended with different amounts of biochar (0%, 1%, 3%, and 5%) was investigated. The results showed that applying biochar to metal-polluted soils effectively reduced the mobility of Pb, promoting the transformation of Pb from exchangeable (EXC) and bound-to-carbonate (Carb) fractions to Fe/Mn oxide (FeMnOx), organic bound (ORG) and residual (RES) fractions. Consequently, a reduction in the mortality and weight loss of earthworms was also achieved by biochar. The accumulation amount of Pb in earthworms steadily increased with exposure time, and with the increasing dosage of biochar, the accumulated Pb decreased by 50.8-78.0% (300 mg kg^-1), 30.9-67.3% (700 mg kg^-1), and 17.4-55.1% (1000 mg kg^-1), which was significantly positively correlated with the mortality of earthworms. Simultaneously, the application of biochar increased the soil pH (0.05-0.23 units), cation exchange capacity (CEC) (0.26-4.54 cmol kg^-1), and content of organic matter (0.54-11.66%). There were higher soil enzyme activities (including sucrase activity, urease activity, and alkaline phosphatase activity) in the treatments with a biochar addition of 3%. Through remediation, Proteobacteria (50.82%), Actinobacteriota (32.37%), Firmicutes (4.83%) and Bacteroidota (1.88%) were the most important phyla in the microbiota communities. Furthermore, soil pH value and leaching toxicity concentration showed the most striking effects on earthworms. Therefore, the influence of earthworms must be taken into account in the remediation of Pb-contaminated soil with biochar.

Municipal solid waste management: Dynamics, risk assessment, ecological influence, advancements, constraints and perspectives

Global energy consumption has been increasing in tandem with economic growth, putting pressure on the world's supply of renewable energy sources. Municipal Solid waste (MSW) has been reported contributing immensely to the improvement of a secure environment and renewable sources. Energy scarcity and conventional MSW disposal methods in developing countries lead towards many environmental and economic issues. Scientists have been able to experiment with various waste-to-energy conversion technologies in light of this situation. This communication highlights and reviews WtE technologies to convert MSW and other feedstocks into electricity, hydrogen gas, bioethanol along with other value added products like fertilizer(s), platform chemicals as an environmentally friendly products. This review comprehensively summarized the dynamics, risk assessment, ecological influence, advancements, constraints and perspectives altogether in field of municipal solid waste management and treatment. Stare-of-the-art information on ecological influence and risk assessment in handling and transportation of municipal solid waste has been provided. Advanced trends involved in remediation of emerging pollutants and resources obtained from municipal solid wastes have been uncovered. Lastly, this paper comprises constraints and perspectives for uncovering MSW based circular bioeconomy aspects.

Attenuation of antibiotic resistance genes in livestock manure through vermicomposting via Protaetia brevitarsis and its fate in a soil-vegetable system

Scarab larvae (Protaetia brevitarsis) could transform large quantities of agricultural waste into compost, providing a promising bio-fertilizer for soil management. There is an urgent need to assess the risk of antibiotic resistance genes (ARGs) in soil-vegetable system with application of compost derived from P. brevitarsis larvae. We conducted a pot experiment to compare the changes of ARGs in the soil and lettuce by adding four types of manure, livestock manure (chicken and swine manure) and the corresponding larval frass. Significantly low numbers of ARGs and mobile genetic elements (MGEs) were detected in both larval frass compared with the corresponding livestock manure. Pot experiment showed that the detected numbers of ARGs and MGEs in bulk soil, rhizosphere soil, and root endophytes were significantly lower in the frass-amended treatments than the raw manure-amended treatments. Furthermore, the relative abundance of ARGs and MGEs with application of chicken-frass was significant lower in rhizosphere soil and leaf endophyte. Using non-metric multidimensional scaling analysis, the patterns of soil ARGs and MGEs with chicken-frass application were more close to those from the bulk soil in the control. Structural equation models indicated that livestock manure addition was the main driver shaping soil ARGs with raw manure application, while MGEs were the key drivers in frass-amended treatments. These findings demonstrated that application of livestock manure vermicomposting via scarab larvae (P. brevitarsis) may be at low risk in spreading manure-borne ARGs through soil-plant system, providing an alternative technique for reducing ARGs in organic waste.

Vermicomposting of cow manure: Effect of time on earthworm biomass and chemical, physical, and biological properties of vermicompost

Vermicomposting is a biological process for efficient cattle manure treatment, but the vermicomposting time determines the quality of the vermicompost. The objective of this study was to evaluate the effect of cattle manure vermicomposting time on earthworm biomass and the changes in physical, chemical, and biological in properties of the vermicompost. The cattle manure was inoculated with Eisenia andrei earthworms and conducted vermicomposting for 0, 15, 30, 45, 60, and 120 days. The analysis of 44 chemical, physical, and biological properties allowed the vermicomposting process to be divided into initial (<45 days) and final (45-120 days) phases. The initial phase was characterized by high microbial activity and the final by high physical-chemical transformation of the vermicompost and an increase in earthworm density. The organic matter aromaticity increased until the 45th day, subsequently decreasing. Although 30 d of vermicompost are sufficient to obtain a high-quality organic fertilizer, 120 d are necessary for producing matrices.

Eco-risk management of tylosin fermentation residues using vermicomposting

Tylosin fermentation residues (TFR) pose an ecotoxicological risk through antibiotic resistant bacteria (ARBs) and their corresponding genes (ARGs). This study evaluated the ecotoxicity of TFR to soil biological activity, and further explored the mechanisms of vermicomposting to reduce the toxicological risk. The results showed that tylosin (TYL) was moderately degradable with a half-life (t_1/2) of 37.5 d, inducing 28-44% inhibition rate of nitrogen transformation in soil, and the EC₅₀ of earthworm avoidance was 880 mg/kg. The 30-d vermicomposting reduced the pH and OM content, while increased the EC and TN content, accelerated compost maturation (C/N ratio up to 20), and enriched the microbial community. ARGs were reduced by earthworm through removal of TYL (>70% degradation, t_1/2 of <20 d), inhibiting abundance of intI1 and ARBs. We conclude that vermicomposting is an efficient method for TFR treatment and its eco-risk management.

Epigenetic regulations enhance adaptability and valorization efficiency in Eisenia fetida and Eudrilus eugeniae during vermicomposting of textile sludge: Insights on repair mechanisms of metal-induced genetic damage and oxidative stress

Genotoxicity-based assessments of vermitechnology for textile-sludge valorization have rarely been attempted. Therefore, waste sanitization and epigenetic stress-regulation efficiency of Eisenia fetida and Eudrilus eugeniae were evaluated in silk (DSPS) and cotton (CPWS) processing sludge-based vermibeds. Vermicomposting resulted in greater C, N, and P recovery than composting. Earthworm population reduced by 6-50% in DSPS/CPWS, while it significantly increased in cow dung (CD) mixed DSPS/CPWS. The Cr, Cd, Pb, and Zn accumulation efficiency of earthworms was higher in DSPS-based feedstocks than CPWS. However, metal-rich sludge elevated oxidative stress, causing greater inhibition of cell viability and DNA damage in Eudrilus than in Eisenia. Although histo-architecture of chloragogenous tissues was perturbed, earthworms combatted metal-induced lipid peroxidation via the activation of catalase, superoxide-dismutase, and reduced-glutathione. Correlation statistics revealed that genetic integrity in earthworms was restored through DNA-methyltransferase activity, especially in DSPS/CPWS + CD vermibeds. Overall, Eisenia was a healthier choice than Eudrilus for sustainable valorization of textile-sludge.

Constructed wetland substrates: A review on development, function mechanisms, and application in contaminants removal

Constructed wetlands (CWs) are economical, efficient, and sustainable wastewater treatment method. Substrates in CWs inextricably link with the other key components and significantly influence the performance and sustainability of CWs. Gradually, CWs have been applied to treat more complex contaminants from different fields, thus has brought forward new demand on substrates for enhancing the performance and sustainability of CWs. Various materials have been used as substrates in CWs, and their individual characteristics and application advantages have been extensively studied in recent years. Therefore, this review summarizes the development, function mechanisms (e.g., filtration, adsorption, electron supply, supporting plant growth and microbial reproduction), categories, and applications of substrates in CWs. The interaction mechanisms of substrates with contaminants/plants/microorganisms are comprehensively described, and the characteristics and advantages of different substrate categories (e.g., Natural mineral materials, chemical products, biomass materials, industrial and municipal by-products, modified functional materials, and novel materials) are critically evaluated. Meanwhile, the influences of substrate layer arrangement and synergism on contaminants removal are firstly systematically reviewed. Furthermore, further research about substrates (e.g., clogging, life cycle assessment/management, internal relationship between components) should be systematically carried out for improving efficiency and sustainability of CWs.

Sustainable multilayer biomass carbon and polymer hybrid column as potential antibacterial water filter

Stipulation of fresh water for domestic use without any microbial, organic and inorganic contaminants is of high need. Sustainable, efficient, cost-effective and robust water purification technologies is of high need and it can be achieved using nanomaterials and their composite. Nanostructured graphene has unique properties like high surface to volume ratio, higher absorbability, reusability with minimal chemical alterations, and low cytotoxicity. From the validation of these properties, we have developed PLLA-Ag@graphene sandwich structures as an effective adsorbate for water purification application. As the real water bodies have lot of bacterial contaminants, the material is also designed as efficient adsorbate with antibacterial efficacy. In view of achieving these objectives, we have synthesized PLLA fibre mats by electrospinning method, followed by PLLA-Graphene and Ag decorated PLLA-graphene mats. The crystallite size for graphite and Ag@graphene was calculated as 30.82 nm and 43.79 nm, respectively. Furthermore, the UV analysis of Ag@graphene shows two peaks corresponding to graphene and Ag NP at 285 nm and 407 nm respectively. The layers were assembled in the order of polymeric fibre, as-fired biomass graphite, Ag@graphene for methodical filtration process. The filtration efficacy of the filtrate was tested using sewage water and the results shows higher contamination removal percentage of 87 % with TDS values in the drinking water standards after filtration. The antibacterial efficacy results also evidence of the potentialities of the hybrid system towards water purification application.

Natural inhibitors from earthworms for the crystallization of calcium oxalate monohydrate

Two proteins are proposed as CaOx nucleation and crystal growth regulators. The site-specific adsorption of inhibitors is confirmed from both macroscopic and microscopic perspectives.

Processes and prospects on valorizing solid waste for the production of valuable products employing bio-routes: A systematic review

Humanity is struggling against a major problem for a proper management of generated municipal solid waste. The collected waste causes natural issues like uncontrollable emission of greenhouse gases and others. Even though, escalation of waste results in minimizing the areas accessible for disposing the waste. Creating awareness in the society to use organic products like biofuels, biofertilizers and biogas is a need of an hour. Biochemical processes such as composting, vermicomposting, anaerobic digestion, and landfilling play important role in valorizing biomass and solid waste for production of biofuels, biosurfactants and biopolymer. This paper covers the details of biomass and solid waste characteristics and its composition. It is also focused to provide updated information about reutilization of biomass for value creation. Technologies and products obtained through bio-routes are discussed in current review paper together with the integrated system of solid waste management. It also covers challenges, innovations and perspectives in this field.

Fate of Functional Bacterial and Eukaryotic Community Regulated by Earthworms during Vermicomposting of Dewatered Sludge, Studies Based on the 16S rDNA and 18S rDNA Sequencing of Active Cells

DNA sequencing of active cells involved in vermicomposting can clarify the roles of earthworms in regulating functional microorganisms. This study aimed to investigate the effect of earthworms on functional microbial communities in sludge by comparing biodegradation treatments with and without earthworms. PCR and high throughput sequencing based on pretreatment of propidium monoazide (PMA) were used to detect the changes in active bacterial 16S rDNA and eukaryotic 18S rDNA during vermicomposting. The results showed that the nitrate in sludge vermicomposting and control were significantly different from day 10, with a more stable product at day 30 of vermicomposting. Compared with the control, the Shannon indexes of active bacteria and eukaryotes decreased by 1.9% and 31.1%, respectively, in sludge vermicompost. Moreover, Proteobacteria (36.2%), Actinobacteria (25.6%), and eukaryotic Cryptomycota (80.3%) were activated in the sludge vermicompost. In contrast, the control had Proteobacteria (44.8%), Bacteroidetes (14.2%), Cryptomycota (50.00%), and Arthropoda (36.59%). Network analysis showed that environmental factors had different correlations between active bacterial and eukaryotic community structures. This study suggests that earthworms can decrease the diversity of bacterial and eukaryotic communities, forming a specific-functional microbial community and thus accelerating organic matter decomposition during vermicomposting of dewatered sludge.

Earthworm casts restrained the accumulation and phytotoxicity of soil glyphosate to cowpea (Vigna unguiculata (L.) Walp.) plants

The heavy use of glyphosate during the cultivation of glyphosate-resistant crops, would trigger the so called "pseudo-persistent" glyphosate in soil, thereby threatening agricultural environment, crop production, and human health through food safety. Such that, there is pressing need for the development of strategies for the effective management of glyphosate contamination in soil to promote cleaner agricultural production. In this study, as witnessed via characterizing the bioavailability and phytotoxicity of glyphosate to cowpea plants in soils applied with or without earthworm casts (EWCs), EWCs could significantly facilitate glyphosate desorption from soil, thus enhance its bioaccessibility, nonetheless, sharply decreased rather than increased the accumulation of glyphosate in cowpea plants via reducing the residue pool of glyphosate in the soil. Consequently, in comparison with the glyphosate-alone group, EWCs involvement triggered the increase of chlorophyll content, alleviation of ROS accumulation and lipid peroxidation of membrane, and in turn reduced the activity of a series of stress-tolerance enzymes by means of down-regulating the expression of the corresponding mRNA; ultimately, helped plants to reverse the glyphosate-induced growth suppression. Our findings demonstrated that, EWCs were promising candidate for the cost-effective and easy-to-operate remediation and reuse of glyphosate-contaminated soil, while also being able to improve the quality of the cultivated land and promote crop growth and resistance as a nutrients supplier.

Keystone taxa shared between earthworm gut and soil indigenous microbial communities collaboratively resist chlordane stress

Chlordane is an organochlorine pesticide that is applied extensively. Residual concentrations that remain in soils after application are highly toxic to soil organisms, particularly affecting the earthworm gut and indigenous soil microorganisms. However, response mechanisms of the earthworm gut and indigenous soil microorganism communities to chlordane exposure are not well known. In this study, earthworms (Metaphire guillelmi) were exposed to chlordane-contaminated soils to investigate their response mechanisms over a gradient of chlordane toxicity. Results from high-throughput sequencing and network analysis showed that the bacterial composition in the earthworm gut varied more significantly than that in indigenous soil microbial communities under different concentrations of chlordane stress (2.3-60.8 mg kg^-1; p < 0.05). However, keystone species of Flavobacterium, Candidatus Nitrososphaera, and Acinetobacter remained stable in both the earthworm gut and bacterial communities despite varying degrees of chlordane exposure, and their relative abundance was slightly higher in the low-concentration treatment group (T1, T2) than in the high-concentration treatment group (T3, T4). Additionally, network analysis demonstrated that the average value of the mean degree of centrality, closeness centrality, and eigenvector centrality of all keystone species screened by four methods (MetagenomeSeq, LEfSe, OPLS-DA, Random Forest) were 161.3, 0.5, and 0.63, respectively, and that these were significantly higher (p < 0.05) than values for non-keystone species (84.9, 0.4, and 0.2, respectively). Keystone species had greater network connectivity and a stronger capacity to degrade pesticides and transform carbon and nitrogen than non-keystone species. The keystone species, which were closely related to the microbial community in soil indigenous flora and earthworm intestinal flora, could resist chlordane stress and undertake pesticide degradation. These results have increased understanding of the role of the earthworm gut and indigenous soil bacteria in resisting chlordane stress and sustaining microbial equilibrium in soil.

Effects of antimony contamination on bioaccumulation and gut bacterial community of earthworm Eisenia fetida

Antimony (Sb) contamination has brought great environmental problems to the surrounding soils. However, few studies focused on the response of bacterial communities in earthworm gut to Sb. Eisenia fetida was cultured in four soils with Sb contents (5,25,50,100 mg•kg^-1) to investigate the distribution of Sb species in earthworm gut and the response mechanism of bacterial communities to Sb contamination. The results showed that Sb accumulated in the gut and tissues of earthworms, and the mortality of earthworms showed a dose-response relationship with the increase of Sb content. Sb(III) and Sb_exe were the major species in gut, whereas Sb(V) and Sb_srp were predominant in surrounding soil. There were significant differences in bacterial diversity between earthworm gut and soil, but there was no significant between the two with different Sb content. The network constructed by gut bacterial community of earthworm was less stable and more sensitive to Sb species than that in soil. Sb(III) had the greatest influence on the gut bacterial community of earthworm, which not only directly affected the community through Xanthomonadaceae, Rhodomicrobiaceae and Anaerolineaceae, but also indirectly influenced through Chthoniobacteraceae. This study fills a research gap on the effect of Sb contamination on the gut bacterial community of earthworm.

Effects of TiO2 and ZnO nanoparticles on vermicomposting of dewatered sludge: studies based on the humification and microbial profiles of vermicompost

Nanoparticles (NPs) are prevalent in dewatered sludge, and their presence increases the environmental risks associated with the subsequent sludge treatment process. However, until now, their potential effects on sludge vermicomposting have not been clarified. This study investigated the effects of NPs on sludge humification and microbial profiles during vermicomposting by comparing fresh dewatered sludge substrates with substrates mixed with 0 mg/kg NPs (control), 100 mg/kg TiO₂, 500 mg/kg TiO₂, 100 mg/kg ZnO, and 500 mg/kg ZnO. The results showed that addition of TiO₂ and ZnO NPs to sludge did not significantly affect the growth rate of earthworms and the superoxide dismutase activity in their guts during vermicomposting. Moreover, higher concentrations of the selected NPs promoted the humification index of sludge by 20.7-49.6%, through the formation of polysaccharides, aromatic substances, and organic acids in final vermicomposts. Compared with the control without NP addition, bacterial community diversity was enhanced in treatments with TiO₂ and ZnO NPs, and dominant genera differed according to the type and concentration of NPs. This study suggests that the presence of TiO₂ and ZnO NP residuals modify the microbial community of sludge, thus promoting sludge humification during vermicomposting.

Elimination of antibiotic resistance genes from excess activated sludge added for effective treatment of fruit and vegetable waste in a novel vermireactor

Elimination of antibiotic resistance genes (ARGs) from excess activated sludge (EAS) mixed for effective treatment of different fruit and vegetable waste (FVW) by using a novel vermireactor consisted of substrate and bed compartments was investigated. ARGs (tet G, tet M and sul 1) and mobile genetic element gene (intl 1) were targeted and, through quantitative analysis of their abundances in both the compartments and the fresh cast of earthworms, significant reductions in substrate compartments were confirmed for the treatments for FVW added with EAS and EAS alone even if the reduction extents differed among the types of FVW. Apparent reductions were not found in the bed compartment where the final products accumulated. For the fresh cast, the relative abundances of ARGs and intl 1 against to the total bacterial 16S rDNA decreased markedly. The present study provided an insight for proper controlling of ARGs during vermicomposting of FVW and EAS.

Response surface methodology and artificial neural network modelling for enhancing maturity parameters during vermicomposting of floral waste

In this study, the mixture of floral waste and cattle dung in different proportions was utilised to convert into vermicompost using earthworm Eisenia fetida. In the design of the experiment, the optimum amount of floral waste (1325 g) and cattle dung (500 g) was obtained for vermicompost using central composite design (CCD) and compared with the output of artificial neural network (ANN). The optimum proportions of vermicompost showed pH of 7.10, electrical conductivity of 3.39 mS/cm, total organic carbon of 34.01%, C: N ratio of 13, phosphorous of 5.31 g/kg and potassium of 14.45 g/kg. This vermicompost was enriched with sufficient concentration of nutrients like potassium, sodium, phosphorous, and calcium, which are beneficial for the growth of the plants. The current study was based on comparing response surface methodology (RSM) and ANN for maturity parameters and the value of R² in both the cases was near 1.

Transcription profiling-guided remodeling of sulfur metabolism in synthetic bacteria for efficiently capturing heavy metals

Heavy metal contamination is becoming a global problem threatening human health. Heavy metal removal by engineered microbes by cellular adsorption and uptake is a promising strategy for treatment of heavy metal contamination. However, this strategy is confronted with limited heavy metal-capturing elements. In this study, we performed a transcription profiling-guided strategy for construction of heavy metal-capturing synthetic bacteria. Transcription profiling of a heavy metal-tolerating Cupriavidus taiwanensis strain revealed up-regulation of sulfur metabolism-related operons (e.g., iscSAU and moaEDAB) by Pb²⁺ and Cd²⁺. A synthetic Escherichia coli strain, EcSSMO, was constructed by design of a synthetic sulfur metabolism operon (SSMO) based on iscSAU/moaEDAB. Biochemical analysis and X-ray photoelectron spectroscopy (XPS) revealed that the synthetic bacteria had remodeled sulfur metabolism and enhanced heavy metal-tolerating capacity, with higher surviving EcSSMO cells than the surviving control cells Ec0 (not containing SSMO) at 50 mg/L of Pb²⁺ and Cd²⁺ (>92 % versus <10 %). Moreover, EcSSMO exhibited much higher heavy metal-capturing capacity than Ec0, removing>90 % of Pb²⁺ and Cd²⁺ at 5 mg/L of Pb²⁺ and Cd²⁺, and >40 % of both heavy metals even at 50 mg/L of Pb²⁺ and Cd²⁺. This study reveals emphasizes feasibility of transcription profiling-guided construction of synthetic organisms by large-scale remodeling metabolic network.

MOF based engineered materials in water remediation: Recent trends

The significant upsurge in the demand for freshwater has prompted various developments towards water sustainability. In this context, several materials have gained remarkable interest for the removal of emerging contaminants from various freshwater sources. Among the currently investigated materials for water treatment, metal organic frameworks (MOFs), a developing class of porous materials, have provided excellent platforms for the separation of several pollutants from water. The structural modularity and the striking chemical/physical properties of MOFs have provided more room for target-specific environmental applications. However, MOFs limit their practical applications in water treatment due to poor processability issues of the intrinsically fragile and powdered crystalline forms. Nevertheless, growing efforts are recognized to impart macroscopic shapability to render easy handling shapes for real-time industrial applications. Furthermore, efforts have been devoted to improve the stabilities of MOFs that are subjected to fragile collapse in aqueous environments expanding their use in water treatment. Advances made in MOF based material design have headed towards the use of MOF based aerogels/hydrogels, MOF derived carbons (MDCs), hydrophobic MOFs and magnetic framework composites (MFCs) to remediate water from contaminants and for the separation of oils from water. This review is intended to highlight some of the recent trends followed in MOF based material engineering towards effective water regeneration.

Apple orchard waste recycling and valorization of valuable product-A review

Huge quantities of apple orchard waste (AOW) generated could be regarded as a promising alternative energy source for fuel and material production. Conventional and traditional processes for disposal of these wastes are neither economical nor environment friendly. Hence, sustainable technologies are required to be developed to solve this long-term existence and continuous growing problem. In light of these issues, this review pays attention towards sustainable and renewable systems, various value-added products from an economic and environmental perspective. Refined bio-product derived from AOW contributes to resource and energy demand comprising of biomethane, bioethanol, biofuels, bio-fertilizers, biochar, and biochemicals, such as organic acid, and enzymes. However, the market implementation of biological recovery requires reliable process technology integrated with an eco-friendly and economic production chain, classified management.

Fates of Antibiotic Resistance Genes in the Gut Microbiome from Different Soil Fauna under Long-Term Fertilization

Applying organic fertilizers has been well documented to facilitate the dissemination of antibiotic resistance genes (ARGs) in soil ecosystems. However, the role of soil fauna in this process has been seldom addressed, which hampers our ability to predict the fate of and to manage the spread of ARGs. Here, using high-throughput quantitative polymerase chain reaction (HT-qPCR), we examined the effect of long-term (5-, 8-, and 10-year) fertilization treatments (control, inorganic fertilizers, and mixed fertilizers) on the transfer of ARGs between soil, nematodes, and earthworms. We found distinct fates for ARGs in the nematodes and earthworms, with the former having higher enriched levels of ARGs than the latter. Fertilization impacted the number and abundance of ARGs in soil, and fertilization duration altered the composition of ARGs. Shared ARGs among soil, nematodes, and earthworm guts supported by a fast expectation-maximization microbial source tracking analysis demonstrated the trophic transfer potential of ARGs through this short soil food chain. The transfer of ARGs was reduced by fertilization duration, which was mainly ascribed to the reduction of ARGs in the earthworm gut microbiota. This study identified the transfer of ARGs in the soil-nematode-earthworm food chain as a potential mechanism for a wider dissemination of ARGs in the soil ecosystem.

Cleaner production of agriculturally valuable benignant materials from industry generated bio-wastes: A review

Bio-wastes from different agro-based industries are increasing at a rapid rate with the growing human population's demand for the products. The industries procure raw materials largely from agriculture, finish it with the required major product, and produce huge bio-wastes which are mostly disposed unscientifically. This creates serious environmental problems and loss of resources and nutrients. Traditional bio-wastes disposal possess several demerits which again return with negative impact over the eco-system. Anaerobic digestion, composting, co-composting, and vermicomposting are now-a-days given importance due to the improved and modified methods with enhanced transformation of bio-wastes into suitable soil amendments. The advanced and modified methods like biochar assisted composting and vermicomposting is highlighted with the updated knowledge in the field. Hence, the present study has been carried to compile the effective and efficient methods of utilizing industry generated bio-wastes for circularity between agriculture - industrial sectors to promote sustainability.

Centrality of cattle solid wastes in vermicomposting technology - A cleaner resource recovery and biowaste recycling option for agricultural and environmental sustainability

The current review reports the importance and significance of cattle solid waste in vermicomposting technology concerning biowaste pollution in the environment. Needy increasing population evokes livestock production resulting in the massive generation of livestock wastes, especially cattle dung. Improper disposal and handling of biowastes originating from agriculture, industries, forests, rural and urban areas lead to nutrient loss, environmental pollution and health risks. Among the organic waste disposal methods available, vermicomposting is regarded as an environmentally friendly technology for bioconversion of agricultural, industrial, rural and urban generated organic solid wastes which are serving as reservoirs of environmental pollution. In vermicomposting of organic wastes, cattle dung plays a central role in mineralization, nutrient recovery, earthworm and microbial activity leading to vermifertilizer production. Even though the vermicomposting studies use cattle dung invariably as an amendment material, its importance has not been reviewed to highlight its central role. Hence, the present review mainly emphasizes the key role played by cattle dung in vermicomposting. Vermiconversion of cattle dung alone and in combination with other biowaste materials of environmental concern, mechanisms involved and benefits of vermicompost in sustainable agriculture are the major objectives addressed in the present review. The analysis reveals that cattle dung is indispensable amendment material for vermicomposting technology to ensure agricultural and environmental sustainability by reducing pollution risks associated with biowastes on one hand, and nutrient-rich benign vermifertilizer production on the other hand.