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Engine oil consists of hazardous substances that adversely affect the environment and soil quality. Bioremediation (employing organisms) is an appropriate technique to mitigate engine oil pollution. In the present study, the earthworm species, Drawida modesta (epigeic) and Lampito mauritii (anecic) were used to restore the soil polluted with polycyclic aromatic hydrocarbons (PAHs) and total petroleum hydrocarbons (TPHs) from used engine oil. Four treatments were set up in addition to positive and negative controls. A maximum of 68.6% PAHs and 34.3% TPHs removal in the treatment with soil (1 kg), cow dung (50 g), used engine oil (7.5 mL) and earthworms was recorded after 60 days. Undoubtedly, earthworms effectively removed PAHs and TPHs from the oil-contaminated soil. PAHs were more strongly accumulated in D. modesta (16.25 mg kg-1) than in L. mauritii (13.25 mg kg-1). Further, histological analysis revealed the epidermal surface irregularity, cellular disintegration, and cellular debris in earthworms. The pH (6.3%), electrical conductivity (12.7%), and total organic carbon (35.4%) were significantly (at P < 0.05) decreased after 60 days; while, total nitrogen (62%), total potassium (76.2%), and total phosphorus (19.2%) were substantially increased at the end of the experiment. The seed germination assay with fenugreek indicates that germination percentage (95%), and germination index (179), were dramatically increased in earthworm inoculated treatments when compared to the negative control (without earthworms). The results reveal that there is a great scope for utilizing the earthworms, D. modesta and L. mauritii for the bioremediation of soils contaminated with PAHs and TPHs.

Earthworms are known to reclaim soil contamination and maintain soil health. In the present study, the concentration of DTPA extractable heavy metals, Cd, Cu, Cr, Pb, and Zn in vermicasts and tissues of the earthworms (anecic: Lampito mauritii; epigeic: Drawida sulcata) collected from the soils of four different industrial sites, Site-I (Sago industry), Site-II (Chemplast industry), Site-III (Dairy industry) and Site-IV (Dye industry) have been studied. The heavy metals in industrial soils recorded were 0.01–326.42 mg kg−1 with higher Cu, Cr, and Zn contents while the vermicasts showed lower heavy metal loads with improved physicochemical properties and elevated humic substances. The higher humic substances dramatically decreased the heavy metals in the soil. The bioaccumulation factors of heavy metals (mg kg−1) are in the order: Zn (54.50) > Cu (17.43) > Cr (4.54) > Pb (2.24) > Cd (2.12). The greatest amount of metallothionein protein (nmol g−1) was recorded in earthworms from Site-IV (386.76) followed by Site-III (322.14), Site-II (245.82), and Site-I (232.21). Drawida sulcata can produce a considerable amount of metallothionein protein than Lampito mauritii as the metallothionein production is dependent upon the presence of pollutants. The molecular docking analysis indicates a binding score of 980 for Cd, Cr and Cu, and 372 for Zn. Pb may bind with a non-metallothionein protein of earthworms and bio-accumulated in the internal chloragogenous tissues. Metallothionein neutralizes the metal toxicity and controls the ingestion of essential elements.

Poultry litter contains an enormous amount of nutrients that create environmental problems like eutrophication and phytotoxicity. These challenges can be mitigated by stabilizing its nutrients using earthworms. The objective of the present study was to decompose poultry litter amended with cow dung and Tectona grandis leaf litter into vermicompost (VC) using Drawida sulcata, relatively a new earthworm species. D. sulcata is a hardy species, and its survival rate was high during the vermicomposting process under alkaline pH condition. D. sulcata improved the quality of vermicompost by increasing the level of nutrients like total nitrogen, total phosphorous and total potassium and decreased pH, organic carbon and carbon/nitrogen ratio. The quality of VC was checked through seed germination assay using Trigonella foenum-graecum. In comparison with control, 20% (20 g VC + 100 ml water) concentration of VC extract showed a statistically significant (P

The present study demonstrates the vermistabilization of paper mill wastewater sludge (PMS) spiked with cow dung (CD) employing indigenous epigeic earthworm Perionyx excavatus Perrier. A total of six treatments were prepared along with a positive control (PC) and negative control (NC). Twenty earthworms were released into each treatment including PC and NC without earthworms. The different proportions viz., T1 (CD – 100%), T2 (PMS:CD – 1:3), T3 (PMS:CD – 1:2), T4 (PMS:CD – 1:1), T5 (PMS:CD – 3:1), T6 (PMS:CD – 2:1), PC (PMS – 100%) and NC (PMS – 100%) and changes in chemical parameters and microbial properties were recorded during the course of 60 days. Vermistabilization caused a significant decrease in the level of heavy metals: Cd (2.9–27.8%), Cu (0.22–42.3%), Pb (1.3–56.3%) and Cr (0.8–46.2%). The bioconcentration factor (BCFs) was also calculated and great amount of heavy metals accumulated in their body (mg kg−1) that ranged from 0.31 ± 0.003–0.45 ± 0.007 for Cd, 0.12 ± 0.005–0.24 ± 0.003 for Cu, 0.15 ± 0.005–0.31 ± 0.006 for Pb and 0.29 ± 0.007–0.56 ± 0.001 mg kg−1 for Cr, accumulation of heavy metals are in the order: Cr > Cd > Pb > Cu. The physicochemical parameters of earthworm treated substrate such as electrical conductivity, total nitrogen, total phosphorus and total potassium were significantly increased; whereas, pH, total organic carbon, C:N ratio (carbon: nitrogen) and C:P ratio (carbon: phosphorus) were reduced after 60 days of vermistabilization. The vermistabilized materials also had a higher population of bacteria (98.90 ± 0.30 CFU × 106 g−1), fungi (43.75 ± 0.55 CFU × 103 g−1) and actinomycetes (67.65 ± 0.45 CFU × 105 g−1) than initial mixtures. Moreover, several histopathological changes were observed in earthworm tissues viz., disintegration of cells, irregular surface of epidermis, cellular debris, irregular cellular compartmentation, and oval-shaped nucleus. Higher level of histopathological abnormalities was recorded in PC (PMS-100%) while none were detected in lower concentrations of PMS. Furthermore, the study concludes that the paper mill sludge in a mixture of cow dung (1:1 ratio) can be a useful proposition for utilizing this hazardous waste through the adoption of vermitechnology.

The industrial revolution and indiscriminate usage of a wide spectrum of agrochemicals account for the dumping of heavy metals in the environment. In-situ/ex-situ physical, chemical, and bioremediation strategies with pros and cons have been adopted for recovering metal contaminated soils and water. Therefore, there is an urgent requirement for a cost-effective and environment-friendly technique to combat metal pollution. Biochar combined with earthworms and vermifiltration is a suitable emerging technique for the remediation of metal-polluted soils and water. The chemical substances (e.g., sodium hydroxide, zinc chloride, potassium hydroxide, and phosphoric acid) have been used to activate biochar, which also faces several shortcomings. Studies reveal that extracellular enzymes have been used to activate biochar which is produced by earthworms and microbes that can alter the surface of the biochar. The present review focuses on the global scenario of metal pollution and its remediation through biochar activation using earthworms. The earthworms and biochar can produce "vermibiochar" which is capable of reducing the metal ions from contaminated water and soils. The vermifiltration can be a suitable technology for metal removal from wastewater/effluent. Thus, the biochar has a trick of producing entirely new options at a time when vermifiltration and other technologies are least expected. Further attention to the biochar-assisted vermifiltration of different sources of wastewater is required to be explored for the large-scale utilization of the process.

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.

Vermicomposting of pressmud with cow dung and nitrogenous green manures (Gliricidia sepium and Leucaena leucocephala) was carried out using Eudrilus eugeniae (50 days). The reduction in pH, total organic carbon, C/N ratio, water-soluble organic carbon (Cws)/Norg and C/P ratios, and a pronounced increase in NPK contents and microbial population in vermicompost were observed. An enhanced TKN of 3.80% and 3.45% was recorded in vermicomposts of pressmud + cow dung + L. leucocephala (2:1:1) and pressmud + cow dung + G. sepium (2:1:1) respectively. The C/N and Cws/Norg ratios in vermicompost ranged from 11.86 to 16.66 and 0.53 to 1.33, respectively. The activity of dehydrogenase, urease, acid and alkaline phosphatase declined towards the end, indicating the progression of vermicompost maturity. The pressmud and green manure substrates promoted more biomass of E. eugeniae, while cow dung with green manure combination favored reproduction. The amendment of cow dung and green manure plants to pressmud (2:1:1 ratio) results in nutrient-enriched vermicompost production.

In the present study, Eudrilus eugeniae and Perionyx excavatus were used for vermistabilization of textile mill sludge in different combinations with cowdung for 60 days. A higher percentage of metal removal was observed in earthworm treated mixtures for cadmium (54.5%) followed by copper (36.0%), chromium (37.0%) and zinc (35.9%). Vermistabilized textile mill sludge + cowdung (1:1) showed a maximum percentage increase in total NPK, a significant (P

The invasive weed, Ipomoea staphylina (IS) with cow dung (CD) and mushroom spent straw (MS) in four different combinations (IS:CD:MS), V1 (1:1:0), V2 (2:1:1), V3 (1:0:1) and V4 (1:1:1) were pre-decomposed for 21 days followed by 50 days vermicomposting using Eudrilus eugeniae in triplicates in order to alleviate and to utilize the weed biomass in an environment-friendly manner. The contents of organic matter, organic carbon, cellulose, lignin, C/N and C/P ratios showed a decrease, while electrical conductivity, total NPK, calcium, sodium, and nitrate-nitrogen showed a significant increase in vermicompost over control. Water-soluble organic carbon to organic nitrogen ratio and C/N ratio in V1 (0.52 and 17.55) and V4 (0.43 and 16.56), respectively, were in conformity with the maturity of vermicomposts. Scanning electron micrographs of the end products clearly showed more fragmented, fine, and porous particles in vermicompost. Copper, chromium, cadmium, lead, and zinc in vermicomposts were below the permissible limits. Dehydrogenase, acid phosphatase, alkaline phosphatase, cellulase, and protease activities were significantly higher in V4 than other treatments, implying the role of MS and CD addition during vermicomposting. Though V3 combination supported worm biomass, V4 combination was found to favor the fecundity of Eudrilus eugeniae. Results reveal that 1:1:1 combination of SI + CD + MS (V4) is suitable for utilizing the weed biomass for vermicompost production and nutrient recovery. From the biomass of environmentally problematic weed, Ipomoea staphylina, nutrient-rich vermicompost can be produced through vermitechnology for sustainable environmental management and agriculture.