Recycling of lignocellulosic waste as vermicompost using earthworm Eisenia fetida

Innovative production of value-added products using agro-industrial wastes via solid-state fermentation

The prevalence of organic solid waste worldwide has turned into a problem that requires comprehensive treatment on all fronts. The amount of agricultural waste generated by agro-based industries has more than triplet. It not only pollutes the environment but also wastes a lot of beneficial biomass resources. These wastes may be utilized as a different option/source for the manufacturing of many goods, including biogas, biofertilizers, biofuel, mushrooms and tempeh as the primary ingredients in numerous industries. Utilizing agro-industrial wastes as good raw materials may provide cost reduction and lower environmental pollution levels. Agro-industrial wastes are converted into biofuels, enzymes, vitamin supplements, antioxidants, livestock feed, antibiotics, biofertilizers and other compounds via solid-state fermentation (SSF). By definition, SSF is a method used when there is little to no free water available. As a result, it permits the use of solid materials as biotransformation substrates. Through SSF methods, a variety of microorganisms are employed to produce these worthwhile things. SSFs are therefore reviewed and discussed along with their impact on the production of value-added items. This review will provide thorough essential details information on recycling and the use of agricultural waste.

Vermicomposting technology - A perspective on vermicompost production technologies, limitations and prospects

The need for environmental sustainability while increasing the quantity, quality, and the rate of waste treatment to generate high-value environmental friendly fertilizer products is highly in demand. Vermicomposting is a good technology for the valorisation of industrial, domestic, municipal and agricultural wastes. Various vermicomposting technologies have been in use from time past to present. These technologies range from windrow, small - scale batch vermicomposting to large - scale continuous flow systems. Each of these processes has its own merits and demerits, necessitating advancement in the technology for efficient treatment of wastes. This work explores the hypothesis that the use of a continuous flow vermireactor system of a composite frame structure performs better than batch, windrow and other continuous systems operated in a single container. Following an in-depth review of the literature on vermicomposting technologies, treatment techniques, and reactor materials used, to explore the hypothesis, it was found that vermireactors operating in continuous flow fashion perform better in waste bioconversion than the batch and windrow techniques. Overall, the study concludes that batch techniques using plastic vermireactors predominate over the other reactor systems. However, the use of frame compartmentalized composite vermireactors performs considerably better in waste valorisation.

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.

Earthworm stocking density regulates microbial community structure and fatty acid profiles during vermicomposting of lignocellulosic waste: Unraveling the microbe-metal and mineralization-humification interactions

Earthworm-induced microbial enrichment is the key to success in vermitechnology, yet the influence of initial earthworm stocking density on microbial community profiles in vermibeds is unknown. Therefore, vermicomposting of lignocellulosic feedstock was performed with different stocking densities of two earthworms (Eisenia fetida and Eudrilus eugeniae) compared with composting. Eventually, earthworm growth, microbial (activity and community profiles), and physicochemical dynamics were assessed. The earthworm population significantly increased under low stocking, while denser stocking (15/kg) was stressful. The XRD-based crystallinity assessment revealed that comminuting efficiency of Eisenia and Eudrilus was prudent at 7 and 10 worm/kg stockings, respectively. Moreover, the 5 and 7 worm/kg stockings effectively mobilized microbial activity, promoting NPK-mineralization and C-humification balance. Correlation statistics indicated that earthworm stocking density-driven microbial community shift and fatty acid profiles strongly influenced metal removal in vermibeds. Hence, the findings implied that 5-7 worm/kg stockings of earthworms produced high-quality sanitized vermicompost.

Seaweed (Gracilariopsis funicularis) biochar incorporation into a goat manure–food waste vermicompost for optimized vermidegradation and nutrient release

Vermicomposts are organic fertilizer sources that are being promoted; however, their concentrations of macronutrients such as NPK are very low. This study, therefore, evaluated the effects of amending goat manure–food waste mixture with biochar prepared from seaweed (Gracilariopsis funicularis) at 0% (control), 2, 4, 6, and 8% on vermicompost degradation and macronutrient release. After 10 weeks of vermicomposting, the highest pH of 9.06 was observed within the control, whilst the lowest was 8.7 in the 8% treatment. The electrical conductivity showed a positive relationship with the level of biochar incorporation with the highest of 16.5 mS/cm from the 8% treatment, whilst the lowest was within the control with 6 mS/cm. There were no significant differences between treatments on humification parameters; however, there were significant differences in the changes in a C/N ratio with the final C/N ratio of 14.4, 14.9, 16.7, 15.1, and 14.4 for the control, 2, 4, 6, and 8% treatments, respectively. A higher incorporation rate resulted in the higher concentration of potassium with a value of 32.3 g/kg at week 8. The final percentage change in Olsen P was 19, 14.2, 7.3, 4.1, and 3.0% for the 8%, 6%, control, 4%, and 2% treatments, respectively. An optimized level of 6% to 8% biochar incorporation ratio can be recommended. However, the incorporation of G. funicularis biochar does not seem to influence changes in the vermidegradation efficiency, though it can significantly improve the macronutrients such as P, K, and Mg concentrations as well as the macroelement concentrations.

Valorization of phyto-biomass with tertiary combination of animal dung for enriched vermicompost production

A study was conducted for 90 days in two cycles on 45^thday (Cycle I), and 90th day (Cycle II) in 144 vermibins with precomposted cow dung (T1), elephant dung (T2), cow dung + elephant dung (T3) in combination with leaf substrates of Ficus religiosa, Azadirachta indica, Terminalia catappa, Carica papaya, Vitex negundo, Acalypha indica and Borassus flabellifer to generate nutrient-enriched vermicompost. Different vermibin feedstock materials were retained as experimental setup in other substrates with earthworm (vermicompost) and without earthworm (compost). This method was employed in the current study to decompose environmental leaf debris into the earthworm's mass production and transform it into high-value manure for long-term soil fertility control. The majority of the substrates exhibit pH and electrical conductivity in vermicomposts showed an increment while the total organic carbon and carbon to nitrogen ratio were significantly lowered. A prominent percentage increment of total NPK contents (P < 0.05) in vermicompost over initial values (N: 7.09-164.03; P: 4.39-101.09; K: 0.45-84.10). Among the vermibed substrates, Ficus religiosa leaf litter mixed with T3 showed stabilized cocoons and juveniles in Cycle I (45 days), while sub-adults and adults growth was favored in Cycle II (90 days). The higher reproductive potential of earthworms could be due to the composition and palatability of the substrate combination. This study provides a platform for utilizing leaf wastes in combination with animal wastes amended to reproduce earthworms, nutrient enrichment which could benefit soil fertility improvement.

Nutrient recovery and changes in enzyme activity during vermicomposting of hydrolysed chicken feather residue

Chicken feathers are hazardous to the environment because of their poor digestibility and potential as a source of environmental contaminants. However, this waste contains valuable plant nutrients that can be recovered and used to improve soil fertility and agricultural productivity. The objectives of this study were to evaluate how effective vermicomposting is at recovering nutrients and changes in enzymatic activity during vermicomposting of hydrolysed chicken feather residues (HCFR). The study included four treatments with three replications at different HCFR and pelletized wheat straw (PWS) mixing proportions: (T1) 25% HCFR+75% PWS with earthworms, (T2) 25% HCFR+75% PWS without earthworms, (T3) 50% HCFR+50% PWS with earthworms, and (T4) 50% HCFR+50% PWS (w/w) without earthworms. Eisenia andrei was used in the experiment for 120 days. Earthworm treatments recovered more available plant nutrients than non-earthworm treatments by 14% N - NO 3 - (T1); 50% K (T3); 47% Mg (T3); 75% P (T3); 55% B (T3); 34% Cu (T3); 40% Fe (T1); 46% Mn (T3); 11% Zn (T1). However, N - NH 4 + was significantly reduced by -80% (T1). Acid phosphatase, arylsulphatase, alanine aminopeptidase, and leucine aminopeptidase were more active in the treatments with earthworms and positively correlated with P and C: N ratio. Alanine aminopeptidase (3752 µmol AMCA.g-1.h-1) and leucine aminopeptidase (4252 µmol AMCL.g-1.h-1) had higher activities in T3 on day 60 of vermicomposting. As a result, the earthworm treatment recovers more plant nutrients than the non-earthworm treatments, and it can be recommended as a better vermicomposting approach for nutrient recovery from HCFR.

Sustainable treatment and nutrient recovery from leafy waste through vermicomposting

The present investigation was carried out to evaluate the vermicomposting potential of two cruciferous vegetables' residual biomasses under laboratory conditions. Cabbage and cauliflower residual biomasses were spiked with 60% cow dung and vermicomposted for 90 days. The results showed a decrease in pH (5.3-9.8%), Total Organic Carbon (36.7-42.8%); increase in Electrical Conductivity (33-99.4%) and ash content (144.7-187.8%) after vermicomposting. Significant reduction in C:N ratio (49.5-76.4%) and C:P ratio (62.8-66.04%), increase in Total Kjeldahl Nitrogen (49.3-85.3%), Total Available Phosphorus (68.2-98.1%), Total Potassium (91.8-120.3%) were observed. FT-IR spectra of the vermicomposts had lesser band heights and peak intensities than raw materials. This evidenced decomposition of organic compounds and vermicompost stability. Germination Index values was calculated to determine the phytotoxicity level. Earthworms' growth and prolificacy was evaluated in terms of biomass gain, cocoons production and worm growth rate. Finally, it was inferred that cruciferous vegetables' biomass can be used for vermicomposting. The cauliflower residual biomass has shown better decomposition efficiency than cabbage residual biomass.

Eisenia fetida for vermiconversion of waste biomass of medicinal herbs: Status of nutrients and stability parameters

Vermiconversion possibility of waste biomass of two medicinal herbs Zingiber officinale and Curcuma longa has been investigated. The Eisenia fetida, an epigeic earthworm was used in the vermicomposting process. The vermicomposting caused shifting in pH towards neutral range, reduction in electrical conductivity, total organic carbon, C/N and C/P ratios whereas1.8-2.73 folds enhancement in macronutrients (TKN, AP, T Ca and T Mg) and ash contents in the substrate mixture. The heavy metals and trace elements content in the vermicompost were found within 3.25-1380 mg/kg and are under the permissible limits of compost applications. Besides, high germination index value in the vermicompost extract indicates loss of phytotoxicity and safe agricultural application potential of the end product. Finally, enhanced growth in Eisenia fetida confirms the application potential of harvested waste biomass as the raw materials for vermiconversion process.

Hemicellulolytic bacteria in the anterior intestine of the earthworm Eisenia fetida (Sav.)

Tropical agriculture produces large amounts of lignocellulosic residues that can potentially be used as a natural source of value-added products. The complexity of lignocellulose makes industrial-scale processing difficult. New processing techniques must be developed to improve the yield and avoid this valuable resource going to waste. Hemicelluloses comprise a variety of polysaccharides with different backbone compositions and decorations (such as methylations and acetylations), and form part of an intricate framework that confers structural stability to the plant cell wall. Organisms that are able to degrade these biopolymers include earthworms (Eisenia fetida), which can rapidly decompose a wide variety of lignocellulosic substrates. This ability probably derives from enzymes and symbiotic microorganisms in the earthworm gut. In this work, two substrates with similar C/N ratios but different hemicellulose content were selected. Palm fibre and coffee husk have relatively high (28%) and low (5%) hemicellulose contents, respectively. A vermicomposting mixture was prepared for the earthworms to feed on by mixing a hemicellulose substrate with organic market waste. Xylanase activity was determined in earthworm gut and used as a selection criterion for the isolation of hemicellulose-degrading bacteria. Xylanase activity was similar for both substrates, even though their physicochemical properties principally pH and electrical conductivity, as shown by the MANOVA analysis) were different for the total duration of the experiment (120 days). Xylanolytic strains isolated from earthworm gut were identified by sequence analysis of the 16S rRNA gene. Our results indicate that the four Actinobacteria, two Proteobacteria, and one Firmicutes isolated are active participants of the xylanolytic degradation by microbiota in the intestine of E. fetida. Most bacteria were more active at pH 7 and 28 °C, and those with higher activities are reported as being facultatively anaerobic, coinciding with the microenvironment reported for the earthworm gut. Each strain had a different degradative capacity.

Microbial and chemical dynamics of brewers' spent grain during a low-input pre-vermicomposting treatment

The eco-sustainability of industrial processes relies on the proper exploitation of by-products and wastes. Recently, brewers' spent grain (BSG), the main by-product of brewing, was successfully recycled through vermicomposting to produce an organic soil conditioner. However, the pre-processing step there applied (oven-drying) resulted in high costs and the suppression of microbial species beneficial for soil fertility. To overcome these limitations, a low-input pre-processing step was here applied to better exploit BSG microbiota and to make BSG suitable for vermicomposting. During 51 days of pre-treatment, the bacterial and fungal communities of BSG were monitored by denaturing gradient gel electrophoresis (DGGE). Chemical (carbon, nitrogen, ammonium, nitrate content, dissolved organic carbon) and biochemical (dehydrogenase activity) parameters were also evaluated. Mature vermicompost obtained from pre-processed BSG was characterized considering its legal requirements (e.g., absence of pathogens and mycotoxins, lack of phytotoxicity on seeds), microbiota composition, and chemical properties. Results obtained showed that throughout the pre-process, the BSG microbiota was enriched in bacterial and fungal species of significant biotechnological and agronomic potential, including lactic acid bacteria (Weissella, Pediococcus), plant growth-promoting bacteria (Bacillus, Pseudomonas, Pseudoxhantomonas), and biostimulant yeasts (Pichia fermentans, Trichoderma reesei, Beauveria bassiana). Pre-processing increased the suitability of BSG for earthworms' activity to produce high-quality mature vermicompost.

Caffeine adsorptive performance and compatibility characteristics (Eisenia foetida Savigny) of agro-industrial residues potentially suitable for vermifilter beds

The caffeine adsorptive performance and compatibility characteristics (Eisenia foetida Savigny) of rice husk, peanut shell, corn cob and coconut fiber were studied, aiming to assess the suitability of these residues for vermifilter beds. For this purpose, the agro-industrial residues were characterized and the E. foetida Savigny compatibility was determined by acute and chronic toxicity tests. Batch adsorption tests were performed using caffeine solutions. Optimal adsorption conditions, kinetic models, isotherm type and the influence of three particle sizes (120-150, 300-600, 800-2000 μm) in the caffeine removal were determined. Coconut fiber (120-150 μm) proved to be the most efficient residue for the caffeine removal (94.2%), requiring 4 g/L for 30 min. However, coconut fiber was the less compatible for earthworms (14d-LC₅₀ = 82%). The results obtained allow to define adequate strategies, such as mixing highly adsorptive residues with the more compatible ones, to choose the most effective materials for vermifiltration technologies.

Management of invasive weed Parthenium hysterophorus through vermicomposting using a polyculture of Eisenia fetida and Eudrilus eugeniae

Parthenium hysterophorus is considered one of the most noxious terrestrial weeds which needs to be efficiently managed to sustain the environment and vermicomposting are a promising eco-friendly management technique. In the current study, vermicomposting of P. hysterophorus was carried out using a polyculture of two epigeic earthworm species, i.e., Eisenia fetida and Eudrilus eugeniae employed in five different vermireactors referred as Rp1, Rp2, Rp3, Rp4, and Rp5 with five mixing ratios 3:7, 4:6, 5:5, 6:4, and 7:3 respectively of P. hysterophorus to cow dung as a blending material. The nutrients in the final vermicompost were determined by analyzing different physico-chemical parameters and the efficiency evaluated by the growth rate of earthworms. After vermicomposting, TKN, TP, and K contents increased with the highest percentage change of 74.74%, 91%, and 47.2% respectively, compared to initial values. Reduction in C/N ratio was observed in all the vermireactors with the lowest C/N ratio of 9.76. EC increased for all the vermireactors during the process and reached in the range of 3.7-3.85 ds/m at the end of the process. The highest percentage gain in biomass of earthworms was 46.25% in Rp2. Vermicomposting of P. hysterophorus is possible for the management of this invasive weed through polyculture of the earthworms E. fetida and E. eugeniae to obtain a value-added organic fertilizer, i.e., vermicompost by a sustainable process.

Management of banana crop waste biomass using vermicomposting technology

This study reports the vermicomposting of banana crop waste biomass by Eisenia fetida. Cow dung has been used as bulking agent in this study. The experiment was conducted in six vermireactors containing different ratios of banana leaf waste biomass (BL) and cow dung (CD) for 105 days. Earthworm activity significantly reduced pH, TOC, C:N and C:P ratio of the wastes. Whereas macronutrients and micronutrients content increased after vermicomposting. TOC content of wastes reduced by 40-64% and C:N ratio of the vermicomposts was in the range of 8.9-24.3. The benefit ratio for heavy metals (Cu, Fe, Zn, Cd, Pb, Mn and Cr) was in the range of 0.23-3.44. The results indicated that the growth and fecundity of the earthworms was best in the vermireactors having 20-40% BL. Finally, it was concluded that vermicomposting can be included in the overall scheme of banana crop waste management.

The non-negligibility of greenhouse gas emission from a combined pre-composting and vermicomposting system with maize stover and cow dung

The acceptance of combined pre-composting and vermicomposting systems is increasing because of the advantage in rapidly stabilizing organic wastes and reducing emission of greenhouse gasses (GHG). However, GHG emission during the pre-composting phase is often neglected when evaluating the system. This study aimed to quantify GHG emission from a combined pre-composting and vermicomposting system and to investigate the effects of earthworms on GHG emission. A combined system using Eisenia fetida was employed to stabilize maize stover and cow dung (mixing ratio 60:40). The inoculating densities were 60 (T₁), 120 (T₂), and 180 (T₃) earthworms per kilogram of substrate. A traditional composting system without earthworms was set as a control (T₀). The results indicated that earthworms increased CO₂ while decreased CH₄ and N₂O emissions compared to the control. Higher emission of CO₂ suggested that the earthworms promoted the degradation of the substrates. Lower emission of CH₄ and N₂O showed the advantage of the combined system because CH₄ and N₂O possess extremely higher global warming potential than that of CO₂. T₂ is recommended for stabilizing maize stover and cow dung when making a tradeoff between stabilization rate and reduction of GHG. The percentages of GHG emission during pre-composting relative to total GHG emission in T₁, T₂, and T₃ were 34%, 35%, and 30%, respectively. GHG emission is non-negligible when using a combined system, especially the emission of GHG during the pre-composting phase cannot be ignored.

Metallothionein dependent-detoxification of heavy metals in the agricultural field soil of industrial area: Earthworm as field experimental model system

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.

Nutrient recovery from pineapple waste through controlled batch and continuous vermicomposting systems

The largest portion of pineapple peels and pulp generated from production points is disposed of haphazardly contributing to a number of environmental and health challenges. However, these wastes contain valuable plant nutrients that could be recovered to boost soil fertility, and increase agricultural production. This study evaluated the variation in physico-chemical parameters in batch and continuous vermicomposting systems as potential pathways for nutrient recovery from pineapple waste. The study compared the efficiency of waste reduction and nutrient recovery for batch (B), and continuous (C) vermicomposting systems during a 60-day period. The substrates were pineapple peels (PW), and cattle manure (CM) fed in a ratio of 4:1 (w/w). Control reactors were fed with 100% CM in both the feeding modes. Results indicated that waste degradation was 60%, and 54% while earthworm biomass increased by 57% and 129% for BPW, and CPW, respectively. pH significantly decreased with time in both systems. Total phosphorous increased with vermicomposting time with that of B being significantly higher than C systems. Nitrogen, potassium, and sodium significantly increased in the control experiments while the three elements significantly reduced for BPW, and CPW owing to high leachate production in the latter. The N, P, K, and C retention in vermicompost was 24.2%, 90.4%, 67.5%, 41.1%, and 32.6%, 91.2%, 79.3%, 46.1%, for BPW and CPW, respectively. Continuous systems produced higher earthworm biomass and retained more nutrients in vermicompost than batch systems, and can therefore, be recommended as better systems for pineapple waste vermicomposting.

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.

Management of lignocellulosic green waste Saccharum spontaenum through vermicomposting with cow dung

Saccharum spontaenum is considered as an invasive terrestrial weed spread across the world and its management possess big challenge to the research community. The current study illustrates the potential of vermicomposting for the management of lignocellulosic terrestrial weed Saccharum spontaenum under green waste management. The vermicompost experiments were done in five different mixing ratio of Saccharum spontaenum amended with cow dung 3:7, 4:6, 5:5, 6:4, 7:3 in vermireactors referred as R_ef1, R_ef2, R_ef3, R_ef4, R_ef5 respectively. The vermicomposting was carried out for total 45 days with one time feeding of the earthworms. The study indicates a mature vermicompost can be obtained with enhanced nutrients from proper mixing ratio. The different physicochemical parameters were observed to be varied among the reactors and between vermicomposting time significantly. The final C/N ratio was within 10-16 with highest decrease in R_ef1. Earthworm growth was observed to be highest in R_ef2 with percentage change of net biomass of earthworms with 34.25%. The highest TOC loss was observed to be 31.4% change in R_ef2 and maximum TKN was 2.95% in the final vermicompost of Ref3. Even though the mixing ratio of R_ef1 and R_ef2 was found to be ideal for the degradation of Saccharum spontaenum, the other reactors also produced acceptable quality end product. The study further reveals that the earthworm species Eisenia fetida was highly suitable for the biodegradation of this lignocellulosic weed material.

An insight to municipal solid waste management of Varanasi city, India, and appraisal of vermicomposting as its efficient management approach

Varanasi, India's historic cultural capital, struggles with efficient waste management practices. This impacts environment and human well-being in terms of waste generation that is estimated around 550-650 TPD with a generation rate of 0.42 kg capita^-1 day^-1 (n = 117). The present study aims to explore and characterize wastes, current practices, ecological profiling, and phytotoxicity of an abandoned open dumping site, and vermicomposting of organic fraction of municipal solid waste (OFMSW) as sustainable waste management approach. Compositional analysis of waste indicates organic fraction (46.13%) as a major component along with a considerable amount of heavy metals. The calorific value and moisture content of municipal solid waste (MSW) was 2351.4 cal g^-1 and 34.72%, respectively. Ecological profiling of the dumping site revealed that floral diversity and ecological species/indicators were negatively affected. Likewise, phytotoxicity results displayed a negative impact on germination and physiology of maize (Zea mays L.) plants grown on dumping site soil. Vermistabilization of OFMSW showed a significant increase in N (56.10-89.48%), P (33.93-82.87%), and K (25.55-50.42%) and a decrease in total organic carbon (15.15-24.81%). Similarly, C/N and C/P ratios decreased by 1.89-2.51 and 1.72-2.18 folds, respectively. A survey of stakeholders suggested that open dumping was the main practice adopted by Varanasi Municipal Corporation (VMC) during 2013-2015. Recently (2017-2018), VMC adopted different methods, such as door-to-door collection and source segregation for effective waste management. Waste characteristics and nutrient profile of the vermicompost explains that vermicomposting could be used for efficient waste management in Varanasi, further reducing the collection, transportation, and disposal costs of waste, which enables to close the loop and move towards a circular economy. Moreover, implications of existing waste management practices and possible management options need to be addressed scientifically. Therefore, this research outcome will help in designing a successful waste management plan for Varanasi and other cities with similar waste characteristics.