Pradip Bhattacharyya

Vermicomposting of Tea Factory Coal Ash: metal accumulation and metallothionein response in Eisenia fetida (Savigny) and Lampito mauritii (Kinberg).

Earthworms can accumulate heavy metals in their intestines to a great extent. Impact of feed materials and duration of metal exposure on natural activity of earthworms are rather unclear; this investigation therefore addresses the impact of metal rich Tea Factory Coal Ash (TFCA) on reproduction, composting and metal accumulation ability of Eisenia fetida and Lampito mauritii. Earthworm count and cocoon production increased significantly during vermicomposting. pH of the vermicomposted mixtures shifted toward neutrality, total organic C decreased substantially and total N enhanced significantly compared to composting. High heavy metal (Mn, Zn, Cu, As) accumulation was recorded in the intestine of both the earthworm species. Moreover, gradual increase in the metal-inducible metallothionein concentration indicated the causal mechanism of metal accumulation in these species. TFCA+cow dung (CD) (1:1) were most favorable feed mixture for E. fetida and TFCA+CD (1:2) were good for L. mauritii in regard to metal accumulation and compost quality.

Hazard remediation and recycling of tea industry and paper mill bottom ash through vermiconversion

Considerable amount of bottom ash (BA) is produced by tea and paper factories in Northeast India. This significantly deteriorates soil and surface water quality through rapid acidification, releasing sulfur compounds and heavy metals. The present investigation endeavoured to convert this waste to organic manure through vermicomposting by Eisenia fetida. Substantial increment in bioavailability of N, P, K, Fe, Mn and Zn along with remarkable decline in toxic metal like Cr due to vermicomposting was noteworthy. Furthermore, vermicomposted mixtures of Tea Factory BA (TFBA) or Paper Mill BA (PMBA) with organic matter (OM) attributed profuse pod yield of French Bean (Phaseolus vulgaris L.). Hence, bioconversion of TFBA and PMBA is highly feasible through vermicomposting and the converted materials can be utilized as potential organic fertilizer.

Metal remediation and biodegradation potential of earthworm species on municipal solid waste: A parallel analysis between Metaphire posthuma and Eisenia fetida

Information on vermicomposting with Metaphire posthuma is scanty. This paper, therefore, aims to evaluate the bioconversion efficiency of this species against Eiseniafetida. For comparative analysis, different combinations of municipal solid waste (MSW) and cow dung were used as substrates. The contents of total N and availability of P, K, and Fe increased significantly in both Metaphire and Eisenia systems which was accompanied by substantial reduction in pH and total organic C. Both species exhibited similar levels of urease activity and microbial respiration. Moreover, bioavailability of heavy metals (Pb, Zn, Mn, and Cu) was reduced substantially during vermicomposting, irrespective of the earthworm species. In contrast, each species was distinguished by the enhancement either in microbial biomass C and phosphatase activity (Eisenia) or in humification and fulvic/humic acid C (Metaphire). The overall results suggest that indigenous earthworm, M.posthuma could be utilized as a successful candidate for bioprocessing of toxic wastes.

Exploring metal detoxification and accumulation potential during vermicomposting of Tea factory coal ash: sequential extraction and fluorescence probe analysis.

Metal contamination from coal ashes (CAs) is widely recognized as a significant environmental concern. To learn more about metal detoxification and accumulation potential of earthworm species, metal-rich tea factory coal ashes (TFCA) were fed to Eisenia fetida and Lampito mauritii by employing a fluorescent tag detection method. Fascinatingly, on feeding fluorescence probed Zn and Cd along with cow dung to Eisenia fetida, the detection of the gut-proteins with a molecular mass higher than 100 kDa was a distinct evidence of metal binding. Significant increases were observed in the content of humified organic C [humic acid (HAC) and fulvic acid C (FAC)] and degree of humification during vermicomposting. Concurrently, considerably large amount of toxic metals (Cr, Cd, Pb, and Zn) was transformed from exchangeable to recalcitrant (organic matter and mineral bound) fractions. Moreover, total metal concentrations were reduced with high removal efficiency upon vermicomposting.

Efficacy of bioconversion of paper mill bamboo sludge and lime waste by composting and vermiconversion technologies.

Paper mill bamboo sludge (PMBS) and Paper mill lime waste (PMLW) are extensively produced as solid wastes in paper mills. Untreated PMBS and PMLW contain substantial amount of heavy metals (Zn, Pb, Ni, Cd, Cr) in soluble forms. Efficiency of vermiconversion and aerobic composting with these wastes is reported here. Adopted bioconversion systems enhanced the availability of some essential nutrients (N, P, K and Zn) in various combinations of cow dung (CD) with PMBS and PMLW. Colonization of nitrogen fixing bacteria and phosphate solubilizing bacteria considerably intensified under the vermiconversion system. Moreover, significant metal detoxification occurred due to vermiconversion. Various combinations of bioconverted PMBS and PMLW were applied to tissue cultured bamboo (Bambusa tulda) and chilli (Capsicum annum). Accelerated nutrient uptake coupled with improved soil quality resulted in significant production of chilli. Furthermore, vermiconverted PMBS+CD (1:1) and PMLW+CD (1:3) confirmed as potential enriching substrate for tissue cultured bamboo.

Excellent N-fixing and P-solubilizing traits in earthworm gut-isolated bacteria: A vermicompost based assessment with vegetable market waste and rice straw feed mixtures

Vermicomposting is a dependable waste recycling technology which greatly augments N and P levels mainly through microbial action. This paper aims to identify efficient N-fixing (NFB) and P-solubilizing (PSB) bacteria from earthworm intestines. Various combinations of vegetable market waste, rice straw, and cowdung were fed to two earthworm species (Eisenia fetida and Perionyx excavatus). Total organic C decreased, pH shifted towards neutrality, and NPK availability, and microbial (NFB, PSB, and total bacteria) population increased remarkably during vermicomposting with E. fetida. Therefore, 45 NFB and 34 PSB strains isolated from Eisenia gut were initially screened, their inter-dominance assessed, and 8 prolific strains were identified through 16SrRNA sequencing. Interestingly, two novel N-fixing strains of Kluyvera ascorbata emerged as an efficient biofertilizer candidate. Moreover, both N-fixing and P-solubilizing strains of Serratia and Bacillus were isolated from earthworm gut. All the isolated strains significantly improved soil health and facilitated crop growth as compared to commercial biofertilizers.

Metal accumulation, biochemical response and yield of Indian mustard grown in soil amended with rural roadside pond sediment.

This present study aims to discern the effect of roadside pond sediments on Brassica juncea (L.) Czern. (cv. Rohini) by examining heavy metal uptake by different parts of the plant and its influence on biochemical properties, biomass, yield and oil content in plant. Although the treated soils were clearly contaminated with heavy metals (HMs) after application of pond sediments and chemical fertilizers, but the metal content in mustard leaves and seeds are below the permissible limit of consumable food. HMs accumulation was proportionally lesser in grains than in shoots and roots. All the biochemical characteristics were significantly (p<0.05) responded to the pond sediments application as compared to the control. Increase in photosynthetic pigment was also observed during growing period while pond sediment was used as amendment. This study revealed that Brassica juncea is well adapted to tolerate and accumulate high quantities of HMs due to increased level of antioxidants (cysteine and ascorbic acid) in roots, shoots and leaves. Multivariate techniques like principal component analysis and cluster analysis (CA) were used as classification techniques. On the basis of factor loadings and principal component scores, different parameters were grouped based on their similarity or closeness, separately in leaves, roots and seeds. A very similar grouping was also obtained using CA. However, pond sediment did not thwart the enhancement of mustard yield and oil content. Therefore, pond sediment would be a valuable resource for mustard as an alternative soil amendment for nutrients, but long-term use may require the cessation to restrict HMs contamination in soils.

Novel synthesis of an iron oxalate capped iron oxide nanomaterial: a unique soil conditioner and slow release eco-friendly source of iron sustenance in plants

Iron (Fe) is a vital plant-derived micronutrient in the human diet. Fe availability in soil largely depends on the pH and leaching behaviour of the soil. Although common salts (FeSO4) and chelates (EDTA) of Fe ensure high availability of the nutrient, they often interfere with P availability in the soil. Considering such disadvantages of the well-known Fe sources, we attempted to evolve efficient Fe3O4 nanomaterials that are independent of soil reaction (i.e. pH) and do not prevent P solubility in soil. The present investigation resulted in a novel, green and an easy pathway of large-scale synthesis of orthorhombic Fe–oxalate capped-Fe-oxide (Fe3O4) (OCIO) nanomaterial with a prolific agricultural applicability. This nanomaterial did not affect the growth of beneficial soil bacteria and had no phytotoxic effects on seed germination. The Fe release profile from the OCIO was uniform at different pH (4 to 9) conditions due to its exceptional H+ ion scavenging quality. Significantly higher P availability was recorded in aqueous and soil media treated with OCIO as compared to FeSO4 and Fe–EDTA. Additionally, application of OCIO@10–20 mg kg−1 considerably increased organic C, N, P, and enzyme activity in soil. Furthermore, the OCIO dramatically recovered Fe deficiency, maintained steady P availability, and stabilized pH in poorly fertile soil which promoted healthy growth and productivity of tomato.

The effects of composting approaches on the emissions of anthropogenic volatile organic compounds: A comparison between vermicomposting and general aerobic composting

Emission patterns of 13 VOCs were investigated in three types of vermicomposting systems (Eisenia fetida, Metaphire posthuma, and Lampito mauritii) in reference to a traditional aerobic composting system by feeding the systems with mixtures of three materials (coal ash (CA), municipal solid waste (MSW), and cow dung (CD)). On an average, the emission rates of aromatic VOCs (benzene, toluene, xylenes, and styrene) were two to three times higher than all other groups (aldehyde, ketones, esters, and alcohols) from all three types of feeding mixtures. However, the emission rates of aromatic VOCs were generally reduced over time in both aerobic composting and vermicomposting systems. Such reduction in the emission rates was most prominent from Eisenia-treated CD + MSW (1:1), Lampito-treated CD + CA (1:1), and Metaphire-treated CD. The results clearly indicated that the increase in humified organic C fractions (humic acid and fulvic acid) and the microbial biomass present during the biocomposting processes greatly reduced the emissions of VOCs. Hence, the study recommends that vermicomposting of coal ash and municipal solid waste in combination with cow dung in 1:1 ratio is an environmentally gainful proposition.

Effect of new organic supplement (Panchgavya) on seed germination and soil quality

We studied the suitability of Panchgavya (five products of cow), new organic amendment, application on seed germination, plant growth, and soil health. After characterization, Panchgavya was mixed with water to form different concentration and was tested for seed germination, germination index, and root and shoot growth of different seedlings. Four percent solution of Panchgavya was applied to different plants to test its efficacy. Panchgavya and other two organic amendments were incorporated in soil to test the change of soil chemical and microbiological parameters. Panchgavya contained higher nutrients as compared to farm yard manure (FYM) and vermicompost. Its application on different seeds has positively influenced germination percentage, germination index, root and shoot length, and fresh and dry weight of the seedling. Water-soluble macronutrients including pH and metal were positively and negatively correlated with the growth parameters, respectively. Four percent solution of Panchgavya application on some plants showed superiority in terms of plant height and chlorophyll content. Panchgavya-applied soil had higher values of macro and micronutrients (zinc, copper, and manganese), microbial activity as compared to FYM, and vermicompost applied soils. Application of Panchgavya can be gainfully used as an alternative organic supplement in agriculture.