Eisenia fetida mediated vermi-transformation of tannery waste sludge into value added eco-friendly product: An insight on microbial diversity, enzyme activation, and metal detoxification. (10th May 2022)

• Record Type: Journal Article
• Authors: Chakraborty, Priyanka; Sarkar, Sampad; Mondal, Sandip; Agarwal, B.K.; Kumar, Arvind; Bhattacharya, Sabyasachi; Bhattacharya, Satya Sundar; Bhattacharyya, Pradip
• Is Part Of: Journal of cleaner production. Volume 348(2022)
• Publication Date: 2022-05-10
• Subjects: Tannery waste sludge -- Chromium metal -- Vermicompost -- Eisenia fetida -- Metal accumulation; Factory and trade waste -- Management -- Periodicals; Manufactures -- Environmental aspects -- Periodicals; Déchets industriels -- Gestion -- Périodiques; Usines -- Aspect de l'environnement -- Périodiques; 628.5
• DOI: 10.1016/j.jclepro.2022.131368
• Languages: English
• ISSNs: 0959-6526

Abstract

Abstract: Chromium contamination from tannery waste sludge (TWS) is a significant environmental concern. Vermicomposting is useful for conversion of toxic TWS into sanitized nutrient-enriched product for agricultural application. However, interactions among microbes and heavy metals are yet to be studied in Eisenia fetida incubated TWS-based vermireactors. The prime research hypotheses/objectives were to identify the most favorable feedstock combination for efficient vermiremediation; to generate novel information about the microbe-metal interaction during vermicomposting; and justify the functionality E. fetida by studying the TWS-induced shift in microbial community structure, nutrient dynamics, and metal removal. Earthworm population increased by 2.58–2.67 folds in TWS vermibeds. Water soluble and exchangeable fractions of potentially toxic metals (Cr, Pb, Ni, and Cu) considerably reduced by 48–69%. The alkalinity in TWS-dominated feedstocks [TWS + CD (3:1 and 2:1)] was also significantly neutralized with substantial reduction in organic C and increase in NPK availability. Microbial biomass C and different enzyme activities (fluorescein diacetate hydrolysis, urease, phosphatase, sulphatase, and glucosidase) substantially increased in the TWS-vermibeds. Interestingly, PLFA and species diversity analyses revealed that microbial community structure and fatty acid profiles greatly alter depending on the TWS proportion in the feedstocks and the metal-induced stress on microbial communities was substantially low in TWS + CD (1:1) feedstock. The correlation statistics explained that microbial activity and growth have strongly suppressed heavy metal bioavailability in TWS-vermibeds. Overall, the results indicate that TWS + CD (2:1 and 1:1) mixtures were favorable substrates for Eisenia fetida and microbial proliferation. The study revealed new information on microbial influence on metal remediation during vermicomposting and the results suggests that E. fetida could be utilized as a potential candidate for vermiremediation of toxic TWS. Highlights: Eisenia fetida produced sanitized vermicompost from tannery waste sludge (TWS). High metal availability significantly retarded microbial growth in vermibeds. 48–69% removal of toxic metals (Cr, Pb, Cu) was achieved due to vermicomposting. Shift in microbial communities and PLFA profiles resulted due to TWS exposure. 1:1 TWS + cow dung mixtures was most favorable substrates for E. fetida and microbes.