Design, performance evaluation and investigation of the dynamic mechanisms of earthworm-microorganisms interactions for wastewater treatment through vermifiltration technology

The study brings insight to earthworms-microorganism's symbiotic interactions for wastewater treatment for the most essential mechanisms (antimicrobial and enzymatic activity) during vermifiltration. The results showed that vermifilter (VF) resulted in effluent with biochemical oxygen demand (BOD) <5 mg/L, chemical oxygen demand (COD) <30 mg/L, coliforms <103 MPN/100 mL, signifying higher treatment efficacy. The study reported the microbial community diversity for influent, effluent, filter media, earthworm's body, casts and its coelomic fluid to understand the correlations & symbiosis to decipher the mechanisms. The results further showed that earthworm body were dominated by Gammaproteobacteria, and the percentages arrived to 60% of the microbial species, while VF showed presence of Firmicutes and Actinobacteria, which signifies that earthworms had a profound effect on controlling microbial biomass and improving microbial activity. The protein profiling of the bacteria associated with VF showed that earthworms feeding and earthworm–microorganisms interactions were responsible for enhanced treatment performance. © 2020 Elsevier Ltd