Anoxic-aerobic SBR system for nitrate, phosphate and COD removal from high-strength wastewater and diversity study of microbial communities

摘要

Anoxic-aerobic sequencing batch reactor (SBR) system was operated for 180 days (under ambient temperature, 20 days SRT, 24 h HRT, influent CODitrate: 4 and COD/phosphate: 137) to treat a high strength wastewater (1000 mg/L nitrate and 4000 mg/L COD). The unique aspect was elimination of anaerobic cycle due to availability of nitrate (NO3) and oxygen as electron acceptors in anoxic and aerobic phases respectively. Simultaneous removal of nitrate (98%), phosphate (86%), and COD (72%) was achieved in anoxic phase. The subsequent aerobic phase experienced 26% of residual COD removal along with phosphate release (similar to 3.4 mg/L), reducing the overall P-removal to 76%. A long anoxic phase (18 h) could sustain denitrifying dephosphatation with less MLSS generation. Pyrosequencing data were analyzed through Ribosomal database project (RDP) and DECIPHER while diversity of sampling was analyzed using Chao1 and Shannon index. Rarefaction curve reflected adequacy of sampling for total species diversity study. Overall analysis revealed Proteobacteria, Alphaproteobacteria, Rhodobacterales, Rhodobacteraceae and Paracoccous as the prominent phylum, class, order, family, and genus respectively.