Efficient nitrogen removal from municipal wastewater using an integrated fixed-film activated sludge process in a novel air-lifting loop reactor: A pilot-scale demonstration.

A novel air-lifting loop reactor combines anoxic, oxic, and settling zones to achieve organic and nutrient removal, as well as solid-liquid separation. To address sludge settling ability and operation stability issues caused by low dissolved oxygen in aerobic zones, this study proposes using modified polypropylene carriers to establish a fixed-film activated sludge (IFAS) system. A pilot-scale demonstration of the IFAS-based air-lifting loop reactor is conducted, and the results show successful operation for approximately 300 days. The pilot-scale reactor achieves a maximum aerobic granulation ratio of 16% in the bulk liquid. The IFAS system contributes to efficient removal of organic matter (96%) and nitrogen (94%) by facilitating simultaneous nitrification and denitrification, as well as fast solid-liquid separation with a low sludge volume index of 34 mL/g. Microbial analysis reveals enrichment of functional bacteria involved in nitrification, denitrification, and flocculation throughout the operation process.

Removal of bisphenol A by waste zero-valent iron regulating microbial community in sequencing batch biofilm reactor.

The removal of bisphenol A (BPA) by waste zero-valent iron (ZVI) regulating microbial community in sequencing batch biofilm reactor (SBBR) was investigated. Compared with SBBR-BPA, the acclimation time of microorganisms in the presence of waste ZVI and BPA (SBBR-ZVI+BPA) decreased from 56 d to 49 d. During stable operation period, BPA was removed completely at 150th min and 100th min in the SBBR-BPA and SBBR-ZVI+BPA, respectively. The optimal initial pH and BPA concentration in the SBBRs were respectively 8.0 and 10 mg/L. The composition and content analysis of extracellular polymeric substances (EPS) using fluorescence spectrometer showed that the yield of EPS was enhanced by the addition of ZVI. The analysis of microbial community structure in the SBBRs using Illumina Miseq sequencing method indicated that the indexes of ACE, Chao1 and Shannon were higher and Simpson index was lower in the SBBR-ZVI+BPA. Moreover, the abundance of BPA biodegradation strains was increased in the presence of ZVI. This study provided a promising method with low cost of effectively removing BPA from wastewater.