Water supply sludge-based ceramsite denitrification filter: Pollutant removal and microbial community characteristics

Abstract

Using water supply sludge to prepare ceramsite for sewage treatment is one of the methods to realize resource utilization. In this study, water supply sludge-based ceramsite was prepared, and analyzed the preparation conditions, reaction conditions, and characterization of water supply sludge-based ceramsite. The results showed that water supply sludge-based ceramsite had the best adsorption performance (for NO3−-N and PO43−-P were 31.2 % and 64.5 %) when the mass ratio of water supply sludge to kaolin was 85:15, the firing temperature was 1150 °C, and the firing time was 10 min. The removal efficiencies of chemical oxygen demand (COD) and total nitrogen (TN) were 67.0 % and 79.9 %, respectively, with the water supply sludge-based ceramsite as denitrification biofilter carrier, when the optimal hydraulic retention time (HRT) and carbon‑nitrogen ratio (C/N) were 0.5 h and 2:1. However, the removal efficiency of total phosphorus (TP) gradually decreased. During the biofilm formation of denitrification biofilter, the microbial community richness remained basically stable, but the microbial diversity decreased in the later stage of biofilm formation. The main dominant microbial communities were Acinetobacter and Methylophilaceae; and the relative abundance of amino acid metabolism genes increased, with the extension of biofilm formation time.