Upcycling of used ceramic membrane as media in upflow biological reactor treating low strength wastewater

Abstract

This work investigates the feasibility of media prepared from used (fouled) ceramic membrane (CM) in an upflow biological reactor (UBR) treating synthetic low strength wastewater (chemical oxygen demand, COD ∼ 200 mg/L) representative of an urban drain. The UBR was operated over 163 days at different hydraulic retention times (HRTs) of 48 h, 36 h, 24 h, 12 h and 6 h with corresponding upflow velocity between 0.06 m/d and 0.45 m/d. The COD removal was comparable at HRTs between 48 h and 12 h i.e., 83.4 ± 5.2 % (48 h), 80.5 ± 7.5 % (24 h), 76.2 ± 6.7 % (36 h) and 84.7 ± 7.2 % (12 h), followed by a marginal drop at 6 h HRT (69.9 ± 5.6 %). Ammonia removal was observed at HRTs of 48 h (37.6 ± 24.3 %) and 36 h (50.1 ± 20 %) only. Phosphate followed the same trend with removal observed at higher HRTs alone: 48 h (28.9 ± 12.5 %), 36 h (33.2 ± 8.7 %) and 24 h (23 ± 26.8 %). Total suspended solids (TSS) in the treated effluent was the lowest at 12 h HRT (6.2 mg/L). Only ∼ 3 % reduction in media porosity was observed after 163 days of operation. Overall, this media showed the recycling potential of fouled CM in a biological wastewater treatment system.