Effects of high-concentration influent suspended solids on aerobic granulation in sequencing batch reactors treating real textile wastewater

Abstract

The formation of aerobic granular sludge (AGS) in real textile wastewater (TWW) is time-consuming and challenging. The present study investigated the effects of high-concentration influent suspended solids (SS) on aerobic granulation, pollutant removal, microbial activity, and community in the real TWW treatment by using two sequencing batch reactors (R1: 41.7 ± 22.8 mg influent-SS/L; R2: 416.1 ± 21.4 mg influent-SS/L). The results showed that complete granulation was achieved in R1 within 97 days (SVI30: 34.5 mL/g, SVI30/SVI5 = 0.91), while it only required 52 days in R2 (SVI30: 18.2 mL/g, SVI30/SVI5 = 0.92). The high-concentration influent SS also enhanced compactness and settleability of AGS. Long-term adaption of sludge improved the COD removal from real TWW, which was possibly due to the increase in phyla Firmicutes and Actinobacteria abundances. The real TWW did not adversely affect the nitrification process as indicated by the high NH4+-N removal in both reactors (>93 %). Although the formation of compact AGS in R2 did not exhibit better removal performance under the present experimental condition, it exhibited the potential for better COD removal from real TWW as indicated by the higher microbial activity and functional bacterial abundances in R2 than in R1.