Influence of various operating conditions on cleaning efficiency in sequencing batch reactor (SBR) activated sludge process. Part II: Backwash and water rinsing introduced membrane filtration process

Abstract

In this paper, the influences of backwashing conditions on the washing efficiency ( P) were systematically investigated by a combination of orthogonal table and multivariate linear regression methods. The experiments were performed with the feed suspension from SBR and deionized water in laboratory-scale dead-end microfiltration test unit with 0.1 μm PES microfiltration membrane. The impact of shearing stress on the backwashing recovery ( r i ), and mass-transfer coefficient on washing efficiency ( P) were studied respectively. The results showed that backwash and water rinsing introduced membrane filtration process could restore the declined flux close to 100%. However, the ability of backwashing was gradually reducing with the increase of backwashing cycle, which was associated with the increasing accumulation of irreversible fouling onto and into the membrane pores. r i and P increased with the increase of transmembrane pressure ( TMP), and decreased with the increase of operating temperature. Since the foulants are more susceptible to be washed away from the membrane pores during a longer backwash, the r i got a high value, on the contrary, the productivity decreased with an increase of backwash duration due to the back pumping of more detergent. The average contribution of backwashing conditions on P were detergent temperature (50.49%) > transmembrane pressure (39.84%) > backwashing times (7.27%) > backwashing time (2.39%). The backwashing conditions were optimized and the relationship between backwashing conditions and washing efficiency ( P) was analyzed and defined quantitatively.