Optimization of In Situ Backwashing Frequency for Stable Operation of Anaerobic Ceramic Membrane Bioreactor

Abstract

The cost-effective and stable operation of an anaerobic ceramic membrane bioreactor (AnCMBR) depends on operational strategies to minimize membrane fouling. A novel strategy for backwashing, filtration and relaxation was optimized for stable operation of a side stream tubular AnCMBR treating domestic wastewater at the ambient temperature. Two in situ backwashing schemes (once a day at 60 s/day, and twice a day at 60 s × 2/day) maintaining 55 min filtration and 5 min relaxation as a constant were compared. A flux level over 70% of the initial membrane flux was stabilized by in situ permeate backwashing irrespective of its frequency. The in situ backwashing by permeate once a day was better for energy saving, stable membrane filtration and less permeate consumption. Ex situ chemical cleaning after 60 days’ operation was carried out using pure water, sodium hypochlorite (NaOCl), and citric acid as the order. The dominant cake layer was effectively reduced by in situ backwashing, and the major organic foulants were fulvic acid-like substances and humic acid-like substances. Proteobacteria, Firmucutes, Epsilonbacteria and Bacteroides were the major microbes attached to the ceramic membrane fouling layer which were effectively removed by NaOCl.

New Insights into the Microbial Diversity of Cake Layer in Yttria Composite Ceramic Tubular Membrane in an Anaerobic Membrane Bioreactor (AnMBR)

“…A continuous stirred tank reactor (CSTR) made of plexiglass with an effective working volume of 15 L was used in this work and it was similar to our previous work [11,12]. The tubular membrane was made of ceramic, Yttria, Zirconia with a nominal pore size of 0.1 µm, and a total area of 0.11 m 2 (HeFei ShiJie Membrane Engineering Co. Ltd., Hefei, China).…”

“…AnMBR coupled with ceramic membranes (AnCMBR) has been previously studied in numerous studies investigating performance, and fouling, etc. [8][9][10][11][12].…”

Effects of Solids Retention Time on the Anaerobic Membrane Bioreactor with Yttria-Based Ceramic Membrane Treating Domestic Wastewater at Ambient Temperature

“…A continuous stirred tank reactor (CSTR) made of plexiglass with a working volume of 15 L (Diameter × Height = 120 mm × 650 mm) used in our previous study [28] was used at laboratory scale ( Figure 1) under different operational conditions. A level sensor (AF-E2A3C1D1B2), pH, and oxidation/reduction potential (ORP) probe (ACTEON5000, PONSEL group, Aqualabo Analysis, Caudan, France) were placed inside the reactor.…”

“…A Xin Xishan DP-35 diaphragm pump (Xin Xishan industries Co., Ltd, Shanghai, China) was used for membrane feeding and recirculation. The backwash pump (25WZR-15, Xin Xishan industries Co., Ltd, Shanghai, China) was used for backwashing once a day for 60 s based on [28]. A programmable logic controller (PLC) (LAB VIEW, PLC, Siemens AG, Frankfurt, Germany) automatized the setup operation.…”

“…The influent C/N ratio was adjusted to 5:1 based on [30], as carbon and nitrogen are the vital nutrients and source of energy for the growth of microorganisms [29]. This ratio is important for the microorganisms to function at maximum efficiency, resulting in a stable anaerobic digestion process [28,29,31]…”