Continuous and sequencing membrane bioreactors applied to food industry effluent treatment

Abstract

This work focuses on the performances of two immersed membrane bioreactors used for the treatment of easily biodegradable organic matter present in food industry effluents, for the purpose of water reuse. Two reactor functioning modes (continuous and sequencing) were compared in terms of organic carbon removal and of membrane permeability. For each working mode, pollutant removal was very high, treated water quality presented a low COD concentration (< 125 mg x L(-1)), no solids in suspension and low turbidity (< 0.5 NTU). The quality of the treated water (including germ removal) enabled its reuse on site. Moreover, by developing high biomass concentrations in the reactor, excess sludge production remained very low (< 0.1 gVSS x gCOD(-1)). The performances appeared slightly better for the continuous system (lower COD concentration in the effluent, < 50 mg x L(-1), and lower sludge production). In terms of filtration, a distinct difference was observed between continuous and sequencing systems; transmembrane pressure showed a small and constant evolution rate in continuous membrane bioreactor (CMBR) although it appeared more difficult to control in sequencing membrane bioreactor (SMBR) probably due to punctually higher permeate flow rate and modified suspension properties. The rapid evolution of membrane permeability observed in SMBR was such that more frequent chemical cleaning of the membrane system was required.

Water Reclamation and Reuse

“…Excellent MBR permeate quality with removal efficiency for turbidity, COD, BOD 5 , TN, NH 4 , TP and fecal coliforms found to be 98%, 85%, 94%, 63%, 72%, 19% and 99% respectively. Pilot-scale continuous and sequencing MBR for the treatment of high concentrations of organic matter present in food industry effluents showed COD concentrations of <125 mg/L, turbidity of <0.5 NTU, and zero suspended solids could be achieved in the treated effluent with this technology (Lobos et al, 2007).…”

Biotreatment of Winery Wastewater Using a Hybrid System Combining Biological Trickling Filters and Constructed Wetlands

“…A literature review reveals that the percentage removal of COD (or removal rates) achieved in this study are among the highest reported compared to previous studies where aerobic microbiological treatment processes were used in different suspended or attached systems (conventional activated sludge: up to 92.2% [48] and 50% [9], sequencing batch reactor: up to 95% [52], jet-loop-activated sludge reactor: 80%-90% [47,53], rotating biological contactor: 23%-43% [54,55], aerobic lagoons: 91% [56], fixed-bed biofilm reactor: up to 91% [14], biological sand filter: up to 98% [57], membranes: up to 97% [2,[58][59][60][61]). Although the most efficient aerobic biological process appears to be membrane application (where higher COD removal rates are achieved at shorter hydraulic retention times, and simultaneously exhibit stable operation under various organic loadings), these reactors present significant disadvantages such as high capital and operating costs, membrane fouling and difficulty in dewatering the produced waste sludge [16].…”

Investigation of HRT effects on membrane fouling in sequencing batch membrane bioreactor with respect to batch filtration mode

“…According to the results of a study conducted by Lobos et al , SBMBRs exhibited higher membrane fouling rates compared with continues mode membrane bioreactors (MBRs). Applying higher fluxes due to the intermittent effluent discharge (batch filtration mode) is accounted as a reason for the higher fouling rate in SBMBRs . On the other hand, during the filtration phase in SBMBR systems, the hydraulic head decreases depend upon the volumetric exchange ratio (VER) adopted.…”