The characteristics of foulant in the cake layer and bulk suspended solids of a 10 L submerged anaerobic membrane bioreactor (AnMBR) used for treatment of palm oil mill effluent (POME) were investigated in this study. Three different organic loading rates (OLRs) were applied with prolonged sludge retention time throughout a long operation time (270 days). The organic foulant was characterized by biomass concentration and concentration of extracellular polymeric substances (EPS). The thicknesses of the cake layer and foulant were analyzed by confocal laser scanning microscopy and Fourier transform infrared spectroscopy. The membrane morphology and inorganic elements were analyzed by field emission scanning electron microscope coupled with energy dispersive X-ray spectrometer. Roughness of membrane was analyzed by atomic force microscopy. The results showed that the formation and accumulation of protein EPS in the cake layer was the key contributor to most of the fouling. The transmembrane pressure evolution showed that attachment, adsorption, and entrapment of protein EPS occurred in the membrane pores. In addition, the hydrophilic charge of proteins and polysaccharides influenced the adsorption mechanism. The composition of the feed (including hydroxyl group and fatty acid compounds) and microbial metabolic products (protein) significantly affected membrane fouling in the high-rate operation.

A two-stage submerged anaerobic membrane bioreactor (2-sAnMBR) was operated to demonstrate the technology concept and to accelerate anaerobic biodegradation of Palm Oil Mill Effluent (POME). Then, the impact of different high organic loading rates (OLR) was investigated with a focus on water quality and biogas production. OLR higher than 50 kgCOD.m-3.d-1 induced an increase of volatile fatty acids (VFAs). As a consequence, the biogas production decreased from 19.8 to 11.0 L.d-1 and CH4 yield between 0.23 to 0.38 LCH4/gCODremoved. Nevertheless, the highest OLR (98 kgCOD.m-3.d-1) made it possible to reach a COD removal effectiveness of 70%, where the membrane contribution was around 23.9% to 34.7%. The ratio of propionic acid/acetic acid appeared to be a key indicator to prevent the AnMBR operation failure. Indeed, as soon as the value of 0.7 has been exceeded, several signs of AnMBR failure appeared. The methanogenic activity in AnMBR was inhibited by a hydrolysis ratio of 13% which transformed to VFA accumulation in system. The 250 mg.L-1 of Phenol concentration in POME was an inhibitory of the microbe in this system. Suspended solids concentration, proteins, polysaccharides, and volatile fatty acids were the substantial parameters that influenced the fouling rate.

This article is to present a review of anaerobic membrane bioreactor (AnMBR), process, operational condition, fouling mechanism and future challenge for high strength wastewater. Since1969s, membrane filtration technology has been used and continuously developed for wastewater treatment and recovery. AnMBR has proposed for the economic feasibility owing to the low footprint, high yield production under the relatively low energy consumption. Continuous stirred tank reactor (CSTR) configuration is the widely used couple with a flat sheet or hollow fibre modules. The various factors of operating condition are influence on the performance such as hydraulic retention time (HRT= 6 – 12 d), solid retention time (SRT > 100 d) and operating temperature (T = 10 - 56oC). In addition, the increase in temperature is related to high methanogenic activity and high COD removal efficiency (85% - 99%). However, the limitation of this process is fouling that occurs from the soluble microbial product (SMP), exopolymer substance (EPS) and biopolymer cluster (BPC). Almost of appropriate operating conditions for high performance, anti-fouling, the majority of effective microorganisms and energy balance are discussed in detail. For the challenge work, improvement of the prevention membrane fouling and high energy recovery in the hybrid/combination system with forward osmosis (FO), membrane distillation (MD) and powder activated carbon (PAC)-AnMBR.