Recent developments in anaerobic membrane reactors

Anaerobic membrane reactors (AnMBRs) have recently evolved from aerobic MBRs, with the membrane either external or submerged within the reactor, and can achieve high COD removals (∼98%) at hydraulic retention times (HRTs) as low as 3 h. Since membranes stop biomass being washed out, they can enhance performance with inhibitory substrates, at psychrophilic/thermophilic temperatures, and enable nitrogen removal via Anammox. Fouling is important, but addition of activated carbon or resins/precipitants can remove soluble microbial products (SMPs)/colloids and enhance flux. Due to their low energy use and solids production, and solids free effluent, they can enhance nutrient and water recycling. Nevertheless, more work is needed to: compare fouling between aerobic and anaerobic systems; determine how reactor operation influences fouling; evaluate the effect of different additives on membrane fouling; determine whether nitrogen removal can be incorporated into AnMBRs; recover methane solubility from low temperatures effluents; and, establish sound mass and energy balances.

► Anaerobic membrane reactors (AnMBRs) can achieve high COD removal (98%) at 3 h HRTs.
► No understanding of the effect of reactor operation on SMP production and fouling.
► Addition of PAC and precipitants can reduce fouling in anaerobic membrane reactors.
► Membranes can enhance performance at extreme temperatures and toxins/shock loads.
► Robust pilot plant data on energy use and solids production is needed for AnMBRs.