Anaerobic Membrane Bioreactors: Applications and Research Directions

Membranes provide exceptional suspended solids removal and complete biomass retention that can improve the biological treatment process, but their commercial application to anaerobic treatment has been limited. This review summarizes the state of the art with respect to anaerobic membrane bioreactors (AnMBRs), determines the types of wastewaters for which AnMBRs would be best suited, and identifies the research required to increase implementation. AnMBRs have been tested with synthetic, food processing, industrial, high solids content, and municipal wastewaters at laboratory, pilot, and full scale. Chemical oxygen demand removal ranges from 56% to 99%, while the reported design membrane fluxes range from 10 to 40 L/m²/h. AnMBRs should be immediately applicable to highly concentrated, particulate waste streams like municipal sludges where the membrane can decouple the solids and hydraulic retention times. Opportunity for application to dilute wastewaters also appears strong, while application to highly concentrated soluble wastewaters is likely limited. Greater assessment of vacuum-driven immersed membranes, combining external or immersed membranes with retained biomass reactor designs, control of membrane fouling, and economic feasibility are the key research areas to be addressed.

Keywords:

• anaerobic wastewater treatment
• biogas production
• membrane configuration
• membrane flux
• membrane fouling

This work was supported by the Natural Sciences and Engineering Research Council of Canada.

Notes

^a L = laboratory/bench scale, P = pilot scale.

^b CSTR = completely stirred tank reactor, PB = packed bed, UASB = upflow anaerobic sludge blanket, M designates the location of the membrane (no M indicates the membrane produced the final effluent).

^c —Indicates value not reported.

^d units are TOC instead of COD.

^e Composition not reported.

^f Units are cellulose instead of COD.

^a L = laboratory/bench scale, P = pilot scale, F = full scale.

^b CSTR = completely stirred tank reactor, FB = fluidized bed, UASB = upflow anaerobic sludge blanket, UFAF = upflow anaerobic filter, M designates the location of the membrane (no M indicates the membrane produced the final effluent).

^c —Indicates value not reported.

^a L = laboratory/bench scale, P = pilot scale.

^b CSTR = completely stirred tank reactor, FB = fluidized bed, UFAF = upflow anaerobic filter.

^c —Indicates value not reported.

^d Units are BOD instead of COD.

^e Units are AOX (adsorbable organic halogen).

^a L = laboratory/bench scale, P = pilot scale, F = full scale.

^b CSTR = completely-stirred tank reactor, Hybrid = UASB with anaerobic filter instead of a solids/liquid/gas separator, M designates the location of the membrane (no M indicates the membrane produced the final effluent).

^c —Indicates value not reported.

^d Units are VSS instead of COD.

^e Units are TOC instead of COD.

^a L = laboratory/bench scale, P = pilot scale.

^b CSTR = completely-stirred tank reactor, FB = fluidized bed, Hybrid = UASB with anaerobic filter instead of a solids/liquid/gas separator, Hydrol = side-stream suspended solids hydrolysis reactor plus methanogenic reactor for combined hydrolysate and primary clarifier effluent, UASB = upflow anaerobic sludge blanket, M designates the location of the membrane (no M indicates the membrane produced the final effluent).

^c —Indicates value not reported.

^d Units are BOD instead of COD.

^e Units are VSS instead of COD.

^a Reference 68.

^b References 92 and 103.

^c Values chosen as representative from Table 5.

^d Units are BOD instead of COD.

^e Reference 101.

^f Reference 62.

^g Reference 34.

^h Reference 110.

ⁱ Electricity use by bioreactor and membrane/secondary clarifier only.

^j Membrane energy use based on immersed modules.

^a All membranes were external cross-flow unless otherwise noted.

^b L = laboratory/bench scale, P = pilot scale.

^c D = Daltons (molecular weight cutoff).

^d —Indicates value not reported.

^e Pressure reported as kg/cm².

^f Submerged membrane.

^a L = laboratory/bench scale, P = pilot scale.

^b D = Daltons (molecular weight cutoff).

^c —Indicates value not reported.

^d Units are mmHg instead of kPa.

^e Pressure reported as kg/cm².

^f Submerged membrane.

^a Based on references 11, 14, 40, 42, 83, and 103.

^{b b}Based on reference 20.

^c Not applicable.

^a ABR = anaerobic baffled reactor, AF = anaerobic filter, AH = anaerobic hybrid (UASB with packing instead of solids/liquid/gas separator), CSTR = completely stirred tank reactor, EGSB = expanded granular sludge bed, FB = fluidized bed, UASB = upflow anaerobic sludge bed.