Hydrogen-based membrane biofilm reactors for nitrate removal from water and wastewater

H₂-based membrane biofilm reactor (MBfR), a kind of autotrophic denitrification system, is a novel and special membrane bioreactor using hydrogen as inorganic electron donor to reduce nitrate and nitrite in water and wastewater. In this paper, the state of the art of recent research on denitrification through H₂-based MBfRs is reviewed, including theoretical fundamentals, key influencing factors, possible problems and applications. Hydrogen/nitrate counter-diffusion has been described as Dual substrates limitations. The denitrifying bacteria in H₂-based MBfR were summarized. The key factors affecting the performance of H₂-based MBfR were listed in terms of substrate concentrations, membrane materials, reactor types, biofilm management and operation conditions. The pH value, salinity, dissolved oxygen, HRT (hydraulic retention time) and carbon source have been identified as main operational conditions affecting H₂-MBfR performance. Furthermore, membrane fouling in H₂-based MBfRs was emphasized. H₂-MBfR was proved excellent in denitrification based on its high performance for groundwater, IX brine and aquaculture wastewater treatment. Several aspects may be considered in future works were proposed.