Incorporating membrane gas diffusion into a membrane bioreactor for hydrogenotrophic denitrification of groundwater.
A hydrogenotrophic denitrification system, comprising a suspended growth membrane bioreactor (MBR) with membrane hydrogen gas diffusion, was developed to remove nitrate from groundwater. A hollow fiber gas permeable membrane module was designed for hydrogen delivery and a commercially available hollow fiber membrane module was used for solid/liquid separation. The MBR was operated at an SRT of 20 days and at room temperature. Four nitrate loading rates of 24, 48, 96 and 192 NO3(-)-N mg I(-1) d(-1) were applied to the system. As the nitrate loading was raised, pH increased due to increased denitrification and release of OH- ions. The oxidation reduction potential (ORP) remained fairly stable when full denitrification was achieved, but increased when nitrate loading rates reached 192 NO3(-)-N mg I(-1) d(-1) and residual nitrate was present in the reactor. Nitrate removal was complete (100%) in the first three nitrate loadings and 72% in the system with 192 NO3(-)-N mg I(-1) d(-1). Nitrate utilization rates of 30.6, 23.4, and 37.7 g NO3(-)-N m(-3) d(-1) were achieved in the first three loadings. Average effluent dissolved organic carbon (DOC) concentration of approximately 8 mg l(-1) was observed in all four nitrate loading regimes, possibly owing to the generation and release of soluble microbial bi-products (SMP).
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Department of Civil Engineering, University of Manitoba, Winnipeg MB R3T 5V6, Canada. ummoh@cc.umanitoba.ca
Oleszkiewicz
J A
JA
Cicek
N
N
Rezania
B
B
D019149:Bioreactors; D004058:Diffusion; D005740:Gases; D006859:Hydrogen / Q000737:chemistry*; D008567:Membranes, Artificial; D009573:Nitrites / Q000737:chemistry / Q000378:metabolism*; D013997:Time Factors; D014873:Water Pollutants / Q000302:isolation & purification; D018508:Water Purification / Q000379:methods*; D014881:Water Supply
D005740:Gases; D008567:Membranes, Artificial; D009573:Nitrites; D014873:Water Pollutants; D006859:Hydrogen