title: Control of struvite precipitation by selective removal of NH(4)+ with dialyzer/zeolite in an anaerobic membrane bioreactor.
abstract: This study focused on the mitigation of membrane fouling caused by struvite precipitation using a dialyzer/zeolite (D/Z) unit in an anaerobic membrane bioreactor. The D/Z unit was designed to selectively remove NH(4)+ ions, one of the main components of the inorganic foulant, struvite. The maximum mass transfer coefficient for NH(4)+ through the dialyzer was estimated to be 0.92 l m(-2)h(-1), whereas the Na-substituted zeolite had the highest ion exchange capacity with respect to ammonium among intact or differently pretreated zeolites. During a single passage of dialysate through the zeolite column, substantial NH(4)+ removal (in excess of 90%) was achieved, leading to the reduction in struvite precipitation in the digester. The D/Z unit played a significant role in controlling struvite precipitation, thereby enhancing permeate flux for the case of the ceramic membrane, in which struvite fouling would be more pronounced compared to the polymeric membrane. For the polymeric membrane, however, no significant improvement in flux was observed even with the D/Z unit because the fouling of the polymeric membrane was mainly due to the deposition of biomass rather than the struvite precipitation.
authors.affiliation: Daewoo Shipbuilding & Marine Engineering, 140, Da-Dong, Jung-Gu, Seoul, Republic of Korea.
authors.forename: Junhong
authors.initials: J
authors.lastname: Kim
authors.forename: Chung-Hak
authors.initials: CH
authors.lastname: Lee
authors.forename: Kwang-Ho
authors.initials: KH
authors.lastname: Choo
mesh_terms: D000693:Anaerobiosis; D019149:Bioreactors; D001709:Biotechnology / Q000379:methods; D011232:Chemical Precipitation; D003956:Dialysis / Q000379:methods*; D004867:Equipment Design; D005374:Filtration; D017616:Magnesium Compounds / Q000737:chemistry*; D008567:Membranes, Artificial; D010710:Phosphates / Q000737:chemistry*; D000644:Quaternary Ammonium Compounds / Q000032:analysis* / Q000737:chemistry; D000069877:Struvite; D014865:Waste Disposal, Fluid / Q000379:methods; D014867:Water / Q000737:chemistry; D018508:Water Purification / Q000379:methods; D017641:Zeolites / Q000737:chemistry*
chemical_list: D017616:Magnesium Compounds; D008567:Membranes, Artificial; D010710:Phosphates; D000644:Quaternary Ammonium Compounds; D014867:Water; D017641:Zeolites; D000069877:Struvite