Enhancement of nitrifying biofilm formation using selected EPS produced byheterotrophic bacteria

The possibility of enhancing nitrifying biofilm formation rate with the aid of selected EPS produced by heterotrophic bacteria was investigated. When EPS production characteristics were examined for four kinds of heterotrophs isolated from a domestic wastewater treatment reactor, two strains obtaine d from biofilms (B1, B2) exhibited a higher polysaccharide production rate than those from suspended flocs (A1, A2). Among EPS components, the concent ration of uronic acids gave a good correlation with flocculation ability, w hich suggests that acidic polysaccharides play a major role in bioaggregate formation. Addition of 1g/L D-glucuronic acid as an EPS substitute enhance d the homocoagulation rate of autotrophic Nitrosomonas europaea and altered its zeta potential from (n) over tilde 30.4mV to + 4.3mV, which indicates a possibility that particular EPS components produced by heterotrophs are u tilized as neutralising reagents for nitrifying biofilm formation. Moreover , when heterotrophic isolates with Nitrobacter winogradskyi were cultured i n batch with fabric supports, biofilm formed on the substratum, These exper imental results suggest the application of selected EPS for enhancing nitri fying biofilm formation.