Kinetic model for nitrate removal from saline water using polybutylene succinate as energy source

The insoluble biodegradable polymers pellets that constituted with polybutylene succinate were investigated as the simultaneous solid carbon source and the biofilm carrier for the nitrate removal in synthetic saline wastewater. The denitrification performance and kinetic procedure were evaluated as plug-flow mode in order to provide the technical parameters for potential-applications in recirculating aquaculture system (RAS). The experimental results indicated that hydraulic retention time played an important role on the nitrate removal efficiency. The maximum nitrate volumetric removal rate of 0.21 kg/(m3·d) was achieved at an influent loading rate of 0.32 kg/(m3·d), when the temperature was (29±1)℃ and the nitrate concentrations of 25-236 mg/L, respectively. Under influent loading rate below 0.32 kg/(m3·d), the nitrate volumetric removal rate increased linearly with the influent loading rate, and the maximum nitrate volumetric removal rate was achieved at 0.21 kg/(m3·d) when the influent loading rate at 0.32 kg/(m3·d). Further increasing of loading rate results in the declined performance and nitrite accumulate in effluent, respectively. The kinetic results show that the denitrification procedure of polybutylene succinate as the solid carbon source and the biofilm carrier follow first-order rate. Based on the kinetics characteristics, constants n and K were deduced by used of Eckenfelder model, which could be applied successfully for the prediction of effluent nitrate concentration. The verification of kinetic model was demonstrated validly that could be applied for the design and management of the RAS.