Effects of salinity on treatment of aquaculture wastewater by dynamic membrane bioreactor with intermittent aeration

Salts are detrimental to biological treatment systems by causing plasmolysis and/or loss of cell activities, thereby the biological treatment of mariculture wastewater which with high sanity is difficult. A dynamic membrane bioreactor(DMBR) with intermittent aeration was used to treat aquaculture wastewater under different salinity. The effects of salinity on organic matter degradation and denitrification process were studied. The results show that when salinity increased from 0 to 35 g/L, the CODMn removal rate and TN removal rate by intermittent aeration dynamic membrane bioreactor for treating aquaculture wastewater reduced from 89.5% to 75.5% and from 89.9% to 74.4%, respectively. Because of the inhibition effect of salt on microorganism, the organic matter degradation and denitrification efficiency decreased in saliferous condition. Moreover, in the salt concentration of 0-35 g/L, the constants of CODMn and NO3－-N reduction rate in the reactor decreased linearly with the improvement of salinity by kinetic analysis, and the coefficients of determination(r2) of linear regression models were 0.9838 and 0.9665, respectively. Salt has stronger inhibit effect on denitrification process than organic matter degradation process of aquaculture wastewater.