Start-up And Efficiency Of Biofilm Carrier Module For Nitrogen Removal

In recent years,surface water such as river water has been polluted by nitrogen appearing black and smelly.The existing plan for nitrogen removal is inefficiency and slowly starting up.And the concentration of nitrate in the tail water of WWTP is high,which is hard to reach the upgrading discharge standard.Aimed at the nitrogen removal demand above,two modular equipments were designed and constructed with carrier as corpus to treat slightly-polluted water and tail water of WWTP.The practicability of simultaneous nitrification and denitrification,solid carbon source for nitrogen removal and the optimization of modular equipment were studied.A modular system assembled polyurethane bio-carrier,aquatic plants and sediments was designed and built for treating simulative slightly-polluted water in river course.The device can be start-up rapidly by loading the polyurethane bio-carrier with the activated sludge of municipal wastewater treatment plant in advance.Simultaneous nitrification and denitrification was achieved by processing simulative black-odor water in a way of phased continuous flow mode.The result indicated that COD_Mn could be reduced from 10-25 mg·L^-1 to 4-6 mg·L^-1,NH₄⁺-N could be reduced from 5-9 mg·L^-1 to 0-0.5 mg·L^-1,TN could be reduced from 5-10 mg·L^-1 to 0.5-2.0 mg·L^-1 and the removal rate could respectively reach up to 75%,97%and 80%.The aquatic plants could grow in polyurethane bio-carrier.The microfauna in sediments attained sludge reduction.A denitrification modular system assembled polyurethane bio-carrier and Loofah solid carbon source was built for treating simulative tail water of WWTP.Comparative test of Loofah,composite carriers and polyurethane bio-carrier by loading them with the activated sludge of WWTP in advance.The result showed that Loofah solid carbon source achieved denitrification,the highest removal rate of nitrate nitrogen can reach 76%,the NO₃^--N in effluent is low to 3mg/L,and the solid carbon souce showed slightly COD dissolution.Optimizing process and increasing N-lord,the system can stabilize the nitrate nitrogen removal after 3 days.The best removal rate can reach 62.4%,and the NO₃^--N concentration of the effluent is less than 4 mg/L;the problem of COD dissolutin is solved,and the effluent COD_Mn is basically lower than 1mg/L.The module achieves denitrification of solid carbon source,and the operation of the special designed tank is flexible;the mud discharge is handy,and the blockage of carrier is prevented.