Abstract:In view of the more stringent effluent quality requirements for the expansion project of a large-scale water quality purification plant in Zhejiang Province, a set of process schemes that are stable, compliant and operate in a low-carbon manner is proposed, providing a reference for the expansion and upgrading project of high-standard discharge wastewater treatment plant. Based on an recheck of the designed influent and effluent qualities and the capacity constraint of the receiving water body, a process route of “coarse screen and influent pump house + fine screen and aerated grit chamber + modified Bardenpho bioreactor + high-efficiency sedimentation tank + sulfur autotrophic denitrification filter + sodium hypochlorite disinfection” is built. And the denitrification capacity under low-temperature and peak flow conditions is verified through a 200 m3/d sulfur autotrophic denitrification pilot plant. The pilot-scale results show that when the influent temperature is above 13 °C and the empty bed contact time (EBCT) is 26.17~31.40 min, the sulfur autotrophic denitrification filter can maintain a stable nitrogen removal effect. Under the peak flow condition, the EBCT as 20.93 min can still meet the denitrification demand of 6 mg/L. This process can effectively reduce the reliance on external organic carbon sources under the condition of a low carbon-nitrogen ratio. And through the precise aeration, backwash control and alkalinity regulation, the stable compliance with total nitrogen standards and the low-carbon operation are achieved.
