The impact of sea water flushing on biological nitrification-denitrification activated sludge sewage treatment process.

摘要: The process performance of the two largest activated sludge processes in Hong Kong, Sha Tin and Tai Po Sewage Treatment Works (STW), deteriorated initial period after introduction seawater flushing 1995 1996, respectively. High effluent ammonia nitrogen (NH 4 -N) total suspended solids (TSS) excess discharge standards resulted from incomplete nitrification changes floc characteristics. A desktop study on inhibitory effects salinity, particularly nitrification, was subsequently conducted using STW operating data. To assist upgrade a five-month extensive bench-scale investigation simple but flexible modified Ludzack-Ettinger configuration with bio-selector to quantify due saline concentration. consists restoration its original design capacity (conventional process) 205,000 m 3 /day currently much reduced as Bardenpho process. Only volume existing biological clarifier is be utilized. concentration ranges 3,500 up 6,500 mg Cl - /L, both daily seasonally. greatly fluctuating concentrations have been known inhibit nitrification. Design consideration should also given peak seasonal TKN loading three times average. Although nitrifiers maximum specific growth rate significantly low 0.25 day −1 , inhibition considered tolerable NH N NO consistently at