The impact of organic carbon on the performance of a high rate nitrifying trickling filter designed to pre-treat potable water

摘要

The application of nitrifying trickling filters (NTFs) to potable water treatment is less wellnunderstood than their application to wastewater treatment, particularly regarding the effectnof low ammonia substrate concentrations and organic carbon loading on filter performance.nA large pilot-scale NTF was operated under conditions that simulated the raw water qualitynof poorly protected catchments typically found in SE Asia, with the objective of reducingnthe ammonia driven chlorine demand during disinfection. The efficacy of a high rate NTFnto remove low concentrations of ammonia (0.5–5.0mgNH4-NL21n) in the presence of highnorganic carbon (1–12mg soluble biochemical oxygen demand (sBOD5)L21n) was investigated.nResults demonstrated that 90 to 100% of nitrification was maintained only when the carbonnload was less than 0.7 g sBOD5m22nd21n(,4mg sBOD5 L21n). Once the organic load wasnincreased beyond 0.75 to 2.1 g sBOD5 m22nd21n(4.5–12.1mg sBOD5 L21n), a linear declinenin nitrification from 70 to 15% was observed within a timeframe of 8 to 10 d. The impactnof high organic loads on the distribution of nitrification down the NTF was also investigated.nResults confirmed that carbon loads greater than 0.95 g sBOD5 m22nd21n(.5.5mg sBOD5 L21n),nseverely suppressed nitrification throughout the entire filter bed.