RERATING NITRIFYING TRICKLING FILTER CAPACITY THROUGH FIELD TESTING AND PROCESS MODELING

A 4-month full-scale field testing program was conducted by the Truckee Meadows Water Reclamation Facility in Reno, Nevada to evaluate the treatment capacity of nitrifying trickling filters (NTFs). Seven sample ports were installed along the height of one of the NTFs to collect ammonia profile data during the test period. Process modeling of nitrification rate data was performed to rerate the capacity of the NTFs. In addition to apparent nitrification rates, internal nitrification rates were analyzed to yield definitive nitrification kinetic relationships to evaluate the “true” capacity of the NTFs. The capacity evaluation found that high nitrification rates could be obtained for NTFs using a high-density (68 sf/cf) cross-flow plastic media with periodic centrate treatment. Cost savings could be achieved when using high-density media compared to medium-density media to minimize the size of NTFs. Sample port data can also be used to assess whether an NTF should be taken out of service for cleaning or treatment to reduce the risks of ammonia breakthrough during normal operation.