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UBC Theses and Dissertations

Attached growth nitrification using Ringlace media Setter, Kevin J.


This thesis reports on an attempt to grow nitrifying bacteria attached on the submerged growth media Ringlace® in the aerobic zone of a pilot scale Biological Enhanced Phosphorus Removal (BEPR) process treating municipal sewage. The Ringlace® media was a fibrous rope modified PVC material stretched over frames that were immersed into the process. Nitrification on the support media was meant to enhance overall process nitrifying capacity. The overall process operating parameters HRT, SRT, and DO were manipulated to investigate their effects on the nitrification rate of the bacteria attached to the support media. Growth on the media consisted of an array of higher life forms and bacteria. Worm infestation on the media appeared to increase with increased DO concentration. Cyclic anaerobic periods of 12 to 24 hours controlled worm infestations at operating DO levels of 3.5 mg/L and lower but proved to be unsuccessful at tested DO concentrations above that. Sludge settling in the test process improved over the control process during a run with 6 hour HRT, 4 day SRT, 5.5 mg/L DO level, and 18 °C temperature. During this run the control process average specific nitrification rate was 2 mg-N/gTSS-hr and the test process average rate was 0.5 mg-N/gTSS-hr. This run had the highest DO level of the experiment and the Ringlace® support media had the highest amount of worms observed on it for the entire experiment. It is believed that the significant reduction in nitrification rate and the improved sludge settling were a result of interference from the worms. The results of batch testing Ringlace® frames removed from the flow through system throughout the experiment showed the biomass attached to the Ringlace® support media never exhibited specific ammonia uptake rate significantly greater than zero at the 5 % significance level. The suspended growth portion did display specific ammonia uptake rates which were approximately the same as rates reported in the literature for similar suspended growth studies. In selected batch tests the biomass on the media was shown to take up soluble carbon indicated by BOD5 measurements.

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