SR0084526_SSNL - Laserfiche WebLink

Home Browse Search

deteriorated for the final 10 months (Appendix 1 &2). The single high value of 46.30 mg/l for Unit 2 recorded September 6, 2000 was higher than average influent TN, of 35.21 and deserves comment. Upon rechecking the data source, we found no reason to Table 3. Total Nitrogen removal performance of the Waterloo Biofilter® system during testing at the Massachusetts Alternative Septic System Test Center - June 1999- June 2001. Total Nitrogen (m /1) Re licate 1 Replicate 2 Replicate 3 Influent Mean %Removal Average 11.9 17.8 13.2 35.0 14.4 58.8% Median 12.6 16.7 12.5 34.4 13.9 Standard Deviation 3.4 6.3 2.5 3.6 Maximum 19.8 46.3 18.7 46.3 Minimum 4.8 7.5 9.9 28.4 Count 46 46 32 46 Count > 19 mg/1 1 15 1 0 exclude this value. Another higher value, 54.56 mg/l for Unit 2 TN was measured on July 2, 2001 (after the 2 year testing cycle was complete) so the value was not an anomaly. Both BOD and TSS data for Unit 2 were consistent with the other units throughout the test period. The NH4 data for all three units for the testing period show a seasonal rise in ammonium in both years, but both Units 1 &2 showed higher NH4 values in the second winter, with Unit 2 showing variably elevated NH4 levels during the final ten months. The higher levels in the second winter indicate increasingly incomplete nitrification in the Biofilter®. Higher NH4 levels can indicate flow short-circuiting within or without the media column, poor distribution of spray on the filter, or poor oxygenation of spray and of liquid on the media surface. Spray nozzles were changed to a new design October 14, 2000 in all three units and this may have affected the nitrification in the filter units. Performance Results — WaterlooBiofilter® Page 8 of 28