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Orenco Systems Inc. March 2002 AdvanTex AX 10 Test Report 5. SUMMARY AND CONCLUSIONS 1. At 500 gpd (60 gpd/ft2), the AdvanTexTm AX10 unit achieved effluent CBOD5 concentrations of less than 20 mg/L (about 90% CBOD5 removal) and TSS _ concentrations less than 15 mg/L during the first three months of operation. The CBOD5 loading rate during that period was 0.31 kg/m2A. 2. As shown in Figure 7, the CBOD5 concentrations began to rise during the 4'h thirty- day period. During the 5`h thirty-day period, average CBOD5 concentrations exceeded the NSF/ANSI Standard 40 limit of 25 mg/L. Two probable causes for the rising CBOD5 effluent levels were identified. First the underdrain was partially blocked by accumulated biosolids, because the drainpipe connecting the filter pod to the recirculation compartment was too flat and complex (again, this underdrain configuration was constructed to facilitate future testing and was not typical of actual installations). This problem caused ponding to occur at the bottom of the filter pods and restricted airflow through the system. Second, a heavy black-coloured biomat buildup appeared in distinctive strips on the surface of the filter medium, in a pattern corresponding with the rows of the distribution orifices. Based on the areal extent of the biomat, less than 30 percent of the media surface was being utilized. Subsequently, it was decided that each potential cause would be attended to one at a time so that its effects on performance could be sequentially documented and evaluated. 3. On April 4th (in Week 25), the drain pipe between the filter pod and the recirculation compartment was shortened to 30 inches to improve the drainage characteristics (pipe slope). At that time, approximately 4 inches of ponded effluent drained €€em the bottom of the filter pod. The effluent CBOD5 and TSS concentrations did not appear to improve over the next two weeks. 4. On April 25th (in Week 28) the filter distribution manifold was replaced with one having staggered (diamond configuration) orifices (photograph #2). The orifices were staggered to improve distribution of effluent over the surface area of the media. The effluent CBOD5 and TSS concentrations subsequently showed steady improvement, and, within two weeks, the CBOD5 had recovered to below the NSF/ANSI Standard 40 30-day concentration limit of 25 mg/L. This recovery has been sustained since then, as shown in Figure 7. 5. The overall average effluent CBOD5 and TSS through the 13.5 months of testing were 21 mg/L and 17 mg/L, respectively, at an average hydraulic loading rate of about 53.5 gpd/ft2. 6. A meaningful relationship exists between the performance levels and loading rates at the Mamquam testing facility and results from other testing (Figures 14 and 15). Nova Tec Consultants Inc. Page 28 of 38