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Orenco Systems Inc. March 2002 — AdvanTex AX 10 Test Report 4.3 Impact Of Manifold Replacement The original manifold system consisted of five laterals each with seven distribution caps (see Photograph #1), with a total of 35 distribution caps. The caps along each manifold were beside each other and spaced at equal intervals along the manifold. The replacement manifold contained two laterals with six caps located in between three laterals with seven caps (i.e. total of 33 distribution caps as shown in Photograph #2), and the cap arrangement was staggered in a "diamond" configuration. The objective was to improve liquid distribution over the filter. The performance of the unit improved following the manifold system replacement on Day 193 (Week 28). Forty percent (40 %) of the distribution caps were moved (i.e. two of five distribution lines) to areas of the filter with less biofilm growth. This was expected to increase the amount of effective filter area, by about forty percent, as the entire surface of the top of the filter had some degree of biomass even with the previous manifold cap configuration. Orenco reported that their research and monitoring programs had noted that the CBOD5 concentration in the recirculation tank characteristically plateaus at a CBOD5concentration of about 40 mg/L at hydraulic loading rates up to 1.5 m/d (36 gpd/sq.ft), while achieving an CBODseffluent quality of less than 10 mg/L. On April 25 a sample was collected from both the recirculaton compartment and the filter drain, noting CBODS concentrations of 70 and 43 mg/L, respectively. The reduction in CBOD5 concentration across the filter media of about 30 mg/L is consistent with Orenco's previous research observations (i.e., the filter — can be expected to decrease the applied CBODS concentration by about 30 mg/L). The increase in effective media surface area due to the new manifold configuration occurred during a period of higher influent CBODS loading (Weeks 23 to 40). The media was subjected to a higher hydraulic and organic loading than previous research and monitoring, with only a modest (less than 40 percent) increase in effective media surface area. Nonetheless, performance improved and CBODS removal percentages improved in spite of the higher CBODS loading. 4.4 Effect of Increased Filter Dosing Frequency The ability of the fixed film growth to decrease the CBOD5 concentration is affected by the amount of time the biomass is in contact with the liquid passing through the filter. It was observed that the majority of the drainage from the filter occurred within one minute of cessation of dosing (spraying). Based on this observation, one method of increasing the biomass and liquid contact time would be to increase the dosing frequency. The initial dosing frequency for the test program was set by Orenco staff at once every 20 Nova Tec Consultants Inc. Page 24 of 38