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Orenco Systems Inc. March 2002 AdvanTex AX 10 Test Report 2.5 Test Unit Changes A number of physical changes were made to the test unit during the testing program that were intended to address the deteriorated effluent quality observed over the first 5 months of testing, and to improve overall system performance. The changes and the rational for each change are described briefly in this section. 2.5.1 Pipe Replacement Although the effluent quality during the first few months of testing was well within the NSF/ANSI Standard 40 criteria, by the 5'" month of testing effluent quality had deteriorated such that the 30-day average CBODS concentration exceeded the NSF/ANSI Standard 40 limit of < 25 mg/L. The test unit was inspected in early March, 2001 and it was observed that the filter pods were not completely draining and there was an accumulation of biosolids within the drain pipe. Biosolids had also blocked the annulus between the effluent pipe and drainpipe, causing the liquid to back-up into the filter pods. Orenco staff determined that the solids accumulation was due to the atypical drainpipe connecting the filter pod to the recirculation compartment. As noted in Section 1.1, the AX10 filter pod normally drains directly into the recirculation compartment. However, to facilitate additional nutrient removal testing scheduled to follow the NSF/ANSI Standard 40 testing, a relatively long length of drainpipe with bends and connections set up (for future additional treatment units) had been used. Although the filter bottom positioned at a typical elevation above the recirculation _ compartment (normally sufficient for direct drainage) the gradient along the additional drainpipe was too shallow, causing biosolids to accumulate. _ On April 4, 2001 (Day 171 in Week 25) the pipe connecting the filter and the recirculation chamber was excavated and replaced with a shorter length of drainpipe directly connecting the two components. The underdrain pipe that was removed was observed to contain excessive biosolids, which caused ponding in the bottom of the pods that backed up into the filter media (which normally hangs about two inches above the underdrain liquid level). 2.5.2 Filter Manifold Replacement Inspection of the filter material during the fifth month of testing also noted that the distribution of liquid across the top of the filter material was not uniform. Portions of the media had significantly greater biological growth than others. Sections of the filter directly below and immediately adjacent to the distribution caps had characteristically greater amounts of biofilm than areas at a greater distance, as noted in Photograph #1. The biofilm in the immediate vicinity of the distribution caps was black in colour, in comparison to more distant areas of the filter which were light grey in colour. Gentle Nova Tec Consultants Inc. Page 13 of 38