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Fecal Coliform Removal <br />Fecal coliform is often used as a surrogate measure of public health significance. <br />Wastewater treatment systems that remove fecal coliform are thought to concurrently <br />reduce the discharge of human pathogens. In general, the Waterloo Biofilter removed <br />>99% of the fecal coliform in the influent (Table 4). <br />Table4. Fecal Coliform removal performance of the Waterloo Biofilter® system during <br />testing at the Massachusetts Alternative Septic System Test Center. June 1999- June 2001. <br />Fecal <br />Coliform <br />CFU/100 ml <br />Replicate <br />1 <br />Replicate 2 <br />Replicate <br />3 <br />Influent <br />Mean <br />%Removal <br />Log Mean <br />2.6E+04 <br />3.0E+04 <br />1.3E+04 <br />2.7E+06 <br />2.2E+04 <br />99.2 <br />Maximum <br />7.5E+05 <br />4.3E+05 <br />2.4E+05 <br />2.6E+07 <br />Minimum <br />8.0E+02 <br />5.0E+02 <br />2.0E+02 <br />1.0E+04 <br />6. Operation and Maintenance Monitoring — Waterloo Biofilter® <br />Slumping of the basket support structures: <br />Slumping of the basket support structures occurred in all three units at about the same <br />time, month ten. This problem did not recur during the rest of the test period. Waterloo <br />Biofilter® claimed that the filter enclosures were shipped with incorrectly sized baskets. <br />Some of the support for the baskets is provided by the enclosure. Since the baskets were <br />too small, the added space around the baskets allowed the baskets to lean and then slump. <br />Waterloo Biofilter® units are now all equipped with rigid support for the foam media as a <br />response to this problem. <br />Spray nozzle clogging <br />Clogging of the plastic spray nozzles occurred on seven occasions between start-up and <br />October 14, 2000 when the spray nozzle design was changed from a helical spray head to <br />a splash plate design similar to a fire sprinkler. After that alteration, clogging of nozzles <br />did not recur. A high water alarm typically announced a problem with the nozzles. <br />Septic tank effluent filters <br />The Zabel effluent filters needed cleaning on August 28,2000, about 14 months after <br />start-up. There was about a 1.5 -inch fall in the septic tank level after removing the filter <br />for cleaning on August 28, 2000, confirming the need to clean the Zabel filter. The 14 - <br />month interval between filter cleaning is consistent with the hydraulic load of 330 gallons <br />per day. This volume is about 1.5 to 2 times higher than the average household usage of <br />100-200 gallons per day, and should also shorten the maintenance interval for cleaning <br />the effluent filter. In Massachusetts servicing is required at quarterly intervals, and we <br />Performance Results — WaterlooBiofilter® Page 9 of 28 <br />