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Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  Pp. 52-61 in On-Site Wastewater Treatment, Proc. Ninth Natl. Symp. on Individual and Small Community Sewage Systems (11-14 March 2001, Fort Worth, Texas, USA), ed. K. Mancl., St. Joseph, Mich. ASAE  701P0009.(doi:10.13031/2013.6060)
Authors:   G.W. Loomis, D.B. Dow, M.H. Stolt, A.D. Sykes, A.J. Gold
Keywords:   Alternatives, Onsite wastewater treatment, Performance evaluation, Nitrogen removal, Fecal coliforms, BOD

An evaluation of the treatment performance of twelve, full-scale, innovative treatment systems was initiated in 1997 under a State of Rhode Island-funded project targeted in a priority watershed that is both pathogen and nitrogen sensitive. Loomis and Dow (1998) reported on the site conditions, constraints encountered, types of systems installed, actual measured hydraulic loading rates to these systems, targeted water quality goals, construction cost estimates, strategies for educating participating clientele groups, and startup performance results from these systems. In this paper we report on the treatment performances of one at-grade recirculating sand filter, two single pass sand filters, three Maryland style recirculating sand filters, five foam cube biofilters, and one recirculating textile filter. The data were collected over an 18 month period. All the sand filter systems studied reduced TSS and BOD5 by 90 to 99%; achieved 2.3 to 3.8 log10 reductions in fecal coliform levels; and produced TN reductions ranging from 8 to 75%, depending upon type of sand filter system and season (temperature). Mean TSS and BOD5 effluent concentrations for the foam biofilters and the textile filter were both less than 20 mg/l. TN concentrations in recirculating textile filter effluent averaged 13 and 29 mg/l for the warm and cold seasons, respectively; whereas fecal coliform concentrations averaged 3,000 and 52,500 counts/100 ml. Log10 reductions of fecal coliform for the foam biofilters averaged about 1.5 regardless of season. Mean effluent TN concentrations and percent TN reductions in the foam biofilters ranged from 28 to 61 mg/l and 10 to 23%, respectively. All systems operated hydraulically without mishap, with the exception of the recirculating textile filter that needed retrofitting about midway through the study.

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