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A novel hybrid filter for the treatment of septic tank effluent

ARAN - Access to Research at NUI Galway

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dc.contributor.author Rodgers, Michael
dc.contributor.author Healy, Mark G.
dc.contributor.author Prendergast, John
dc.date.accessioned 2012-07-19T11:40:31Z
dc.date.available 2012-07-19T11:40:31Z
dc.date.issued 2006
dc.identifier.citation Rodgers, M., Healy, M. G. & Prendergast, J. (2006) 'A novel hybrid filter for the treatment of septic tank effluent'. ASCE Journal of Environmental Engineering, 132 (7):764-768. en_US
dc.identifier.issn 1943-7870
dc.identifier.uri http://hdl.handle.net/10379/2915
dc.description Journal article en_US
dc.description.abstract Intermittent sand filtration is a common and effective method for treating septic tank effluent. However, if the loading rate is too high, clogging and ponding of the sand filter surface layer can occur due to the accumulation of excessive biomass and the deposition of suspended solids. This ponding limits the practicality of sand filtration as it makes it necessary to take the filter out of service for maintenance. The objective of this study was to develop and test, on-site, a new hybrid filter system that would reduce the risk of clogging at an organic loading rate substantially greater than the maximum recommended loading rate for intermittent sand filters. The system comprised a 0.6 m deep horizontal flow biofilm reactor (HFBR) over a 0.85 m deep stratified sand filter. The HFBR consisted of a stack of 20 horizontal corrugated polyvinyl chloride sheets, at 32 mm vertical spacings. The sheets were arranged so that the wastewater flowed over and back along alternate sheets down through the stack. The main biofilm growth formed on these sheets. The hybrid filter was loaded with septic tank effluent from an office/garage complex at the rate of 206 L/m(2) day for a period of 400 days in two phases. During the first phase, the effluent volume of 600 L/day was applied in 24 doses/day for 10 min/dose, and during the second phase in 6 doses/day for 40 min/dose. Biofilms in the HFBR substantially reduced the organic and suspended solids loads that reached the sand filter surface and allowed an average total biochemical oxygen demand (BODT) loading rate, based on HFBR plan area, of 37 g BODT/m(2) day to be applied to the system without clogging. This rate was substantially greater than the maximum recommended loading rate of 24 g BODT/m(2) day for intermittent sand filters. During both loading phases a BODT removal of 94% was achieved and nitrification was nearly complete. The average effluent BODT was 12 +/- 4 mg/L during both phases. The hybrid filter system appeared to perform better in terms of suspended solids handling and nitrification during the more frequent dosing phase. The hybrid filtration system offers a more compact alternative to intermittent sand filtration on its own with little risk of clogging. en_US
dc.format application/pdf en_US
dc.language.iso en en_US
dc.publisher ASCE en_US
dc.relation.ispartof ASCE Journal of Environmental Engineering en
dc.subject Waste treatment en_US
dc.subject Wastewater disposal en_US
dc.subject Waste disposal en_US
dc.subject Waste management en_US
dc.subject Hybrid methods en_US
dc.title A novel hybrid filter for the treatment of septic tank effluent en_US
dc.type Article en_US
dc.date.updated 2012-07-16T11:05:53Z
dc.identifier.doi DOI 10.1061/(ASCE)0733-9372(2006)132:7(764)
dc.local.publishedsource http://dx.doi.org/10.1061/(ASCE)0733-9372(2006)132:7(764) en_US
dc.description.peer-reviewed peer-reviewed
dc.contributor.funder |~|
dc.internal.rssid 1148303
dc.local.contact Mark Healy, Dept. Of Civil Engineering, Room E210, Civil Engineering Building, Nui Galway. 5364 Email: mark.healy@nuigalway.ie
dc.local.copyrightchecked Yes
dc.local.version ACCEPTED

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