The performance of fibrous peat biofilters in treating domestic strength wastewater

Peat is an abundant resource in Ireland and has the capacity to be used in low-cost, low-maintenance wastewater treatment systems for single houses. In this study four fibrous peat columns, of varying depths were constructed and tested in the laboratory for their capacity to remove contaminants from domestic-strength synthetic wastewater. The four filters had peat depths of 0.3 m, 0.6 m, 0.9 m and 1.2 m. During the 360 day study the filters were intermittently loaded with domestic strength synthetic wastewater at a hydraulic loading rate of 180 l/m(2)center dot d. Hydrographs and residence times for each filter were examined as was their ability to remove impurities from the wastewater. Removal of 5-day biochemical oxygen demand (BOD(5)) and total chemical oxygen demand (COD(t)) were >= 96% and 84%, respectively, in all filters with almost complete nitrification (>= 99%) being recorded for each filter. The removal of total suspended solids (TSS) was excellent at >= 94% and no clogging was recorded on any filter during the study. For the 0.6 m, 0.9 m and 1.2 m deep filters, total viable counts (TVC) were less than EU surface water directive limits for Class A2 potable water sources. The systems were cheap to construct and very easy to maintain.