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Journal article
Washing-down parlours and standing areas, following milking on dairy farms, produces dairy soiled water (DSW) that contains variable concentrations of nutrients. Aerobic woodchip filters can remove organic matter, nutrients and suspended solids (SS) in DSW, but the effluent exiting the filters may have to be further treated before it is suitable for re-use for washing yard areas. The performance of a single-layer sand filter (SF) and a stratified SF, loaded at a 20 L m-2 d-1, to polish effluent from a woodchip filter was investigated over 82 days. Average influent unfiltered chemical oxygen demand (CODT), total nitrogen (TN), ammonium-N (NH4-N), ortho-phosphorus (PO4-P) and SS concentrations of 1991±296, 163±40, 42.3±16.9, 27.2±6.9 and 84±30 mg L-1 were recorded. The single-layer SF decreased the influent concentration of CODT, TN, NH4-N, PO4-P and SS by 39, 36, 34, 58 and 52%, respectively. Influent concentrations of CODT, TNT, NH4-N, PO4-P and SS were decreased...
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