Per capita phosphorus loading from domestic sewage

Abstract To assess the phosphorus contribution from domestic sewage to Lough Neagh, Northern Ireland, daily per capita loadings were measured by monitoring the effluent from a housing estate. A modern estate with 472 houses was chosen because it was free from industry and had separate foul and storm drainage systems. By a house-to-house census the total population was found to be 1645. Daily loadings in the foul sewer were calculated from measured hourly flow rates and concentration data. The effective population contributing to the foul sewer was estimated by making allowances for export from or import to the estate of excrement by workers and school-children. An attempt was made to verify the assumptions used in estimating the effective population by monitoring the loading in the foul sewer of creatinine, a metabolic end-product excreted in constant amounts in urine. Predicted creatinine loadings, using population data and per capita excretion values, were in good agreement with measured loadings. Per capita daily loadings of soluble orthophosphate, total soluble phosphorus, total phosphorus and BOD were calculated using the effective population and measured loadings for Mondays to Fridays during three weekly survey periods. The results indicated a per capita value of 1.8 g day −1 for total phosphorus in domestic sewage.