SOURCE SEPARATED URINE-NUTRIENT AND HEAVY-METAL CONTENT, WATER SAVINGAND FECAL CONTAMINATION

Human urine is by far the largest contributor of nutrients to househol d wastewater. Source separation of urine can significantly decrease th e nutrient load on the recipients. By recycling the urine to agricultu re as a fertiliser, with very low levels of heavy metals, the nutrient s are made into resources instead of becoming pollutants. The amounts and concentrations of nutrients and heavy metals in urine solution fro m a source separating sewage system were measured. The concentrations of nutrients were high. The ratio of nitrogen to phosphorus was close to the expected value, indicating that the system did not have any lar ge nitrogen loss. The heavy metal concentrations in the urine were low , much lower than that in most chemical fertilisers. Per inhabitant an d day, 1.34 litres of urine solution were collected Of this, 0.34 litr es was flush water. The low flush water volume was due to the double f lush mechanism of the toilets, which saved 48% of the flush water comp ared with conventional water closets. Per inhabitant and day, 4.9 g of nitrogen and 0.42 g of phosphorus were collected, which was 86 and 81 % respectively of the expected amount. The contamination level of faec al material in the source separated urine was low. (C) 1997 IAWQ. Publ ished by Elsevier Science Ltd.