Struvite Production As a Value Added Product from Human Urine

Abstract

Human urine is rich in nutrients like Nitrogen, Phosphorus, Potassium, etc. Therefore, it can be used as a fertiliser in agriculture. Separate urine-collecting systems help in achieving maximum recovery of nutrients from urine without any harmful materials such as heavy metals. However, direct use of human urine as agricultural fertiliser is associated with many problems such as handling, storage, transport, nutrient loss to the atmosphere and spreading on arable land. Therefore, to overcome these difficulties human urine is processed for capturing the nutrients present in it into solid mineral form. On addition of small amounts of MgSO4 to human urine major amounts of phosphorus, potassium and nitrogen were precipitated, with struvite (MgNH4PO4.6H2O) as a major component. Struvite precipitation is influenced by many factors like MgSO4 dosage, temperature, pH. Therefore, optimisation of these parameters is need to be done for effective struvite recovery. Different experiments were conducted to know the optimum value of each parameter by keeping other to parameters constant. The optimum pH for struvite precipitation was found to be around 10.2. Struvite precipitation was high at normal room temperatures. Different MgSO4 dosages were tested to know the optimised dosage, where there was maximum struvite formation by keeping pH and temperature constant