Alternatives for indirect use of urine as fertilizer through processing with clinoptilolite

Indirect use of human urine as fertilizer was investigated through adsorption/ion exchange using the natural zeolite, clinoptilolite. First, ammonium, orthophosphate and potassium were removed from urine, then these nutrients were recovered through desorption. Between urinals and storage tank, urea conversion to ammonia was almost complete and phosphate precipitation occured. The capacities for ammonium, orthophosphate and potassium in urine were measured as 28 mg NH4/g clinoptilolite, 1.5 mg PO4-P and 10 mg K/g clinoptilolite, respectively in the isotherm experiments. Removal of nutrients from urine is highly dependent upon initial loadings. Nutrient concentrations in residual urine could be decreased to the level of domestic wastewater when stagewise loading was applied. Individual target nutrients may be obtained using different loading conditions, and fertilizers with either ammonium or orthophosphate predominance may be produced using the method suggested. Release of ammonium continued for a long time, release of orthophosphate was quick and potassium release was intermittent during recovery experiments. High ammonium recovery was achieved because of the high ammonium concentration in urine. Results similar to synthetic fertilizer suggested that the product may be used as a potential fertilizer. A full scale sufficiency investigation revealed that the product obtained was self-sufficient as a fertilizer for a summer housing site. Results of survey showed that direct and indirect application of human urine as fertilizer received more acceptance for landscape plants than uncooked crops and indirect application of urine was more preferable.