Urea hydrolysis in anthropogenic nutrient solution

Treatment of nutrients in domestic wastewater is complicated and costly. On the other hand, none of the processes employed provides recovery. Separation of domestic wastes ensures relatively easy and economic treatment and reuse of nutrients. Separated human urine is the most important source of nutrients. The treatment of urine follows the steps of urea conversion into ammonia and its separation. Of these steps, urea hydrolysis is a critical and complicated one. In this paper, urea hydrolysis process was experimentally investigated with human urine samples to provide data comparable with actual conditions. Appropriate amounts of the enzyme urease were added to the urine samples, and the process was observed to assess urea conversion and the changes taking place in the characteristics of urine. The results indicated that enzyme concentration is very effective on the rate of hydrolysis. Dilution of the urine resulted in reduction of hydrolysis rate, proportional with dilution ratio. pH was found to be a critical parameter, not only for the rate of hydrolysis but also determining the extent of product inhibition caused by ammonia accumulation.