ISSN 2249-2127 * Corresponding author E-mail: chariarv@rdat.iitd.ac.in Md Rahman and Vijayaraghavan Chariar Int. J. Environmental Sciences Vol 4 (3&4) : pp 110 - 124 (2015) Original Research Paper International Journal of Environmental Sciences 110 OPTIMIZATION OF UREA HYDROLYSIS FROM HUMAN URINE AND EFFICACY COMPARISON OF DIFFERENT EXPERIMENTAL DESIGNS Md Azizur Rahman, Vijayaraghavan M Chariar* Centre for Rural Development and Technology, Indian Institute of Technology Delhi, India-110016. Abstract Laboratory scale tests for optimizing urea hydrolysis in Human Urine were conducted using different experimental designs, namely - full factorial, response surface methodology (RSM), and Taguchi methods. The effect of initial pH, temperature and time were studied and compared by different design of experimental tools. The proximity of the predicted value shows that RSM is rated above full factorial and Taguchi methods. However, in terms of effort, Taguchi method excels over the other designs. The optimal range for maximum urea hydrolysis in the three experi- ments are as follows : initial pH range (9-10), temperature range (50-60°C) and reaction time (50-60 mins) . Key words: Human urine, Urea Hydrolysis, Design of Experiment, Full Factorial, Response Surface Methodology, Taguchi Method. INTRODUCTION Wastewater treatment and reclaiming of nutrients from waste streams has gained increasing attention owing to rising concerns about pollution of water bodies. Strict standards regulating discharge into water bodies as well as the possibility of recycling of nutrients present in waste streams is promoting research as well as remediation of wastewaters for addressing the issue of nutrient reserves (Lui et. al., 2008). However, notwith- standing the strict regulation and increased interest in recycling nutrients from waste water streams, the high cost of recovery of N and P from domestic wastewater may act as a roadblock for early and widespread adop- tion of these nutrient recovery technologies in the de- veloping world. The current nutrient recovery technolo- gies are focused on removal of nutrients (Lui et. al., 2008). Among the different components of municipal wastewater, while human urine constitutes only 1 % volume of municipal wastewater by quantity, it contrib- utes 80% of N, 50% of P and 90% of K in wastewa- ter. (Larsen et. al., 2001). Another report states that human urine contains higher concentrations of urea, sodium chloride, sulfate and magnesium (Larsen and Gujer, 1996). In addition to the above components, if the urine is source separated, it prevents the accumula- tion of heavy metals, hormones and pharmaceuticals in the flowing municipal waste (J¨onsson et al., 1997; Larsen and Udert, 1999; Pronk et al., 2006). Therefore, if it were to be possible to separate human urine from