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Application of hydroponic systems for the treatment of source-separated human urine

Yang, Linyan, Giannis, Apostolos, Chang, Victor W.-C., Liu, Bianxia, Zhang, Jiefeng, Wang, Jing-Yuan
Ecological engineering 2015 v.81 pp. 182-191
Ipomoea aquatica, ammonia, ammonium nitrogen, chemical oxygen demand, humans, hydrolysis, hydroponics, leaves, microorganisms, models, nitrification, nitrogen, oxygen, potassium, streams, total suspended solids, urea, urine, wastewater, water content, Singapore
Hydroponic systems are widely used for the treatment of nutrient rich wastewaters. In this study, a hydroponic system was applied as the final treatment stage of source-separated human urine after urea hydrolysis, induced-struvite precipitation and ammonia stripping in tropical conditions (Singapore). The results showed that water spinach grew efficiently in the pretreated urine with 1:50 dilution ratio at the growth rate 0.68cm/d, leaf number 2.27 pieces/d, shoot dry mass 0.33g, water content 93.86%, and nitrogen and potassium conversion rate 0.46 and 0.51mg/mg, respectively. This hydroponic system removed 58–66% chemical oxygen demand (COD), 41–49% total nitrogen (TN) and up to 47% total suspended solid (TSS), indicating sufficient urine stream polishing. Nitrification was observed when COD reduced by 60%, possibly because of oxygen competition between nitrobacteria for nitrification and microbes for COD degradation. The kinetic study revealed that zero-order model provided best fitting for COD and ammonia-nitrogen (NH4+-N) removal, while second-order model was more suitable for TN removal.