Tel: (011) 706-6272
 zhenye@eng.hokudai.ac.jp
Researcher:
Shinya Hotta
COE Post-Doctoral Fellow
Water Quality Control Eng. Lab.


Nitrogen losses from composting toilet
using sawdust as matrix


Abstract

The aims of this study are 1) to measure nitrogen balance in composting toilet and 2) to evaluate the effect of water evaporation on ammonia volatilization due to its high solubility into water. The nitrogen balance data from the operation of the toilet showed that approximately 25% of nitrogen remained in the sawdust matrix and ammonia emission was always detected. The rate of ammonia volatilization and water evaporation changed during the experiments. This change in ammonia volatilization was caused mainly by pH value of water in the sawdust. Especially, at low water content the sawdust pH kept less than pH 6 even if ammonia concentration was high.


The basic study hydrolysis of the effect of feces
contamination on urea


Abstract

In the treatment of black water, source separation of feces and urine has been recommended for more effective nutrient recovery. The nitrogen recovery is the most difficult issue due to the ammonia volatilization caused by urea hydrolysis. In this study, the effect of feces contamination on the urea hydrolysis was evaluated. The time course of ammonia concentration was measured during the urine storage process, and the rate of urea hydrolysis was estimated. The rate of urea hydrolysis strongly depended on feces contamination, and little increase of ammonia concentration was observed in the case with no feces contaminations. The model for describing the urea hydrolysis was developed. The comparison of simulated results with experimental data showed the validity of the model for describing the hydrolysis process of urea in urine with feces contamination.