Human urine contains nitrogen, phosphorus, and potassium, which can be applied as natural fertilizer for agriculture instead of commercially available fertilizer. However, due to low contents of nutrients in urine, its huge quantity is required to be transported to farmland to meet nutrient demand of crops, which increases transportation cost. To address transportation issue, a new onsite volume reduction system was tested at laboratory scale. Mathematical water transport model was proposed to evaluate performance of the system. Mass transfer coefficient and resistance of water flow through the vertical gauze sheet for the water transport model were obtained from laboratory-scale experiments using water as one of the model samples. The results agreed with simulated data thereby confirming the proposed model. The existing design procedures pertaining to an onsite volume reduction system were established incorporating the water transport model. The existing design procedure was then applied to dry climate of Southern Pakistan having an average air temperature of 30–40 °C and air humidity 20–40% for 80% volume reduction to reduce transportation cost. The findings revealed that the estimated size of the vertical gauze sheet is 2060–440 cm2, which requires small area for setting up the system at individual household level.
Effective evaporation area Capillarity Mass transfer coefficient Saturated vapor pressure Solubility Water transport model
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