Optimization of human urine to synthetic wastewater ratio for pollutants removal, power generation in a bioelectrochemical system

Abstract

When the human urine is mixed with the domestic wastewater, it leads to 70 % increase in nitrate level and 50 % increase in phosphorus level in the domestic sewage. So, the treatment of municipal sewage becomes more expensive and energy-intensive. Human urine is a waste and contributes to only 1 % (v) of domestic municipal wastewater, but yet it contributes 75 % nitrogen, 50 % phosphorus and 10 % chemical oxygen demand (COD) in the entire municipal wastewater. In this study, the optimization studies of human urine to synthetic wastewater ratio for power generation and pollutant removal in a dual chamber microbial fuel cell (MFC) is investigated. As diluted human urine has shown promising results in terms of power generation, current studies carried out the investigation by feeding the MFC with raw human urine diluted by synthetic wastewater in various ratios. Over the course of 336 h, the MFC were operated in batch mode. Along with bioelectricity generation and COD removal, certain physic-chemical parameters like pH, electrical conductivity, and dissolved oxygen levels were also assessed on a regular basis. A maximal power production of 7.74 W/m2 was achieved in the final batch scale with human urine and synthetic wastewater of 2:7 ratio, whereas a quite lower power generation, i.e., 1.64 W/m2, was reported in the first batch scale with urine and synthetic wastewater in a 1:8 ratio. The initial batch scale, which used synthetic wastewater and urine in a 1:8 ratio as feed, attained a maximum COD reduction of 50 %.