Potential nutrient recovery from source-separated urine through hybrid membrane bioreactor and membrane capacitive deionisation

Human urine is rich in nutrients and an important source of fertilisers, especially when source-separated urine is available. Due to the increasing focus on the need for nutrient removal and recovery, various technologies and processes are being investigated. This study investigated a hybrid membrane bioreactor (MBR) and membrane capacitive deionisation (MCDI) where the source-separated urine was treated in MBR, and the subsequent MBR permeate was used as a feed for the MCDI for further nutrient removal and recovery. Overall, nitrate, phosphate and ammonium removal were 66 %, 49 % and 58 %, respectively, in the treated urine using MCDI. Additionally, the recovery rate of nitrate, phosphate and ammonium were 80 %, 64 % and 76 % in the concentrated brine. The energy demand for recovery of NH4+ was between 3.03 and 11.25 kWh/kg of NH4+-N and between 3.87 and 14.75 kWh/kg of NO3 -N for the three different voltages used in the study. The study further demonstrates the viability of MCDI application for nutrient recovery and concentration, effectively using both the adsorption and desorption phases of MCDI operation without using any chemicals.

Automated summary

Human urine is a valuable source of fertilisers, and this study investigated the use of a hybrid MBR and MCDI system for nutrient removal and recovery. The results showed that MCDI effectively removed nitrate, phosphate, and ammonium from the treated urine, and achieved high recovery rates in the concentrated brine. The study further demonstrated the feasibility of using MCDI for nutrient recovery without the need for chemical additives.