Characterization of the organic micropollutants behavior during electrochemical ammonia recovery

Abstract

Nutrient recovery systems can be impacted due to the presence of organic micropollutants (OMPs). TAN (total ammonium nitrogen, sum of ammonium and ammonia) recovery from wastewater can be achieved by combining an electrochemical system with membrane stripping. Essential components of these processes are cation-exchange membranes and a hydrophobic gas-permeable membrane. These membranes are barriers between the OMPs source (wastewater) and recovered products. Despite reports about OMPs – ion exchange membrane interactions, there is limited knowledge about the transport of OMPs in ammonium recovery systems. This work gives a first detailed description of the transport mechanism of a broad group of OMPs with varying properties during electrochemical ammonium recovery supplied with a complex matrix (digested blackwater). Even after continuous exposure to OMPs and consequent system equilibration, OMP concentrations in the effluent were often lower than in the inflow stream. The highest removal and transport towards the concentrate were found for positively charged OMPs. The presence of organic matter contributed to the adsorption and transport of OMPs. Although OMPs were transported over the CEMs, the gas permeable hydrophobic membrane for ammonia recovery retained all OMPs.