(308d) Removal of Ammonium and Organic Compounds by Ion Exchange and Adsorption

Adsorption using activated carbon and ion-exchange is used to remove a range of organic compounds and ammonia respectively from treated wastewaters. Such treatment may follow secondary biological treatment to reduce BOD. Organic nitrogen (e.g. proteins) is degraded to ammonia and residual organic compounds may also be present following secondary treatment. Residual organic compounds may be those which are recalcitrant and may include fatty acids, aromatic compounds, and detergents. Adsorption and ion exchange may offer an alternative to further biological treatment. Possible advantages include good response to shock loading, and low sensitivity to variations in temperature, pH, and anti-microbial activity. Three areas of investigation were undertaken and are described here; adsorption of organic acids onto activated carbon, the adsorption of aromatic compounds and proteins onto activated carbon and onto ion exchange resins, and the ion exchange removal of ammonium from an actual waste-water in the presence of organic compounds. Three cationic ion exchangers were studied: Clinoptilolite, Dowex 50w-x8 and, Purolite MN500. Three adsorbents were evaluated: two samples of activated carbon: Norit GAC 1240, and Aldrich activated carbon; and crushed glass (AFM). The results show that phenol, benzoic acid, methanoic, ethanoic, and propionic acid were successfully adsorbed on to the activated carbon. AFM was an ineffective adsorbent. It was also shown that successful ammonium removal by ion exchange in the presence of organic compounds was possible. In the presence of real wastewater, there were significant variations in the removal performance.