Introduction of some new materials for combined biological and ion-exchange wastewater treatment for ammonia removal

摘要

Ammonia is a water pollutant that causes serious problems in terrestrial and saline receiving waters. The classical solution to the problem of ammonia removal is biological waste treatment that can be easily inhibited by toxic shock, pH change, low dissolved oxygen concentration and low temperatures. Ion-exchange materials have been used as an alternative to the biological process. However, chemical regeneration of ion-exchangers can be expensive and if ammonia concentration in the influent drops, desorption may occur resulting in increased ammonia concentration in the effluent. When ion-exchange and biological oxidation processes are combined some drawbacks can be overcome. Literature review suggests that only clinoptilolite (natural zeolite), has been investigated in terms of biological regeneration. In the research described in this paper some new materials have been evaluated in terms of biological activation. Those materials include: mordenite (natural zeolite); MN 500 (belonging to the group of materials known as Macronets), as well as chemically modified zeolite for ammonia removal from saline waste water. Enriched cultures of nitrifying bacteria in a growth medium were established and have been used for obtaining the batch adsorption results on biologically active materials. Uptake onto biologically active and bacteria free materials was compared. The same experiments have been done in terrestrial and saline wastewater. In the case of non saline media, natural materials, zeolites, have overall better ammonia uptake and experience highly biological regeneration when compared to the synthetic MN 500. In saline media, synthetic material MN 500 showed better ammonia removal compared with modified zeolite ZZ.