The Influence of the Biofiltration Method on the Efficiency of Ammonium Nitrogen Removal from Water in Combined Sorption and Nitrification Processes

Abstract

This study assessed the impact of the method of conducting the biofiltration process on the efficiency of ammonium nitrogen removal from water in combined sorption and nitrification processes. The research was carried out on diatomite deposits using biofiltration with gravity and counter-gravity flow. The following physicochemical water parameters were controlled during the research, including ammonium nitrogen, nitrite nitrogen, nitrate nitrogen, and dissolved oxygen. Unconventional flow turned out to be more beneficial because it allows for optimal use of the entire bed surface, natural regulation of the biofilm thickness, and maintaining constant microbiological activity of the biofilm. The automatic regulation of the biofilm thickness during water flow prevented excessive growth of dead organic matter and limited the development of heterotrophic bacteria. Biofiltration with counter-gravity flow also resulted in reduced oxygen consumption. Regardless of the flow direction used, water after the single-stage biofiltration process was characterized by an increased content of nitrite nitrogen. The introduction of the second stage of filtration made it possible to obtain water that meets the requirements for water intended for human consumption.