A Sequential Anammox Zeolite-Biofilter for the Removal of Nitrogen Compounds from Drinking Water

Abstract

The ever-increasing consumption of ammonium fertilizer threatens aquatic environments and will require low-power water treatment processes. With a focus on the treatment of drinking water, the scope of this study was to investigate the feasibility of a sequential Anammox zeolite-biofilter with an anaerobic river and tap water mixture (NH4+: 4.3 mg/L; NO2−: 5.7 mg/L). When the filter velocity was set to 0.032 m/h, NH4+ and NO2− were removed with efficiencies of 86% and 76%, respectively. Remarkably, lowering the substrate concentrations and operating temperatures only resulted in a minor reduction in the efficiencies of nitrogen removal compared to wastewater treatment plants. The coupling of the zeolite and Anammox processes influenced the NO2−/NH4+-ratio as the zeolites removed NH4+ at a higher rate. Reliable process monitoring can be achieved by correlating the electrical conductivity and the removal of nitrogen compounds (R2 = 0.982). The WHO threshold values of all nitrogen compounds could be met using this setup, and thus, it could lead to a significant improvement in drinking water quality around the world. Thus, the Anammox zeolite-biofilter is promising as a cost-effective and low-power technology, especially for decentralized use in threshold and developing countries, and should therefore be the subject of further investigation.