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

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 (R-2 = 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.

Automated summary

This study investigated the feasibility of a sequential Anammox zeolite-biofilter for the treatment of drinking water. The results showed that high removal efficiencies of ammonium and nitrite could be achieved with low filter velocities. Lowering substrate concentrations and operating temperatures had minimal impact on nitrogen removal efficiencies. The coupling of zeolite and Anammox processes influenced the ratio of nitrite to ammonium, and reliable process monitoring could be achieved through electrical conductivity measurements. This technology has the potential to significantly improve drinking water quality worldwide and is especially suited for decentralized use in threshold and developing countries.