The City of St. Martin was in need of a water treatment plant to address iron, manganese and ammonia in the community water supply. The treatment of ammonia using chlorine can be costly and troublesome, while removal through stripping using aeration can be difficult. Biological removal was suggested as a cost saving alternative. A three month pilot study with Tonka Water, a U.S. Water Brand was successful in proving the effectiveness of treating the contaminants through a biological process, largely due to a high level of participation from the local community. Following the results of the favorable pilot study, Tonka Water was selected to provide the customized VertaCell™ pressure filters that would facilitate this biological process.
The treatment process begins with the addition of air as water enters the first of three VertaCell pressure filters. The oxygen source feeds aerobic bacteria that in turn, oxidizes iron treating the water through a biological process. As water flows to the second vessel, additional air is added to assist in the treatment of ammonia. This second biological process converts ammonia to nitrate. The nitrate produced is below the MCL (maximum contaminant level) and does not present the process challenges often associated with ammonia. As water enters the third filter, chlorine is added as an oxidant, which prevents additional biological growth. This filter provides traditional filtration of manganese via oxidation/filtration with Greensand Plus™ media, and acts as a barrier between the biological treatment and the distribution system. The third stage filter also provides redundancy, with the ability to remove iron and manganese during biological acclimation, or in the event of a biological upset.
The filters are backwashed using our Simul-Wash™ combined air/water method to provide optimum cleaning and prevent buildup of solids.