حذف نیترات از آب آشامیدنی و آب فرآوری مواد غذایی با استفاده از بیوفیلتر هیدروژنی

The current approaches applied for removing nitrate from drinking water, commonly uses many chemical additives that may have undesirable or unknown effects on human health and in some cases caused many by products more dangerous than nitrate in drinking water. In present there are few appropriate and economic processes in this field and because of water scarcity in many areas development a suitable technology for treatment of nitrate contaminated drinking water for application in actual scales is crucial. In this research we develop an economic process with high selectivity for nitrate removal and minimum disturbance in other drinking water quality parameters that utilizes only hydrogen and carbon dioxide, produced in a methanol based electrochemical gas generator by applying a very low DC voltage (5-10 volt). We evaluate the ability of hydrogenotrophic denitrification for removal of nitrate in a bioreactor packed by light expanded clay aggregates known as LEACA. The results showed by proper coupling of electrochemical gas generator and denitrification bioreactor only by injection of tow clean and harmless gases, hydrogen and carbon dioxide and without any other chemicals addition for common concentrations of nitrate in natural waters by hydraulic retention time of 2-5 hr, removal efficiencies greater than 95% can be achieved. Also in comparison with other conventional methods such as ion exchange, reverse osmosis, electrodialysis, and biological heterotrophic with organic carbon source this system has several advantages such as: high selectivity for nitrate ion, low biomass yields, low electrical energy consumptions, without any problems resulted from organic carbon source addition (for example: taste and odor problem, carcinogenic THM production in disinfection process and rapid clogging of biofilter), easy operation, and compatibility with health issues in drinking water treatment.