Technology of de-ironing of weakly acidic low alkaline underground water containing ammonium nitrogen

Abstract

Most of the existing de-ironing stations were designed by the technologies of simplified or deep aeration that do not provide for comprehensive purification and are in need of modernization. The research was carried out in several stages on natural waters: pH 6.2-6.4; Fe2+=4.0-10.6 mg/dm3; alkalinity 1.25-1.5 mg-eqv/dm3; NH4+ to 2.0 mg/dm3; H2S to 2.0 mg/dm3; permanganate oxidization to 6.0 mgO/dm3. The main equipment consisted of an industrial installation with capacity of 2.5 m3/h. Which included: aeration block (ejector or hydrodynamic cavitator), contact column of diameter 420 mm, height 4000 mm, two lighting filters of diameter 720 mm, height 3300 mm. The filters were equipped with a hydro automated system for flushing. We examined the efficiency of using combinatorics of physical-biochemical methods of cleaning. We determined optimal concentration of reagents: soda ash 35-45 mg/dm3, coagulant 15-20 mg/dm3, flocculant 1-1.5 mg/dm3, the velocity of filtration (up to 5 m/h), filtration cycles duration (up to 24 hours) and the intensity of flushing (12 l/cm2). The technology and equipment for purification of multi-component groundwater were designed. The technology is based on stage-by-stage destruction of complicated iron organic complexes, ammonium nitrogen through the processes of hydrodynamic cavitation, biochemical additional oxidation, coagulation of colloids and the ultimate separation of phases in the volume of filtering loading. The obtained data may be useful both in carrying out renovation of the existing stations and when designing new water treatment plants.