Research And Process Optimization On Disposing Iron Oxide Red Wastewater With High Concentration Of Ammonia Nitrogen Using Electrodialysis

Iron oxide red is an important industrial pigment. The iron oxide red production of china account for 60-70% of global.90% of enterprises produce iron oxide red with wet process. A large number of wastewater which contain high Fe2+, high color with low pH was produced from process. High concentration of ammonia nitrogen was remarkable characteristics of the wastewater. The process of alkaline chemical precipitation and aeration Stripping were widely used in the enterprises of iron oxide red at present. The Fe2+ could be recycled effectively, and the indexes of color and pH could meet the discharge standard. But the removal efficiency of NH3 was low relatively. The average of effluent concentration was more than 60mg NH3-N/L which was could not meet discharge standard. With the published of New Environmental Protection Laws on 2015.1.1, the enterprises of iron oxide red is facing an unprecedented challenge of environmental protection. Therefore how to ensure standard discharge, especially the NH3 with cost-effective process was urgent affairs in the enterprises of iron oxide red.Artificial high ammonia nitrogen wastewater was studied in experiment with Electrodialysis. The technical parameters and process conditions were determined in the treatment of artificial high ammonia nitrogen wastewater with Electrodialysis. The high ammonia nitrogen wastewater from a certain enterprise of iron oxide red in Yangzhou was studied in experiment on the basis. Based on existing treatment facilities in the enterprise, the Air Stripping and Electrodialysis were contrasted from technical and economic according the result of environment. The optimizing process was proposed. A theoretical basis was provided for the similar enterprise to ensure standard discharge. The research shows the results as follows:The limiting current density of Electrodialysis reactor was increased with increase of influent ammonium concentration. When the influent ammonium concentration was 1000mg/L, the trend of increasing was gentle. The limiting current density of Electrodialysis reactor was increased with increase of influent flow. The ions in free state were increased, meanwhile, the polarization phenomenon will eliminated difficulted.The removal efficiency of NH3 was increased with increase of electrodialysis voltage. When the voltage meet 25V, the removal efficiency of NH3 will not increase with the increasing of voltage. The removal efficiency of NH3 reach up to 95%. The removal efficiency of NH3 was decreased with increase of pH. The efficiency decrease rapidly when the pH>8 and have no obvious change when the pH6.5-8.The removal efficiency of NH3 could reach 97% when the influent ammonium concentration was 600mg/L in wastewater of iron oxide red, electrodialysis voltage=25V, influent flow=25L/h, pH=7-8 which the result was basically identical with the result of experiment. The removal efficiency of NH3 was unaffected by the other pollutants in wastewater of iron oxide red.The investment of treatment for wastewater of iron oxide red from a certain enterprise of iron oxide red in Yangzhou with the process of "Air Stripp+SBR" was ?845,000, and the operation cost was ?3.490 yuan/m3. The investment with the process of "Electrodialysis" was ?398,000, and the operation cost was ?1.145 yuan/m3.30%investment and 70%operation cost were saved with the "Electrodialysis". Therefore, the process of Electrodialysis on the basis of fully utilizing existing processing facilities was recommended to guarantee for the NH3 discharge standardly.