Contact Oxidation Filter Enchanced By Potassium Permanganate For Manganese Removal:Quick Start And Performance Of Treatment

In recent years,manganese pollution of surface water has become more and more serious.In order to remove manganese,KMnO₄ was added to start contact oxidation filter quickly in water purification plant.In this experiment,the influence of oxidant,hardness,KMnO₄ dosage and filter material on the start-up of contact oxidation filter was investigated.Considering the complex and changeable water quality environment of surface water,4 key water quality parameters,water hardness,pH,Fe²⁺,NH₄⁺-N,and filter operation speed,were selected as influencing factors to explore their influence on the removal of Mn²⁺by mature contact oxidation filter.The safety of KMnO₄ dosage was also studied.The morphology and physicochemical analysis of the filter material before and after film hanging were carried out.The water quality environment of low iron and high manganese in surface water was simulated.Controlled influent Mn²⁺concentration is 1.0 mg/L and Fe²⁺concentration is 0.3 mg/L.The following results and conclusions have been achieved.When quartz sand is operated under natural oxidation conditions for 120 days,only0.3 mg/L of Mn²⁺can be removed,the removal rate is 30%;the removal of Mn²⁺by NaClO fluctuates greatly,and the contact oxidation filter can not be started in a short time;after adding KMnO₄ for 48 days,the quartz sand filter column successfully realized the quick start of contact oxidation manganese removal function.When the dosage of KMnO₄drops 1 gradient in 5 days?gradient is 10%or 5%of theoretical dosage?,the start-up time is the shortest,the dosage is the lowest,and the effluent is safe and stable.Natural zeolite and modified zeolite adsorbing Mn²⁺saturated were added to KMnO₄ for 37 days and 32days respectively to realize rapid start-up of contact oxidation filter for manganese removal.At the filtration rates of 3 m/h,5 m/h,8 m/h and 10 m/h,the limit concentration of manganese removal for Mn²⁺was 3.5 mg/L,1.8¹.9 mg/L,0.7 mg/L and 0.4 mg/L respectively.At the filtration rate of 5 m/h,the limit concentration of manganese removal for Mn²⁺was suitable for most of the surface water with manganese pollution.The removal capacity of Mn²⁺by mature quartz sand filter column decreases with the increase of water hardness.When the inlet pH of mature quartz sand filter is 6.0 and 6.5,the effective period of removing manganese is 3 days and 7 days respectively.At pH 7.0 and7.5,the filter column has a stable ability to remove manganese.When Fe²⁺concentration is lower than 1.9 mg/L,it will not affect the normal removal capacity of"manganese active filter membrane".When Fe²⁺concentration is higher than 1.9 mg/L,the"iron removal zone"will overcompress the"manganese removal zone",which cannot guarantee the effective removal of Mn²⁺.The removal capacity of mature quartz sand filter column for NH₄⁺-N is between 0.4⁰.6 mg/L,and the removal effect is unstable.Therefore,the concentration of NH₄⁺-N in water cannot exceed 0.9 mg/L.When the concentration of NH₄⁺-N in water is lower than 0.9 mg/L,it has little effect on the manganese removal capacity of the filter column.Natural zeolite and modified zeolite can keep the effluent up to standard for 11 days and 14 days respectively without adding KMnO₄.When the amount of KMnO₄ is too much,the maximum amount of KMnO₄ for quartz sand,natural zeolite and modified zeolite to ensure the constant red effluent is 1.2,1.4 and 1.4 times of the theoretical amount respectively.Modified zeolite is superior to natural zeolite and quartz sand in terms of the safety of KMnO₄.The surface elements of mature"manganese active filter membrane"are mainly Mn and O,with the characteristics of Mn-O bond and Mn-OH hydroxyl group.Its porous structure and well-developed fissure structure are composed of irregular folded structure,which increases the area of adsorption of Mn²⁺by active filter membrane and improves the mass transfer efficiency.