The Efficiency Of Phosphorus Removalby Iron-rich Filler Post-processing Of BAF

With social progress and development of industrialization, a global environmental problem has arisen—the eutrophication of water body, which is mainly caused by phosphorus. A study on the cause of eutrophi cation and the corresponding harms and also summarize existed technology of phosphorus removal from wastewater. At present, the most commonly used technology of phosphorus removal from wastewater is biological phosphorus removal and chemical phosphorus removal. It is difficult to meet the requirements of national discharge standard though the biological phosphorus removal has the advantages of sludge residue, no drugs and low cost. Otherwise, chemical precipitation is a kind of effective method of phosphorus removal, which has following features:simple operation, flexibility. After analysis the advantages and disadvantages of two kinds of method, it is believed that the combination of two methods will be fine. This paper aimed to the problem of poor effects of biological phosphorus removal and found that the use of iron-rich media to treat phosphorus wastewater which has been treated by BAF. Thus promoting the urban sewage treatment and resource utilization.The analyzation the influence of iron-rich media to chemical phosphorus removal from the following six aspect:the dosage of iron-rich meia, the share of iron-rich media and zeolite, particle diameter,reaction time, the initial concentration of phosphorus and the pH. It was found that the removal effect of phosphorus wastewater is better with dosage of iron-rich media. Especially when the proportion of iron-rich media and zeolite are the same, phosphorus removal effect is best. The smaller the particle size, the better phosphorus removal effect is. The removal rate of TP can reach its maximum when reaction time at80min. the smaller the initial concentration of phosphorus, the higher phosphorus removal rate is. When pH value between6.0and8.0, the phosphorus removal effect is best.In order to prevent iron-rich media harden, zeolite mixed into it. The diameter of filter material grain is6mm to8mm, the proportion of iron-rich media and zeolite are the same. At the same time, zeolite replaced by the same volume of ceramsite as a comparison experiments. In a stable system, studying of flow rate, reaction time, and filter height shows that:at the conditions of flow rate is2.0m/h, the filter height is120cm and backwash cycle for3days, it can achieve the best removal efficiency and the removal rate of TP increased with filter height.Zeolite and iron-rich media are used to react with low concentration of phosphorus wastewater, then remove part of the zeolite and let the rest of zeolite react with high concentration of phosphorus wastewater. The effect of zeolite through the static and dynamic experiment validated respectively. The experiment shows that:in the static experiments, the smaller the particle diameter, the more obvious the zeolite effect; in the dynamic experiment, because of experimental filter diameter is big, the removal rate of TP increased modestly despite the fact that zeolite improve the effect of phosphorus removal.Measured the factor such as the orthophosphate, DO, pH. etc. in the phosphorus removal with iron-rich media process at the optimal experimental conditions, and analysed the mechanism of chemical phosphorus removal with iron-rich media, analysed dynamics of the reaction of phosphorus removal with iron-rich media through time and treatment of phosphorus wastewater.the related experiment shows that it fit a first-order reaction.