مهندسی عمران شریف (May 2020)
POST-TREATMENT OF LEACHATE BY MICROWAVE-FENTON PROCESS USING OFAT ANALYSIS METHOD
Abstract
Industrial and economic development along with changes in lifestyle over recent decades in most countries has resulted in considerable growth of different waste. Since biodegradable organic materials constitute approximately 60\% of the total municipal solid waste in developing countries, leachate treatment is considered as a big concern for solid waste management in these areas. Application of biological processes is one of common method in leachate treatment. However, due to presence of refractory pollutants, biological process alone cannot treat leachate on its own. In order to enhance the quality of leachate to the discharge standards, post treatment of biologically treated leachate is essential. One appropriate solution for complementary treatment of leachate and removal of refractory materials is the application of advanced oxidation rocesses. The Fenton process is one of homogenous advanced oxidation processes has been applied for leachate treatment. However, this method is time-consuming and expensive. In order to improve the performance and reagent utilization efficiency, in this paper microwave enhanced Fenton process was utilized for post-treatment of composting leachate. Batch laboratory scaled experiments were employed on effluent of leachate treatment plant of a composting factory in Iran. Initial experiments were conducted and then the effects of variables were determined separately by one factor at a time (OFAT) method. The effects of factors such as pH, ratio of concentration of $H_{2}O_{2}$ to initial COD, ratio of concentration of $H_{2}O_{2}$ to $Fe^{2+}$, and Microwave irradiation power on the microwave enhanced Fenton process efficiency were investigated. According to obtained results the maximum removal efficiency of Microwave enhanced Fenton process was obtained at pH=3, ratio of H2O2 concentration to initial COD equals to 3.75, ratio of $H_2O_2$ concentration to $Fe^{2+}$ concentration of 3, and Microwave irradiation power of 170W. The experimental results indicated that, under this optimum conditions, the removal of COD, total nitrogen, color, and turbidity were 72\%, 70\%, 75\% and 88\% respectively. Results of this research addresses that, applied process is unable to reduce organic load of the leachate in a way that it could be discharge in receiving environment. However, the ratio of $BOD_5/COD$ was elevated from 0.01 to 0.25, representing substantial improvement in biodegradability. By so doing, a common biological process such as activated sludge could be hopefully utilized to reduce remaining organic load to the limits set by the standard.
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