Treatment of Leather Wastewater by Electro-Fenton Method

• Main Authors: Fu, Chi-Feng, 傅啟峰
• Other Authors: 駱尚廉
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/61959343682064012159

碩士 === 國立臺灣大學 === 環境工程學研究所 === 89 === Abstract Traditionally, industrial wastewater is treated by secondary treatment processes including chemical precipitation and activated sludge. The main characteristics of tannery wastewater are: high salinity, high organic loading (COD, BOD5), high content of ammonia and organic nitrogen, and presence of specific pollutants (sulphide, chromium). Because of these undissolvable toxic substances and high-molecular-weight organic compounds, tannery wastewater can’t be mineralized efficiently by activated sludge process. This study combines Fenton method and electrochemical; it is called Electro-Fenton method, which is for treating secondary effluent and tannic acid liquid. The experiment is designed for two parts. The first part is to investigate the best operating condition of Electro-Fenton method; the second part is to compare the variation of concentration of ferrous ion and hydrogen peroxide, and the removal efficiency of TOC among electrochemical, Fenton, and electro-Fenton methods during the reaction period, to clarify the advantages of Electro-Fenton method. The results of experiment show that the best ratio to treat secondary effluent for using hydrogen peroxide and ferrous ion dosage is 10:1 (w/w), higher than the best ratio of 5:1 in Fenton method; it means the demand of ferrous ion for Electro-Fenton method is less than Fenton method. The best pH value is 3, removal efficiency of TOC will come down while pH value and temperature is raised. The best ratio to treat tannic acid liquid for using hydrogen peroxide and ferrous ion dosage is also 10:1 (w/w), it appears that this operating condition is available for general tannery wastewater. During the reaction, the concentration of hydrogen peroxide of Electro-Fenton method is lower than that of Fenton method. The concentration of ferrous ion of Electro-Fenton method is higher than that of Fenton method. It also appears Electro-Fenton method is demonstrated that it can maintain a high concentration of ferrous ion and can strengthen the exhaustibility of hydrogen peroxide, increase the speed of reaction and shorten time under process. The TOC removal efficiency of Electro-Fenton method is better than a series connection of electrochemical and Fenton methods both on treating process and economic effect; therefore Electro-Fenton method is demonstrated to efficiently combine the electrochemical and Fenton methods. Besides, secondary effluent can be reached Effluent Standard of COD after 2.5 hrs of treatment and over 80% of removal efficiency of decolorizing after 30 minutes. Key words－Tannery wastewater ; Tannic acid ; Electro-Fenton method ; Fenton method ; Electrochemical