A Study Of Tridecane Dicarboxylic Acid Wastewater Treatment By The Coupling Of Electrolytic Oxidation And Nanofiltration

The COD of the tridecane dicarboxylic acid wastewater is high about ten thousands, and there is high concentration sodium sulfate in the wastewater. A method by the coupling of electrolytic oxidation and nanofiltration was used to make the wastewater to be discharged according the discharge standards and reclaim sodium sulfate in it. In this paper, the influence of boron-doped diamond thin film electrodes in degradation of organic pollutants under different conditions was studied to confirm the fitting electrolytic conditions, and the effect of different factors in nanofiltration was researched to get the suitable operating condition.The wastewater treatment scheme was also preliminary designed base on the experiment results.The experiment result shows, current efficiency decreases and specific energy consumption increases with the addition of cell voltage, electrolysis time and electrode distance. Degradation speed of organic pollutants and specific energy consumption increase with the reduction of specific electrode surface in constant current. The low original pH of feed solution and enhancement transfer are benefit to improve degradation efficiency of organic pollutants. With overall consideration of all factors, the optimum operating condition is that specific electrode surface: 0.175cm-1 or larger, electrode distance: 5-10mm, cell voltage: about 1.6V, electrolysis time: 7h. The wastewater should be forced circulated without any pH regulation.The nanofiltration of the simulated electrolyte wastewater was studied by membrane DL and SE, the result shows, permeation flux and rejection increases with addition of pressure, cross-flow velocity and reduction of feed concentration. With the addition of temperature, permeation flux increase and rejection decrease slightly of the two membranes. According to the experiment, the optimum operating condition is that operating pressure:1.2～1.4MPa, cross-flow velocity: 0.15m/s for membrane DL and 0.12m/s for membrane SE, temperature: 35?C～40?C.The intermittent treating capacity of wastewater is 2 m3/time, according to the capacity of wastewater is 100T/month.In preliminary design, the working volume of electrolytic cell is 2 m3 and the electrode area is 0.35m2. The COD of the wastewater can be degraded from 10000～12000mg/L to about zero. Two 8040F DL membrane modules are used as the first sect membrane process to concentrate the electrolyzing solution from 9000mg/L to 30000mg/L, and one 8040F DL membrane modules are used as the second sect membrane process to concentrate the permeated liquid of DL from 3300mg/L to 9000mg/L.The concentrated solution of SE is back to the first sect, and the permeated liquid 1.41m3/time of SE can be let and recycled. The nanofiltration time of two sect membrane processes is 3h, cleaning time is 0.5h.The concentrated solution 0.59m3/time of DL can be reclaimed to produce anhydrous sodium sulfate by evaporation-crystallization process.