The Study On The Reuse Of Wastewater Generated From PTA Production By Electrodialysis

Purified terephthalic acid (PTA) is a kind of important chemical product, which is often used as raw material for the production of chemical fiber. China is a big country of chemical fiber production. As the PTA raw materials, terephthalic acid (TA) production accounts for about30%of world output. PTA production waste water has become one of the major sources of water pollution. Electrodialysis (ED) is an electrochemical separation process in which ion exchange membranes and electrical potential difference are applied to separate ionic species from an aqueous solution and other uncharged components. Electrodialysis technology is one of the very maturely membrane separation technologies and embraces many merits, such as easy operation, low energy consumption and so on. This paper preliminarily studies the feasibility of electrodialysis for the PTA waste water disposal and recycling, and explores the conditions of the ion exchange membrane electrodialysis for desalination test.In the process of experiment, the influences of the operation parameters on the removal rate of desalination was studied, such as the applied voltages, the sodium salt concentration and the flow rate. According to the experimental results, the optimal operating conditions were determined as follows the operating voltage per pair of membrane is1V, the flow rate of all compartments is6cm/s. For the PTA waste water whose concentration is about4000μS/cm, about85%of removal rate can be obtained within40min according to the above operating conditions. Furthermore, the limiting current density and the total energy consumption was determined. The experimental results showed that the electrodialysis can be used effectively for the treatment of the PTA wastewater with low cost. For an example, the energy consumption is only1.17kw·h/m3for the PTA wastewater when the recovery was set as75%.According to the above experimental results, the author designed a Industrialization project of15000m3/d PTA production waste water for disposal and recycling. The project have be operated at Jiangyin City, Jiangsu Province.