Treatment Of Chemical Pharmaceutical Wastewater And Mechanisms With Internal Electrolysis Technology

In this paper, a typical chemical pharmaceutical wastewater was selected as the target water and the internal electrolysis (IE) and combined technologies were chosen as the main treatment technologies. The biotoxicity removal of the IE process on the typical pharmaceutical wastewater was investigated, Moreover, the changes of the biodegradability and the the degradation products after IE treatment were analyzed and the removal mechanisms of the main pollutants in the pharmaceutical wastewater were discussed, further, the combined technologies composed of IE and other physical chemical technologies were studied, simultaneously .to understand the mechanism of fillings agglomeration, various techniques were implemented to characterize in order to provide the basic basis to the rational application of the internal electrolysis in the treatment of the toxic chemical wastewater.Long operation results showed that the internal electrolysis was an effective pre-treatment technology, the COD removal efficiency was 20%, the B/C enhancement efficiency was 60% and the acute biotoxicity removal efficiency was 40%. The iron carbon mass ratio was 2; low initial pH was favorable to the treatment. A new kinetics model was established, according to the model, the best reaction factors were obtained under initial pH value of 2.5 and the iron carbon mass ratio of 2.125.The process of the organics removal was complicated; the internal electrolysis reactions were the main effect. Some compounds with cyclic or long carbon chain could be decomposed into small molecule substance; in addition, suspended particles and colloidal matters of wastewater could be adsorbed by the newborn iron oxide hydroxide which was good flocculants with high activity of adsorption and flocculation.The comparisons of the results by there internal electrolysis combined technologies were studied. The COD removal efficiency for IE-Fenton technology was 61.5%, the B/C enhancement efficiency of these three technologies was 50%; the acute biotoxicity of IE-ultrasonic irradiation technology was 88% and it was 80% for the IE-Fenton technology. Accoding to the comparison of the effects and the cost, the internal electrolysis-Fenton technology was chosn to treat the chemical wastewater.Actual mixed chemical wastewater was treated using the internal electrolysis-Fenton technology, with long operation times (more than 2 months), the COD removal efficiency was 30%, the B/C enhancement efficiency was 60% and the acute biotoxicity was 50%. To understand the mechanism of agglomeration, various techniques were implemented to characterize. Scanning electron microscopy (SEM) indicated that there were granular matters on the surface of agglomerate fillings to arouse the agglomeration. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) indicated that the granular matters were ferric hydroxide and the crystal structure was amorphous. XPS and Fourier transform infrared (FTIR) indicated that adsorption of the internal electrolysis was chemical adsorption and ferric hydroxide could easily adsorb the organics which contained the donating electron groups. The deposition on the surface of fillings by ferric hydroxide which adsorbed the organics was the main reason of agglomeration of the internal electrolysis technology.