Enhancement effect of microwave irradiation for treatment of low biodegradable organic wastewaters with a new combined process

From various aspects, enhancement effects of microwave irradiation were investigated systematically to treat various low biodegradable organic wastewaters. The results showed when microwave irradiation process was introduced to enhance coagulation and Fenton oxidation process, the degradation efficiency of organic substances was promoted greatly, and treatment time and various dosages of flocculant, oxidant and catalyzer were also reduced respectively. The mechanism discussion also indicated that microwave irradiation process brought not only the thermal efficiency but also the non-thermal efficiency, which embodied mainly the special effect of microwave electromagnetism field on the structure of organic substance. The electromagnetism field could reduce the chemical bond intensity of molecule through polarization effect, hydrogen bond distortion and activation energy change, and heighten the oxidation effect of hydroxyl radical to degrade some special refractory organics. The excellent performance of this new combined process was mostly attributed to the synergetic effect between microwave irradiation, homogeneous Fenton oxidation and coagulation process.