On Oxidation Characteristics Of Treating Chinese Medicine Wastewater With Chlorine Dioxide

Chinese traditional medicine wastewater is a kind of acidic organic wastewater to be hardly treated with the characteristics of high concentration of COD, BOD, SS and low pH value. Because of this, the traditional biological or physical chemistry techniques can not make the wastewater clean enough to satisfy the treatment criteria at an acceptable expense. Thus, it is a difficult problem to be solved to treat the high concentrated industrial wastewater in the field of environmental protection techniques in our country. In order to solve the problem of wastewater acidity restricting the treatment ways, the oxidation method of chlorine dioxide is adapted to dispose the Chinese traditional medicine wastewater in laboratory scale studies in this thesis. The oxidation law of that the Chinese traditional medicine wastewater is treated by chlorine dioxide has been discovered. The experimental researches provide not only the basic data for the further studies of chlorine dioxide disposing Chinese traditional medicine wastewater, but also the new idea of treating the acidic wastewater with high concentration.The contaminations of Chinese traditional medicine wastewater are oxidated and decomposed by using stabilized chlorine dioxide solution as an oxidant. Taking the chemical oxygen demand (COD) of the wastewater as the index of oxidation efficiency, the influences of the original concentration of chlorine dioxide (expressed by [ClO2]: COD), pH value and reaction time on the disposal effect of the Chinese traditional medicine wastewater are investigated under the condition of the normal temperature (291-298K) and normal atmospheric pressure (1.013x105 Pa).The experiment project is determined by orthogonal design method and 48 oxidation decomposition experiments divided into 3 groups are carried out. The analyses and researches of the experimental results show that: (1) when the ratio of C1O2 to COD is the range of 1.0 ~ 0.4, the average removal rate of COD exceeds 42%, and when this ratio is greater than 1.0 or smaller than 0.4, the average removal rate of COD is only 27 ~ 35%; (2) when the pH value equals 2.0 ~ 4.0, the removal rate of COD exceeds 40%, and when the pH value is equal to or greater than 10.0, the removal rate of COD can reach 59%; (3) with the increase of the reaction time, the removal rate of COD increases, and whenthe time of oxidation reaction is about 30 min, the removal rate of COD can arrive at 40%, besides, when the time is 105 min the corresponding value reaches 63%; (4) under the condition of the normal temperature and normal atmospheric pressure, the primary and secondary order of the factors affecting the disposal effect of Chinese traditional medicine wastewater is the reaction time, the initial concentration of chlorine dioxide and the pH values, the best technological conditions of treating Chinese traditional medicine wastewater are that the ratio of ClO2 to COD is 0.7, the pH value is 6.0 and the reaction time is 105 min, the corresponding removal rate of COD is 49% and that of BOD5 is 75%.