UV-Fenton光催化法深度处理紫胶漂白废水

Advanced treatment and degradation kinetics of shellac bleaching wastewater by UV-Fenton photocatalytic process

采用UV-Fenton联合的方法处理紫胶漂白废水,单因素实验研究了H_2O_2用量、FeSO_4用量、反应时间和初始pH值对紫胶漂白废水降解的影响,并通过数学回归模型和响应曲面法优化得到UV-Fenton深度处理紫胶漂白废水的最优条件:初始pH值5.0,H_2O_2用量49 g·L^(-1)、FeSO_4用量2.6 g·L^(-1)、反应时间为4 h。经最优工艺条件深度处理后的紫胶漂白废水COD、BOD_5、悬浮物、色度、总氮和总磷分别降低至48 mg·L^(-1)、32 mg·L^(-1)、27.3 mg·L^(-1)、24 NTU、0.027 mg·L^(-1)、0.021 mg·L^(-1),除BOD5稍高外,其余指标均达到污水综合排放一级标准。在最优条件下,以紫胶漂白废水COD值和COD去除率为指标的降解动力学模型可分别表示为:lny=0.034 98+0.001 85x+6.898×10^(-6)x2和z=95.36-92.78×0.9706t。由动力学方程可看出,废水COD值在反应开始的前2 h内,降低幅度接近90%,且以反应开始时最为剧烈,随着反应的进行,反应剧烈程度迅速减弱。

The purpose of this study was to develop an appropriate way to provide advanced treatment of shellac bleaching wastewater and to obtain treated wastewater that would meet the emission requirements of the China national standard. A combined method,UV-Fenton,was employed to degrade organics in the wastewater. Some single factors,including concentration of H2O2 and FeSO4,reaction time,and initial pH were discussed and the optimum conditions were obtained by modeling and optimizing with the response surface method. The optimum conditions were： initial pH 5. 0,concentration of H2O2 and FeSO449 and 2. 6 g·L^-1,reaction time 4. 0 h. After treatment under the optimum conditions,the emission indexes（ i. e.,COD,BOD5,suspended solids（ SS）,chroma,total nitrogen,and total phosphorus） were reduced to 48 mg·L^-1,32 mg·L^-1,27. 3 mg·L^-1,24 NTU,0. 027 mg·L^-1,and 0. 021 mg·L^-1,respectively. All the index values conformed to Grade I of the China national standard. In addition,under the optimum conditions,the kinetic equation with COD（ or COD removal rate） as the functional value was expressed as lny = 0. 034 98 ＋ 0. 001 85 x ＋ 6. 898 × 10^（-6）x2 and z =95. 36-92. 78 × 0. 970 6t. The result from the kinetic equation indicated that the COD decreased approximately90% in the first 2. 0 hours after initiation of the reaction. The reaction was most vigorous initially and rapidly weakened the longer it was sustained.