Abstract:

Heterogeneous Fenton process is mainly used to degrade wastewater COD. Compared to traditional Fenton process, heterogeneous Fenton can avoid the generation of iron sludge, while the utilization rate of H₂O₂ still need to be improved. In this work, two type of ceramic membranes assisted heterogeneous Fenton process were proposed. One membrane was used as H₂O₂ distributor, while another was used for separating and recycling the catalyst. Different catalysts and their COD degradation performance were investigated first. The adding dose and rate of H₂O₂ and permeate flux were optimized subsequently. The stability of the catalytic and the membrane fouling condition were finally evaluated. The results revealed that cubic Cu₂O possessed the best COD degradation performance. When the reaction conditions were that Cu₂O (1 g·L^-1), H₂O₂ dosage (0.8 ml·L^-1), wastewater permeability (137 L·m^-2·h^-1) and reaction temperature(30℃), the COD degradation amount of RO(Ⅰ)-RO(Ⅳ) were 11, 130, 291 and 417 mg·L^-1. The utilization rate of H₂O₂ for RO(Ⅰ)-RO(Ⅳ) were 9%, 106%, 232% and 334%, the utilization efficiency of H₂O₂ exceeded 100% means there are chlorine free radicals play a role in COD degradation. The COD degradation amount increased linearly with increasing of Cl-concentration. The COD degradation rate had an increasing tendency with the decreasing of the permeability of separation membrane. In the 360 min reaction process, Cu₂O catalyst may form a reversible cake layer on the surface of the membrane distributor. However, this cake layer has scarcely effect on the permeation resistance. The COD degradation were greater than 65% stably. Moreover, with the increase of conductivity in pulp wastewater, catalysts would become instability with more of Cu ion dissolution. In heterogeneous Fenton process, ceramic membrane can enhance the treatment efficiency to pulp waste water, which performed in increasing of the utilization rate of H₂O₂ and improving the stability in continuous operation process.

Key words: pulp wastewater, membrane, Cu₂O catalyst, residence time distribution, oxidation

摘要：

类Fenton工艺又称非均相Fenton工艺，主要用于降解废水COD，可避免传统Fenton工艺产生的铁泥问题，但双氧水利用率尚有待提高。采用1个陶瓷膜分布H₂O₂，另1个陶瓷膜分离催化剂，构成双膜促进的非均相Fenton新工艺，考察了不同催化剂对制浆废水中COD的降解效果，优化了H₂O₂进料速率和反应渗透通量，分析了催化剂的稳定性和陶瓷膜污染情况。结果表明，自制立方体结构的Cu₂O对制浆废水中COD降解效果最佳，当Cu₂O添加量为1 g·L^-1，H₂O₂加入量为0.8 ml·L^-1，反应温度为30℃，反应渗透通量为137 L·m^-2·h^-1时，RO（Ⅰ）～RO（Ⅳ）4种废水的COD降解量分别为11、130、291和417 mg·L^-1，H₂O₂的利用率分别为9%、106%、232%、334%，H₂O₂利用率大于100%的主要原因是废水中大量的氯离子与铜催化剂作用产生氯自由基参与了降解反应，COD降解量与Cl-含量呈现线性关系，并且COD降解率随膜渗透通量的减小而增大。360 min的连续运行表明陶瓷膜分布器在非均相Fenton反应过程中会形成可逆滤饼层，膜污染较小，COD降解率稳定保持在65%以上。随着制浆废水中盐浓度的增大，Cu₂O催化剂稳定性变差，Cu离子的溶出量增大。陶瓷膜可以强化非均相Fenton工艺处理制浆废水效果，提高双氧水的利用率和连续运行的稳定性。

关键词: 制浆废水, 膜, Cu₂O催化剂, 停留时间分布, 氧化