脱木素工艺处理造纸废水的实践与机理

脱木素工艺为中小制浆企业的黑液治理提供了新的方法。系统中酸化纤维污泥减小碱木素胶粒间的斥力 ,吸附废水中已析出的木质素和细小纤维 ;酸破坏了系统中胶体的水化膜 ,增大了胶体的粒径 ;混凝剂中和胶体表面电荷 ,增加颗粒间的接触机会 ,同时发挥了絮凝沉降的作用。该工艺与传统工艺相比 ,减少了酸及混凝剂的用量 ,木素沉降速度快。当试验废水pH =5、绝干纤维污泥与进水CODCr质量之比为 1.1、硫酸铝投加量为 160mg/L时 ,CODCr去除率高于 63 %。

Application and mechanism of the lignin removal process for the treatment of paper mill wastewater

The lignin removal process(LRP) is a new treatment method of black liquor for middle and small pulp mills. In the LRP system, the acidified fibre sludge reduces the repulsion forces between particles and adsorbs precipitated lignin and fine fibre. The acid changes the colloid from stable state to unstable state and increases the particle size in the system. The flocculent enhances the flocculation and precipitation of colloid. Compared with conventional processes, LRP decreases the flocculent dotage and accelerates the precipitation of the lignin. For the tested wastewater, the optimum conditions are obtained: pH at 5.0, the weight ratio of anhydrous fibre sludge to influent COD Cr at 1.1 and the dotage of aluminium sulphate at 160 mg/L. Under these conditions, the COD Cr removal rate is above 63%.