金属铁铝对混凝强化初沉污泥中温厌氧消化的影响简

选取FeCl₃和AlCl₃·6H₂O作为混凝剂对城市污水进行一级强化混凝处理，降低二级生物处理的进水负荷，减少污水生物处理系统的能量消耗。主要研究混凝过程投加的金属盐对一级强化混凝产生的初沉污泥中温厌氧消化的影响。和剩余污泥相比，初沉污泥更适合厌氧消化处理，污泥降解性能和产气性能更高。当采用城市污水一级强化混凝处理时，污泥中的金属和金属盐水解引起的pH降低，使混凝强化初沉污泥的厌氧消化受到一定抑制。随着污泥中铝含量的降低和铁含量的增加，厌氧消化的COD降解率和挥发性固体（VS）降解率逐渐升高，生物气产量逐渐增大，产气速率加快。当混凝强化初沉污泥只含有铁时（铁含量为10.16 mg/L），混凝强化初沉污泥厌氧消化效果最好，产气稳定，而且产气速率高，生物气产量为237 mL，生物气甲烷含量为55.5%，降解单位VS产气量为0.80 L/g，均高于其他含铝的混凝强化初沉污泥。污泥中的铁对初沉污泥厌氧消化的抑制作用远远小于铝的作用，说明铁盐适合用于城市污水的一级强化混凝处理。

Effect of iron and aluminium content on anaerobic digestion of primary sludge enhanced by coagulation

FeCl₃ and AlCl₃·6H₂O were selected as coagulants to enhance primary sewage treatment, to reduce influent load and energy consumption of secondary biological sewage treatment. Effect of the metals dosed in the enhanced sewage treatment with coagulation on the mesophilic anaerobic digestion of the primary sludge was investigated in this study. Compared with excess activated sludge, the primary sludge was more easily digested with better characteristics of the organic matter degradation and biogas production. When the primary sewage treatment was enhanced with coagulation, the metals in the sludge and the pH reduction caused by metal hydrolysis hindered the anaerobic digestion of the primary sludge. With the decrease of the aluminum content and the increase of iron content in the primary sludge, COD and volatile soild (VS) degradation efficiency, biogas volume and biogas production rate increased. When the primary sludge only contained iron with a iron content of 10.16 mg/L, the best effect of the anaerobic digestion of the primary sludge was achieved. The biogas production was stable and the biogas production rate was high with a biogas volume of 237 mL, a methane content in biogas of 55.5%, a biogas production per unit VS degradation of 0.80 L/g, which were higher than that for the other primary sludge containing aluminum. The inhibitory action of iron on the anaerobic digestion of the primary sludge was much smaller than that of aluminum, indicating that FeCl₃ was suitable for the enhanced primary sewage treatment with coagulation.