剩余污泥混合对絮凝污泥厌氧消化的强化

为了考察絮凝污泥与剩余活性污泥混合中温(35℃)厌氧消化效果,分析了不同混合比例、不同投配率下的总化学需氧量(TCOD)去除率、挥发性固体(VS)降解效果,通过pH值与氨氮浓度的变化来分析各反应器的稳定性。结果表明:污泥混合后消化效果明显得到提高,且污泥消化效率随着投配率的增加先提高后下降。5%投配率时,絮凝污泥/剩余污泥(VS比)为1:2时厌氧消化效果最好,TCOD去除率达到47.8%,VS降解率达到46.8%,分解单位VS产气量达到了435 mL/g,pH值与氨氮浓度分别保持在7.4和269 mg/L左右,混合污泥厌氧消化系统较稳定。这说明与剩余污泥的混合消化能有效提高絮凝污泥的厌氧消化性能。污泥絮体的显微分析表明:厌氧消化过程中絮体面积百分比逐步减小,污泥结构逐步解体,可以解释污泥消化的微观过程。

Enhancement of mixing with waste activated sludge to anaerobic digestion of flocculated sludge

In order to examine the effect of mesophilic (35℃), anaerobic co-digestion of flocculation sludge and waste-activated sludge, the removal rates of total chemical oxygen demand (TCOD) and the degradation effect of volatile solids (VSs) were analyzed at different mixing ratios and dosing rates, and the stability of each reactor was evaluated through the changes in pH and ammonia nitrogen. The results indicated that the digestion was improved after mixing two kinds of sludge, and the sludge digestion efficiency first increased and then decreased with the increase in dosing rate. When the dosing rate was set at 5%, the best anaerobic digestion of flocculation sludge/waste-activated sludge (VS/VS) at a 1:2 ratio was achieved; the removal rate of TCOD reached 47.8%, VS degradation rate reached 46.8%, and gas production of unit VS degradation ran up to 435 mL/g. Moreover, pH and ammonia concentration remained at approximately 7.4 and 269 mg/L, respectively. The anaerobic digestion system of mixed sludge was more stable than the others, which illustrated that co-digestion with waste-activated sludge can improve the performance of anaerobic digestion of flocculated sludge. Microscopic analysis of the sludge flocs demonstrated that the percentage of floc size gradually decreased during the anaerobic digestion, and the structure was gradually broken, which could explain the microscopic process of sludge digestion.