低温条件下MUCT工艺污泥膨胀的产生与控制

Occurrence and control of sludge bulking under low temperature in MUCT process

为进一步探讨丝状菌污泥膨胀的影响因素和建立控制策略,以MUCT工艺为研究对象,考察低温对活性污泥沉降性能的影响及相应的污泥膨胀的控制措施.结果表明:当系统的反应温度低于15℃时,Microthrixparvicella大量生长繁殖,改变了活性污泥的结构,发生污泥膨胀,SVI值最高达到381 mL/g;通过采取控制系统的反应温度为25±1℃、污泥龄减少至6 d、硝化液回流比α减小为2.5以及混合液回流比γ增大为1等措施可有效抑制Microthrixparvicella的生长繁殖,提高污泥的沉降性能,经过36 d的运行,使SVI值降至127 mL/g;膨胀期与恢复期系统对COD、TP的去除效果较好,而且膨胀期对TN的去除效果也较好,但在恢复期则因污泥龄的降低而明显下降.

In order to further find out the factors causing sludge bulking and establish the corresponding control strategies, the effect of low temperature on sludge settling characteristics and the control strategies for inhibiting the growth of filamentous bacteria were investigated based on MUCT processes. The results show that the sludge bulking occurs in the reactor due to the alteration of activated sludge＇ s structure at the reaction temperature below 15 ℃, which results in the excessive growth of microthrix parvicella, and the maximum SVI value reaches 381 mL/g. The excessive growth of microthrix parvicella can be efficiently inhibited by controlling the reaction temperature at 25 ± 1 ℃, decreasing SRT to 6 days, and decreasing the nitrate recireulation ratio α to 2. 5 or increasing the mixed liquor recirculation ratio γ to 1. The SVI value is decreased to 127 mL/ g after the operation for 36 days. The good removal effieiencies of COD and TP are achieved during the bulking and reestablishing periods. The removal efficiency of TN is also good during the bulking periods, but the adverse result is that its removal rate is reduced with the decrease of SRT during the reestablishing periods.