低DO微孔曝气变速氧化沟脱氮能力恢复效果分析

活性污泥法低温运行中的污泥膨胀主要是由丝状菌引起,微丝菌(M.Parvicella)则是污泥膨胀中的优势丝状菌.针对微孔曝气变速氧化沟中试系统中因低温引起的污泥严重膨胀及其污泥硝化能力降低的问题,采取增大曝气量快速培养污泥硝化菌含量,再逐渐增加A:O比为0,0.1,0.5,1.1,1.8提高反硝化能力,从而恢复污泥脱氮能力.在恢复期间,污泥絮体中的疏水性M.Parvicella附着于反硝化产生气体上,在选择池和氧化沟表面形成浮泥,对其进行去除,以减少絮体中丝状菌含量,提高硝化菌含量及其硝化能力.同时对不同微丝菌含量的污泥絮体(沟内混合液和表面浮泥)的硝化和反硝化速率进行测定,结果表明微丝菌含量高的活性污泥其硝化能力较弱,而快速反硝化能力较强,则对慢速和内源反硝化影响不大.进一步证明M.Parvicella也是除了DO浓度,水温和负荷之外影响活性污泥硝化能力和污泥沉降性能的重要因素之一.

Recovering biological nitrogen removal in pilot-scale variable-velocity oxidation ditch under low concentration

Activated sludge bulking, mainly caused by filamentous bacteria-Microthrix Parvicella, was one of the most important reasons in activated sludge process under low temperature. This study was aimed at resolving the problem of sludge bulking and low nitrification ability caused by low temperature, low DO and low influent loading in a variable-velocity oxidation ditch pilot with fine bubble. Experiments results showed that taking the whole DO tank as aerobic zone was benefit for improving nitrifying bacteria content and meeting effluent NH4+-N concentration below 5 mg/L. And then A: O ratios of 0, 0.1, 0.5, 1.1, 1.8 were gradually increased the quantity of nitrifying bacteria quickly in accordance with above the standard of effluent NH4+-N. Also identifying filamentous bacteria showed that dominant microorganism was M. Parvicella with hydrophobicity. Flocs with mass M. Parvicella was floated due to denitrifying nitrogen and formed foaming on the surface of selector and OD. After the foaming was ripped off in order to decrease the quantity of M. Parvicella, nitrifying as increasing the quantity of nitrifying bacteria was improved. The further analysis of nitrification and denitrification performance under different activated sludge contents of M. parvicella showed that M. parvicella was benificial to denitrifying and adverse to nitrifying.It also showed that M. parvicella the maijor reason of impacting nitrifying, denitrifying and sludge settleability except for DO concentration, water temperature and influent load.