钙离子浓度对活性污泥处理系统脱氮效果的影响

考察了钙离子浓度对活性污泥系统脱氮效果的影响。在单级序批式反应器(SBR)中,对于化学需氧量(COD)为680 mg/L、氨氮(NH⁺₄-N)质量浓度为20 mg/L的自配废水,逐步增加钙离子浓度,测定了在不同钙离子浓度下的总氮(TN)去除率、NH⁺₄-N去除率、亚硝酸氮(NO^-₂-N)和硝酸氮(NO^-₃-N)累积量及污泥体积指数(SVI),并采用最大或然数(MPN)法测得亚硝酸菌、硝酸菌和反硝化菌数量的变化规律。结果表明,在钙离子质量浓度为480~1000 mg/L时,SVI为25 mL/g,污泥颗粒密实度较大,系统中硝酸菌与反硝化菌的数量均维持在10⁴~10⁵数量级,TN和NH⁺₄-N去除率均在90%以上,NO^-₃-N累积量小于0.25 mg/L,实现了同步硝化反硝化(SND)作用,这是实现较高脱氮效果的主要原因。

Influence of Ca2+ Concentration on the Nitrogen Removal in Activated Sludge Process

 The influence of Ca2⁺ mass concentration on the nitrogen removal rate of synthetic Ca²⁺ -containing wastewater with chemical oxygen demand (COD) of 680 mg/L and ammonia nitrogen (NH⁺₄-N) mass concentration of 20 mg/L treated by activated sludge process in a single sequencing batch reactor (SBR) was studied under the condition of Ca²⁺ mass concentration increasing step by step. The total nitrogen (TN) and NH⁺₄-N removal rates, nitrite nitrogen (NO^-₂-N) and nitrate nitrogen (NO^-₃-N) accumulations, sludge volume index (SVI) were measured, and also nitrite bacteria, nitrobacteria, denitrifying bacteria numbers were investigated by most probable number (MPN) method. It was detected that when Ca²⁺ mass concentration was in the range of 480-1000 mg/L, SVI reached 25 mL/g, the compactness of sludge granules became larger, the order of magnitude of nitrate bacteria and denitrifying bacteria was 104-105, TN and NH⁺₄-N removal rates were more than 90%, and NO^-₃-N accumulation was less than 0.25 mg/L in the system. The simultaneous nitrification and denitrification (SND) was the main reason for obtaining higher nitrogen removal rate in the system.