造纸废水曝气池中钙的去除及迁移转化规律研究

Study on the removal,migration and transformation of calcium in the aeration tank of paper mill wastewater

针对造纸废水好氧处理中钙离子(Ca^2+)浓度过高影响生化过程和后续膜处理的问题,在实验室模拟废水曝气,研究Ca^2+存在对COD去除效果的影响;对厌氧出水进行曝气实验,探究曝气量对钙去除效果的影响;分析表征造纸废水液相中Ca^2+浓度和固相污泥中钙的形态,探究造纸废水曝气池中钙的迁移转化规律.结果发现:Ca^2+的存在会影响活性污泥的活性,进而导致曝气过程中COD的去除率从71.76%降至36.94%;厌氧出水曝气初始阶段内曝气量越大,Ca^2+的去除率越高;Ca^2+浓度从厌氧出水到二沉池出水过程中逐渐下降,从游离态转变为CaCO3的结合态而除去.

Aiming at the problem that high concentration of Ca^2+in aerobic treatment of paper mill wastewater affects the biochemical process and its subsequent membrane treatment,this study firstly analyzed the effect of Ca^2+on the removal of COD in the experiment of calcium removal by the simulated wastewater.Then the anaerobic effluent was used to investigate the effect of aeration rate on calcium removal.The concentration of Ca^2+in the liquid phase of paper mill wastewater and the form of calcium in the solid phase sludge were finally characterized to explore the migration and transformation of calcium in the aeration tank of paper mill wastewater.The results show that the presence of Ca^2+has a negative influence on the active sludge,resulting in a significant decrease of removal rate of COD from 71.76%to 31.94%.In the process of anaerobic effluent aeration,the Ca^2+removal rate increased with the aeration rate at the beginning.From the anaerobic to secondary sedimentation pond,the Ca^2+concentration reduction occurs gradually during the process of aerobic treatment.The calcium mainly was transformed into calcite after it entered the solid phase from the liquid phase.