高钙废水生物处理中钙质污泥减量化研究

The calcium-containing waste sludge mainly comes from gelatin industry which is a major water consumer and polluter. The biological treatment of the waste water would lead to a 4-7 ton of sludge per ton of gelatin and 20-30 ton of such sludge per day. Consequently, the secondary waste of sewage treatment, i.e., the residual activated sludge becomes a serious pollution source, which is treated mainly by stacking or land-filling nowadays, and it causes a great pressure to the environment due to its amount and pollution...High calcium content of wastewater should be primarily responsible for the large amount of sludge discharge, e.g., each liter of calcium-phosphorus wastewater contains 600-10,000 mg of Ca2+. The calcium ion would be separated during the biological aeration process, then it would adhere to the surface of the activated sludge to restrain the mass transfer and adsorption and biodegradation ability of the activated sludge, resulting in a shortened SRT (sludge retention time) of 7 days and an increased output of sludge. Testing shows that the organic and inorganic compounds of calcium dominate the components of the sludge-over 77% in the dried sludge. New sewage disposal technique with lower sludge production is desirable given the present immature end treatment and comprehensive utilization...In the early experiments by us ,anti-sludging agent was added during the biological treatment so as to reduce the deposition of the calcium salt on the surface of the activated sludge. Results show that the sludge yield drops by 60.56%, COD removal rate increases by 16.25%, the inorganic ash content significantly decreases in the sludge, and consequently the sludge output is greatly reduced. Calcium ion is transfered into the water which can be recycled during the lime process in the gelatin manufacturing...The research concentrates on three respects pre and post the addition of the calcium salt anti-sludging agent into the activated sludge system: the precipitation of the calcium salt and its performance under some critical situations, the influence of excessive calcium salt on the biological activity of the sludge, and the biodegradation of calcium salt anti-sludging agent. On the basis of the above-mentioned fundamental research work, the property change of the sludge during the high-calcium content wastewater treatment by the activated sludge aerated system is characterized, the quantitative relationships between calcium salt and the microorganism activity is established, and the methods to choose and evaluate biodegradable anti-sludging agent is built.

高钙废水如明胶生产废水，经活性污泥法处理后，钙质污泥产量为20～30 t/d，污泥产量巨大。本课题研究开发低污泥产量的高钙废水处理技术，进行污泥减量化。其主要方法是在高钙废水处理的过程中，把阻垢剂应用于生物曝气系统，以缓解钙质在活性污泥表面的沉积，减少污泥产量，其出水可以回用到明胶生产的相应工段进行循环利用。前期实验结果显示，在活性污泥系统中投加阻垢剂可使COD去除率提高16.25%，使污泥产率有60.56%的降低率。本课题主要研究内容包括：投加阻垢剂前后，活性污泥曝气系统钙盐析出行为的过程表现及临界表征；过量钙盐对污泥生物活性的影响；阻垢剂的生物可降解性。通过以上三个方面的基础研究，分析阻垢剂在高钙废水生物处理过程中对污泥产率的影响程度，得到钙盐沉积相对微生物活性之间的量变规律，建立选择及评价可生物降解性阻垢剂的方法，从而确认阻垢剂在生物系统中应用的可行性。

无害化、减量化、稳定化、资源化是剩余污泥处理的发展方向。而来自高钙废水如明胶生产废水生物处理过程中的高钙污泥，因为产量大、钙质含量高、资源化受限，其减量化处理尤其必要。本项目主要研究低污泥产量的高钙废水生物处理技术，进行污泥减量化。主要研究内容包括生物处理过程中钙盐析出行为的过程表现及阻垢剂的污泥减量化效果；绿色阻垢剂PESA(聚环氧琥珀酸)在活性污泥系统中的生化效应；活性污泥酶活性、微生物种群结构在钙离子及PESA作用下的变化；生物预酸化处理对活性污泥减量化的贡献。 . 研究结果表明：随Ca2+浓度的增加，污泥增长速率加快，微生物活性降低，排泥周期减小，证明在明胶高钙废水活性污泥处理过程中，钙质是造成剩余活性污泥排放量巨大的主要原因。实验监测到生物曝气过程中存在CaCO3、CaSO4、Ca3(PO4)2和CaHPO4四种钙盐的析出行为；投加阻垢剂PESA，污泥中CaCO3和CaSO4减少，磷酸盐消失，污泥产率系数下降，可达到污泥减量化效果27%，证明 PESA能达到到污泥减量化的目的；实验证明了 PESA-Ca螯合物的生成，并参照OECD301B进行二氧化碳生成量( PCD)实验，得出PESA为易降解物质，其螯合生成物PESA-Ca为可降解物质，说明PESA适用于生物处理系统；研究发现高钙离子浓度对活性污泥四种酶的活性都有明显的抑制作用，而PESA的加入则对其中两种酶有复苏作用；基于高通量测序技术，发现活性污泥的优势种群中，Proteobacteria（变形菌门）对高钙离子的耐受性比较强，而Bacteroidetes（拟杆菌门)则会受到抑制，PESA可使得Bacteroidetes的生长得到恢复，对Proteobacteria则影响甚微；项目增加了生物预酸化工艺对污泥减量化作用的研究内容，发现生物预酸化处理后污泥中无机灰分减少，并预先去除了37.7%的碳源（COD）,使得活性污泥生物量逐渐减少， MLSS减量率提高了49.3%，也可达到污泥减量化的目的。项目研究结果利用实际明胶废水进行了验证，确定投加PESA具有污泥减量化效果，减量化效果在27%-63.6%之间。同时由于阻垢剂的分散作用，使得设备的结垢现象得到缓解，出水更加适应于循环利用。