石灰投加比对污泥低温干燥特性及冷凝液性质的影响

为研究污泥石灰低温干燥特性，分别向脱水污泥中投加0%、3%、5%、7%、10%、12%和15%的石灰，对投加石灰后污泥低温干燥过程中含水率和干燥速率变化进行了研究，并对干燥后冷凝液的性质进行了分析。结果表明：低温条件下，向污泥中投加石灰后，污泥干燥过程中的含水率迅速降低，石灰投加比与混合后污泥初始含水率呈线性关系，与污泥临界含水率呈二次函数关系；投加石灰可以提高污泥的最大干燥速率；用干污泥代替部分石灰对污泥进行干燥，既可降低成本，又不影响干燥效率；污泥石灰低温干燥的冷凝液呈弱碱性，随着石灰投加比的增加，冷凝液中COD和TOC浓度降低，NH4+-N浓度略有升高，但冷凝液中污染物浓度均较低，可不经处理直接排入城镇污水处理系统。

Effects of lime addition ratio on sludge lime drying at low temperature and the properties of condensate

In order to study the low temperature lime drying characteristics of sewage sludge, 0%, 3%, 5%, 7%, 10%, 12% and 15% of lime was added into dewatered sludge. The variations of moisture content and drying rate of sludge during the process of sludge lime drying at low temperature were studied, and the properties of the condensate after drying was analyzed. The results showed that under the condition of low temperature, the moisture content of sludge decreased rapidly after the addition of lime during the drying process. Moreover, lime addition ratio not only had a linear relationship with the initial moisture content of sludge after mixing, but also had a quadratic function relationship with the critical moisture content of sludge. Lime addition could increase the maximum drying rate of sludge. The drying of sludge with dried sludge instead of partial lime could not only reduce the cost, but also not affect the drying efficiency. The condensate of sludge lime drying at low temperature was weakly alkaline. With the increase of lime addition ratio, the concentration of COD and TOC in the condensate decreased while the concentration of NH4+-N increased slightly. However, the condensate could be directly discharged into sewage treatment system without treatment for the low concentration of pollutants.