基于DEA和SBM-Undesirable模型的山东省污水处理效率研究

为探究污水处理效率提升方法，选取覆盖山东省所有地级市的105座污水处理厂2018年污水处理数据为样本，在数据包络分析法(DEA)的基础上，通过SBM-Undesirable模型将部分产出指标作为非期望产出进行对比，分析山东省污水处理厂运行效率及制约其发展的关键因素.结果表明:①山东省2018年污水处理效率平均值为0.64，其中技术效率值为0.67，规模效率值为0.92，高于全国平均水平(全国平均值分别为0.62、0.62、0.96)，技术效率是影响山东省污水处理效率的主要因素.②设置非期望产出后的效率值低于传统DEA效率值，说明COD、氨氮与总磷的排放对污水处理产生负面效应.③技术分类中，A2/O处理工艺在大型污水处理厂的技术效率最高，达0.8；其他活性污泥技术在小型污水处理厂的技术效率为0.7，且在COD及总磷的处理上具有优势；氧化沟处理工艺技术效率平均值为0.55，其对总磷的处理效果差，适用于中小型污水处理企业.研究显示，技术类型、规模大小及主要污染物对污水处理效率的影响具有交互作用，山东省应根据各污水处理厂具体情况，通过规模与技术的协同改进提高污水处理效率. 

Efficiency of Sewage Treatment in Shandong Province Based on DEA and SBM-Undesirable Model

In order to improve sewage treatment efficiency, the data of 105 sewage treatment plants covering all prefecture-level cities in Shandong Province in 2018 were selected as samples. On the basis of data envelopment analysis (DEA), partial output indexes were compared as undesirable outputs by SBM-Undesirable models. This paper evaluated the efficiency of the plants and the key factors that contribute the low efficiency. The average sewage treatment efficiency was 0.64. The technical efficiency value and the scale efficiency value were 0.67 and 0.92, respectively, which are higher than the national average (the national average is 0.62, 0.62 and 0.96, respectively). Low technical efficiency was the main restriction on the comprehensive efficiency of the sewage treatment industry in Shandong Province. After setting undesirable output in the same input-output index, the overall efficiency is lower than that of the traditional DEA model, indicating that the discharge of COD, ammonia nitrogen and total phosphorus had a negative effect on sewage treatment. In the technical classification, the technical efficiency of the A2/O treatment process in large sewage treatment plants reached the highest value of 0.8. The technical efficiency of other activated sludge technologies in small sewage treatment plants was 0.7, and they had the advantage in treating COD and total phosphorus. The average technical efficiency of oxidation ditch treatment process was 0.55 and the total phosphorus treatment effect was poor, which is suitable for small and medium-sized sewage treatment enterprises. The technology types, scale and main pollutants have interactive effects on efficiency of sewage treatment. Shandong Province should improve the sewage treatment efficiency through the coordinated improvement of scale and technology according to the specific situation of each sewage treatment enterprise.