城镇污水处理设施运行效率及其规模效应研究

Assessing the Efficiency and Scale Effect of Municipal Sewage Treatment Facilities in China

污水处理设施运行效率的定量评价及其规模效应研究是当前备受关注的问题。笔者基于全要素生产率框架,采用数据包络分析(DEA)方法构建了污水处理设施运行效率评价模型,以固定资产总额、年运行费用、污水处理人员数和年耗电量为投入变量,以污水年处理量、BOD5和氨氮削减量为产出变量,对2014年我国315座排放标准为一级且处理工艺相同的污水处理设施进行效率评价,进而对运行效率和设计处理能力之间的关系进行检验,并对样本的投入冗余和产出不足情况进行定量分析。研究发现:有32个样本的运行效率达到相对最优,可成为其余效率不足样本改进的标杆;有10个样本纯技术效率有效但规模效率无效,需改进其规模;DEA无效样本中规模报酬状态为递增的占70.0%,表明我国污水处理行业总体上处于规模收益递增的发展阶段;通过Kruskal-Wallis检验发现,样本污水处理设施具有规模效应,规模越大的运行效率越高;283个DEA无效样本存在不同程度的投入冗余和产出不足,是今后进行效率改进的重点对象。

The quantitative assessment of the efficiency of municipal sewage treatment facilities（ STFs）is a key issue that need to be solved,as well as the scale effect of sewage treatment industry. For this purpose,under the framework of total factor productivity,data envelopment analysis（ DEA） is employed to established evaluation model of the efficiency of STFs,including inputs indices of gross fixed assets,annual operating cost,employment and annual power consumption,and output indices of wastewater treatment capacity,pollutant reduction of BOD5 and NH3-N. 315 samples are selected as the empirical analysis objects which have the same discharge standard and treatment process. It is found that 32 samples reach relative efficiency,which means these samples could be a benchmark for other samples. 70. 0% of the DEA invalid samples show increasing returns to scale,which indicates the sewage treatment industry in China is in the process of rapid development and being high potential to increase the profits by augmenting investments in the industry. Furthermore,through Kruskal-Wallis Test,it was verified that the larger plants run more efficiently than smaller plants,which indicates the scale effect existing in the industry,as was to be expected. Different levels of input redundancy or output slack exist in the 283 DEA invalid samples and these samples should be the key objects to improve the operating efficiency.