Empirical Study on Drainage System and Cost in Sewerage Industry

2021 Fiscal Year Final Research Report

• Project/Area Number: 20K13483
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 07040:Economic policy-related
• Research Institution: Doshisha University (2021); Kobe University (2020)
• Principal Investigator: Kitamura Tomohiro 同志社大学, 商学部, 助教 (10822900)
• Project Period (FY): 2020-04-01 – 2022-03-31
• Keywords: 下水道 / 下水排除方式 / 確率的フロンティア分析 / メタフロンティア / 効率性

Outline of Final Research Achievements

There are two types of sewage removal methods: a combined type in which rainwater and sewage flow into the same sewerage pipe, and a diversion type in which both flow into separate sewerage pipes. However, the combined type has the disadvantage that the amount of sewage that exceeds the capacity that the sewerage can treat is discharged into rivers or sea without being treated, which causes problems such as water pollution and landscape deterioration. Therefore, in Japan, replacement of the combination type with the diversion type has been promoted.
This study examined which is more efficient for Japanese sewerage companies, the group of companies that adopt the combined sewerage pipe and the group of companies that do not.
As a result, we found that the group of companies that adopted only the diversion type sewerage pipe was more cost effective than the group that adopted the combined sewerage pipe.

Free Research Field

公益事業の生産性・効率性に関する実証研究

Academic Significance and Societal Importance of the Research Achievements

日本および海外における下水道事業の費用構造、効率性、グループ別最小化費用などの分析は多くなされているが、合流式下水道管を採用しているか否かに着目した分析はほとんどなされていなかった。そこで、分流式下水道管への置き換えが進んでいる日本のデータを用いた分析を行い、分流式下水管のみを採用している事業者グループのほうが合流式下水管を採用している事業者グループよりも費用面で効率的であることを明らかにし、分流式下水道管の採用や分流式への置き換えの経済的メリットを示した。この点が、本研究の成果の意義である。