Case Study of a Cost Reduction Trial Based on Postponement of Sludge Withdrawal from an Oxidation Ditch Process with a Small Sludge-Reduction Process

Abstract

 The cost of government services to citizens during Japan’s long-term economic depression poses a challenge for local governments. To ease the burden of running costs of sewage treatment at the local government level, a waste sludge reduction trial was performed in a real-scale plant by postponing sludge withdrawal from the plant. Sludge reduction was also observed in a small-scale sludge-reduction process. Approximately 30,000 USD of the sludge disposal cost was saved by postponing sludge withdrawal from the plant. Sludge reduction reached approximately 35 %. In terms of CO₂ emissions related to SDGs (Sustainable Development Goals), an 8,000 kg reduction in emissions was observed owing to reduced waste sludge incineration in the sludge reduction trial described in this study.