The Wisdom of Recycling that Returns to the Earth - Kofu City's Sewage Sludge Composting Project - April 2001

The Wisdom of Recycling that Returns to the Earth - Kofu City's Sewage Sludge Composting Project - April 2001

The Kofu City Sewerage Public Corporation generates approximately 17,000 tons of sewage sludge annually, of which approximately 4,890 tons are reused as compost. In this composting project, sawdust and immature compost are mixed and fermented to produce organic fertilizer. The fermentation process is divided into two stages: first, the primary fermentation takes about two weeks, followed by a 60-day ripening period before the final product is completed.

Annual production amounts to approximately 2,500 tons, of which more than 80% is sold to farmers. Sales are conducted mainly through economic federations to promote agricultural use. The aim is to reduce the burden on final disposal sites and reduce the environmental burden by converting sludge into a resource. In recent years, with the tightening of final disposal sites, disposal costs have been rising (from 10,000 yen/ton to 15,000-20,000 yen/ton), making the use of this type of recycling technology even more important.

Kofu City's compost is particularly supported by local farmers, who are adjusting its composition and improving its supply system in order to improve its quality as compost. In addition, due to the revision of the Fertilizer Control Law, sludge compost, which was previously considered a "special fertilizer," is now certified as an "ordinary fertilizer," and is increasingly accepted in the market.

### Related Information
1. **Ministry of the Environment, "2010 White Paper on the Environment, 2010 Edition," Chapter 3: Formation of a Recycling-Oriented Society**.
- The report details the amount of sewage sludge generated, the status of its recycling, and specific recycling methods (cement raw materials, green farmland use, energy use, etc.).

2. **Public Investment Journal: Column "From Interview Notes "**
- The column mentions the position of sewage sludge compost under the Fertilizer Control Law, its quality as a fertilizer, and the possibility of promoting its use.