This plant is one of the seven major treatment plants, which serves a large residential district on the city’s west side. Coming into operation in 1974 at a cost of $40 million, the plant has a capacity of 150,000 cubic meters per day. It illustrates many distinctive aspects of this overall system. 

First, before it was begun there was a one year period of negotiation with neighborhood groups, and considerable resistance to the idea of having a sewage treatment plant in their area. To address that resistance, the plant was built primarily underground. On the surface is a 2 hectare sports park with a spectacular view of the new Awaji Bridge. The park has a swimming pool, tennis courts, a golf range, baseball fields and car wash with a waterfall and stream running through the park. The stream and car wash are supplied with water treated at the plant. 

Technically, waste water runs through a series of settling and aeration tanks where heavy sludge settles out and natural microorganisms oxidize the wastes. From the anaerobic bacterial action breaking down the sludge, methane gas is produced. Some of this gas runs the boiler that keeps the sludge at 380 Celsius, the rest is pumped out to be further refined to be used in the city’s natural gas driven buses. The clean waste water goes through a final chemical sterilization process and is discharged into the sea. About 3,000 cubic meters goes back into the system and into the park, and near 100,000 cubic meters is discharged into the bay. The discharged water is above the national legal standard in cleanliness. Air from the settlement and aeration tanks is pumped through a carbon filer and blown, odorless, into the skies above the park. The process also produces about 40 tons of sludge per day, which is hauled away by a private company, incinerated and the ash is used to produce paving bricks and asphalt filler for roads. Some residue can also be used as fertilizer for the city’s parks. All this is managed by 48 technical and 2 clerical staff!

Questions about the plant are translated	An engineer shows the waterfall

The control system	A youth puts the park facilities to good use

Reflecting the impact of various environmental education campaigns, and the 2,000 visitors this plant receives yearly, the water treatment system has seen the gradual decline of BOD levels at the intake stage. This indicates a gradual cleaning of the waste water that comes from the household and industrial users. Conservation campaigns and more efficient water use procedures have reduced the total water pumped into the system by users from 600 liters to 400 liters per day. At the old rate Kobe would have produced 900,000 cubic meters a day rather than the 600,000 it does today. 

Finally, the overall system is constantly being improved. The Tarumi plant is now being extended to increase the capacity to 235,000 cubic meters per day. The older Sannomiya plant, heavily destroyed by the great Hanshin-Awaji earthquake of 1995 will be decommissioned and its function taken over by the expanded Tarumi plant. Moreover the new elements of this plant are designed to be earthquake proof.