3) Countermeasures against exhaust gas

4,COUNTERMEASURES AT POLLUTION-GENERATING SOURCE

Dust concentration in exhaust gas, particle size and contained cadmium concentration were repeatedly measured until scientifically pinpointing the amount of cadmium discharge in exhaust gas. Operation and maintenance control were strengthened and the collection system improved, The Major improvements were as follows.

1. Countermeasures against leaks such as better sealing in volatile furnaces
2. The heavy oil-burning rotary kiln used to dry waste was replaced with a high pressure dewatering press.
3. Bagfilters were put into use.

As a result, the discharged volume of cadmium taken from dust collectors on the exhaust gas system was reduced from the 3.5 kg per day of 1973, to one third by 1978, at approximately 1 kg per day (Fig.4-3).