Perspective COD Model for ASBs, 1999 Environmental Conference Proceedings

Robert Sackellares, Talat Mahmood & Sujit Banerjee

In 1995, Georgia-Pacific and IPST began a project to develop a COD treatment model. There were two drivers behind this effort.

First, when EPA proposed Cluster Rule in 1992, they contained limits for COD. In April, 1998 the Cluster Rule was promulgated for the bleached subcategory and EPA reserved the right to set limits at a later date.

Second, mills must currently meet BOD limits for BOD. The BOD test takes five days to perform. To tightly control performance, a quicker surrogate test is needed. The COD test can be performed in less than three hours. This is adequate for the control of lagoons, because they have long retention times.

Historically, it has been difficult to predict effluent COD. There are two reasons for this:

· The COD in mill effluents has not been characterized very well.

· The transformation of COD within a treatment system has not been well understood.

We developed a method of easily fractionating COD into four parts:

· Particulate

· Soluble inorganic

· Soluble biodegradable

· Soluble non-biodegradable

This technique was performed at four mills. A performance model was developed. This model has been tested at three mills. It can predict soluble COD within 10 % and total COD within 15 %. To date, Georgia-Pacific has used the model to increase aeration efficiency and save ~$500,000.