MODELING THE DISTRIBUTION OF CHEMICAL OXYGEN DEMAND TO DETERMINE THE OPTIMAL MILL EFFLUENT OUTLET LOCATION

Abstract

This paper aims to evaluate three location alternatives and determine the best one for the water
effluent outlet based on the resulting chemical oxygen demand (COD) distribution. A prospective bleached
chemi-thermomechanical (BCTM) pulp mill located in Muan River, East Kalimantan Province, Indonesia is
taken as a study case. The study involves field measurement and numerical modeling using a Surface-water
Modelling System. The measurements cover bathymetry, tidal elevation, current velocity, and water quality
survey. Using the data from field measurement and NaoTide, the hydrodynamic model (using the RMA2
module) performs well in the validation of tidal elevation and current velocity. In the water quality model
(using the RMA4 module), it is found that by placing the outlet at the downstream of Muan River as in
Alternative 1, the least COD average distribution is obtained. Further, Alternative 1 is selected as the best
location, resulting in 0.0465 km/m3 average COD annually.