THE STUDY OF DEOXYGENATION RATE OF RANGKUI RIVER WATER DURING DRY SEASON

Abstract

Rangkui River is a river that passes through the area of Pangkalpinang City, Indonesia. The
condition of the River Rangkui is now polluted, especially in the urban areas. Utilization of water quality
model is one popular method to recover the river condition. Deoxygenation rate is an important coefficient in
the BOD-DO formula used in the water quality model. This study was aimed to find out the actual coefficient
of water deoxygenation rate of Rangkui River, especially in the dry season. Sampling was conducted at two
location points that are considered to represent the condition of rivers in urban areas. The method of
laboratory analysis used in the calculation of deoxygenation rate was using Winkler Method and Slope
Method, while empirical formula used in deoxygenation rate calculation was using Hydroscience Equation
formula for normal flow. The results showed that the value of deoxygenation rate range (K1) in the Rangkui
River was between 0.14 to 0.41 per day and the BOD Ultimate (La) range was between 8.53 to 70.64 mg / L.
As for the value of deoxygenation rate range (K1) on the River Rangkui using empirical formula was ranging
from 0.49 to 0.55 per day. Higher values of deoxygenation rate generated from the empirical formula show
the characteristic of typical polluted urban rivers.