Study on the Self-purification of Tanjaro River

Abstract

Self-purification capacity of a river is a significant indicator for the river health and it is in great importance in polluted water. Tanjero River lies southwest of Sulaimani city formed by linking two streams (Qiliasan and Kani-Ban streams) along its path the sewage of wastewater is discharged into the river that causes serious pollution and threatens the quality of water. Samples of water were taken from six stations (S1, S2, S3, S4, S5 and S6) along the Tanjero river. The data obtained from sample locations include velocity, depth, river discharge, water temperature, pH, electrical conductivity (EC), total dissolved solids (TDS), turbidity, dissolved oxygen (DO) and BOD. The De-oxygenation coefficient (k1) and re-oxygenation coefficient (K2) are then used to estimate the deficit value of predicted oxygen using the Streeter Phelps equation. The maximum de-oxygenation rate (K1) and reaeration (K2) rate (8.259541 day−1) and (15.22917day−1) were recorded in site (4) respectively. The fair ratio (f) or self-purification factor, for the Tanjero river was determined. The maximum fair ratio (f) value of (2.219) was recorded at site (2). The average fair ratio (f) was found to be (1.507) which classifies the river into large streams of low to normal velocities. This study revealed that using Streeter-Phelps method the natural self-purification occurred along the river as a result of continuous increasing of DO value and decreasing BOD value.