Assessment of Self-Purification Capacity of the Mooi River Catchment of South Africa

Thabang Mmutle, Saheed Adeyinka

2022

Abstract

Dissolved oxygen is the most essential element in natural water bodies for one of the most important reasons, namely aquatic life. This content is usually affected by the type and amount of pollution introduced in natural water bodies. The dissolved oxygen level is usually lowered at any point where a natural water body such as a river is contaminated (deoxygenation); however, using natural purification forces, rivers work hard to gain back the amount of oxygen lost in the water due to pollution (re-oxygenation). This study articulated the self-purification capacity of the Mooi River catchment as a function of the rate of change of the amount of dissolved oxygen in flowing water to illustrate the purification strength of a river flow segment between sampling points. This is to subsequently present the impact of inflowing pollution from different types of adjacent sources and tributary rivers. This was achieved by conducting measurements of dissolved oxygen and temperature directly from the river, using an electrolyte dissolved oxygen meter. Respective samples (three-litre samples) were also collected at every sampling point for a biochemical oxygen demand laboratory analysis taken over five days. Using the biochemical oxygen demand and oxygen deficit analysis, deoxygenation and re-oxygenation factors or constants were determined for every flow segment. The mathematical ratio between the two constants were then used to calculate the self-purification capacity of every segment. Because the hydraulic dynamics of the river also influence the strength of the river to purify itself, a re-oxygenation model of hydraulic properties, such as flow velocity hydraulic depth and radius, was developed and presented by means of a regression analysis. The findings have proven that the river has the capacity to purify itself along its existing length for both dry and wet seasons. The purification fluctuations were high during the wet seasons due to the increase in hydraulic flow depth and pollution by run-off. Oxygen deficiency was very low before the Mooi River confluences with the Vaal River; therefore, it did not significantly affect the oxygen content of the Vaal River.

Paper Citation

in Harvard Style

Mmutle T. and Adeyinka S. (2022). Assessment of Self-Purification Capacity of the Mooi River Catchment of South Africa. In Proceedings of the 3rd International Symposium on Water, Ecology and Environment - Volume 1: ISWEE; ISBN 978-989-758-639-2, SciTePress, pages 101-105. DOI: 10.5220/0011913200003536

in Bibtex Style

@conference{iswee22,
author={Thabang Mmutle and Saheed Adeyinka},
title={Assessment of Self-Purification Capacity of the Mooi River Catchment of South Africa},
booktitle={Proceedings of the 3rd International Symposium on Water, Ecology and Environment - Volume 1: ISWEE},
year={2022},
pages={101-105},
publisher={SciTePress},
organization={INSTICC},
doi={10.5220/0011913200003536},
isbn={978-989-758-639-2},
}

in EndNote Style

TY - CONF

JO - Proceedings of the 3rd International Symposium on Water, Ecology and Environment - Volume 1: ISWEE
TI - Assessment of Self-Purification Capacity of the Mooi River Catchment of South Africa
SN - 978-989-758-639-2
AU - Mmutle T.
AU - Adeyinka S.
PY - 2022
SP - 101
EP - 105
DO - 10.5220/0011913200003536
PB - SciTePress