Assessment of the Viability of the Reuse of Sedibeng District Municipal Secondary Effluent in Southern Gauteng, South Africa

Gugulethu Given Skosana,Hein H Du Preez

doi:10.4236/jwarp.2017.98069

Abstract

Population growth, urbanization, water resources pollution, environmental awareness, uneven distribution of water resources and water scarcity have necessitated water reuse especially in arid and semi-arid countries. Influent and effluent data of chemical and biological analyses from four wastewater treatment plants (WWTPs) in the Sedibeng district municipality (SDM) were used to assess the viability of water reuse. Available worldwide water reuse criteria of Water Reclamation Plants (WRPs) for different reuse options were used to characterize the SDM’s four WWTPs for potable water, power and steel industrial water reuse. Only WWTP4 does not meet the influent design criteria of the New Goreangab WRP in Windhoek, Namibia of 43 mg/l and the DWAF general limit of discharge of 75 mg/l used by Beaufort West WRP in South Africa for COD. WWTP2 and 4 do not meet the DWAF general limit of 25 mg/l for suspended solids. Some of the water quality parameters of the effluents from these plants were non-compliant to the requirements for reuse in power generation and steel manufacturing. However, the implementation of advance treatment technologies such as membrane or advanced oxidation processes (AOPs) as part of the treatment train in a potential WRP would address the water quality issues. Water reclamation of SDM effluent either through direct (DPR) or indirect potable (IPR) water reuse, power generation and steel manufacturing industry has the potential of reuse in the Southern Gauteng region. The success of the selected option would be depended on cost effectiveness, stakeholder commitment and public acceptance of the reuse strategy.

Highlights

The increase in demand of water because of the requirements for human consumption, agriculture, mining and industrial development complicated by inaccurate pre-empting of impacts of climate change makes a search for alternative water sources
Worldwide chemical oxygen demand (COD) is not used as a primary aggregate parameter for wastewater treatment plants (WWTPs), but in South Africa and neighbouring Namibia it is used extensively [9] [29]
The Beaufort West Water Reclamation Plants (WRPs) for potable drinking water purposes COD maximum concentration requirement from the WWTP is the DWAF general limit of 75 mg/l which is less stringent compared to the Goreangab WRP [32] [33]

Summary

Introduction

The increase in demand of water because of the requirements for human consumption, agriculture, mining and industrial development complicated by inaccurate pre-empting of impacts of climate change makes a search for alternative water sources. Municipal wastewater effluent would be a feasible alternative water source as it is available throughout the year, and would reduce the demand for conventional source water. Existence or nonexistence of an environmental buffer by default or design differentiates between direct and indirect reuse This buffer is a water body or aquifer, perceived by the public as natural which can serve to sever the connection between water and its history and based on its attributes removes and/or dilutes contaminants by providing residence time [1] [2] [3] [4]. Worldwide main reuse applications of municipal wastewater are agricultural and urban irrigation, non-potable reuse (e.g. toilet flushing, mining and industrial applications) and rarely for DPR [5]. The dynamics of climate and geology, water availability, population growth and urbanization, industrialization, economic growth and perceptions on wastewater reuse determine the type of wastewater reuse option for an individual country [1] [4]

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