Abstract
M.Ing. (Civil Engineering)
To relieve the extreme pressure placed on overburdened water and wastewater infrastructure, the reuse of light wastewater was identified as a possible source of water supply for non-potable applications. The light wastewater discharge intercepted on-site can be recycled, treated and thereafter distributed to fixtures for agricultural, sanitation and gardening based activities. Sources for this light wastewater stream includes bathroom showers, bath tubs, hand wash basins including that of kitchens, laundry and washing machine outflows of recyclable quality. This type of re-usable water is called greywater (GW). This on-site re-use concept has potential to offer greater potable water savings if correctly implemented. For the purpose of this research, this particular type of waste stream excluding the kitchen and laundry discharge was the water source considered for the supply to this greywater treatment plant (GWTP). In 2009, the Water Research Commission (WRC) funded a greywater pilot study in a joint venture between the University of Witwatersrand (WITS) and the University of Johannesburg (UJ). Over the last few years, this project had progressed with new outcomes each year. The pilot GWTP at Unit 51, Student Town, UJ in Auckland Park was used for the purpose of this study. The selected reuse application for the GW effluent was for toilet flushing. GW was supplied to two toilets in a residential student complex housing 16 female and male students i.e. 8 students on each floor. The highlights of the WRC study included: a lack of satisfactory treatment efficiency and a well-defined protocol to address the problems associated with the slightly poor quality of effluent produced (i.e. unpleasant odours, greyish appearance and the unacceptable microbial count). Determining and addressing the user perceptions and user education about GW usage, respectfully, was a significant component in the successful management of the project. In this report, a practical evaluation of three crucial components of the GWTP was completed. These three components viz. treatment efficiency, user perceptions and quality standards, were common aspects of concern for existing decentralised GWTP’s within residential or small commercial stands.