IMPROVING A GREYWATER REUSE UNIT FOR THE PURPOSE OF TOILET FLUSHING IN A STUDENT RESIDENCE AT THE UNIVERSITY OF JOHANNESBURG, SOUTH AFRICA

摘要

Any type of wastewater generated from domestic use (excluding toilet wastewater), can be defined as greywater but for the purpose of this study greywater is defined as only bath, hand basin and shower water. A small greywater treatment plant was installed at a 16 student occupant residence for the purpose of utilising greywater for toilet flushing. Greywater reuse applications are extremely dependent on the wastewater source, composition and quality. Environmental conservation and human wellbeing (i.e. user health, education and comfortability), are major dynamic principles to consider. Proficient regulatory and governing framework for greywater quality and reuse does not currently exist in South Africa and therefore the perceptions of the occupants utilising the greywater unit were tested. Quality parameters such as pH, temperature and turbidity are vital tests methods which have also been used for sample analysis, yet the alerting parameter was pathogenic presence. E.Coli and Total Coliform microbials within the greywater was efficiently monitored and treated to some extent. Perception surveys from the occupants indicated that issues such as colour, odour and visual appearance was important to the users and therefore the small greywater treatment plant was altered to enhance the aesthetic nature of the greywater. The design and installation of a practical and low maintenance sand filter for the operational greywater plant was conducted at the unit. Sand filtration reduced turbidity by ± 40 NTU and the filter media amplified the pathogenic count in the effluent. Sand filtration proved to be more effective (53.2 % efficient) for turbidity reduction as compared to chlorination (39.1 %). In anticipation, the effluent visually improved, although a degraded biological quality had occurred. The data identified that sand filtration and chlorination treatment options could be used together to achieve higher quality of greywater as well as the aesthetic nature of the greywater. This progressive performance evaluation will hopefully present insight to water regulators in South Africa to establish regulatory and a governing framework for greywater quality and reuse.