Investigations into the performance of bio-sand filters to treat domestic greywater for the purpose of reuse for toilet flushing and irrigation

Ronan Costello, Purdue University

Abstract

It is common practice in developed world dwellings to always treat water to a potable standard despite the majority of it being used for non-potable uses. Correspondingly, all wastewater is too often considered equal in how it is dealt with, despite the fact that greywater has a lesser level of contamination than black water (Mourad et al., 2011). This suggests that money is being wasted in over-treating water before and after its use. Systems of water treatment by biological and physical means only without any power supply are commonly designed for developing countries. Domestic water conservation systems are not generally attractive to consumers in developed countries as they do not often prove economically viable. This research examined a low-tech, low cost technology and addressed if it could be successfully implemented into a domestic setting of a developed country to conserve water by reuse. The study addressed methods of conserving water by the design of infrastructure that has a limited effect on the user's experience, i.e. conservation through alterations in system design, rather than concentrating on influencing behavioural changes to conserve water. In an area where public acceptance is an issue, a system that conserves water without the user having to unwillingly change their behaviour may boost the attraction of the system. The bio-sand filtration equipment employed in this study has previously been utilized for research regarding water treatment for potable means in a developing world setting, which yielded successful results. Largely the same apparatus was used for this study, with the reused water being greywater and the treated water intended for toilet flushing and domestic irrigation. The equipment did not perform as required in order to yield positive conclusions about the ability of bio-sand filtration to treat greywater to a suitable non-potable standard. Clogging prevented sufficiently high enough flow rates for the filters to be considered for practical use. Influent turbidity of the greywater was at too high a level to be treated effectively with the apparatus examined. Anaerobic conditions were assumed to have developed in the filters, effecting the biological treatment of the greywater. The compositions of the effluents were not at the required quality level to be considered for practical use for the outlined purposes.

Degree

M.S.

Advisors

Dyrenfurth, Purdue University.

Subject Area

Water Resource Management

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