Groundwater recharge with secondary treated wastewater

Ford, Anthony John (1983) Groundwater recharge with secondary treated wastewater. Masters by Research thesis, Murdoch University.

Abstract

The infiltration of treated wastewater into soil is a generally accepted method of effluent disposal and groundwater recharge. In Perth, Western Australia, a pilot recharge scheme has been commissioned to test the feasibility of using secondary treated wastewater to recharge the extensive shallow unconfined aquifer of the surrounding coastal plain. This aquifer is predominantly comprised of Bassendean sand, a leached silicaceous sand of low adsorption capacity and high hydraulic conductivity. This study investigated the feasibility of utilising red mud, a byproduct of the Bayer process for extraction of alumina from bauxitic ores, as an additive to Bassendean sand to improve its ability to retain and remove pollutants from the recharging wastewater, with particular regard to the removal of nitrogen.

The principal mechanisms of nitrogen removal in soil systems during recharge are transport of solutes, adsorption and nitrification of ammonium, leaching of nitrate resulting from nitrification, and denitrification of nitrate being leached and contained in solution. These mechanisms may be expressed by mathematical expressions, which can be integrated to form a model for the overall process of nitrogen removal. From this model a set of optimum conditions for nitrogen removal can be derived for a given effluent quality, including desirable soil characteristics, operating regime, and temperature.

The red mud/Bassendean sand mixture used in the column experiments was selected to satisfy these criteria as far as possible. Operation of experimental columns using treated wastewater from the Canning Vale WWTP proceeded under three flooding regimes, and the efficiency of nitrogen removal during column operation was assessed in relation to removal mechanisms and to the criteria determined from the model.

It was concluded that the red mud/Bassendean sand mixture under investigation was satisfactory for the removal of nitrogen under conditions of recharge, provided an additional carbon source was available and infiltration rate was not greater than about 0.3 m/day.

Item Type:	Thesis (Masters by Research)
Murdoch Affiliation(s):	School of Environmental and Life Sciences
United Nations SDGs:	Goal 12: Responsible Consumption and Production
Notes:	A digital copy of this thesis is not available. Your library can request a copy from Murdoch University Library via Document Delivery. A fee applies to this service.
Supervisor(s):	Ho, Goen, Newman, Peter and Mathew, Kuruvilla
URI:	http://researchrepository.murdoch.edu.au/id/eprint/38186

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