Orica's Groundwater Treatment Plant and use of Renewed Water at Botany, NSW
Contamination of groundwater at Botany Industrial Park was first identified in a survey conducted in 1990. A range of chlorinated hydrocarbons were identified, with the main contaminant being ethylene dichloride.
Orica’s Groundwater Treatment Plant (GTP) is part of Orica’s $167 million (before tax) commitment to address its groundwater issues at Botany. Groundwater extraction pumps (114) have been installed to intercept flowing groundwater before it reaches Botany Bay. The GTP extracts and destroys the contaminants and purifies the water for industrial and commercial reuse. The GTP has the capacity to process 15 megalitres a day of groundwater - equivalent to 1% of Sydney’s total daily water usage - and use of the Renewed Water will significantly benefit Sydney’s water supply.
The GTP air strips volatile organic compounds (VOCs) from the groundwater. The contaminated ‘off-gas’ enters a thermal oxidiser where the VOCs are destroyed. Heat is recovered from the gases before passing through a quencher, HCl absorber and caustic scrubber. Water ‘stripped’ of VOCs flows to an Actiflo where Iron, Aluminium and some organics are removed by flocculation. The water passes through mulitmedia filters and then Granular Activation Carbon (GAC) units, which support biological growth to effectively remove non-volatile organics such as chlorinated phenols. The water is dosed with chloramine and processed by Reverse Osmosis. Chloramines have proven effective in mitigating microbial fouling on RO cartridge filters and RO membranes.
The paper elaborates on key challenges, solutions implemented and how the Renewed Water will be used by industrial customers.