Managing the reverse osmosis concentrate from the Western Corridor Recycled Water Scheme

Abstract

The Western Corridor Recycled Water Scheme consists of three advanced water treatment plants (AWTPs), with the combined capacity to recycle 232 ML/d. Each AWTP process consists of pre-treatment, microfiltration (MF), reverse osmosis (RO), UV/peroxide advanced oxidation and chlorination. A key objective of the project is to improve the environmental health of regional waterways, particularly in relation to nutrient discharges. Reverse osmosis processes produce a concentrate stream (ROC), which is the main reject stream of the AWTPs. Options for management of ROC were assessed, and ultimate disposal to nearby waterways was the only feasible option identified. ROC flows for the scheme total 41 ML/d at full capacity, divided between the three AWTPs. The contaminants in this stream are generally 6 to 7 times more concentrated than in the feed water. Environmental risks were identified due to potential increased toxicity associated with these higher concentrations, which were exacerbated due to chlorine and ammonia dosed in the AWTP process. Target ROC contaminants have been identified as nitrogen, phosphorus, ammonia, metals and chlorine. The paper presents the selected toxicity management and nutrient reduction strategies for each AWTP, and the results of full-scale operation to date are also summarised.

Experiences in Using MBBR and Denitrification Filters for Nitrogen Removal from Saline Wastewater

“…A description of the overall goals of the water recycling project and the issues evaluated during process selection and system design are provided in Wallis-Lage et al (2008) and Solley et al (2010).…”

In vitro bioassays to evaluate complex chemical mixtures in recycled water

“…Increasingly, water providers are considering alternative water resources, such as recycled water for potable reuse applications (Asano and Levine, 1996; Leverenz et al, 2011; Solley et al, 2010). Water reuse often utilize advanced oxidation processes (AOPs), including ultraviolet light (UV) with hydrogen peroxide and ozone-based technologies.…”

Technologies to Recover Nutrients from Waste Streams: A Critical Review

“…Other advantages are ease of operation, flexibility to changing conditions and low capital cost to reduce effluent P concentration to less than 1 mg L -1 . 39 Disadvantages associated with chemical accumulation by precipitation include high operating costs, increased salinity in the effluent (mainly as chloride or sulfate), increased sludge production (up to 35 volume percent), 39 the addition of heavy metals present in the raw coagulant 40 and inhibitory effects on the biological process such as anaerobic digestion following the coagulation process. 41 It should be acknowledged that the sludge produced from chemical accumulation techniques, particularly with aluminium and iron coagulation, is agronomically less useful due to low bioavailability of the strongly bound P. 42 Consequently, if this accumulation technique is to be applied as part of an overall nutrient recovery strategy, a subsequent release step can be essential to improve bioavailability of the bound nutrients.…”