Perth Laboratory – Public Seminar Series 2009

National Water Week Event

Suitability of Industrial By-Products for Water Treatment in the Swan-Canning Catchment

Dr Laura Wendling
CSIRO Land and Water | Water for a Healthy Country Flagship

Thursday 22 October 2009 at 3.30pm, CSIRO Auditorium

PowerPoint Presentation
(2.3 MB)

Abstract

Extensive modification of the Swan-Canning catchment due to urbanisation and intensive agriculture has resulted in the accumulation of a substantial inventory of nutrients. Effective removal of nutrients and other contaminants such as trace metals and pathogens from the catchment is pivotal to long-term management of the adjoining Swan-Canning Estuary. The use of abundant, low-cost industrial by-products as filtration media offers a potentially cost-effective solution. Recent trials to attenuate nutrients that enter the Swan Canning Estuary in drains that intercept groundwater have shown that organic forms of nutrients, which often comprise the main fraction of total nitrogen and phosphorous, are not removed using traditional remediation techniques and treatment media. The objective of this study was to investigate the reuse of high volume, low value, mineral-based by-products in in-situ water treatment schemes to manage dissolved organic carbon (DOC) and nutrients within the Swan Coastal Plain.

A series of laboratory column sorption experiments were conducted to examine the removal of nutrients and DOC from surface waters using 24 different mineral-based by-products or mixtures as sorbents. Water from Ellen Brook, a DOC and nutrient-rich tributary within the upper Swan River catchment, was pumped through the columns in a saturated up-flow mode at a constant flow rate. Eluents from experimental columns were analysed for pH, alkalinity, nutrient and DOC content, major cations and anions, and selected metals.

Of all by-products examined, NUA, a by-product of heavy mineral processing, displayed the most potential in terms of application to water treatment schemes, exhibiting good removal of all analytes investigated. Over nearly 180 d, a column containing NUA as the sorptive phase yielded more than a 39% decrease in DOC. The NUA also demonstrated excellent capacity for sorption of nitrogen removing 79% of nitrate and 77% of ammonia. The NUA was particularly effective in the removal of phosphate from influent water, exhibiting more than 95% phosphorous removal. The uptake capacity of NUA for phosphate was not reached during the experiment and trends did not indicate that the NUA was approaching capacity. Importantly, NUA shows particular promise as an environmental amendment for the treatment of soils and waters containing high concentrations of phosphorous, nitrogen and DOC. If applied within nutrient intervention structures, NUA has the potential to assist in the attenuation of eutrophication in freshwater systems. One such system is Ellen Brook, a tributary to the upper Swan River, which is estimated to supply 60% of phosphorous to the Swan-Canning Estuary. Effective attenuation of this major nutrient source, which is now theoretically possible, would constitute the largest ever single reduction in nutrients to the Swan-Canning Estuary.

In the specific context of the Swan Coastal Plain, a combination of materials, specifically NUA alone or blended with one or more additional by-products, could be used as a broad spectrum nutrient and DOC removal medium in nutrient intervention schemes subject to optimisation of design parameters. Where acidity derived from anthropogenic or acid sulphate soils are also present other materials such as steelmaking by-product, red sand or calcined magnesia may also be incorporated to attenuate acidity whilst maintaining nutrient and DOC uptake capacity. Additional investigation is required to evaluate NUA or NUA-blend performance in field-based trials.

About the speaker

Dr Laura Wendling is research scientist within the Urban and Industrial Water program of CSIRO Land and Water. Her interest in environmental chemistry was encouraged by an undergraduate research assistantship with an aquatic ecology research group at Iowa State University. Following six-months spent as an international exchange student at Curtin University of Technology in Perth, Western Australia, she completed a Bachelor of Science degree in Biology, a Master of Science degree in Soil Science and a Doctor of Philosophy degree in Soil Science (Environmental Biogeochemistry).

Dr Wendling’s dissertation research investigated geochemical effects on caesium mobility and phytoavailability in soils at the Idaho National laboratory in Idaho, USA. After completing a post-doctoral appointment at the United States Department of Agriculture-Agricultural Research Service she commenced employment with the CSIRO Land and Water in 2005.

Dr Wendling is currently working to identify industrial, mining and mineral processing by-products “fit for purpose” for specific environmental applications. She is also investigating a proposed novel technique to modify the treatment of mineral processing wastes to obtain a mineral-based material which is stable, less reactive, and more suitable for long-term storage.

This research is being delivered through CSIRO’s Water for a Healthy Country and Minerals Down Under flagships.

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