Treat fine sediments, nutrients and other toxicants

Fine sediments, nutrients bound to particles (particulate nutrients), dissolved nutrients (especially nitrogen) and toxicants (including pesticides, herbicides, heavy metals) can be exported from agricultural areas through surface runoff or leaching/deep drainage into groundwater. They can be transported long distances and can cause eutrophication and algal blooms, alter primary productivity and food webs and kill sensitive plants and animals in waterways, coastal wetlands and marine environments, including the Great Barrier Reef[8]. Treatment systems can remove these pollutants from surface run-off or groundwater through a range of physical, chemical and biological processes and need to be specifically designed to maximise the treatment processes for the target pollutant. Dissolved inorganic nitrogen (DIN) is the main nutrient of concern for intensive agriculture but it can be removed by denitrification and other processes in treatment systems  and natural vegetated wetlands[1][3]. These processes are explained on the nitrogen conceptual model pages.

Quick facts

Denitrification

is the dominant nitrogen removal process in wetlands[2]. For more see here.

Which treatment systems can I use?

• Algae treatment
• Bioreactor
• Floating wetland
• High efficiency sediment basin
• Recycle pit
• Treatment wetland
• Vegetated drains

Treatment systems for agriculture – Treat fine sediments, nutrients and other toxicants

Select from the tabs below

• Overview
• Understand system
• BMP
• Treat coarse sediment
• Treat nutrients, toxicants

Numerous physical, biological and chemical processes act to remove, transform, sequester and adsorb/absorb fine sediments, nutrients and other toxicants (Table 1). Individual treatment systems are designed to enhance natural physical, biological and chemical treatment processes, targeted at specific types of pollutants (Table 2) and use the specific components and processes of these systems to do so. Understanding the treatment processes and the nature of the pollutant helps to identify what features (components and processes) are needed in the treatment system to effectively remove the target pollutant/s. For example, in the case of herbicides the physiochemical properties (e.g. the soil adsorption coefficient Koc) and half-life of each chemical will determine the most appropriate treatment processes[7].

NB: pesticide removal is highly variable depending on the type of pesticide and the system design.

Table 1 on the main treatment system page provides more details on main treatment processes, type of flow treated and land uses treatment systems have been primarily used in.

References

1. ^ Adame, Franklin, H, Waltham, NJ, Rodriguez, S, Kavehei, E, Turschwell, MP, Balcombe, SR, Kaniewska, P, Burford, MA & Ronan, M (2019), 'Nitrogen removal by tropical floodplain wetlands through denitrification', Marine and Freshwater Research, vol. doi.org/10, no. September.
2. ^ Bachand, PAM & Horne, AJ (2000), 'Denitrification in constructed free-water surface wetlands: II. Effects of vegetation and temperature', Ecological Engineering, vol. 14, pp. 17-32.
3. ^ Kavehei, E, Hasan, S, Wegscheidl, C, Griffiths, M, Smart, JCR, Bueno, C, Owen, L, Akrami, K, Shepherd, M, Lowe, S & Adame, MF (22 November 2021), 'Cost-Effectiveness of Treatment Wetlands for Nitrogen Removal in Tropical and Subtropical Australia', Water. [online], vol. 13, no. 22, p. 3309. Available at: https://www.mdpi.com/2073-4441/13/22/3309 [Accessed 21 December 2021].
4. ^ Melbourne Water (28 September 2017), Constructed wetlands. [online], Melbourne Water. Available at: https://www.melbournewater.com.au/planning-and-building/developer-guides-and-resources/standards-and-specifications/constructed-0 [Accessed 27 February 2018].
5. ^ Minnesota Pollution Control Agency (14 July 2017), Processes for removing pollutants from stormwater runoff. [online], Minnesota Pollution Control Agency. Available at: https://stormwater.pca.state.mn.us/index.php?title=Processes_for_removing_pollutants_from_stormwater_runoff [Accessed 29 July 2018].
6. ^ Osmond, DL, Line, DE, Gale, JA, Gannon, RW, Knott, CB, Bartenhagen, KA, Turner, MH, Coffey, SW, Spooner, J, Wells, J, Walker, JC, Hargrove, LL, Foster, MA, Robillard, PD & Lehning, DW (1997), 'WATERSHEDSS: Water, Soil and Hydro-Environmental Decision Support System', Journal of the American Water Resources Association. [online], vol. 33, no. 2, pp. 327-341. Available at: https://www.epa.gov/ceam/watershedss.
7. ^ Vymazal, J & Brezinova, T (2015), 'The use of constructed wetlands for removal of pesticides from agricultural runoff and drainage: a review', Environment International, vol. 75, pp. 11-20.
8. ^ Waterhouse, J, Schaffeike, B, Bartley, R, Eberhard, R, Brodie, J, Star, M, Thorborn, P, Rolfe, J, Ronan, M, Taylor, B & Kroon, F (2017), Scientific Consensus Statement. [online], The State of Queensland, Brisbane. Available at: https://www.reefplan.qld.gov.au/__data/assets/pdf_file/0029/45992/2017-scientific-consensus-statement-summary.pdf.
9. ^ Wong, T, Fletcher, T, Duncan, H, Coleman, J & Jenkins, G (2002), 'A model for urban stormwater improvement conceptualization', Global Solutions for Urban Drainage, pp. 8-13.

Last updated: 2 October 2022