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Bioreactors — Planning and design

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Footprint is scalable and bioreactor beds as big as 150m in length have been constructed.

There is no set width for bioreactor walls, but the width of an excavator bucket (approximately 1m) can be cheap and effective. Walls can be any length and are usually constrained by available land.

Bioreactors consistently removing 100% of the nitrate load under extended overly long retention times resulted in sulfate reduction and possible formation of methyl mercury. Residence times should therefore be managed to avoid this[1][3][4].

Site selection

Walls can be placed at the edge of field to avoid loss of productive land.

Beds are connected to tile drains or open drains and can be located inline (within the drain) or offline.

Before deciding on a site or constructing a wall, survey the soil to slightly deeper than the proposed depth of the wall, and ensure the texture (and permeability) profile is suitable[2].

Design requirements

  • Must be designed to connect with local hydrology.
  • Sufficient volume of carbon source to remove the nitrate present in the water, based on typical removal rate of 5g N m-3 d-1.
  • Suitable location on site – edge of field, or adjacent to or in stream/drain.
  • Careful consideration of the design of inlet and outlet structures in bioreactor beds to maintain water levels and anoxic conditions for denitrification; minimise dead spots (i.e. short-circuiting of water) within the bioreactor; and provide a mechanism for overflow of excess water.


In addition to the standard disclaimer located at the bottom of the page, please note the content presented is based on published knowledge of treatment systems. Many of the treatment systems described have not been trialled in different regions or land uses in Queensland. The information will be updated as new trials are conducted and monitored. If you have any additional information on treatment systems or suggestions for additional technologies please contact us using the feedback link at the bottom of this page.


  1. ^ Christianson, LE & Schipper, LA (2016), 'Moving Denitrifying Bioreactors beyond Proof of Concept: Introduction to the Special Section', Journal of Environmental Quality, vol. 45, pp. 757-761.
  2. ^ Queensland Department of Agriculture and Fisheries (2018), Bioreactors: key aspects for effective design, operation and monitoring - Interim guideline for bioreactor trials July 2018. [online], Queensland Department of Agriculture and Fisheries, Queensland. Available at:
  3. ^ Schipper, L, Robertson, WD, Gold, AJ, Jaynes, DB & Cameron, SC (2010), 'Denitrifying bioreactors—An approach for reducing nitrate loads to receiving waters', Ecological Engineering, vol. 36, pp. 1532-1543.
  4. ^ Weigelhofer, G & Hein, T (2015), 'Efficiency and detrimental side effects of denitrifying bioreactors for nitrate reduction in drainage water', Environmental Science and Pollution Research, vol. 22, pp. 13534-13545.

Last updated: 5 October 2018

This page should be cited as:

Department of Environment and Science, Queensland (2018) Bioreactors — Planning and design, WetlandInfo website, accessed 13 May 2021. Available at:

Queensland Government
WetlandInfo   —   Department of Environment and Science