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Updated: Jul 20, 2026
08:49
Vegetated Treatment Systems for Removing Contaminants Associated with Surface Water Toxicity in Agriculture and Urban Runoff
Published on: May 15, 2017
Selenium and nitrate removal from agricultural drainage using the ALWPS technology
F B Green1, T J Lundquist, N W T Quinn
1Hydroecological Engineering & Advanced Decision Support Group, Center for Environmental Biotechnology, Earth Sciences Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, MS 70A-3317, Berkeley, CA 94720, USA. FBGreen@lbl.gov
Summary
Selenium removal from agricultural drainage is critical for compliance with discharge limits. An Algal Bacterial Selenium Removal (ABSR) facility achieved over 77% soluble selenium removal, with further improvements anticipated.
Area of Science:
- Environmental Engineering
- Environmental Microbiology
- Water Treatment Technologies
Background:
- California and U.S. EPA established Monthly Maximum Discharge Limits (MMDL) for selenium due to avian teratogenesis at Kesterson Reservoir.
- Farmers and drainage districts in the San Joaquin Valley must reduce selenium in irrigation discharge to meet MMDL and future Total Maximum Discharge Limits (TMDL).
- Advanced Integrated Wastewater Pond Systems (AIWPS) technology offers a potential solution for selenium reduction.
Purpose of the Study:
- To evaluate the effectiveness of an Algal Bacterial Selenium Removal (ABSR) facility in reducing selenium concentrations in irrigation drainage.
- To compare different operational modes and bacterial substrates within the ABSR system.
- To assess the removal rates of nitrate and selenium.
Main Methods:
- Design and construction of a 0.4-hectare ABSR facility using AIWPS technology, featuring Reduction Ponds (RP) and High Rate Ponds (HRP).
- Integration of Dissolved Air Flotation (DAF) and slow sand filters for particulate selenium removal.
- Operation of two identical systems with varied modes and bacterial substrates, utilizing harvested microalgae as a carbon source.
Main Results:
- Achieved mass removals of total soluble selenium exceeding 77% over a three-year operational period.
- Demonstrated removal of nitrate and selenate via bacterial reduction (assimilatory and dissimilatory) and algal assimilation of nitrate.
- Ongoing investigations focus on particulate selenium removal to potentially exceed 90% overall selenium reduction.
Conclusions:
- The ABSR facility effectively reduces soluble selenium concentrations in irrigation drainage.
- The system shows promise for enabling compliance with regulatory discharge limits for selenium.
- Further optimization for particulate selenium removal is expected to enhance overall treatment efficiency.
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