Residual food waste from cans/bottles, antifreeze, emulsified oils
Most forms of COD are water soluble
Biochemical oxygen demand (BOD) – a slightly more refined measure of water quality constituents than COD. BOD measures the amount of organic components that can be biologically degraded in a sample.
Dissolved oxygen (DO) – a measure of oxygen dissolved in water.
None. Dissolved oxygen water quality criteria depend upon natural stream temperature and dissolved oxygen level. [i]
High levels of COD in water often correlate with threats to human health including toxic algae blooms bacteria from organic wastes and seafood contamination. [ii]
High COD levels decrease the amount of dissolved oxygen available for aquatic organisms. Low (generally under 3 mg/L) dissolved oxygen, or “hypoxia,” causes reduced cell functioning, disrupts circulatory fluid balance in aquatic species and can result in death of individual organisms[iii] as well as large “dead zones”[iv]. Hypoxic water can also release pollutants stored in sediment.[v]
Chemical oxygen demand (COD) is often used to measure organic matter in wastewater, treated effluent, and receiving waters. Although COD measures more than organic constituents, the organic fraction usually predominates and is the constituent of interest.[vi] Chemical oxygen demand was developed as an alternative to the more lengthy BOD analysis.
Sources of COD in stormwater are varied. However, soluble organic compounds are most likely to contribute to escalated COD concentrations. Residual food waste from bottles and cans, antifreeze, emulsified oils are all high in COD and are common sources of COD for industrial stormwater. A typical COD concentration for soda and beer is about 100,000 mg/L.
The StormwateRx Aquip® industrial filtration system uses an innovative recirculating enhanced sand filtration process to effectively remove COD (emulsified oil, sugar from soda pop and beer) from industrial stormwater runoff
Left: Sample of cutting-oil laden stormwater
Right: same water after Aquip COD treatment.*
The Purus™ Stormwater Polishing System (previously known as the AquiPlus) provides the most advanced level of stormwater treatment, and is designed for challenging stormwater conditions or targeted pollutant removal. Purus reduces dissolved zinc and other metals to the parts per billion (ppb) range as well as eliminating bacteria such as E. coli and reducing turbidity to single digit NTU standards.
*Results after 20 circulations through the Aquip® system. Typical results show 50% reduction in COD after the fi rst circulation. Actual results may vary.
[i] U.S. EPA, National Recommended Water Quality Criteria, http://www.epa.gov/waterscience/criteria/wqctable/index.html#U (last visited July 7, 2010).
[ii] See National Science & Tech. Council, An Assessment of Coastal Hypoxia and Eutrophication in U.S. Waters, 2 (2003) available at http://oceanservice.noaa.gov/outreach/pdfs/coastalhypoxia.pdf.
[iii] Ambient Aquatic Life Water Quality Criteria for Dissolved Oxygen (Saltwater): Cape Cod to Cape Hatteras, 65 Fed. Reg. 71317, 71318 (Nov. 30, 2000).
[iv] Ecological Society of America, Hypoxia http://www.esa.org/education_diversity/pdfDocs/hypoxia.pdf (last visited Aug. 11, 2010).
[v] Ecological Society of America, supra.
[vi] Standard Methods, 5-14(Andrew Eaton, et al. eds., 21st ed. 2005).
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