Iron

Chemical symbol/abbreviations:

Fe, Fe2+, Fe3+

Form commonly found in stormwater:

Dissolved iron as Fe2+ (ferrous iron) and Fe3+ (ferric iron), particulate iron

Adverse human impacts:

Although iron is an essential mineral, diseases of aging such as Alzheimer’s disease, other neurodegenerative diseases, arteriosclerosis, diabetes mellitus, and others have been linked to excess iron intake.[i]
Excess iron in drinking water can produce an unpleasant taste and stain home fixtures.[ii]

Adverse impacts on the environment:

Iron is an essential dietary mineral for fish and other animals as it is for humans.  Iron toxicity has been observed in certain fish species at concentrations in excess of 1,380 mg iron/kg in their diet.[iii]
Iron can also cause algae blooms, which create biological oxygen demand[iv] can kill fish, smother aquatic plants and produce potent neurotoxins.[v]

Even low concentrations of iron (0.1-1.0 mg/L) may cause nuisance algae species to replace inoffensive species[vi]

Stormwater Treatment to Remove Iron

Iron in Stormwater FAQs

How does iron get into stormwater runoff?2019-07-26T13:54:30+00:00

Iron is white, silvery metal that oxidizes quickly when encountering water and oxygen. Dissolved iron as ferrous iron (Fe2+), ferric iron (Fe3+) and particulate iron, are forms commonly found in stormwater. Naturally present in groundwater, iron in these forms can make its way into the environment through stormwater in contact with groundwater and surface water.[xi] For example, drainage from abandoned mines can deliver toxic levels of iron into rivers and streams.[xii] Elevated levels of iron in stormwater can be caused by rusting steel in constant contact with standing water.

Iron ore (image courtesy of Wikipedia)

Why should iron be removed from industrial stormwater runoff?2019-07-26T13:55:55+00:00

Iron should be removed from stormwater because excessive amounts in drinking water and the environment can cause harm to human health and wildlife habitat. Although iron is an essential mineral, diseases of aging such as Alzheimer’s disease, other neurodegenerative diseases, arteriosclerosis, diabetes mellitus, and others have been linked to excess iron intake.[i] High concentrations of iron in drinking water can produce an unpleasant taste and stain home fixtures.[ii]

While iron in in trace amounts is an essential dietary mineral for fish and other animals as it is for humans, iron toxicity has been observed in certain fish species at concentrations in excess of 1,380 mg iron/kg in their diet.[iii]

Indirectly, iron can kill fish by causing algae blooms, which create biological oxygen demand[iv], smother aquatic plants and produce potent neurotoxins.[v] Even low concentrations of iron (0.1-1.0 mg/L) may cause nuisance algae species to replace inoffensive species[vi], adversely affecting fish habitats.

How is iron removed from stormwater runoff?2019-07-26T13:53:34+00:00

Because iron in stormwater primarily exists in solid, particulate form, passive media filtration and polishing can be used to effectively remove particulate iron from stormwater prior to discharge to help facilities meet benchmarks or NALs. The Aquip passive media filter offers an enhanced level of iron removal from stormwater. Learn more about our stormwater media filtration technologies.

Background:

Iron is white silvery metal that oxidizes quickly when coming into contact with water and oxygen. It is the fourth most abundant element in the earth’s crust, making up about 5% of its mass. It is soft, malleable, and strongly magnetic. Within humans and all other animals, iron plays a crucial role of carrying oxygen within the blood in the form of hemoglobin.1

Pure iron is not often used to manufacture products. Iron is much stronger and more useful when alloyed with carbon. Wrought iron and steel are examples of such iron alloys with carbon contents of 0.2 – 1.5%.[viii] Due to its abundance and mechanical strength, iron in the form of steel is used as a common building material for anything from bicycles to bridges.

In 2002, eleven open pit mines were responsible for supplying 99% of the iron ore produced in the United States. The U.S. produced 5% of the world’s iron supply while consuming about 7%.[ix] The world production of iron ore in 2004 was 1.4 billion tons. China, Brazil, and Australia generated 57% of the global production.[x]

U.S. EPA recommended water quality criteria:

[vii]

Freshwater – Aquatic Organisms (Total Recoverable; pH 6.5-9.0)Saltwater– Aquatic OrganismsHuman Health for the consumption of
Acute (µg/L)Chronic (µg/L)Acute (µg/L)Chronic (µg/L)Water + Organism (µg/L)Organism Only (µg/L)
na1000nana300na

Iron is transported into the environment through water typically. It is naturally present in groundwater.[xi] However, drainage from abandoned mines can deliver toxic levels of iron into rivers and streams.[xii] Elevated levels of iron in stormwater can be caused by rusting steel in constant contact with water.

Appendices

[i] George Brewer, Risks of Copper and Iron Toxicity during Aging in Humans 23 Chem. Res. Toxicol. 2, 319–326 (Dec. 2009).

[ii] Illinois Dept. Public Health, Iron in Drinking Water (1999) http://www.idph.state.il.us/envhealth/factsheets/ironFS.htm (last visited July 25, 2019).

[iii] National Research Council Subcommittee on Fish Nutrition, Nutrient Requirements of Fish 19 (1993) available at http://www.nap.edu/openbook.php?record_id=2115&page=19 (last visited July 25, 2019).

[iv] Florida Dept. of Environmental Protection, EcoSummary BioRecon Report, Camp Five Branch below Camp Five Landfill, Escambia County (Mar. 21, 2002) available at http://publicfiles.dep.state.fl.us/DWRM/eco/Camp%205%20Landfill%20Branch.pdf (last visited July 25, 2019).

[v] Queensland Univ. of Tech., Is Iron from Soil a Factor in Algae Blooms? ScienceDaily, Feb. 4, 2010, http://www.sciencedaily.com/releases/2010/01/100128101855.htm; Brandon Keim, Climate Quick Fix Could Create Toxic Algae Blooms, WIRED, Mar. 16, 2010, http://www.wired.com/wiredscience/2010/03/neurotoxic-geoengineering/ (last visited July 25, 2019).

[vi] Stephen Morton & Terrence Lee, Algal Blooms – Possible Effects of Iron 8 Environ. Sci. Technol. 7, 673 (1974) available at http://pubs.acs.org/doi/abs/10.1021/es60092a005 (July 25, 2019).

[vii] U.S. EPA, National Recommended Water Quality Criteria, https://www.epa.gov/environmental-topics/water-topics  (last visited July 26, 2019).

[viii] HyperPhysics, Iron http://hyperphysics.phy-astr.gsu.edu/hbase/pertab/fe.html#c3 (last visited July 26, 2019).

[ix] U.S. Geological Survey, Minerals Commodity Summaries-Iron Ore (2019) available at http://minerals.usgs.gov/minerals/pubs/commodity/iron_ore/feoremcs05.pdf (last visited July 25, 2019)

[x] U.S. Geological Survey, Minerals Commodity Summaries-Iron Ore (2019) available at http://minerals.usgs.gov/minerals/pubs/commodity/iron_ore/feoremcs05.pdf (last visited July 25, 2019).

[xi] The Earth’s Ferrous Wheel, The Nature Education Knowledge Project https://www.nature.com/scitable/knowledge/library/earth-s-ferrous-wheel-15180940 (last visited July 26, 2019).

[xii] U.S. Geological Survey, Water, How does mine drainage occur? https://www.usgs.gov/faqs/how-does-mine-drainage-occur?qt-news_science_products=0#qt-news_science_products (last visited July 26, 2019).

The StormwateRx Aquip® industrial filtration system uses an innovative enhanced sand filtration process to effectively remove soluble and insoluble aluminum and other metals as well as oils, suspended solids, organics and nutrients from industrial stormwater runoff.

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.

2019-07-26T13:45:18+00:00