Zinc

Chemical symbol/abbreviations:

Zn, Zn2+

Form commonly found in stormwater:

dissolved zinc as Zn2+, particulate zinc.

Adverse human impacts:

Zinc is an important dietary element, but concentrations above 5 mg/L can impart an unpleasant taste to water.[i]
Exposure to large amounts of zinc can cause stomach cramps and anemia, and also decrease good cholesterol.[ii]

Adverse impacts on the environment:

In marine waters, aquatic species suffer acute effects from zinc at 90 μg/L.  Adverse effects of dissolved zinc, including altered behavior, blood and serum chemistry, impaired reproduction, and reduced growth, occur to salmon at very low levels  (5.6 μg/L in freshwater).[iii] In mammals, ingesting large amounts of zinc can cause infertility and underweight offspring.[iv]

Stormwater Treatment to Remove Zinc

Zinc and Stormwater FAQs

How does zinc get into stormwater runoff?2019-07-23T16:17:13+00:00

Zinc is a bluish-white, shiny metal that is typically extracted from ore deep within the earth’s crust.[vi] Zinc is the 24th most abundant element in the earth’s crust. In soil, the average zinc concentration is 64 ppm.[vii] Dissolved zinc (Zn2+) and particulate zinc (Zn), are forms commonly found in stormwater. Zinc in these forms can make its way into waterways and human freshwater drinking sources through stormwater runoff.

Common sources of particulate and dissolved zinc in stormwater runoff are from industrial activities such as metal galvanizing and zinc roofing material. Approximately one-third of metallic zinc is used in galvanizing, a process used to coat steel products for weather resistance.[x] Zinc oxide is also another common compound used as a protectant. Zinc oxide is found in rubber, tires, photocopy paper, paints, enamels, pharmaceuticals, and cosmetics. Zinc is also commonly used as an electrolyte for batteries.

Raw zinc (image courtesy of Wikipedia)

Why should zinc be removed from industrial stormwater runoff?2019-07-23T16:16:12+00:00

Zinc can make its way into drinking water sources and aquatic habitats through stormwater runoff in high enough concentrations to have negative effects on humans and wildlife. Although zinc is an important dietary element for humans, zinc should be removed from stormwater because ingesting large amounts of zinc can cause stomach cramps, anemia and can decrease good cholesterol.[i]

Concentrations of 5 mg/L and up can impart an unpleasant taste to water.[ii] In marine waters, aquatic species suffer acute effects from zinc at 90 μg/L. Adverse effects of dissolved zinc, including altered behavior, blood and serum chemistry, impaired reproduction, and reduced growth, occur to salmon at very low levels (5.6 μg/L in freshwater).[iii] In mammals, ingesting large amounts of zinc can cause infertility and underweight offspring.[iv]

How is zinc removed from industrial stormwater runoff?2019-07-23T16:15:25+00:00

Zinc can be present in stormwater in both particulate and dissolved states. Enhanced, passive media filtration can be used to remove particulate zinc. If further reduction is necessary to remove dissolved zinc, advanced polishing technologies can be added. Both types of BMPs combined in a treatment train will remove total zinc from stormwater prior to discharge to help facilities meet benchmarks or NALs. Learn more about the Aquip passive media filter and the Purus metals polisher combined for an advanced level of zinc removal from stormwater.

How is zinc removed from rooftop runoff?2019-07-23T16:14:34+00:00

Zinc in rooftop runoff is typically found in a dissolved state. Dissolved zinc can be removed from rooftop stormwater runoff by running it through an advanced, polishing media filter connected to a downspout. Our downspout units provide this advanced level of rooftop stormwater runoff treatment. Find out more about our Zinc-B-Gone downspout filtration units.

Background:

Zinc is a bluish-white shiny metal that is typically extracted from ore deep within the earth’s crust[vi]
Zinc is the 24th most abundant element in the earth’s crust. In soil, the average zinc concentrations is 64 ppm.[vii]
Zinc alloys such as brass have been used since 4500 BC, but not until the 1400s in India did metallic zinc come into production.[viii] [ix]
Today zinc is mainly used as a protectant from corrosion or oxidation.  Approximately one-third of metallic zinc is used in galvanizing, a process used to coat steel products for weather resistance.[x] Zinc oxide is also another common compound used as a protectant. Zinc oxide is found in rubber, tires, photocopy paper, paints, enamels, pharmaceuticals, and cosmetics.  Zinc is also commonly used as an electrolyte for batteries.
The United States is the fifth largest zinc producer in the world today creating nine percent of global production.[xi]  Nearly 50% of domestic zinc production is done in Alaska with 47% of the remaining zinc production done in Missouri and Tennessee.[xii] Underground mines are predominantly used for zinc mining.[xiii]

Zinc is often found in the water supply as a dissolved constituent since zinc compounds are highly soluble in water.[xiv] One example is rainwater picking up zinc when coming into contact with galvanized surfaces. Galvanized roofs are a common source of zinc in stormwater. Zinc is also released to the environment through tire wear. Tire tread material contains approximately 1% zinc by weight.[xv]

Power plants are a common source of zinc known as cooling tower blowdown zinc.

U.S. EPA recommended water quality criteria:

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)
12012090817400026000

*Based on hardness value of 100mg/L. Criteria vary with the hardness of the receiving water body.[v]

Appendices

[i] Lenntech, Aluminum (Al) and water, http://www.lenntech.com/periodic/water/aluminium/aluminum-and-water.htm (last visited Aug. 12, 2010).

[ii] Lenntech, supra.

[iii] Lenntech, supra.

[iv] Lenntech, supra.

[v] Lenntech, supra.

[vi] U.S. EPA, National Recommended Water Quality Criteria, http://www.epa.gov/waterscience/criteria/wqctable/index.html#U (last visited July 7, 2010).

[vii] Lenntech, supra.

[viii] Lenntech, supra.

[ix] Univ. of Illinois, Primary Metals – Aluminum Smelting & Refining, http://www.istc.illinois.edu/info/library_docs/manuals/primmetals/chapter4.htm (last visited Aug. 12, 2010).

[x] Metals Advisor – Bauxite Mining, http://www.energysolutionscenter.org/heattreat/metalsadvisor/aluminum/process_descriptions/bauxite_mining.htm (last visited Aug. 12, 2010).

[xi] Univ. of Illinois, Primary Metals – Aluminum Smelting & Refining, http://www.istc.illinois.edu/info/library_docs/manuals/primmetals/chapter4.htm (last visited Aug. 12, 2010).

[xii] Univ. of Illinois, Primary Metals – Aluminum Smelting & Refining, http://www.istc.illinois.edu/info/library_docs/manuals/primmetals/chapter4.htm (last visited Aug. 12, 2010).

[xiii] Lenntech, Aluminum (Al) and water, http://www.lenntech.com/periodic/water/aluminium/aluminum-and-water.htm (last visited Aug. 12, 2010).

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.

2019-07-23T16:23:11+00:00