Contaminants

Arsenic occurs widely in the earth’s crust and, as a result, in groundwater in many parts of the world. Because effective removal depends on several water-specific properties, pilot testing is typically required to design an arsenic water treatment system.

Benzene is the base compound in the BTEX family (benzene, toluene, ethylbenzene, and xylenes). These hydrocarbons have been produced industrially in high volumes for decades and are constituents of motor fuels, creating a risk of groundwater contamination from leaking underground storage tanks and other industrial sources. WETS has applied several treatment processes for benzene removal, including aeration and activated carbon; because benzene contamination is usually found alongside other contaminants, a pilot study is generally recommended to identify the optimal treatment process.

Color is related to colloidal suspensions in water, primarily from contaminants of vegetable origin, and is typically more of an issue in surface water than groundwater (though shallow wells can sometimes be affected). WETS typically addresses color removal through coagulation, settling, and filtration.

Hydrogen sulfide is a highly toxic, flammable gas, though its presence in drinking water is not concentrated enough to pose a health threat — its rotten-egg odor is, however, easily detectable. As a dissolved gas, hydrogen sulfide can typically be treated successfully with aeration, though the process is highly pH-sensitive and may require additional treatment.

Because well water is not typically exposed to air, dissolved iron and manganese oxidize on exposure to form insoluble reddish-brown particles, discoloring water and causing problems with laundry and plumbing fixtures. WETS has extensive experience treating water for iron removal, having supplied treatment equipment or entire systems for dozens of projects over the years.

PFAS refers to a class of poly- and perfluoroalkyl substances, most notably PFOA and PFOS, manufactured and used across industries since the 1940s. The EPA has classified PFOA and PFOS as primary drinking water contaminants and is developing corresponding regulations. Effective removal technologies include activated carbon treatment, ion exchange resins, and high-pressure membranes such as nanofiltration or reverse osmosis.

Radon is a naturally occurring radioactive gas formed by the breakdown of uranium in soil and rock. Elevated levels can enter groundwater flowing through granite or granitic sand and gravel formations, and radon is considered the second-leading cause of lung cancer in the U.S. As a gas, radon can be treated through aeration/stripping or radon-specific filtration.

Radium is a naturally occurring radioactive element found in varying amounts in rocks and soils, and can be a concern in deep bedrock aquifers. The optimal removal technology depends on water properties, so a pilot study is generally recommended to identify the best treatment process.

Trihalomethanes (THMs) form as byproducts of chlorine disinfection, when chlorine reacts with organic and inorganic matter in water. Effective THM treatment requires a thorough review of the processing system to identify the best means of reducing formation and/or achieving removal.

Uranium is another naturally occurring radionuclide present in varying amounts in rocks and soils, though it can also enter water from industrial activity. As with radium, a pilot study is typically the best way to identify the optimal removal method.

Hardness refers to dissolved metal ions in water, typically calcium and magnesium, along with contributing ions such as aluminum, barium, iron, manganese, and zinc. It is typically expressed as milligrams of calcium carbonate equivalent per liter.