Breaking Down the Chemicals Used in Wastewater Treatment

Jul 27, 2020
Water molecules

Wastewater treatment is a complex process that requires a variety of chemicals to modify the pH of the water and prevent the release of pollutants, such as heavy metals, volatile and semi-volatile organic compounds and pesticides into the surrounding environment. Chemical treatment of wastewater is used by industries, such as pharmaceutical, energy production, and paper production. Below we discuss the primary chemicals used in wastewater treatment, and their common applications.

Types of Wastewater Treatment Chemicals

To meet both governmental regulations and industry standards for chemical effluents and pollutants, numerous wastewater chemical solutions have been developed. Depending on the application, one or more chemical treatments may be necessary to produce up-to-code wastewater.


Coagulants are aluminum or iron-based chemicals that change the magnetic charge of particles in the water, causing them to attract instead of repel each other. The waste coalesces into larger bodies that can be skimmed or filtered out. Materials often removed from wastewater with coagulants include arsenic, pathogens, organic matter, fluoride, and chemical phosphorus.

Odor Control

Although odor control is a secondary consideration when compared with the detection and removal of highly toxic chemicals, a range of effective methods are available to reduce unwanted smells and effusions, including biofiltration, solids scavenging, oxidation, iron salts, carbon absorption, and liquid phase technology.

The most toxic contaminants of industrial waste often smell innocuous; however, these dangerous contaminants require chemical treatment even before biological water treatment can be considered. Hexavalent chromium, for example, can leach into groundwater undetected, ultimately causing birth defects, cancer, and other chronic and terminal illnesses. The notion of highly toxic wastes that are colorless, odorless, and otherwise invisible was brought to mainstream consciousness by the movie Erin Brockovich in the early 2000s, and industry standards have since been adjusted accordingly.


Flocculants are divided into three categories: natural, chemical, and grafted. Coupled with water agitation processes, flocculants encourage waste particles to adhere to one another in clumps, or flocs, through charge bridging, electrostatic patching, and magnetic neutralization.


Defoamers, as the name implies, are used to control and reduce the level of trapped air and foam created during wastewater treatment processes. This helps to decrease the potential for dangerous overflow.

Organic Polymers

Organic polymers are natural flocculants that use ionized polymer to attract particles into flocs for easier filtration. They are often used in conjunction with inorganic iron or aluminum-based coagulants.

Reducing Agents

Reducing agents, also known as oxidizing agents, include sodium bisulfite, sodium hydrosulfite, and ferrous sulfate. They are typically used to remove harmful substances, such as ozone, hydrogen peroxide, chlorine, and biological contaminants, from wastewater. Coupled with aeration, these chemicals bond to suspended compounds to reduce them to component parts that can settle out of the water and be flocculated and filtered.

Sludge Conditioners

Chemical sediment and waste biomass can be difficult to filter and may require additional conditioning through heat or chemical treatments to thicken the material, reduce the odor, and decrease the sludge volume. This process makes it easier for the sludge to be removed and safely disposed.

Cleaners and Degreasers

Cleaners and degreasers, such as clog busters and alkaline drain openers, are formulated to dissolve grease and oil. They use solvent chemicals to break down the grease to make it easier to remove.

Membrane Cleaners and Antiscalants

Membrane cleaners and antiscalants are injected into wastewater prior to treatment, to prevent dissolved mineral salts from coalescing on filtration membranes, thereby ensuring adequate fluid flow. Common membrane cleaners and antiscalants used in water treatment applications include:

  • Chlorine Dioxide
  • Muriatic Acid
  • Soda Ash
  • Algicide
  • Chlorine
  • Sodium Bicarbonate

Biocides and Bio-Dispersants

Biocides and bio-dispersants reduce microorganisms in wastewater, enhancing operational efficiency of wastewater treatment operations. Biocides include cleaners, scale removers, dispersants, penetrants, and disinfectants.

Heavy Metal Precipitants

Heavy metals in wastewater are often ionically bonded with chelating agents or other bonding chemicals that prevent them from becoming soluble. Heavy metal precipitants dissolve those bonds allowing dangerous heavy metals to precipitate out of the wastewater.

pH Control

pH control adds acidic or basic chemicals to the wastewater, thereby allowing hydroxide ions to bond with heavy metals and precipitate out of the solution. In addition, greater acidity will kill bacteria and organic compounds by breaking them down at a cellular level.

Wastewater Chemical Solutions from MacDermid Envio

As an ISO 9001:2015 certified water treatment chemical manufacturer, MacDermid Envio offers a broad selection of proprietary chemicals to ensure your wastewater treatment operation runs smoothly. We are dedicated to meeting and exceeding governmental regulations and industry standards, and make it a point to stay abreast of industry developments and updated regulations.

To learn how our wastewater chemical solutions can enhance your operations, contact us today.