Water Treatment Chemicals
29 May 2019
Water is an essential resource in every industry, and its treatment is vital to public health, environmental protection, and operational efficiency. Wastewater treatment involves a combination of physical, biological, and chemical processes to remove contaminants and ensure that discharged water meets safety standards. Among these, chemicals play a crucial role in enhancing the effectiveness and speed of the treatment process.
The initial stage of wastewater treatment often focuses on removing suspended solids and colloidal particles. These contaminants are too fine to settle on their own and must be bound together through coagulation and flocculation.
Aluminum sulfate (Alum)
Alum hydrolyzes in water to produce aluminum hydroxide, which forms a gelatinous precipitate that traps fine particles. The process also neutralizes negative surface charges, encouraging particles to clump together (Tchobanoglous et al., 2014).
Ferric chloride
A powerful coagulant especially effective in high-turbidity water. Ferric salts destabilize particle suspensions by reducing the electrostatic repulsion between particles, allowing them to aggregate.
Polyaluminum chloride (PAC)
A pre-hydrolyzed aluminum-based coagulant that works faster than alum and produces less sludge. It performs well over a wider pH range and generates more compact flocs (Bourgeois et al., 2019).
Biological contaminants such as bacteria, algae, and fungi can rapidly multiply in untreated or partially treated water. Biocides are used to control this microbial activity and prevent biofilm formation.
Calcium hypochlorite / Sodium hypochlorite
These are oxidizing biocides that release free chlorine in solution. The chlorine disrupts microbial cell membranes and denatures enzymes, leading to microbial death. They are especially useful in municipal wastewater disinfection (World Health Organization [WHO], 2017).
Sodium bromide (used with oxidants)
When combined with chlorine or ozone, sodium bromide forms hypobromous acid, which is more stable at higher temperatures and pH levels, making it ideal for cooling water systems (Baker et al., 2020).
Glutaraldehyde
A non-oxidizing biocide that penetrates biofilms and cross-links proteins in microbial cells. It is often used in closed-loop water systems where long-term microbial control is needed without forming harmful by-products (Gordon et al., 2016).
Foam formation during treatment can overflow tanks, damage equipment, and disrupt biological processes. Antifoams and defoamers reduce surface tension and collapse foam structures.
Silicone-based defoamers
Highly effective at low dosages, these compounds spread over the foam surface and cause bubble collapse. They are non-reactive and suitable for various wastewater streams.
In industries where water is used in steam generation, proper treatment is critical to prevent scaling, corrosion, and foaming, which can reduce boiler efficiency and lifespan.
Sodium sulfite
Acts as an oxygen scavenger, reacting with dissolved oxygen to prevent oxidative corrosion inside the boiler (Snoeyink & Jenkins, 2020).
Phosphates
Added to react with calcium and magnesium to form soft, non-adherent sludge, thereby preventing hard scale deposits.
Cooling towers are prone to scale formation, biofilm growth, and microbial fouling, all of which reduce heat transfer efficiency and increase operational costs.
Hydrochloric acid
Used during scheduled cleaning to dissolve calcium carbonate and other mineral deposits. Its effectiveness requires careful pH monitoring to avoid corrosion.
Oxidizing biocides (chlorine, bromine)
Routinely dosed to eliminate algae and bacterial growth in tower basins and on internal surfaces (Bartram et al., 2007).
Dispersants
Help in detaching organic fouling, debris, and scale from tower fill materials, making them easier to flush out during clean-in-place (CIP) operations.
While these chemicals are effective, they must be used responsibly. Overdosing, incorrect mixing, or poor storage can lead to:
Harmful by-products (e.g., chlorinated organics)
Equipment corrosion
Worker safety hazards
To minimize risk:
Follow OSHA exposure limits and use PPE
Refer to REACH-registered SDS documentation
Ensure proper wastewater neutralization and discharge compliance (ECHA, 2023)
From breaking down suspended solids to disinfecting effluents and maintaining industrial equipment, chemicals play an irreplaceable role in wastewater treatment. Each chemical type has a specific job; chosen for its reactivity, effectiveness, and compatibility with system requirements. Understanding how these chemicals work not only improves water quality outcomes but also ensures cost-efficient, environmentally responsible operations.
Contact us today for a reliable supply of wastewater treatment chemicals, including coagulants, biocides, antifoams, and boiler/cooling system agents.
Tchobanoglous, G., Burton, F. L., & Stensel, H. D. (2014). Wastewater Engineering: Treatment and Resource Recovery (5th ed.). McGraw-Hill Education.
Bourgeois, W., Burgess, J. E., & Stuetz, R. M. (2019). Sensors for Wastewater Treatment Process Monitoring and Control. Sensors, 19(20), 4502.
World Health Organization. (2017). Guidelines for drinking-water quality: Fourth edition incorporating the first addendum. https://apps.who.int/iris/bitstream/handle/10665/254637/9789241549950-eng.pdf
Baker, R. W., & Lu, C. (2020). Water treatment: Principles and design (3rd ed., pp. 1247–1249). Wiley.
Gordon, G., & Adam, L. C. (2016). Disinfection By-Products and Biocide Chemistry. American Water Works Association.
McDonnell, G., & Russell, A. D. (2016). Antiseptics and disinfectants: Activity, action, and resistance. Clinical Microbiology Reviews, 12(1), 147–179. https://doi.org/10.1128/CMR.12.1.147
Tang, Y., Zhang, L., & Wang, S. (2021). Review on Antifoam Agents in Industrial Wastewater. Journal of Environmental Management, 283, 111982.
Snoeyink, V. L., & Jenkins, D. (2020). Water Chemistry (2nd ed.). Wiley.
European Chemicals Agency (ECHA). (2023). Urban Waste Water Treatment. Retrieved from https://www.echa.europa.eu/urban-waste-water-treatment
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