The Science Behind Wastewater Treatment
When you think of wastewater treatment, you probably picture a massive plant with intricate machinery putting in work to siphon sludgy waste from water. While it is true that some machinery and mechanical processing is involved, a significant part of treating wastewater happens at a microscopic level. Chemical processes, including precipitation, flocculation and coagulation are pivotal for transforming murky, contaminated water into something cleaner, safer, and more compliant with local and national regulations. Additionally, biological processes are often used to deal with other dissolved constituents that are not removable via the chemical processes.
What Is Chemical Precipitation, Coagulation, and Flocculation?
Simply put, chemical precipitation is a treatment method that changes the form of dissolved materials in water to make them less water soluble and easier to remove. This process often involves chemical treatment that targets pollutants like metals, inorganics, FOGs (fats, oils, grease) and some organic substances. It is often the first step of a multi-part treatment regimen. Once dissolved pollutants have been converted into insoluble solids, they need to be removed from the water.
Coagulation and flocculation are two additional steps used after chemical precipitation. They target suspended particles that are too small to settle out by gravity alone — stuff like dirt, silt, algae, bacteria, and viruses. Left unchecked, these particles would not only make water cloudy but also pose severe health and liability risks.
Coagulation involves adding chemicals, known as coagulants, to the water. These chemicals, such as aluminum sulfate or ferric chloride, carry a positive charge. Since the suspended particles usually have a negative charge, they neutralize, destabilizing the unwanted materials and allowing the particles to come together more easily.
This is where flocculation comes in. During this phase, the water is gently mixed, often with synthetic polymers, encouraging the neutralized particles to collide and bind together into larger clumps called flocs. These flocs are dense and more readily settle or float, making them easier to remove.
Why Are These Processes Important?
Beyond just clearing up the water, chemical precipitation, coagulation and flocculation play a crucial role in reducing disease-causing pathogens and making water treatment more effective overall. By eliminating particles that could shield harmful microorganisms, these processes also make disinfection stages more successful. Overall, the type and scope of wastewater treatment will vary depending on the exact water to be treated. For example wastewater that is high in fats oils and grease will require a different set of chemical processes than wastewater that is high in dissolved metals. A water treatment expert should be consulted to determine the most optimal approach to treating wastewater.
Extra Considerations and Conclusions
While effective, these treatment methods must be carefully managed. Overdosing of chemicals can lead to excess chemical residues in discharge or re-use water and might mean overpaying for chemicals. On the other hand, underdosing could mean the treatment is ineffective and the water remains non-compliant for discharge. An optimal treatment program can be designed by water treatment experts (like us!) to get the most out of your wastewater treatment programs. We design simple, minimalist programs for your specific water needs. That means minimal chemicals, compliance with all regulations, and no overdosing or overpaying.