Wastewater Nutrient Removal - An Overview: Part 1
Processing industries face a significant challenge when it comes to industrial wastewater. Due to the difficulties or high cost of industrial nutrient removal and wastewater treatment, many processing projects have been canceled. Many countries have implemented large-scale environmental initiatives, which has resulted in strict environmental regulations regarding industrial wastewater discharge and nutrient removal.
Although operators might have installed industrial wastewater treatment plants to comply with local regulations, these systems required expensive upgrades to meet the newer and more stringent regulations for nutrient removal. Many of which could not reach these strict requirements even after extensive modifications.
Inorganic and organic matter in industrial wastewater are often found in different concentrations. Many substances are toxic, mutagenic, and carcinogenic. The wastewater contains many substances that are not easily biodegradable and require nutrient removal.
Primary treatment is the process of nutrient removal for removing solids, particles, and oils from the industrial wastewater stream. Therefore, primary treatment often includes basic physical methods as well as solid and oil separators like primary clarifiers, oil separators, and screens.
Secondary treatment is where residual organic compounds and suspended particles are broken down. Secondary treatment involves the biological (or bacterial) destruction of contaminants and pollutants. Secondary treatment is best done with activated sludge. It's a simple, economical, and highly effective form of wastewater nutrient removal.
Combinations of aerobic and anaerobic treatment have been shown to be effective in removing many pollutants, including soluble biodegradable organ pollutants. Industrial wastewater treatment and nutrient removal is increasingly used in membrane-based technologies.
Due to stricter wastewater treatment limits, chemical oxidation techniques for wastewater treatment and nutrient removal are on the rise. Modern industrial wastewater units have used both classical and advanced chemical treatment.
Tertiary treatment typically includes polishing, a kind of final filter step and finishing stages. This article focuses on nutrient removal and wastewater treatment technologies.
Removal of Oils
There are several conventional methods to treat oily wastewater. These include gravity separation, skimming, and dissolved air flotation. For industrial wastewater nutrient removal, it is possible to remove oil from the water by using gravity separation and skimming and can be a widely accepted and low-cost, effective primary treatment option.
The oil-water separator separates oil and suspended solids from water. However, an many advanced separators or even basic oil-water separators are not capable of removing small oil droplets or emulsions. Sedimentation in a primary clarifier can effectively remove oil that sticks to solid particles.
Chemical pre-treatment can be used to stabilize emulsified oil in industrial wastewater that requires nutrient removal. Then, gravity separation is performed. To reduce viscosity, increase density differences, and weaken interfacial film stability of the oil phase, the wastewater is frequently heated.
Coagulation and Flocculation
Many industrial wastewater treatment units incorporate sedimentation into their processes. The process of sedimentation (also known as clarification) is when the velocity of wastewater drops below its suspension velocity and suspended particles are forced out by gravity. Sludge is used to remove settled solids, while scum is used to remove floating solids. The sedimentation tank is filled with industrial wastewater that requires nutrient removal.
Retention time, temperature, tank requirements, and other factors affect the efficiency or performance of the process. However, without coagulation and flocculation, sedimentation can remove only coarse suspended matter that will settle rapidly out of the wastewater without the addition of chemicals.
This type of sedimentation is usually performed in a reservoir, sedimentation, or clarification tank at the beginning of treatment. Coagulation and flocculation is based on the addition of chemical products that accelerate the sedimentation (coagulants) in the clarification tanks.
Inorganic or organic compounds, such as aluminum hydroxide chloride, aluminum sulphate, or aluminum sulphate are all coagulants. This coagulant is used to remove nearly 90 percent of industrial wastewater suspended solids at this stage of the treatment process. All of which is a crucial step in the nutrient removal process.
For further insights and the second half of content on nutrient removal, see the article titled Wastewater Nutrient Removal - An Overview: Part 2.