We use various products to make our lives livable and easy. But it comes at a cost. The byproduct that we get from the current lifestyle includes wastewater. Wastewater is water that we have already used in some capacity.
Wastewater is water from homes, industries, or businesses. It is unsuitable for any use or consumption. With the help of wastewater treatment, we can make the wastewater potable and usable.
Wastewater treatment is the method of cleaning domestic water and sewage. In the process, the contaminants get removed in the form of organic matter. There are some common ways to treat wastewater. Read on and know the methods in detail.
There are mainly four common ways to treat wastewater. It contains physical water treatment, chemical treatment, biological water treatment, and sludge treatment.
Physical Wastewater Treatment
In this method, physical methods are used for cleaning the wastewater. The solids get removed by screening, sedimentation, and skimming. Also, sand filters come in use sometimes. It separates the oil and grease particles from the water.
- Screening: Water screening is a crucial feature of industrial and municipal wastewater treatment plants. That is because it retains particles comprised in the wastewater. These particles must get removed at the start only. Further, these materials include paper, leaves, twigs, rags, and other trash. Or it could block the flow through the plant or damage equipment. They are coarse or fine screens.
Coarse screens have the materials like rods, parallel bars, wires, perforated plates, or wire mesh having circular or rectangular gaps. They prevent large materials (such as logs and fish) from entering the treatment plant. Also, they can save it from damaging mechanical equipment.
Fine screens come after the coarse screens. Their work is to keep out material that blocks pipework at the plant. They consist of steel bars 5–20 mm apart. Moreover, fine screens can flush out 20 to 35 percent of the broken solids.
- Aeration: After the screening, the next process is aeration. It passes over a sequence of steps. In that process, all the oxygen gets absorbed from the air. This helps to remove soluble gasses such as hydrogen sulfide and carbon dioxide. Also, it flushes the gaseous organic compounds. It might give an unpleasant taste to the water. Aeration also removes the extracts of iron or manganese.
- Coagulation: Coagulation removes the fine particles from the water. Then, a chemical named coagulant is mixed in the water. It balances the negative electrical charge of the minute particles.
- Flocculation: In this process, water gets gently mixed by paddles in a flocculation bay. And the flocs enter into contact with each other to form larger flocs. Chemicals called flocculants are mixed to improve the process.
- Sedimentation: The larger flocs need to settle out, and it happens in the process of sedimentation. In this process, water is kept in the tank for many hours. And all the sludge sits on the bottom of the tank.
- Filtration: In filtration, the solids are extracted from the liquid. The solids which remain after the sedimentation process, it removes in this process. Moreover, air and clean water are pumped back up the filter to displace the tangled contaminants. And the water that holds the dirt gets back into the sewerage system.
- Chlorination: Chlorination is a process that eliminates the remaining pathogenic microorganisms. Chlorine is the most commonly used disinfectant. The reason behind that is it is somewhat inexpensive and easy to use. Further, some amount of chlorine is left in the water until it reaches the consumers.
- Supplementary Treatment: In this process, a mixture of fluoride gets combined in the water. The optimum balance of fluoride is around 1 mg per liter of water (1 mg l–1).
Biological Water Treatment
This method uses biological techniques to break down the organic matter that is present in wastewater. Microorganisms absorb organic substances in wastewater in biological therapy. Further, this method has three categories:
- Aerobic Process: Bacterias decompose or eat organic substances. And it transforms it into carbon dioxide, which the plants can use. There is a use of oxygen in this process.
- Anaerobic Process: In this process, the sludge and waste get fermented at a precise temperature. There is no use of oxygen in this process.
- Composting: The process gets done in the presence of oxygen. The sludge gets mixed up with sawdust or other carbon sources.
Chemical Water Treatment
As the name implies, this treatment comprises the use of chemicals. Chlorine is the chemical most often used to treat sludge and other types of wastewater. The process is known as chlorination. Further, this process is one of the most efficacious means of killing different viruses and bacteria.
When it comes to treating industrial wastewater, the best method is neutralization. Neutralization is a process in which the acid or base gets added to obtain the water to its natural pH of 7. Chemicals control the bacteria from multiplying in water. Hence, it makes the water pure. In addition, for treating acidic water, lime is also used for it.
Sludge Treatment
This is a process in which solid-liquid gets separated, where the least possible remaining moisture is in the solid phase. And the least possible solid particle residues remain in the separated liquid phase.
An example of this contains the dewatering of sewage from sewage plants or industrial wastewater. In the process, the excess moisture in dewatered solids decides the disposal prices. Additionally, the centrate rate defines the pollution load restored to the treatment facility.
A centrifuge is a solid-liquid partition instrument. It extracts the solids from the wastewater. Thus, it helps in this process.
Conclusion
These are a few methods of wastewater treatment. What treatment solution you should use, depends on the type of wastewater. It depends on the contaminants present in the water. Also, it depends on the use of water after its treatment.
The best techniques to treat wastewater should coincide with the rules and regulations required in the state and locality. Besides, make sure the methods you use are as environmentally safe as possible.
