Water treatment

More than 80% of the water available in the ecosystem is waste in India and is responsible for severe health hazards, mainly due to improper wastewater management. Industries and large cities are the cause of this wastewater. The main motto of wastewater management is to make the water clean and safe. 

Sources of wastewater

There are two sources of wastewater-

(i) Point source

(ii) Non-point source

Two ways of treating the wastewater and sewage plant in an integrated manner- 

(i) Natural ways- Conventional sedimentation includes filtering and chlorinating the water where more harmful materials and heavy metals have been removed.

(ii) Artificial manner- marshes, algae, fungus, seaweed, and over six connected meshes are brought by the biologists for 60 hectares to neutralize the water naturally.

• Marshes also help grow marine life such as fishes, animals, and birds.
• FOAM – Friends of Arcata Marsh took care of this wastewater management. It is one of the most significant steps in safeguarding nature.
• Ecological sanitation is practical hygiene, cost-efficient method for excreting human waste by dry compost toilets. It is one of the nutrient-rich fertilizers for plants.
• This project is undergoing in Kerala and Sri Lanka under the name of EcoSan.

Wastewater treatment plant

In this water treatment process, all the contaminants present in the wastewater are removed, making them sustainable for usage. Make kind of wastewater is treated in this phase like domestic, industrial, agricultural, sewage, and leachate.

Sludge is considered the end product of this waste treatment plant. Processes include sedimentation, polishing, and oxidation. The recycled water from the plant is known as reclaimed water.

Types of Wastewater treatment plant

Based on the type of contamination-

1. Industrial wastewater treatment plants
2. An agricultural wastewater treatment plant
3. Leachate treatment plant
4. Sewage treatment plant

Industrial treatment plant

• In this water treatment process, unwanted products are treated and recycled into the water cycle.
• Many industries like petrochemical plants and refineries have their treatment plant as they have many toxic materials, oil, grease as the by-products.
• To eliminate the contamination, enterprises set up wastewater treatment plants and reuse the same water for manufacturing purposes.
• Brine treatment removes solids, organic acids, alkaline, grease, oil, and toxic pollutants in the industrial water treatment process.

The agricultural wastewater treatment plant

• In this process, the wastewater that comes from the animal and plant operation is removed.
• The recycled water is used for milk and egg production.
• Sometimes it may be disposed of with the help of a sprayer and trickles.
• This process takes runoff from the agricultural land containing pesticides, fertilizers, animal slurry, plant residue, and animal residues.

Leachate treatment plant

In this process, leachate water is treated from landfills. The water treatment process involved in this treatment is

• Biological treatment
• Mechanical treatment
• Treatment with active carbon filters
• Electrocoagulation
• reverse osmosis using disc tube

 Sewage treatment plant

• the sewage treatment plant is one of the integrated wastewater treatment
• In this treatment, all the sewage waste from domestic, pre-treated industries are treated to remove the harmful metal and make it suitable for the environment.
• Many sewage treatment plants are built based on biological aspects by considering the quantitative and qualitative elements.
• In rural areas, on-site sanitation includes a septic tank, OSS (on-site sewage system), vermifilters, and drain fields.
• In some countries, even the fourth treatment stage is followed to remove micro pollution.
• Sanitation is one of the parts of the sewage treatment plant to treat solid waste, human waste, and drainage waste.
• STP-sewage treatment plant for sewage works. WWTP – wastewater treatment for the treatment of industrial wastewater.
• The main objective of the sewage treatment plant is to degrade all the biodegradable components, including organic matter and, remove nutrients, pathogens, micropollutants and make them suitable for the environment.
• Even sewage sludge is treated before use. It is divided into biosolids and fertilizers.

Systems of sewage treatment processes- 

1. Decentralised system (On-site treatment system)
2. Large centralized system (connection of extensive network of pipe)

Mainly there are two types of processes

(i) Low tech, extensive, or nature-based processes

(ii) High tech, intensive, or mechanized processes

Low tech, extensive, or nature-based processes

• In this case, little or no energy is required
• For example, toilet wastewater is provided with a septic tank for pre-treatment.
• Nature-based treatment plants take place in urban and rural areas.
• This type of sewage treatment plant is one of the integrated wastewater treatment plants based on the natural treatment process
• One of the best examples of the natural-based low-cost treatment plant is Waste stabilization ponds. One can avoid operation and maintenance costs.

High tech, intensive, or mechanized processes-

This sewage treatment is a bit expensive. As the maintenance and operation costs are high. High effluent quality is available in the mechanized process. Here are some systems and methods are known in the mechanized process that are

• Activated sludge system
• Reverse osmosis
• Filtration
• Membrane bioreactor
• Extended aeration
• Aerobic treatment system

Different types of sewage treatment are-

1. Preliminary treatment – All the coarse material that can block or clog the pipe is removed in this process. Some  steps followed in the preliminary treatment are

1. Screening
2. Grit removal
3. Flow equalization- fat and grease removal

2.   Primary treatment – In this process suspended, and the organic matter is removed. 
3.   50 – 70% of the suspended solids
4.   25-40% of BOD (biological oxygen demand) is removed.

3. Secondary treatment- Here a biological digester is installed to remove the organic matter and solid particles, toxic materials are removed as much as possible. Many micrograms grow on it and form flocs. These flocs remain on the sludge and reduce the concentration of the pollutants.

4. Tertiary treatment- In this process, nutrients and micro-pollutants are removed. More than one process is performed in the tertiary treatment.

 Conclusion

Many health hazards can occur due to the mismanagement of wastewater. Wastewater management aims to keep the water clean and safe. Through this process, the water can be used for drinking, washing, and commercial use. Based on the type of contamination, the treatment plant includes -Industrial wastewater treatment plants, agricultural wastewater treatment plants, Leachate treatment plants, and Sewage treatment plants.