Wastewater is any water that requires cleaning after use, for instance water that has been used for toilets, kitchens, bathing etc.
Wastewater treatment is a process of removing contaminants from all these kinds of water.
In addition, the treatment takes place in a Wastewater Treatment Plant (WWTP), often regarded as a Waste Resource Recovery Facility(WRRF) or Sewage Treatment Plant(STP).
What’s in it for me:
- Types of Wastewater
- Stages of Wastewater treatment
- Processes
- How India treats it’s waste water
- Conclusion
- FAQs from answer the public
Types of Wastewater
There are mainly three types of wastewater but only one has subcategories and they are:
- Storm-water runoff
- Industrial sewage
- Domestic sewage
- Grey water
- Black water
Domestic sewage carries wastewater from houses and apartments, it is also known as sanitary sewage.
In addition, industrial sewage is used water from manufacturing or chemical processes.
Storm sewage is runoff from precipitation that is collected from collection of pipes or open channels.
Stages of Wastewater Treatment
Water is one of the most precious resources on the planet, making the process of treating contaminated wastewater one of the most important today.
So there are 3 main stages of the wastewater treatment process, aptly known as primary,secondary and tertiary water treatment.
Quaternary water treatment, a more advanced treatment used for some applications.
Primary stage:
Wastewater is funneled through collection systems and treated with odor neutralizing chemicals.
It then goes through screening in which large items, such as bottle bottle tops and plastics are removed from the water supply.
The water then moves towards primary treatment in which wastewater is temporarily held in a settling tank where heavier solid sinks to the bottom.
While the lightest solid floats to the surface.
Large scrappers remove this solid waste, known as sludge and will later pump it out of the tanks for further treatment.
Secondary stage:
This stage works on a deeper level then primary level.
Firstly, it starts with an aerobic treatment system, water equipment pumps air into two large aeration tanks.
Secondly, these tanks mix wastewater with a small amount of sludge, known as seed sludge, to promote the growth of bacteria and other microorganisms that will consume the remaining organic matter.
In addition, this process produces large particles that settle at the bottom of aeration tanks.
Moreover, wastewater typically passes through this system automation for a period of 3 to 6 hours.
Tertiary stage:
The aim of tertiary wastewater treatment is to raise the quality of the water to domestic and industrial standards.
In the case of water treated by municipalities tertiary treatment also involves the removal of pathogens which ensures the water is safe for drinking purposes.
Further, for this stage wastewater facilities need special equipment and chemical feed stations powered by system automation to effectively sanitizer water.
Processes of Wastewater Management:
In the treatment of wastewater biological processes are used.
These processes may include for example aerated lagoons activated sludge slow sand filters.
There are seven processes of wastewater treatment and they are:
Phase Separation:
Firstly, phase separation transfers impurities into a non-aqueous phase.
It may occur at intermediate points in a treatment sequence to remove solid generated during oxidation or polishing.
Solids often require de-watering of sludge in a wastewater treatment plant.
Disposal options for dried solids vary the type and concentration of impurities removed from water.
Production of waste brine, however, may discourage wastewater treatment removing dissolved inorganic solids from water by methods like ion exchange reverse osmosis and distillation.
Sedimentation
Solid like stones, grit and sand may be removed from wastewater by gravity when density differences are sufficient to overcome dispersion by turbulence.
Gravity separation of solids is the primary treatment of sewage where the unit process is called primary settling tank or primary sedimentation tank.
Solid that are heavier than water will accumulate at the bottom of quiescent setting basins.
More complex clarifies also have skimmers to simultaneously remove floating grease like soap scum and solids like feathers or wood chips.
Filtration
Suspended solid and colloidal suspensions of fine solids may generally following some form of coagulation, be removed by filtration.
Through fine physical barriers distinguished from coarser screens or sieves by the ability to remove particles smaller than the opening through which the water passes.
Other types of water filters remove impurities by chemical or biological processes described below.
Oxidation:
Further, it reduces the biochemical oxygen demand of wastewater and may reduce the toxicity of some impurities.
Secondary treatment converts organic compounds into carbon dioxide, water and bio-solids.
Biochemical oxidation
To enumerate, secondary treatment by bio-chemical oxidation of dissolved and colloidal organic compounds is widely used in sewage treatment.
And is also applicable to some agricultural industrial wastewater.
Chemical oxidation
As a result, disinfection by chemical oxidation kills bacteria and microbial pathogens by adding ozone chlorine and hypochlorite to waste water.
Polishing:
It refers to treatment made following the above methods.
It minimizes chemical reactivity of wastewater following chemical oxidation.
Carbon filtering removes remaining contaminants and impurities by chemical adsorption onto activated carbon.
How India treats it’s wastewater?
India generates staggering 1. 7 million tonnes of fecal waste a day.
Official figures show that:
78% of the sewage generated remains untreated in India.
If you want to know how India manages it’s waste Check it out
The two main sources of wastewater are sewage and industrial waste.
With both the population of India and its industrial landscape increasing at a phenomenal speed; wastewater volume is also at an alarming rise.
Further, the untreated sewage directly flows into the nation’s river polluting the main source of drinking water.
Yamuna, considered as one of the most holy rivers by Indians is now the most polluted river of India because of Delhi garbage and poor sewage system.
In India rules does not matter to people.
That’s why India still faces some of the challenges like:
- Firstly, the lack of awareness
- Secondly, it lack of public- private partnership on wastewater management
- lack of apathy by some governments and
- In addition, the imbalance in the amount of wastewater and treatment plants.
Current status in India is that while urban water access is high on average, significant gaps remain across the country, and wastewater treatment remains stuck at the national average of around 33%.
Large wastewater generator- Punjab, Maharashtra can potentially treat 65 to 100% of their urban wastewater.
Despite this, many popular States such as Madhya Pradesh, Bihar have only enough installed capacity to treat less than half of their waste water.
Further several, North eastern and Himalayan States have low or no capacity for treatment.
The methods commonly used in India to treat wastewater are:
1. Physico-chemical treatment:
Pollutants are usually classified according to size and different methods are used accordingly.
Largest particles can be separated but smaller particles are much more difficult to separate. This is where physico- chemical treatment is particularly useful.
2. Biological treatment:
Unlike physico-chemical methods, biological treatment uses organisms to treat pollutants.
Over the years scientists have developed various aerobic or anaerobic processes to treat wastewater.
3. Zero Liquid Discharge system:
Many people view this as cutting edge technology.
Moreover, it removes all dissolved solids from wastewater giving us distilled water.
It uses methods like RO to purify water.
Source: Wateronline
Conclusion:
To sum up all the above content we can conclude one thing that water is rare and is depleting at a fast rate.
And if India continues to let the water untreated and do not take proper waste water management measures.
A time will come when we will not have a drop of fresh water and not only India but the whole world should take wastewater management serious because:
“Pure water is the world’s first and foremost medicine”
-Slovakian proverb
FAQ from answer the public:
Ans: Water is one of our most important resources and its being squandered.
To protect and preserve this precious resource water waste management is necessary.
To convert wastewater into fresh and drinkable quality of water wastewater management is needed.
Ans: industrial wastewater treatment describes a process used for treating wastewater that is produced by industries as an undesirable by-product.
After treatment, industrial wastewater may be reused or released to a sanitary sewer or to a surface water in the environment.
Ans: To build a model of a wastewater treatment plant. The different parts that make up the whole are:
1. Screening out Large Objects and Grit.
2. Primary treatment in a settlement tank.
3. Secondary treatment in an Aeration Lane.
4. Final treatment in a settlement tank.
5. Filtration through a Bed of Sand.
Ans: Yes, waste water can be directly re-used depending on the contaminants present in it.
Ans: Yes, it can carry variety of pathogens like Enterobacter cloacae, Enterococcus faecalis etc.
