Sewage treatment Process mainly involves two stages, called primary and secondary treatment, while advanced treatment also include a tertiary treatment stage with polishing processes and nutrient removal. Secondary treatment can reduce organic matter (measured as biological oxygen demand) from sewage,  using aerobic or anaerobic biological processes.

Where in Attached growth process Bacteria in Secondary treatment is attached to External media or Equipment’s , ex:- RBC ( Rotating Biological Contactor, Trickling filters, Bio Towers etc. Where in Suspended growth process bacteria in secondary treatment is suspended in water. ex:- ACT (Activated sludge process), ACT is further use different process mode Like -Conventional treatment, extended Aeration, Sequencing batch Reactor etc .

The per person organic matter load is a parameter used in the design of sewage treatment plants. This concept is known as population equivalent (PE). The base value used for PE can vary from one country to another. We used calculation of 135 ltr per person per day.

Smell emitted by sewage treatment are typically an indication of an anaerobic or septic condition. Early stages of processing will tend to produce foul-smelling gases, which include hydrogen sulfide being most common in generating complaints. Large process plants in urban areas will often treat the smell with carbon reactors, a contact media with bio-slimes, small doses of chlorine, or circulating fluids to biologically capture and metabolize the noxious gases. Other methods of smell control exist, including addition of iron salts, hydrogen peroxide, calcium nitrate, etc. to manage hydrogen sulfide levels.

Greywater refers to domestic wastewater generated in households or office buildings from streams without fecal contamination, i.e., all streams except for the wastewater from toilets. Sources of greywater include sinks, showers, baths, washing machines or dishwashers. Grey water also refer as sullage.

Water used to flush toilets to evacuate human excreta is called “ Black Water” or Sewage.

Sewage contain bacteria type -E.coli.

E.coli is a Bacteria which when get consume, by drinking or other way it is very harmful for human being. As it goes to Intestine and Grow faster, it forms warm blooded creatures like Red worms .

As we Know Much of water that is used for domestic purpose or at home is not required to be Portable (Drinkable ) water. Like water we used for toilet flushing or washing floors, lobbies or road also for Gardening does not need portable water, we can used recycled water. So if we do not treat water and used Portable water all over then we get shortage of portable water for drinking, instead of that if we used recycled water then 30 to 40% of portable water can be save.

According to a report published by Central Pollution Control Board (CPCB) in 2021, India's current water treatment capacity is 27.3% and the sewage treatment capacity is 18.6%

To regulate water pollution, the Water Act is complemented with the Water (Prevention and Control of Pollution) Cess Act, 1977, which came into force in 1992. It augments the financial resources for the Central and State Boards established under the Water Act by applying taxes from individuals carrying on any industry and the local authorities. The Act further provide incentive for the installation of wastewater treatment plants by granting a rebate of 25% on the payable cess.

:- If we wont treat waste water it can not be reuse and hence large quantity of waste water need to discharge in to Sea or on ground water. If we discharge waste water in to sea it will pollute sea water and harm fish and other sea creature. If we discharge waste water on ground it will contaminate ground water source ( ex. Borewell, lake ,well ) which will affect Well and other portable water.

Borewell water is a rain water which seeps into ground and store in Aquifers . we have to drill and pump this water out for our usage. As it contains minerals and other contaminants in mixed form. In may rural areas this is only source of water they used for drinking and other daily activities. As borewell water is get treated in water treatment plant which can be designed on basis of water content which can be found by lab testing. WTP (water treatment plant) basically contains Pressure sand filter, activated carbon filter, Softener and cartridge filter, Ultra Filtration and Reverse Osmosis ect.

Reverse Osmosis is the process where Membrane Used to treat water. In this process Water is pressurised through membrane and it transfer water form Concentrated site to dilute site and make purified water. Here Cylindrical membrane separate water from Contaminated water. The Rejected Impurities and contamination is washed way in the reject water.