1. Pre-chlorination dosing: this is made to disinfect the raw water from any infections.
2. First filtration: by the pressure sand filters to remove turbidity and suspended solids.
3. De-chlorination dosing: to remove the remaining Chlorine after the pressure sand filter.
4. Antiscalent dosing is very important to prevent Calcium Sulphate form scaling.
5. Acid dosing is very important to prevent calcium carbonate form scaling by  Sulphuric acid 98%.
6. Second filtration by cartridge filter (5micron) is important to remove any particles exceed 5 micron size.
7. Feeding water into the membrane after boosting it to indicated pressure 16 bar for membrane input and the water treated to reduce the TDS under high pressure.
8. The permeate water after reverse osmosis must go through another stage
9. Adjusting PH value by Sodium hydroxide 49%
10. Post chlorination dosing for disinfection by Sodium hypochlorite 12%.

Preliminary treatment consists solely in separating the floating materials like dead animals,tree branches,paper,piece of rags,wood etc. and also the heavy settle able inorganic solids. it also helps in removing the oils and greases etc from the sewage. this treatment reduces the BOD of the wast water by about 15 to 30 %. the process used are Screening for removing floating papers,rags,clothes,etc. Grit champers or Detritus tank for removing grit and sand and skimming tanks for removing oils and grease.

Secondary Treatment process involves further treatment of the effluent, coming from the primary sedimentation tank. this is generally accomplished through biological decomposition of organic matter. which can be carried out either under aerobic or anaerobic condition, in this biological spits, bacteria will decompose the fine organic matter, to produce clear effluent.
The treatment reactors, in which the organic matter in decomposed                    ( oxidized) by aerobic bacteria are known as aerobic biological units and may consist of

• Filters( intermittent sand filters as well as trickling filters

• Aeriation Tanks with the feed of activated sludge ( ie the sludge, which is settled in secondary sedimentation tank, receiving effluents from aeration tank)

• Oxidation ponds etc. Since all these aerobic units generally make use of primary settled sewage,  they are easily classified as secondary units.

Primary Treatment process consists in removing large suspended organic solids. this is usually accomplished by sedimentation in settling basins.
The liquid effluent from primary treatment, often contains a large amount of suspended organic materials, and has a high BOD ( about 60 % of original)
Sometimes, the preliminary as well as primary treatments are classified together, under primary treatment.
The organic solids, which are separated out in the sedimentation tanks ( in primary treatment) are often stabilized by Anaerobic decomposition in a Digestion Tank or incinerated. the residue is used for land fills or soil conditioners.

Sewage, before being disposed of either in river streams or on land, has generally to be treated, so as to make it safe. The degree of treatment required, however, depends upon the characteristics of the sources of disposal.
There are many different ways to treat sewage. treatment process are often classified as

1. Preliminary treatment
2. Primary treatment
3. Secondary ( Biological ) treatment and
4. Complete final treatment

Water treatment involves removal of undesirable constituents from water and them disposal of them in easiest and safest manner. to achieve these goals, a variety of treatment operation and process are utilized, which exploit various physical and chemical phenomena to remove or reduce the undeliverable constituents from water. those operation used in this treatment of water in which change is brought about by means of or through application of physical forces are known as Unit operation (UO). Those process used for the treatment of water in which change is brought about by means of chemical reaction are known as Unit Process (UP).

Objective of water treatment are to remove the different impurities in the raw water,to render the water safe and clean and to ensure the treated water quality meets the drinking water standards. the types of treatment required depends on the characteristics of the raw water. the characteristics of the raw water is assessed by taking sample of water from source during different  seasons of the year and analyzing for physical,chemical and bacteriological quality parameters.

1. Reverse Osmosis Process
2. De mineralization Process
3. Ion- exchange Process
4. Distillation Process
5. Disinfection process
6. filtration process
7. Sedimentation process
8. Flocculation process
9. Coagulation process
10. Mixing process
11. Aeration process
12. Micro strainer process
13. Coarse Screen process
14. Trash rack process