Screening: This is the first unit operation that occurs in wastewater treatment plants. A screen is a device with uniform openings and its purpose is to remove large floating solids.

Flocculation: Flocculation is a physical process and does not involve the neutralization of charge. It involves the addition of destabilized particles together into large aggregates so that they can be easily separated from the water.

Coagulation: This is a process in which coagulants are added for the purpose of rapid settlement of minute solid particles in a     liquid into a larger mass. It permits particle removal by sedimentation and filtration.

Primary Clarifiers: These are used to slow the velocity of the water to a point where organic solids will settle to the bottom of the tank and it contain equipment that is used to remove floating solids and greases from the surface.

pH CONTROL: The pH value of effluent should be between 5.5 and 9.0, according to the Bureau of Indian Standards (BIS).pH neutralization is used to modify the pH of the wastewater. For waste that is acidic (low pH),: Bases are used to modify the pH of a solution.

In the case of alkali waste (high pH): Acids are used to modify the pH of a solution.

Primary Clarifier: The primary clarifiers are used to separate settleable solids from the raw incoming wastewater. These are located downstream of the plant. The major function of the primary clarifier is the removal of all settleable and floating solid waste which has a high oxygen demand – BOD.

Aeration Tank: Aeration Tank: An activated sludge process where air is added into the water to encourage microbial growth. The microbes in the water feed on the organic material and form flocs that then settle out. There are two main ways that air is added to the water and they are through blowers and mixers. There are various types of both blowers and mixers.

Aeration is the part of the process that has the most potential recommendations. It is also a rather common practice in industrial applications that can help to reduce BOD.

Possible recommendations are:

• Injecting Pure Oxygen instead of Air
• Replace Coarse Bubble Diffusers with Finer Pore Diffusers
• Install Dissolved Oxygen Probes
• Automatic Dissolved Oxygen Controls
• Replace Positive Displacement with Centrifugal Pumps
• Install on Blowers

Secondary Clarifiers:  The secondary clarifiers remove suspended solids and scum present in the effluent from the rotating biological contactor units. The removal of the settleable solids is accomplished by allowing the wastewater to move through the clarifiers at such a reduced velocity that the larger particles settle out.