Dairy factories generate a high amount of wastewater from cleaning the pipelines, tankers, mixing tanks, packing lines and floors. For every litre of milk produced, twice the amount of waste water would be generated. Each year big factories can generate about 5 million litres of waste water per day. I have chosen to research about the process of how the rinse water is separated into individual components to be left with safe grey water.
Dissolved air flotation is a water cleaning process used to separate solid matter from water. In milk factories this process is used to clean the waste product from milk production. There are a few steps that need to be taken before the mixture and be placed into the Flotation Tank.
-First, the incoming waste water is stored in a holding tank (balance tank) and the water is allowed to mix with other water.
-Then the mixture is pumped through into a reaction tank where the pH is lowered to 4.5
by adding Hydrochloric acid.
-A very long polymer chain (negatively charged) made up of hydrocarbons is added to the mixture to bind all the positively charged solid particles together.
-Next the mixture travels into the separation tank (Dissolved Air Flotation Tank), and the solid particles are lifted to the surface with the help on tiny air bubbles. Now two components have been formed, clean water and solids (sludge).
-The solid waste is sent to a landfill and the water is sent to another reaction tank to have its pH increased to about 6.5- 7.5 so it is safe to release to the sewer or to use for recycling.
The properties that allow for the components to be separated from the other components of the mixture are the lowering of the high pH rinse water to 4.5...