Sewage treatment plant is the plant that works on the top of water treatment process to remove pollutants from wastewater. It includes physical, chemical, and biological processes to remove these pollutants and produce environmentally safe treated wastewater and reusable clean water.
Activated Sludge Process was developed in England in 1914 by Arden and Lockett and was so named because it involved the production of an activated mass of micro organisms capable of stabilizing a waste aerobically.
The aerobic environment in the reactor is achieved by the use of diffused or mechanical aeration, which also serves to maintain the mixed liquor in a completely mixed regime. After a special period of time, the mixture of new cells and odd cells is passed into a settling tank, where the cells are separated from the treated wastewater. A portion wasted corresponds to the new growth of cell tissue associated with a particular wastewater. The level at which the biological mass in the reactor should be kept depends on the desired treatment efficiency and other considerations related to growth kinetics.
A sequencing batch reactor (SBR) is a fill-and-draw activated-sludge treatment system.
SBR system following these steps:
It involves Three steps:
A rotating biological contactor consists of a series of closely spaced circular disks of polystyrene or polyvinyl chloride. The disks are submerged in wastewater and rotated slowly through it.
In operation, biological growths become attached to the surfaces of the disks and eventually form a slime layer over the entire wetted surface area of the disks. The rotation of the disks alternately contacts the biomass with the organic material in the wastewater and then with the atmosphere for adsorption of oxygen. The disk rotation affects oxygen transfer and maintains the biomass in an aerobic condition. The rotation is also the mechanism for removing excess solids from the disks by shearing forces it creates and maintaining the sloughed solids in suspension so they can be carried from the unit to a clarifier. Rotating Biological Contactors can be used for secondary treatment, and they can also be operated in the seasonal and continuous
The bacteria/activated sludge grow on the internal surface of the carriers. The bacteria break down the organic matter from the waste water. The aeration system keeps the carriers with activated sludge in motion. Only the extra amount of bacteria growth, the excess sludge will come separate from the carriers and will flow with the treated water towards the final separator.