Wastewater treatment can be divided into 3 stages - preliminary treatment, primary treatment, secondary treatment. Preliminary treatment consists of physical screening of large objects. In Primary treatment, the wastewater is held in a separation tank to allow particles to settle to the bottom and grease to float to the top. The solids are drawn off the bottom and skimmed off the top and sent for further treatment as sludge. Secondary treatment is a biological treatment to remove dissolved organic matter from the wastewater. Aerobic microorganisms are allowed to consume the dissolved organic matter. For this purpose, sufficient oxygen have to be provided and this is where aeration comes in. For more details, links to other websites are provided below:
Wastewater Treatment Principles and Regulations
Wastewater Treatment, Water Use
AERATION
BOOKS:
Theory and Practice of Water and Wastewater Treatment
Wastewater Engineering: Treatment and Reuse
Small and Decentraliszed Wastewater Management System
Simplified Wastewater Treatment Plant Operations
Water and Wastewater Calculations Manual
