Learning Objectives
• Use water supply and demand data to design balancing storage reservoirs or equalization tanks
• Describe the 2-film theory of gas transfer
• Evaluate different aeration strategies and design an appropriate aeration process for water or wastewater treatment
• Describe different types of screens and their applications in water and wastewater treatment
• Design screens and determine head loss through different types of screens
• Define different types of settling and the conditions under which they occur
• Design different types of settling tanks for primary and secondary clarification
• Describe the double layer model for particles and its application in coagulation processes
• Describe the mechanisms of coagulation and flocculation
• Determine hardness in water and design processes for softening water
• Identify types of filtration processes, evaluate their use for different water samples and design appropriate units
• Describe different types of membrane filters and conditions for their use
• Design membrane filtration processes for drinking water treatment
BALANCING STORAGE OR FLOW EQUALIZATION
A major design unit in water and wastewater treatment is a balancing storage reservoir (water treatment) or a flow equalization tank (wastewater treatment). Since flow is never constant and is subject to seasonal and diurnal variations, fluctuations in water demand and generation of wastewater have to be accounted for in the design of these reservoirs or tanks.
Distribution reservoirs are used in water treatment plants to store treated water for balancing hourly variations in water demand and for emergencies like fires, break-downs, and repairs. These reservoirs are also called service reservoirs. The main functions of a distribution reservoir are:
To balance hourly variations in water demand thus allowing water treatment units and pumps to be operated at a constant rate. This in turn reduces costs and improves efficiency,
To maintain constant heads in the distribution mains. In the absence of storage reservoirs, pressure would fall as demand increases. Use of distribution reservoirs dampens pressure fluctuations,
To allow pumping of water in shifts to meet the whole day's demand without affecting water supply,
To supply water during emergencies like fires, breakdowns or repairs, and
To reduce the size of pumps, pipelines and treatment units, thereby leading to overall economy in design of water supply systems.
Review the options below to login to check your access.
Log in with your Cambridge Higher Education account to check access.
If you believe you should have access to this content, please contact your institutional librarian or consult our FAQ page for further information about accessing our content.