The lack of robust and sustainable technologies for chemical dosing and flow control that don't require electrical power continues to adversely affect the ability to reliably provide safe drinking water. Conventional municipal surface water treatment requires the addition of a coagulant solution as well as the addition chlorine. Ideally the flow control device would have the following characteristics:
Water treatment plants in industrialized nations often use variable speed peristaltic pumps or other positive displacement pumps for this purpose. Many potential water treatment plants sites in the Global South don't have ready access to electricity and frequently the electrical grid is unreliable. The AguaClara team at Cornell University recognized the need for an improved gravity powered flow control device and began evaluating the available technologies and ultimately developed and tested a flow control module with the desired characteristics.
We first recognized the need for an improved flow control module during site visits of community water supply systems in Honduras in 2004. The standard Honduran design for community water supply systems consists of a surface water source that is piped to a distribution tank and then distributed via a pipe network to homes. The only water treatment is the addition of hypochlorite.
Several designs for metering these chemicals have been developed however, none of the desig
Flow control modules will generate a linear response between head loss and chemical flow rate as long as expansion losses are small relative to shear losses and as long as the flow is laminar.
Design of the flow control module consists of choosing a maximum head loss corresponding to the maximum design flow rate, and then determining the diameter and length of the tubing.