Passive chemical dosing and mixing apparatus and method

A method for dosing flowing fluids which may have widely varying flow rates with a regulated, uniform dosing of at least one chemical comprising:

• passing the flowing fluids through an open-channel fluid-flow control device with a known, non-linear, stage-discharge relationship,
• providing a chemical-dispensing system for dispensing chemicals into fluids flowing through said open-channel fluid-flow control device with said chemical-dispensing system having at least two tubes for dispensing chemicals into fluid flowing through said fluid-flow control device, and
• measuring the fluid level in said fluid-flow control device to determine the discharge of fluid passing through said fluid-flow control device using the known stage-discharge relationship of said fluid-flow control device and when said fluid level has reached a first predetermined value, actuating one of said at least two tubes for dispensing a predetermined first amount of chemical into the fluid flowing through said fluid-flow control device and when said fluid level has reached a second predetermined value, greater than said first predetermined value, actuating another one of said at least two tubes for dispensing a predetermined second amount of chemical into the fluid flowing through said fluid-flow control device,
• wherein a regulated, uniform dosing of chemical is achieved in the fluid discharged from said open-channel fluid-flow control device.

An apparatus for treating flowing fluids, which may have widely varying flow rates, with a regulated, uniform dosing of at least one chemical comprising:

• an open-channel fluid-flow control device positioned at a first level, said open-channel fluid-flow control device having a known, non-linear, stage-discharge relationship,
• said open-channel fluid-flow control device having first and second sides, a mouth and a discharge end,
• a gravity powered dispensing system for dispensing at least one chemical into fluid flowing through said open-channel fluid-flow control device, said dispensing system further comprising:
• a chemical reservoir, positioned at a second level higher than said first level,
• said dispensing system further comprising at least two tubes for dispensing chemicals from said reservoir into fluid flowing through said open-channel fluid-flow control device,
• each of said at least two tubes being positioned at a third level between said first and second levels,
• each of said at least two tubes being connected to said chemical reservoir such that chemical from said reservoir may flow by gravity to each of said at least two tubes of said dispensing system,
• each of said at least two tubes further comprising an on-off switch mounted in each said tube,
• each said on-off switch being positioned in each of said at least two tubes and further comprising an independent means to turn each said on-off switch on and permit the flow of chemical through each of said at least two tubes or to turn each said on-off switch off and block the flow of chemical through each of said at least two tubes, with said independent means being capable of turning each said on-off switch on or off independently of any other on-off switch,
• each said independent means further comprising a means in hydraulic communication with said open-channel fluid-flow control device for sensing the fluid level in said open-channel fluid-flow control device and for turning said on-off switch on or off in response to a predetermined, sensed, fluid level in said open-channel fluid-flow control device,
• wherein the means in hydraulic communication with said fluid-flow control device associated with said first tube is arranged to actuate the on-off switch for said first tube at a first, predetermined, sensed, fluid level and wherein the means in hydraulic communication with said fluid-flow control device associated with the second of said at least two tubes is arranged to actuate the on-off switch for the second of said at least two tubes at a second, predetermined, sensed, fluid level and wherein said first fluid level is less than said second fluid level.