Vertical Flow Hydraulic Flocculator
Overview
Currently, the AguaClara team has built a new, more robust baffle system for the small scale vertical flow hydraulic flocculator that models flocculation tanks built in plants in Honduras. This new baffle system allows for faster and easier adjustments to baffle spacing and arrangement. With the ability to adjust the spacing quickly, turbidity profiles of the tank can be compared for different baffle arrangements to determine which configurations work best for different raw water turbidities and will help verify the equations used by the Design team for energy dissipation. Uniform baffle spacing and tapered spacing will be tested. In tapered flocculation the flocs are exposed to high velocity gradients in the beginning of the tank and lower gradients as they travel through the tank. The key to having reliable and pertinent results is to keep the main variable, raw water turbidity, as standard as possible, meaning that multiple tests need to be run on the same day, when turbidity is over a small range. Having an easily and quickly adjustable baffle system will allow us to run multiple configurations in a short time period, making our results directly comparable to one another.
A second system of baffles is being constructed so one system can be adjusted while another system is in and running tests. The systems can then be swapped in and out to run tests on different baffle configurations. Turbidity profiles will be obtained for a range of energy dissipation rates. The design team uses an energy dissipation rate of 0.4 mW/kg so we will be testing energy dissipation rates around this value. To dose alum we will be using previous research conducted by past pilot plant teams as well as utilizing Process Controller's dosage cycling ability to run through several doses over the range we think will be effective.
Flocculator Methods and Maintenance
Flocculator Maintenance Procedures
Process Controller
Process Controller is used to control plant processes such as alum dosing, turbidimeters, etc and to collect data.
Sampling Method
The method used to collect data along the flocculator.
How to Calibrate Turbidimeters
A guide on how to calibrate turbidimeters. For accurate results, turbidimeters should be calibrated every two months.
Results
Tapered vs. Uniform Baffle Configuration
- Determine whether or not tapered flocculation is more efficient than uniform flocculation.
- Determine the optimal alum dose for the flocculator
Turbidity Profiles
In spring 2008 turbidity profiles were developed for the flocculator under various conditions.
Testing of Uniform Baffle Configuration
- Determine the turbidity profile for the Uniform Baffle Configuration.
Spring 2009 Turibidity Profiles
- The calculations and turbidity profile results of testing various uniform and channel-tapered baffle configurations.
- Develop a grab sample method to test the accuracy of the turbidimeters.
Construction History
Testing and Tank Modifications
Construction of Tapered Baffles
Construction of Adjustable Baffle System