New Challenges

Air entrapment in vertical rapid mix tube below micro mix orifice

We have strong evidence that air is being trapped in the vertical section of the rapid mix tube below the micro mix orifice. The head loss in the rapid mix tube increases causing the entrance tank to overflow even though the flow rate is less than the design flow rate.
We hypothesize that the air slow accumulates below the vena contracta because the velocity in the vena contracta is too high for air bubbles to travel upward. Below the vena contracta where the velocities are lower the water velocity is too low to carry the bubbles down and into the flocculator. In addition, the pressure in the middle of the vena contracta can be reduced significantly. At Agalteca the dosing tube was hanging down into the vena contracta. The low pressure in the vena contracta may have caused air to flow through the dosing tube into the vena contracta.
To solve these problems we need to make several changes.

  1. The dosing tube should not be in the vena contracta. The dosing tube should be centered at the very top of the rapid mix tube.
  2. We need a low velocity escape route for air that is caught below the vena contracta. We are proposing that a 1/2" PVC pipe be inserted inside the rapid mix pipe against the inside wall of the pipe and down to a hole in the micro mix orifice plate. This 1/2" pipe will extend up through the maximum water surface in the entrance tank. It will provide a stagnant water path for air bubbles to travel up and out of the rapid mix pipe.
  3. It may be better to have the orifice plate attached to a pipe coupling rather that have the orifice cut into a pipe cap that is at the very top of the pipe going to the flocculator. The plate would be submerged further below the water surface and the dosing tube would not be so close to the orifice. That would provide some opportunity for some mixing before reaching the micromixing orifice.

Powdered Poly Aluminum Chloride

Powdered poly aluminum chloride is being used in Guatemala at one of their hydraulic water treatment plants (El Cambray). This provides a new opportunity for a way to treat water with low alkalinity. Apparently the costs are comparable to alum because you use less of the product, but it costs more per kg. Contact Grasim Industries to determine how to access their product and to see if they are willing to donate some of their product with their charity work.

Outreach

Portable water treatment system that can be used in emergencies.

This topic has come up several times and could be a significant contribution.

Automated Chlorinator for self serve community water stations

Build on the automated dose controller to create a device that automatically meters in the correct amount of chlorine when a valve is opened to take water from a public standpipe.

Technology Selection Guide

Add a technology selection guide to our website. Provide the basic information on selecting the best water sources and the best treatment processes for those water sources. Describe the data necessary to make an informed engineering decision.

AguaClara Technology Overview

Create a clear description of the AguaClara technologies for the website.