Chlorinating Rural Honduran Water Systems

One of the more recent projects that I have been working on is a chlorination program in the municipality of Trinidad.  While our friends from the States, Paul and Clare, were here we visited the community of San Francisco about 20 minutes outside of the town of Trinidad.  Our intention was to go over the steps of the chlorination process with the community leaders.

On the day of that visit we found that their chlorination box (located on the top of the storage tank) did not have the necessary connections in order to drip-feed a chlorine solution to the water.  I went over the chlorination process with the environmental coordinator from the municipality (Irvin) and instructed the community leaders on how to prepare the chlorine box for future use.

2+2=?

The focus of the project is to prepare Irvin to take over this program when I am gone while at the same time training individual community water system operators how to properly disinfect their community’s water supply.

Irvin and I returned a week later to redo the chlorination lesson with the community leaders.  I was very happy with their retrofit chlorine dosing valve.  The original chlorine box didn’t include a way to pass the chlorine to the water supply so we tied a 1/2″ PVC into the clean-out pipe leaving the chloro box.

Drip-feed chlorine into the water piped in from the mountain source

First they measured the volume of the chlorine box.  With that volume we calculated the drip-rate required to drain the box in 4 days (the effective life of chlorine in solution).  Then we used the newly installed chlorine dosing valve to achieve the calculated drip-rate.

Using a baby bottle to calculate the drip rate in milliliters per minute

Next, the flow rate into the tank from the water source was measured using a 5 gallon bucket.  The bucket filled in approximately 11 seconds corresponding to a flow rate of about 27 gallons per minute.  The measured flow is then used to calculate the amount of chlorine powder required to achieve a chlorine concentration of around 1 ppm in the community distribution system.  In this case, 4 lbs of chlorine powder need to be used.

Measuring out 4 lbs of chlorine powder

The 4 lbs of chlorine powder is mixed into a highly concentrated solution.  Chlorine, which is actually a gas, is dissolved out of the chlorine powder into the liquid solution for application.

he refused to wear a mask... ha

Once the solution is ready it is dumped through an old t-shirt into the chlorination box.  The shirt filters out the powder which has already been stripped of its chlorine gas.

Over the following 4 days, the chlorine box will drip chlorine solution into the tank where it will mix with the raw water supply, killing bacteria and other forms of disease causing microbes.  After 4 days the community leaders will have to return to the tank and reapply 4 pounds of chlorine powder.

Irvin and I will continue to visit individual communities to support local water operators to disinfect their drinking water.  We’ll also be revisiting communities to test the water from the tap to see if there is residual chlorine in the water.  We are currently working with other municipal partners to create a monitoring and chlorine distribution program (or chlorine bank).  A chlorination program is completely dependent on an effective monitoring and supply program.