Progress in Ojojona

The Ojojona treatment plant

 

     The Ojojona plant was already built and operable when we showed up. Our job has been to figure out how to operate it, evaluate how well it works, make any necessary changes and, most importantly, train the plant operators how to operate it. At this point I would say we have accomplished the bulk of these tasks. We are confident that the plant is capable of treating water and are comfortable operating it. With water entering with a turbidity of anywhere from 8 to 100 NTU, we can produce an effluent of below 5 NTU.

     We have also made several modifications to the plant, which, while minor in size and cost, have made it more effective and easier to use. The plant now has an overflow at the entrance, so that we can limit how much water enters the plant. We also now have a valve to send the water coming out of the plant to waste if the plant is malfunctioning and we don’t want to contaminate the large storage tank with dirty water coming out of the plant.

     Since we arrived, we have been training the three Ojojona fontaneros (plumbers who operate the water distribution system) Alexis, Mario and Juan to be certified plant opperators. The fontaeros are on a weekly rotation, and each week one of them is assigned to work full time at the plant. Although I say training, it is probably more accurate to say that we are learning along with them. They have much more experience than us working with tanks, pipes and large quantities of water, so often they are giving us practical training. Even with the more technical details of operating the plant, we are learning together. I am confident that they are capable of operating the plant today better than Carol, Antonio and I were able to operate it a couple months ago.

     Carol and I work 80% of the time with Antonio, the Agua para el Pueblo technician assigned full-time to the water treatment plant project, nearly every day. A year ago, when Antonio first started working in Ojojona, he had never done any work with water treatment plants. Now, because of his own interest, hard work and ambition, Antonio is an expert on the treatment plant. Because he is an expert on the treatment plants and understands how water systems and development projects work in Honduras, Antonio is probably the single most valuable resource AguaClara has to promote its technology here in Honduras.

     Unfortunately, even though the Ojojona plant is a functioning technology and we consider ourselves and the fontaneros capable of operating it, we still have not been producing clean water every day. The fontaneros are at the plant only during the day, and the plant needs attention 24 hours a day. When it rains during the night and the water entering the plant becomes dirtier, someone needs to be there to raise the chemical dose. With no one there, the plant doesn’t make flocs and the water leaves it just as dirty as it entered. We have showed up many mornings to find the plant putting out dirty water. The solution to this problem is a night operator. Even with all of their computers and automation, treatment plants in the United States often require around-the-clock operators. The AguaClara plant, although simpler, probably requires even more human attention. Without a nighttime operator I don’t think we will ever get the results we are looking for. The problem is that a nighttime operator costs money.

     While we came here as technical advisors, we have also become involved in the much more difficult task of making the plant an economically sustainable project in Ojojona. Currently, Agua para el Pueblo is buying aluminum sulfate to operate the plant. Beginning in January, the Ojojona Junta de Agua (the water board) will take over full responsibility for the operation of the plant. To buy chemicals and materials for the plant, pay a fulltime operator and save some money for repairs and long-term maintenance, we project the Junta will be spending an average of $395 a month. Divided among 350 connected houses, this comes to an increase of $1.13 in the monthly tariff, from $1.59 to $2.72 per house. We are currently working with the Junta to convince the municipal government of Ojojona and community leaders that an increase in the tariff is necessary. Since the tariff will have to go up in January, and things move pretty slowly here, we are running out of time.

      In the next couple months, our work in Ojojona will be winding down. We want to spend less and less time at the plant so that the operators and the Junta realize that it is now their responsibility. We also will be spending more and more time thinking about the construction of the next AguaClara plant. Construction for the next plant is scheduled to begin in early January in a town called Tamara, 40 minutes north of Tegucigalpa.

The AguaClara Technology

     After being here for almost three months it’s about time I wrote a little more about the work we’re doing here with water treatment plants.

The Problem: Dirty Water

     The problem we’re trying to solve is relatively simple: The water that many communities drink in Honduras is dirty. Water that comes from open streams and wetlands is contaminated with soil and organic matter that runs off the surrounding land. If people or animals live above the water source, bacteria from feces also run off into the source.

     Communities have the majority of their water-quality problems during the rainy season (May through November), when heavy downpours are frequent.
     Most small communities disinfect their water with chlorine. Chlorine works well for treating water that is already clear. If there are a few stray bacteria in the water, the chlorine will kill them. Also, if there is still chlorine in the water when it arrives at the tap, this residual can kill bacteria that may enter the water in the home. For instance, if a pitcher is filled with chlorinated water and a child dips his hand in, the residual chlorine will kill bacteria that may be on the child’s hand.
     Unfortunately, for many Honduran communities, chlorination is completely ineffective. If water is dirty enough to be visibly cloudy, chorine is not able to disinfect it. The chlorine reacts with all of the dirt and organic matter and gets used up before it is able to kill all of the bacteria in the water. After all of the chlorine is spent, there are still harmful bacteria left.
     A measurement called “turbidity” (with arbitrary units of NTU) is used to describe how cloudy water is. In the United States, water from a municipal treatment plant must be below 0.3 NTU on average. Here in Ojojona, the water coming from the sources is sometimes 80 or 100 NTU. If water is above 20 NTU, you can see that it is cloudy. Chlorine is only effective in water with a turbidity of 10 NTU or less. Our goal is to consistently treat water to below 5 NTU.

The bottle on the right was 80 NTU water entering the plant. The bottle on the right is 3 NTU water leaving the plant at the same time.

The AguaClara Solution

     Water appears dirty or cloudy because it has microscopic particles suspended in it. These particles can be soil, organic matter or bacteria. They are so small and light that they do not settle on their own. If you pour turbid water in a glass and come back the next day, most of the particles will still be suspended and the water will still appear cloudy. The goal of our treatment plants is to remove these small particles from the water before it is chlorinated.
     Particle removal is a two-step process. First, we cause the particles to merge to form larger clumps called flocs that will settle out easier. This first step is called flocculation. Second, we allow these flocs to settle out of the water before it leaves the plant. This phase is called sedimentation. Many conventional water treatment plants in the United States use these same exact two processes. In the United States, flocculation and sedimentation are almost always followed by filtration. However, our goal of 5 NTU, safe water that can be chlorinated, is attainable without filtration.
     In flocculation two things must happen for the particles to combine into larger flocs. One, the small particles must collide with each other so that they have a chance to merge. In the treatment plant, we cause particles to collide by mixing the water. Conventional treatment plants mix the water with large mechanical paddles powered by electric motors. To simplify things, the AguaClara treatment plants mix the water by sending it on a winding path through a series of baffles (See Plant Diagram). Each time the water is forced to turn a sharp corner around one of the baffles, it is mixed and particles collide.

 Diagram of AguaClara plant

     The second criterion for flocculation is that when the particles collide they must stick to one another. We use a chemical called aluminum sulfate to accomplish this. The aluminum sulfate is mixed in with the water just after it enters the plant (See Plant Diagram) and just before it is sent to the maze of baffles that we call the flocculator. My chemistry’s not so good, so all I can tell you is that aluminum sulfate dissolves in the water and causes the particles to be attracted to one another.
     After the small particles in the water have been collected into larger flocs, the flocs settle out in the sedimentation tanks (See Plant Diagram). Water enters through pipes in the bottom of the tanks and slowly moves toward the top of the tanks through an array of inclined plastic sheets. Flocs settle faster than the water is moving up, so they come to rest on the plastic sheets. Eventually the flocs slide off the plastic sheets and to the bottom of the tank. When the water reaches the top of the sedimentation tanks it is clear and ready to be chlorinated and sent to houses. The flocs collect in the bottom of the sedimentation tanks and the tanks have to be cleaned about every week.
     Flocculation and sedimentation are not new ideas. Treatment plants around the world and even here in Honduras have been using them for a long time. What makes the AguaClara technology different from other plants is its simplicity. The plant uses no electricity and is relatively simple to operate. Except for a very few hoses and connectors, which would probably fit in a backpack, the plant is built completely from materials available in Honduras. Because of its simplicity, the plant is relatively cheap to build. The construction budget for next plant we’re planning to serve a community of about 3000 people is around $40,000. Considering that the USAID budget for Honduras in 2007 is $41 million, the cost of the plant is pretty small.