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- What makes a flocculator better than other water treatment methods that are available or could be made available in Honduras?
- Flocculation and sedimentation are applied as a first step in many conventional water treatment plants in the U.S. to clean turbid water. Since the problem with most water in Honduras is turbidity, flocculation is an effective treatment option for a community-scale plant.
There are also many options for point of use water treatment (POU), however we believe that community-scale treatment plants are the more cost-effective and are more likely to be operated correctly. With point of use systems, every single community member must be trained how to treat their water, while the treatment plant only requires two or three well-trained operators.
- Flocculation and sedimentation are applied as a first step in many conventional water treatment plants in the U.S. to clean turbid water. Since the problem with most water in Honduras is turbidity, flocculation is an effective treatment option for a community-scale plant.
- How big is the plant?
- This depends on the size of the community. A plant for a community of 3,500 people is about the size of a two-story house.
- Can the AguaClara technology be used if there aren't mountains?
- Normallly, the AguaClara technology is used in water systems where water is delivered to the community by gravity, thus requiring some elevation difference between the water source and the community. However, water could be pumped up to an elevated tank and then run through an AguaClara plant under the power of gravity.
- Is the water leaving the demo plant safe to drink?
- We often use water, clay, alum, and sometimes food dye for in the demo plant. Even though these chemicals are not hazardous to your health, according to laboratory safety rules no one is allowed to drink the water treated in the demo plant.
- How long is the chlorine in contact with the water until people drink it?
- What is flocculation?
- Flocculation refers to uniting small particles suspended in dirty water into larger particles called flocs. The flocs weigh enough to sediment from the water much more rapidly than the original small particles. In the AguaClara hydraulic flocculator, the water is gently mixed to promote collisions among the particles. Before flocculation, a chemical called aluminum sulfate is added to the water. Aluminum sulfate makes the particles attract each other so that when they collide they stick together to form flocs.
- Why is filtration not used/not necessary?
- If the combination of flocculation and sedimentation is done correctly, quite clear water (turbidity below 5 NTU) can be produced. Water below 5 NTU is safe to drink once it is disinfected with chlorine. The AguaClara team is also experimenting with the use of a sludge blanket in the sedimentation tank that could push the effluent NTU even lower. The drawback of filtration is that it relies on clean filters to work. Very turbid water, typical of the rainy season in Honduras, would clog filters very quickly. Pumps are required to clean most rapid sand filters and that requires electricity. Slow sand filters are large and costly to build. They must be cleaned manually, an extensive process.
- How clean is the water that leaves?
- Water cleaned with the AguaCLara technology is consistently less than 5 NTU.
- How do you get rid of the sediment that settles out in the sedimentation tank?
- Sludge is drained from the sedimentation tank once a day while still maintaining a sludge blanket in the sedimentation tank which further acts as a filter.
- Do you have to turn off the plant to do it?
- Normally, the sludge is removed slowly from the bottom of each tank while the tank is still online and functioning. Every couple months, the tanks are thoroughly cleaned, which involves emptying them. Since there are three multiple sedimentation tanks, the plant can still be operating while one of the sedimentation tanks is offline.
- Can you have too much aluminum sulfate used in the plant? How about Chlorine?
- Aluminum sulfate and chlorine are used in conventional water treatment processes around the world. In normal doses, neither chemical causes health problems. If flocculation is working, nearly all of the aluminum sulfate is removed from the water before it leaves the plant. The plant operator is always careful to avoid overdosing, both to prevent costly chemical waste and high chemical residuals in the drinking water.
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