Unit Processes
Plant Layout
The Támara plant layout has a few major changes from the layout of the previous Ojojona plant.
1. The horizontal flocculator was removed. Testing in Ojojona confirmed that the vertical flocculator worked well The vertical flocculator is less costly to build because it does not need to be elevated, so the horizontal flocculator will no longer be used in AguaClara plants.
2. At the request of plant operators in Ojojona, a "bodega" was added to the plant. This walled-in, roofed area is to be used for chemical storage, mixing of chemicals, and possibly a cot for night-time operators.
3. A plant leveling tank was added to replace the pipe elbow level control feature in Ojojona.
4. Chemical barrels were separated. The alum and chlorine barrels will be located on different tables to allow for open walkways without tubes stretching across them, and to allow the tables to be at different heights as necessary.
5. Tanks will be built of brick. APP is more familiar with brick, they believes it is less porous than concrete, and they can build more cheaply with brick.
6. The plant will be more protected. There are two possible scenarios. The first is to have a fence around the plant with a roof over the platform. The second is to have open walls that start at the platform and stretch partway up to a roof. These walls would eliminate the need for a railing around the plant or extra sunlight protection for the tanks. Overall, this decision and design will be left to the plant operators and engineers in Honduras.
7. A catwalk may be added to span the flocculation and sedimentation tanks. Because brick walls will be thin, a catwalk would allow for safer access to these tanks. The AguaClara team envisions a sturdy, metal catwalk that could slide from one end of the tank to the other. However, it is up to the plant operator to decide if this is necessary.The tank walls need to have a ledge inside the external walls of the building covering the plant so there is a place for the catwalk to rest.
Figure 3.
The new plant layout will be ideal for scaling of future AguaClara plants. As long as baffle materials remain available to allow for the same width of tanks, the width of the plant should not change. When a new plant is designed, the only necessary change to the layout will be the length of the tanks. This will allow for more rapid design, easier automated design, and more uniform future plants.
Another important feature of the new layout is that many of the pipes will be under the platform. While this may be somewhat more difficult to build, it allows for easier access with no obstructions to walkways. The area under the platform should be secured so that all of the valves and pipes are protected
Although not shown in the above drawing, all four major tanks will have drains that leave from the entrance side of the tanks. These pipes will go to a waste collection tank under the platform where the operator will be able to see the water that is leaving the plant. In this way he may know when all the dirty water has been flushed out. This will be especially useful when cleaning out the sludge from the bottom of the sedimentation tanks.
Figure 4.