Marcala Water Treatment Plant
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[!Marcala inauguration.JPG|width=300px!|Marcala photos]
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July 10, 2008
The 12,000 person town of Marcala, Honduras took possession of their newly renovated water treatment plant from International Rural Water Association on July 5, 2008. The occasion, covered by live radio and television, was marked by a community celebration, dedication and ribbon cutting ceremony.
The plant was redesigned by IRWA with support from Cornell University's AguaClara group and the engineering firm DeWild, Grant, Reckert & Associates of Rock Rapids, Iowa. The plant, formerly a failed upflow rock filtration plant, was redesigned to a flocculation/sedimentation plant with chlorine disinfection. IRWA and its partners were able to use the existing footprint of the plant creating a series of flocculation and sedimentation basins and finished water storage. Plate settlers were employed in the sedimentation basins to improve plant performance. Construction was accomplished by local labor with oversight by IRWA and our partner organization in Honduras, Agua y Desarrollo Comunitario (ADEC).
The plant was designed to operate without power as electricity is not available at the site. The treatment process including chemical addition is accomplished through gravity flow. Nearly all of the materials used to construct the plant including the plate settlers were procured from sources in Honduras.
Total costs for the plant were $64,000 which were shared by IRWA ($36,000) and the town of Marcala ($28,000). The town has hired two full time operators and has recently been notified by the Honduran national government of a grant to bring electrical power to the site.
Water quality has improved tremendously as a result of the plant. June through November marks the rainy season in Marcala during which the Chieflador River, source for the plant, becomes very muddy. The plant is operating at 500 gallons per minute and has been treating water with turbidity levels as high as 750 NTU. The community is extremely happy with the quality of the water and there is a real sense of excitement for the future. Currently, a new plant is under construction in Marcala,Hondurasunder the supervision of Fred Stottlemyer, former President of International Rural Water Association. Mr. Stottlemyer has asked for assistance from the AguaClara team to calculate some aspects of the design using AguaClara technology. The Marcala plant is being constructed as a retrofit to a failed filtration facility which requires the calculation of design parameters such as the baffle spacing in the flocculation tank, the channel dimensions to route water to sedimentation tanks, and the sludge removal system. Several programs were developed in order to optimize the design process using MathCAD. Additionally, specifications on the cement baffles concerning the strength necessary to withstand draining are outlined.
Several design parameters are necessary for the success of the plant. Firstly, the size of the channel between the flocculation and sedimentation tanks were determined. Secondly, the baffle spacing in the flocculation tank must be determined. Since the nature of this project is to retrofit an exiting plant with existing structural dimensions, determining baffle position was especially difficult. Since the baffles being used will be ferrous cement, they will be mortared to the plant, and hence must be designed correctly from the start. Lastly, the sedimentation tank had to be designed to ensure a working sludge removal system. This includes the sizing and number of orifices on each manifold, carrying water both into and out of the sedimentation tanks.
Much of the structural framework is already in place in Marcala. The objective for is to assist in calculating the dimensions needed in order to turn the Marcala plant into an AguaClaraplant. The treatment plant is being designed with a flow rate of 500 gpm (1900 L/min)[]