McDonald Group International, Inc

Water, Wastewater, Environmental Engineering 


Industrial Wastewater Treatment Plant Process Control and Operations Consulting Guatemala


This  activated sludge, industrial wastewater treatment facility in Guatemala (designedby others) was being used to treat wastewater generated in the process of growing  sterile Med flies.  Med flys pose a threat to the Citrus industry and releasing sterile med flys to breed with wild fertile Med flys was deemed one way to diminish the wild population.    However the process creates about 30,000 US gallons per day in wastewater with a high soluble BOD and a high level of fine screenable material.  McDonald Group International was asked to make an "asbuilt" of the facility, evaluate the treatment process used, make recommendations to improve the process, and provide training and support for operators in process control, including writing a Spanish language operations and maintains manual.


Part of the schematic of the  plant shown above.  The facility discharged to surface water and used UV light as the disinfectant - the equipment can be seen in the photo below this paragraph,  in the background on the concrete slab.  It was a major treatment goal to provide a high level of disinfection  in order to protect the receiving water body, a lake, from the effects of both chlorine which is otherwise used and the effects of   fecal coliform contamination.    In order to work, however,  the effluent entering the UV system has to be highly treated, very low in turbidity.  Which it was not,  hence the need for determining what process improvements were  required and to train operators in the optimum way of operating the plant.  A major outcome of the effort was determining that the influent BOD was about 1100 mg/L (about 5 times normal domestic strength) and improvements in air supply and delivery were needed to assure production of  a settleable liquid with a very clear effluent


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