Shell Mera is a town located in the Eastern foothills of the Ecuadorian Andes approximately 94 miles Southeast of Quito (Figure 1). Today, Shell is a large town of 5,000 people, with a church, hospital, schools, hotels, and a missionary guest house making it a wonderful place to visit. The economy is mostly made up of small businesses and agriculture but the town's beauty is in its large variety of plants, insects, and landforms. The town is located at an elevation of 3,500 feet (1000 m) and has a moderate climate of rainy and 60's, averaging around 48 inches of rain fall per year.
HCJB global built the 28 bed mission hospital in May of 1958 and has since upgraded the facility. Most of the physicians at HVO are board-certified Americans, but host a family medicine residency for Ecuadorian nationals. A full range of family medicine, including obstetrics, general surgery and orthopedics are offered to the people of Shell and the surrounding area at HVO. Classical "tropical diseases" are frequently diagnosed and treated, including tuberculosis, malaria, dengue, intestinal parasites and bacterial dysentery. The hospital also promotes a health program that teaches the surrounding villages in the jungle how to care for their villages, more specifically the health program teaches these communities how to find and treat falciparum malaria.
The main objective of this design project is to present a preliminary design for a wastewater treatment system for the hospital and surrounding area. In addition, a suitable method for solids waste handling will be studied and recommended.The following criteria have been established as the constraints for the design:
-Low capital, operation, and maintenance costs
-Minimum use of mechanical and electrical parts to ensure ease of operation and maintenance
-All parts and materials should be available locally in Ecuador
-Due to the lack of a reliable power source, design must be capable of operating without electricity
-Design must not require the use of any chemicals or materials that might damage the downstream environment
-As there is limited space available on the hospital property, design footprint should be minimized
-The effluent of the system must satisfy the required water quality
-Sludge production should be minimized
-Design must be culturally acceptable to the local population
-Design should not pose any risk of harm to the system operators
The quality of the effluent stream is constrained to a BOD concentration of 2mg/L when mixed in the receiving water. Assuming an effluent dilution of eight volumes of river water, the maximum allowable effluent BOD concentration of the treatment system is 20mg/L (UK Royal Commission Standards). Stabilization ponds are assumed to have a suspended solids removal similar to that of BOD removal (80-90%). As the Motolo River is likely to have a high natural concentration of suspended solids, it is unnecessary to set TSS standards for the effluent in this case.Along with a wastewater treatment system, an appropriate sludge handling method must be developed that meets the same design constraints listed above.