San Fernando WWTP
General: The Empresas Publicas de Medellín (EEPPM), Colombia is undertaking a wastewater collection and treatment program to protect the Medellín River. The project started in the 1960's with a plan developed by Greeley and Hansen to install sewer collection systems. Greeley and Hansen continued the project in the early 1980's with water quality and treatment modeling. Interceptors along the river have been constructed which discharge at selected key locations. The wastewater treatment phase of the project has begun with the design by Greeley and Hansen of the first wastewater treatment plant in the San Fernando area. Phase 1 of the project will be a 1.8 m3/s (41 mgd) activated sludge plant. Construction began in 1997 on the San Fernando plant and will be completed in early 2000.
Long-Term Plan: With the help of a consortium made up of Greeley and Hansen and the local firm of Compañia Colombiana de Consultores (CCC), EEPPM developed a long-term plan to clean up the river. The study conducted in the early 1980's was based on the QUAL II and CAPDET computer models. Hundreds of combinations of treatment levels and plant locations were explored. Estimates were made of the anticipated flows and characteristics from each of the service areas as inputs to the model. The water quality model was then used to determine the effects of various levels of treatment on the river quality. Based on the study, the consortium recommended that a series of interceptors paralleling the river be constructed that would deliver wastewater for treatment to four locations.
Design: In 1994, the team of Greeley and Hansen and CCC again was called on by EEPPM for the design of the San Fernando WWTP. It was determined that for the client to meet their water quality goals that the plant needed to provide secondary treatment. A flow metering and sampling program was conducted. Based on anticipated growth the plant will be constructed in phases, initially with a capacity of 1.8 m3/s (41 mgd). The initial concentrations of influent BOD and TSS is expected to be 210 and 380 mg/L, respectively. Design provisions were made for an ultimate capacity of 4.8 m3/s (110 mgd) with 200 mg/L BOD and 200 mg/L TSS.
Prior to design, a series of comprehensive preliminary design reports were prepared for each proposed facility. Preliminary design reports were also prepared for each auxiliary system including instrumentation HVAC, fire protection, laboratory instruments, valves, and motors.
The final design consisted of the following facilities:
Wastewater Treatment
- Automatic Bar Screens
- Dry-pit centrifugal influent wastewater pumps
- Vortex grit removal tanks
- Covered circular primary treatment tanks
- Step feed activated sludge with fine bubble diffusers and rectangular final sedimentation tanks
- Packed-tower scrubber odor control system
Sludge Treatment and Handling
- Thickening of primary sludge within the clarifiers
- Centrifuge thickening of waste activated sludge
- Anaerobic digestion of combined primary and waste activated sludge in egg-shaped tanks
- Sludge gas engine generators
- Centrifuge dewatering of digested sludge
- Truck transport of dewatered sludge
- Co-landfilling of sludge with solid waste
Miscellaneous
- Distributed control system
- Fire protection system
- Wastewater laboratory
Startup and Training: Greeley and Hansen is also providing the services to assist EEPPM to start up the San Fernando facilities. An operation and maintenance manual for the plant was prepared in both English and Spanish. The operation and maintenance manual will also be place "on-line", which will allow access to training materials and real-time information through the Internet. In 2000, Greeley and Hansen will conduct a comprehensive training program for the plant staff on the operation and maintenance of the San Fernando plant. The training will be tailored to their specific needs and will include business workshops to help form the organizational structure. Greeley and Hansen will also provide a startup team that will work on site with EEPPM staff to bring the new facilities on line. The team will be made up of personnel experienced in plant operation and maintenance.