Designs for improved water purification plant in Brazil

The daily schedule in Alfenas included waking up at 7 AM, working for 10 or 12 hours in the lab, and dining around 9 PM. As a South American, Olive had no trouble keeping up with the late dinners, "but everyone else was a little off." During their three weekends, students met the local authorities and society, visited farms, went sightseeing, and socialized. "Every Friday night we had an invitation to do something or go somewhere, so we had an interesting social life. We had time to wind down a bit, but mainly we worked."

Junifenas, the local university, provided access to the lab in which they have been studying the lake and monitoring conditions for a number of years. "They have a wonderful setup with fine equipment," enthused Olive. "We had a lab almost to ourselves, with three great lab assistants available to us. Whenever we turned around with a questioning face, they would ask, 'What do you need?'"

Lab work on these projects became the basis of the students' MEng theses. Olive says, "I designed a wastewater treatment plant for 20,000 people. The cost of the plant varies from $60,000 to $70,000, depending on various factors such as the type of chemicals and the degree of automation of the process." One competing design for this region in Brazil is a treatment called UASB (upflow anaerobic sludge blanket) that would cost roughly $200,000 to $300,000, and would treat the water to the full extent to meet the regulations.

Without meeting standards for secondary sewage treatment, "CEPT would still improve levels for coliforms and phosphorus by 85 to 90%," calculates Olive. "That's precisely why it's a good application for developing countries it is so cost effective for greatly improving the situation as a first step. It's a huge improvement over dumping raw sewage."

Because the students are implementing CEPT plus disinfection with sodium hypochloride, Olive notes that there is a chance of forming toxic byproducts of the chlorination process. "In this case they're not of concern because of the low concentrations used. The treatment will produce much cleaner and pathogen-free wastewater, and as a bonus we're reusing the sludge, instead of incinerating it or dumping it in landfills." As far as the group can tell, sludge from the CEPT wouldn't contain heavy metals. Each of Alfenas's half dozen industrial plants maintains its own wastewater treatment facility, so the CEPT plant would be cleaning up only water from domestic use.

Olive suspects that CEPT hasn't become more widely used because "it is usually seen as just a little more than conventional primary treatment. I think the tendency is to always apply the more sophisticated treatment with the expectation is that it will be best. People always crave the coolest, newest technology, even if CEPT is really efficient for cost."

CEPT can be used at any scale, including for very small towns. "The basic problem is just convincing people that they can use CEPT as a first step in water clean-up, and plan for more advanced treatment later," states Olive. A functioning CEPT plant will greatly reduce the ongoing pollution, and also allow for a smaller secondary treatment solution than if the planners had to deal with untreated water. Adding the chemicals for CEPT will roughly double the amount of water that can be treated. It is also more cost-effective to build a secondary plant that takes in water already receiving enhanced primary treatment, compared to water undergoing conventional primary treatment.

Major engineering firms would not likely compete for contracts to build and maintain a plant containing very simple, economical, easily obtainable equipment, suspects Olive. Even as its low opportunity for profit makes CEPT less desirable from the industry point of view, "from the technical and scientific point of view, it's absolutely more efficient. It always reduces the cost of secondary treatment." She cites the Point Loma plant near San Diego, which had projected that four tanks would be needed for anaerobic digestion. "After retrofitting their primary tanks with CEPT, they only needed two, although they built a third one just in case."

With the expansion of CEPT plants inextricably tied up with money and contracts, Olive thinks that the concept will be more successful outside the US. "Dr. Harleman is working to get it better known in developing countries. This process is already being used in Brazil for industrial wastewater. A project several years ago led by Frederic Chagnon, Christian Cabral, and Domagoj Gotovac '99 (MEng) and Christian Cabral retrofitted a lagoon system with CEPT at the beachside city of Riviera de São Lourenço. The area could then handle its excess wastewater when the population jumped from its normal population of 20,000 up to 100,000 inhabitants in summer."

Having moved to Puerto Rico during middle school before going back to Argentina, Olive had planned since she was 13 to return to the US for a masters degree. She holds an MEng in Chemical Engineering from the Technological Institute of Buenos Aires, and a professional certificate in Environmental Health and Safety from the National Technical Univ. In Argentina. "Designing plants was one of the things I liked best about being a chemical engineer, so this MEng project really united the environmental and the chemical engineering parts for me," she says.

Compared to the problems of supplying clean drinking water in the developing world, wastewater treatment has been less explored, according to Olive. However, it should not be considered less important. "Wastewater treatment provides a healthier environment, and many waterborne diseases are generated when people drink from wastewater thrown on the street, or latrines are not set up or maintained properly."

This summer, Olive has taken an internship at Millipore Corp. In Bedford, MA, as part of their Environmental Health and Safety corporate team. One of her tasks was to operate the wastewater treatment plant, including much of the same lab work she was in charge of in Brazil. She is currently evaluating job options for the fall.