In September 2015, Sanasa (Sociedade de Abastecimento de Água e Saneamento), the water utility responsible for providing water and sewage treatment to the 1.1 million residents of Campinas in inland São Paulo State, will initiate a pioneering study to set up Brazil’s first system to produce recycled potable water for its population. The project will be carried out with support from the International Reference Center for Water Reuse (IRCWR), of the University of São Paulo (USP), one of the leading research institutions in the area. Water reuse, based on advanced technology in the treatment of domestic wastewater, is being proposed as an alternative to acute water shortages, a problem arising from insufficient rainfall, as has occurred the last two years in the Southeast.
The Sanasa study will establish parameters and analyze the best treatment processes to design a full-scale system of reusable potable water. The pilot-scale project—laboratory research phase preceding the final equipment used in the treatment plant—will have the capacity to treat 700 liters of sewage per hour. “This pilot will be fed by non-potable recycled water we have already produced at Epar (Water Reuse Production Plant) Capivari II,” says Renato Rossetto, a sanitation engineer and Sanasa’s sewage operations manager. “We expect to conclude the study in seven months.”
The reused water can be classified into two types: non-potable and potable. Today, there are only a few utilities in Brazil, among them Sanasa, Sabesp (Companhia de Saneamento Básico do Estado de São Paulo) and Copasa (Companhia de Saneamento de Minas Gerais), producing water for non-potable reuse that can be repurposed to wash floors, flush toilets, irrigate gardens and agricultural crops, as well as used in industrial boilers and cooling systems. Recycled potable water intended for direct human consumption (such as for drinking, cooking and personal hygiene) must already meet high standards of potability and is not yet available in Brazil. This type of reuse can be classified as either direct, when the treated effluent is injected directly into the distribution network, or indirect, when the liquid is released into sources used by utility companies to extract water, and then subjected to a new processing system in water treatment plants.
“We have the technology to treat wastewater and turn it into recycled potable water that people can safely drink at no risk to their health. But we still need legislation in Brazil in this regard,” says engineer Ivanildo Hespanhol, director of the IRCWR, and a leading water reuse expert in Brazil. “With the Sanasa project we are trying to show the feasibility of producing drinking water from sewage and thereby exert pressure on the authorities to write a specific rule on the subject,” he says. Water reuse is an economically viable modern solution, using technology that has been proven effective, according to Hespanhol. It has already been implemented in several countries, including the United States, South Africa, Australia, Belgium, Namibia and Singapore. “Public health problems associated with recycled water have never occurred in those countries,” he says.
Brazil’s largest water and waste management company, Sabesp, is the leading producer of this type of water. With an installed capacity of approximately 830 liters per second, water recycling is done at four sewage treatment plants (STPs) in the São Paulo Metropolitan Region (SPMR)—Barueri, Jesus Neto, Parque Novo Mundo and São Miguel—and at the Aquapolo Industrial Water Production Plant, a project in partnership with the company Odebrecht Environmental. According to Sabesp, the recycled water is sold to about 50 customers, including municipalities, construction companies and industry sectors such as textiles, petrochemicals and pulp and paper. Distribution of the water, which is used exclusively for non-potable purposes, is handled by a pipeline network, and a few customers receive deliveries by tanker truck. The Aquapolo company, established in 2012 by Sabesp, is undertaking, according to the company, the largest such project in Latin America and one of the 10 largest in the world. The plant supplies water to the Mauá industrial complex and industries of the ABC region of São Paulo (the smaller cities of Santo André, São Bernardo do Campo and São Caetano do Sul).
Cleaning up rivers
IRCWR’s Hespanhol is critical of the policy of bringing water from distant places to supply the residents of São Paulo, and he says that a sustainable and long-term solution to São Paulo’s water shortages must of necessity involve reuse technology. In late June, at a workshop on Subsidies to Supply Water in the São Paulo Metropolitan Region, held at USP’s Polytechnic School, he presented a proposal to implement a system using ultrafiltration membranes and advanced technologies.
An indirect system would be implemented during the first five years of the project; sewage would be converted into non-potable water and stored in a reservoir, subsequently treated to become potable water, and then distributed to the population. In stage two, the next five years, direct reuse would be implemented. “Technologies such as membranes, reverse osmosis, advanced oxidation processes and activated carbon would enable sewage to be converted into potable water and distributed directly to the population,” says Hespanhol. Over the subsequent 10 years the Tietê and Pinheiros Rivers would become cleaner, the result of the wastewater no longer entering the rivers but instead being reused under a direct system.
Brazil has already mastered the ultrafiltration membrane manufacturing technology, a key component of membrane bioreactors (MBR), which is the most widely used system for reused water production. “The research to develop the ultrafiltration membrane prototype at USP’s International Reference Center began in 2009, through a FAPESP-funded PIPE project (Innovative Research in Small Businesses Program), involving the Polytechnic School and the company Ambihidro Engenharia Ambiental,” says José Carlos Mierzwa, a chemical engineer and professor with the Department of Hydraulic and Environmental Engineering at the Polytechnic School.
These membranes, with pores measuring 0.01 to 0.1 micrometers in diameter, are an effective barrier, capable of retaining solid particles with a diameter 1,000 times smaller than a human hair, including viruses and bacteria. “There are fewer than 10 large manufacturers of this product in the entire world. We intend to provide the technology that we have developed through a partnership between the International Center and an interested company or even through technology transfer,” says Mierzwa, who is also International Center’s project coordinator.
A comparative study conducted by Izabela Major Barbosa, a doctoral student advised by Mierzwa at the Polytechnic School, showed that the membranes synthesized at the International Center performed better than models currently on the market. “The addition of clay nanoparticles to the composition of the material reduced the biofilm adhesion on the membrane, which increased its filtration capacity. With this, our membrane performed better than other membranes,” says Barbosa. The biofilm that she is referring to is made up of particles trapped in the pores of the membrane. Ultrafiltration membranes are part of the initial sewage treatment stage at water recycling plants, which can have various configurations (see the infographic for the basic steps of a standard system). Then the effluent, now free of much of the pollutant load, is subjected to advanced treatments in series, based on the concept of multiple barriers, to make the product suitable for use.
“The configuration of the advanced treatment system has to be designed according to the characteristics of the sewage to be treated,” says Ivanildo Hespanhol. “But, whatever it is, the technology available today enables the production of recycled water that is safe for human consumption,” he says. “The use of domestic wastewater is a natural way for us to have sustainable water production in Brazil,” says water resources expert Gesner Oliveira, former president of Sabesp and a partner in the consulting firm GO Associados. “Today, recycled water makes up less than 1% of national water consumption. I would like to see more incentives to do this, and the government should establish goals to gradually increase the percentage of recycled water.”
1. Production of polysulfone membrane and nanocomposite polysulfone membrane systems for micro and ultrafiltration in the treatment of water for potable purposes (nº 2006/51800-3); Grant Mechanism Innovative Research in Small Businesses Program (PIPE); Principal Investigator Ivanildo Hespanhol (Ambihidro); Investment R$ 50,408.54 and U$ 5,770.83.
2. Ultrafiltration modified membrane performance in submerged membrane bioreactors (nº 2013/06821-6); Grant Mechanism Doctoral Scholarship (Izabela Major Barbosa); Principal Investigator José Carlos Mierzwa (USP); Investment R$ 112,085.22.