Imprimir Republish

environmental engineering

Impurities Exterminator

Ozone generator born of partnership between a company and an ITA laboratory

MIGUEL BOYAYANThe generators can be dimensioned in accordance with each customerMIGUEL BOYAYAN

A new line of high performance ozone generators has now been installed, tested and assessed; they are for the treatment of industrial and household effluents, ensuring that the water that has been treated is over 90% sterilized. There are four prototypes. One at the Piracicamirim sewage treatment station, of the Municipal Secretariat for Water and Sewage (Semae) in Piracicaba, and another to treat the water at the Aerospace Technical Center (CTA), in São José dos Campos. Another two with the same performance have been installed in a hospital clothes laundry, in São Paulo, and in the laboratory of the Piracicaba Engineering School (EEP); they are being used, respectively, in studying the treatment of contaminated water, and of leachates (the dirty, muddy water from landfills and dumpsites.

The studies and the development of the four prototypes in operation were coordinated by physicist Wilfredo Irrazabal Urruchi, supported by teams from the Plasmas and Processes Laboratory (LPP) of the Physics Department of the Technological Institute of Aeronautics (ITA), and from the School of Mathematical Sciences and Nature and the Carbon Materials Laboratory of the Methodist University of Piracicaba (Unimep), besides the EEP. The funds came from FAPESP’s Small Business Innovation Research Program (PIPE), applied for by the micro-company Qualidor Saneamento Incorporação, of Santa Bárbara d’Oeste, which got in touch with the team from the ITA – where Urruchi had been designated to coordinate the PIPE project – to innovate in the technology for the ozone generators that the company has been making for 30 years.

The partnership proved to be profitable, in the light of the results that corroborated the efficiency of the new generators. The physicochemical and microbiological analyses of the water treated by the prototypes were carried out by the team from the School of Health Sciences at Unimep and by the EEP, for which it was able to count on support from German researcher Julia Sasse, who has a grant from the German Academic Exchange Service (DAAD). “The challenge was for us to develop national technology for generating and applying ozone”, says Urruchi. There are generators on the international market designed for all uses, though their cost is very high.

“We made a generator suited to the Brazilian economic circumstances and adapted to the hot and humid climate, with a view to all the applications where the possibility of contamination from microorganisms or chemical products has to be minimized, without causing any damage to nature, as it is the case of sterilization with chlorine”, explains physicist Choyu Otani – who is assisting with the project at the LPP-ITA. “Even in controlled quantities, chlorine leaves residue from the treatment of water and effluents, and it favors the formation of organochlorines and other byproducts that are harmful to the water sources”. In addition, it is a confirmed fact that ozone is more efficient than chlorine in fighting latent and resistant forms of viruses, bacteria and protozoa present in water, which are responsible for many diseases, such as jaundice, diarrhea, cholera, etc.

According to Urruchi, there is no earlier news in Brazil of the use of ozone in water and sewage treatment stations. Imported generators have been used to apply ozone as a bleach in some pulp and paper industries in the interior of São Paulo, in large food industries, and in a few companies that distribute mineral water, to sterilize the very water that goes into the bottles, as well as the empty bottles. Not to mention the attempts to treat swimming pools, including those made by Qualidor. “The ozone generator developed in this project offers the best technology for the purification of water, it favors the development of a promising branch of industry, and makes a significant contribution towards the preservation of the environment”, he explains.

Water cooled
One of the items that prevents the proliferation of the application of ozone generation is refrigeration. “Our temperature in the summer can go up to as much as 40ºC, which accelerates the degradation of the ozone produced. Accordingly, the first innovation was to build water cooled prototypes, something that Qualidor’s generators didn’t have”, he explains.

The generation of ozone in the equipment uses the principle of dielectric barrier discharge (DBD). “In our generator, a high voltage DBD is formed between two tubular electrodes in a dielectric device (a glass tube), which stores the energy and then releases it. The dry air that circulates between the glass and the electrode is given electrical discharges and is transformed into ozone”. This happens because electrons generated in the discharge disassociate some of the oxygen (O2) molecules, forming some atomic oxygens (O), which rapidly link to other O2 molecules, forming ozone (O3) molecules.

“Electricity cuts are a serious problem for generators, and we have managed to find a solution. We have developed automatic controls with microprocessors, inside the generator, that makes it possible, when the supply is restored, for the voltage to keep growing little by little, until it reaches the ideal point for working, without burning out the system”, says Urruchi. This system also controls the quantity of air that goes into the generator, the current for the discharge, the quantity of ozone produced, and the time the apparatus stays in activity. Another great innovation is a remote control system for these generators, via satellite, which is just awaiting the installation of a special line from Embratel.

The first prototype built by Urruchi’s team produced 20 grams an hour (g/h), in a concentration of 1.8% of ozone, a larger capacity and more efficient than Qualidor’s original equipment, with its 7g/h and a concentration of 1.2%. This kind of generator was installed in Lavanderia da Paz, in São Paulo, a laundry specialized in the hospital area, to begin with to deal with the effluents shed after the washing of the clothes. After January 2002, the ozonized water was used directly in washing and sterilizing the clothes, which allows savings of 40% to be made with water, soap and detergents, besides shedding cleaner water into the public network.

Air transformed
In the second part of the project, larger generators were developed, like the one that is in the sewage treatment station (ETE in the Portuguese acronym) in Piracicamirim, to give the sewage its final treatment. It is made up of a processor of dry and clean air, inside of the equipment. This air is cooled and injected into the reactor, where it is partially transformed into ozone, through the action of the DBD process. The gaseous compound is then injected, in the form of micro-bubbles, into the effluent to be treated. According to Urruchi, this prototype handles up to 2 cubic meters of effluents an hour, which would already be enough to supply the appropriately clean water necessary for the cleaning the ETE’s own filters. To treat all the water at the Piracicamirim ETE, before being sent back to nature – in the Piracicamirim river -, the equipment would have to be some 50 or 100 times larger than the prototype.

“The leachates that have their origin in landfills are a great problem for sanitation”, says Maria Helena Santini Campos Tavares, who coordinates the EEP’s course on Environmental Engineering. These leachates have high concentrations of organic material and heavy metals that pollute the soils and the subsoil, water sources and underground water. According to her, there is no effective treatment for this. The use of ozone generators makes feasible a preliminary treatment, making the leachate biologically degradable. It makes it possible to generate biogas, using the anaerobic treatment, with bacteria that do not need oxygen to survive, which ensures that the landfills are sustainable in terms of their own energy.

The prototype that is in the EEP’s laboratory is being tested as a sterilizer of the water that comes from septic tanks. After a few minutes of ozonization, the household sewage becomes clear, there is a reduction of organic material, and the microorganisms are sterilized. This generator is smaller and simpler in concept than the one installed in thePiracicamirim ETE (the Piracica-Mirim station), and can be adapted to the treatment of effluents from a house or a condominium. “The idea is to make decentralized treatment feasible”, explains Maria Helena.

Trade partners
“Our great challenge now is to meet to the specific needs for the use of ozone of each potential customer”, explains Aluisio Pimentel de Camargo, a director of Qualidor Saneamento Incorporação. “We are going to split our work into seven segments: the treatment of municipal effluents, industrial effluents, air-conditioning systems, underground water, condominium water tanks, swimming pools, and leachates from municipal landfills. We may also work with the effluents generated by the big hog farmers, who contaminate the water sources with organic waste and toxic and carcinogenic products that are resistant to the conventional processes for treatment”.

Another area is the production of plant seedlings, which, in ozonized air, undergo natural selection, resulting in resistant seedlings that need less agro-chemicals. “The possibilities for using these generators are immense”, Camargo warrants. “The great snag for us, after the two prototypes are ready, is to get partners willing to inject capital into the company, which is small and without a structure for the size of the challenge to be overcome from now onwards”, concludes Qualidor’s director.

For Wilfredo Urruchi, there is yet another challenge. Getting the equipment certified. The current standards for verifying efficiency in treating effluents are directly related to the use of chlorine. The biggest challenge, however, which was to develop an innovative ozone generator, has now been mastered.

Purifying element

Ozone (O3) is a pale blue gas, unstable, very oxidant and reactive. It exists in its natural form at altitudes of between 15 and 20 kilometers, where it absorbs the ultraviolet rays of the Sun. In the environment in which we live, between 20º and 30ºC, its useful life lasts a mere 40 minutes. When the temperature goes up to between 35º and 40ºC, it starts to come apart, ceasing to be O3 to go back to being O2 (oxygen). This instability favors the reaction of ozone with cells or molecules. This process, called oxidation, serves to eliminate algae, germs, viruses and bacteria.

Discovered in 1785, it has now been in use for over 90 years. It has shown efficiency over these years in depolluting and purifying water, in the treatment of effluents with organic and chemical compounds coming from such industries as pulp and paper, petrochemicals, textiles, food, medicines, dairy products and meat processors. “At the moment, the technology for the production of ozone is the same, anywhere in the world. What changes is the system that integrates the generator and the medium to be treated with ozone, which is specific for each application”, says physicist Wilfredo Urruchi, the researcher and collaborator from ITA.

In the treatment of water, besides its action on microorganisms, ozone is also used in processes to remove heavy metals and to reduce nitrogenous compounds (urea, ammonia, nitrates and cyanides), and in the chemical and biological control of the oxygen existing in any aqueous medium. The use of ozone is being expanded and encouraged in several countries to meet the ever increasing requirements for purifying the water and preserving the environment.

The Project
Development of a High Performance Ozone Generator (nº 98/15038-1); Modality Small Business Innovation Research Program (PIPE); Coordinator Wilfredo Milquiades Irrazabal Urruchi – ITA/Qualidor; Investment R$ 215,067.00 and US$ 8,984.70