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Chemistry

A fine mixture

A protective film reduces the evaporation of fresh water in reservoirs

LOTUSPond in Brasilia: an economy of 80,000 liters of water in five daysLOTUS

An ultra fine film formed from limestone and surfactants, substances used in cosmetics and medicines and obtained from sources such as vegetable oils and bees wax, manage to reduce evaporation by, on average, 30% for a lake of 13,000 m2 and could be used in reservoirs and dams. Fresh breath for regions such as the semi-arid Northeast, where drought is a chronic scourge mainly due to the high level of water evaporation, and even for the South of Brazil, which is confronting a prolonged spell of dry weather through lack of rains over the last few months, with serious consequences for family agriculture.

The anti-evaporation mixture is presented in the form of a fine white powder that, on being thrown in small quantities onto the water’s surface, rapidly spreads out forming a film, invisible to the human eye. “One can only perceive that a film is covering the water because it remains flat calm, and the naturally occurring ripples on the surface are attenuated”, explains Marcos Gugliotti, the scientific director of the company Lotus Química Ambiental and the coordinator of the anti-evaporation mixture project, funded through FAPESP’s Small Business Innovation Research (PIPE) program. The ultra fine film forms a type of protective barrier between the water and the atmosphere, without interfering in the exchange of oxygen and carbon dioxide gases, important for the maintenance of aquatic life. As the film is biodegradable, a process that takes on average 48 hours, the product has to be re-applied in order to maintain the effect.

After having been tested in open air tanks, last year the product was applied to the Broa reservoir in the town of São Carlos (SP), and on the pond of Annex 1 of the Chamber of Deputies in Brasilia. The test carried out on the pond had the support of the Environmental Administration Center of the Chamber of Deputies. The Broa reservoir, an area of almost 10,000 m2,  into which eight Olympic swimming pools could be placed, was isolated with contention buoys for the realization of the spreading and environmental impact tests.

Rapid spreading
A motor boat was used to distribute the anti-evaporation mixture, a task done manually with the help of a spade sized large spoon, gloves and a mask to avoid inhaling the particles of powder, which is non-toxic but upsets breathing. On being placed on the water, the powder spreads rapidly. Only half a kilogram of the product is sufficient to cover all of the area, a quantity less than had been expected, indicating efficient spreading although the dosage recommended should be 1 kilogram for each 10,000 m2. Various parameters of the water, such as pH, which is a measure of its acidity/alkalinity, temperature, turbidity and conductivity were analyzed at three collection points within the isolated area and within a point of the reservoir outside the isolated area.

A probe containing various sensors for the vertical strata at various depths was used for analysis. “There was no evidence of any environmental impact, including the analysis of zooplankton and phytoplankton”, says Gugliotti. This statement has as its basis the written opinion of the International Ecology Institute, presided over by professor José Galizia Tundisi, of the Post-Graduation Ecology and Natural Resources Program of the Federal University of São Carlos (UFSCar), hired to carry out the analysis.

The product does not treat the water, but as well does not alter its quality, which means  that if it is fit for human consumption, this will be maintained after its application. This is because the quantity applied is very small in relation to the volume of water. As well as this, the fatty alcohols, the components that make up the film, are often used in cosmetics since they are inert and not-toxic.

On the pond of the Chamber of Deputies the anti-evaporation mixture, applied over a total area of 13,000 m2,  avoided the loss of 80,000 liters over a five day period, representing a saving of R$ 800.00, since a liter of treated water used to fill the pond costs around R$ 0,01. Over this period three applications of 1.3 kilograms, totaling 3.9 kilograms of product, were made. Discounting the operation’s total cost, estimated at R$ 156.00, there was an economy of R$ 644.00 over a five-day period.

Calculated evaporation
Daily two evaporation measurements were taken, determined  by the lowering of the water level, five days without the product and five days with the product, from the 9th until the 18th of September of last year. Since the reservoir is made of impermeable concrete and the exits and entrances for water were closed off, the only water loss was through evaporation. “The minimum reduction was 14% and the maximum 55%”, says Gugliotti. The evaporation changes as a function of the observed time of day. The average evaporation measurement of the mirror like surface of 5.88 millimeters per day was reduced by up to 2.62 millimeters.

The two series of daily measurements were compared between the stages with and without the product’s application and arithmetical means were calculated. “In the worst result obtained an average reduction in evaporation occurred of 21.14%, with an economy of 16,000 liters of water per day, sufficient to guarantee the viability of the product’s application”, says Gugliotti.

The interest in the technology came about during his doctorate and post-doctorate work in physics-chemistry on surfaces carried out by Gugliotti at the Chemistry Institute of the University of São Paulo (USP), when he had studied the mechanical properties of ultra fine films, known as monomolecular because they have a thickness of only one molecule, in this case around 25 Angstroms. An Angstrom corresponds to 1 millimeter divided into 10 million parts. “When I began to study, I saw that this technology had been in existence since 1925, the date of the first published scientific article.”

Field tests, however, only began in the decade of the 1950’s, and by 2002 the technology had only been used in an experimental character in various countries. This was when a Canadian company announced the development of a technically and economically viable product using the technology of ultra fine films, considered by the United Nations Environmental Program (UNEP) an alternative technology for the conservation of fresh water.

The surfactants that reduce the evaporation are basically the same, what changed was the additive. In the case of the Canadian company, which sells its product mainly to the Middle East, calcium hydroxide, or hydrated lime , was used. “The choice of calcium hydroxide as the additive restricts a little the commercialization of the product in some countries, because this substance is caustic and can burn the tissue of fish and plants”, says Gugliotti. Before the launch of the Canadian product, also in powder form, two other companies had developed products in liquid form, but without commercial success.

Gugliotti registered his patent request with powdered limestone as the principal additive, which also covers other combinations of additives with a mixture of surfactants. The secret lies in the proportions, which make the application viable. The additive serves to facilitate the product’s spreading over the water and impedes the agglomeration of particles. But, as well as this, the substance added in to the surfactants has to cause the least possible impact on the environment.

Evaluated impact
Studies carried out by American researchers on Lake Hefner, in Oklahoma, have pointed out that fatty alcohols, the surfactants that form the ultra fine film, do not cause any significant environmental impact. Various experiments on evaporation reduction, one of them lasting five years, were carried out to reach this conclusion. In this study, two years were dedicated to the study of the fauna and flora of the 12 km2 lake, a further two to the continued application of the product and the final year to the analysis of the results obtained. The environmental impact is low or imperceptible because the quantity of product used is very small, and the surfactants, as well as being non-toxic, are insoluble, inter-reacting only slightly with the ecosystem and remaining on the surface of the water in the form of a film.

The surfactant molecule is composed of two parts: a hydrophilic part, which interacts with the water, and a hydrophobic part, which repels the water. Due to this structure the molecules align themselves on the surface in such a way that the hydrophilic part remains in contact with the water whilst the hydrophobic part remains directed towards the air, thus forming a film with a thickness equal to the length of a molecule.

Application in reservoirs and dams is only one of the product’s possible uses. Some trials point to the possibility of its use in irrigation canals, if the speed of the water’s course were to be low, and also for the reduction of water evaporation in the soil. Preliminary tests show that it would be possible to reduce evaporation of the water absorbed by the soil by around 4% through the application of the product. By the researcher’s calculations, even with a much lower percentage of evaporation reduction, in the order of 0.5% for example, if the anti-evaporation powder were to be used on thousands of hectares of agricultural lands, it would be possible to economize lots of water.

“Besides reducing water evaporation in the soil, the product diminishes transpiration of the plants, which reduces the need for re-watering them during drier spells”, explains Gugliotti. The fact that the additive of the mixture is limestone, the product most widely used in the world for soil correction, represents an advantage for its application on agricultural lands. Another line of research shows that modifications to the original anti-evaporation product could result in products to control the proliferation of algae and mosquito larvae, including the Aedes aegypti, the principal transmission vector of the virus that causes dengue fever.

Various possibilities for the product’s application indicate that there is lots of work to be done by Lotus, the company established in 2003 to develop environment preservation technologies mainly using mono-molecular films. Resident at the Technology Company Incubator Center (Cietec), located at University City, the company is a family based company. Marcos and his father Eduardo Gugliotti, who has more than 30 years experience in the management of food and pharmaceutical industrial laboratories, and who was also the manager of the water analysis department of the Company of Environmental Sanitation Technology (Cetesb, the environment authority in the state of São Paulo), are working in harmony so that the anti-evaporation powder begins to be developed on a commercial scale.

The business plan that the Lotus company has elaborated was classified as a finalist in the  New Ventures Forum II of Sustainable Business Investors that took place in November of 2005 and is operated in Brazil by the Sustainability Studies Center of the Getulio Vargas Foundation (FGV). And it has attracted investors and other companies interested in licensing the patent, the form of business preferred by the Lotus company partners, since the company’s focus is the development of new formulae. Whilst this is going on, they are preparing to widen their tests.

The project
Development of an anti-evaporation mixture for the conservation of fresh water (nº 03/07630-8); Modality Small Business Innovation Technology (PIPE) Program; Coordinator Marcos Gugliotti – Lótus Química Ambiental; Investment R$ 303,688.00 (FAPESP)

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