In a note published by the specialized media País Circular, Spanish researcher Beatriz Ortiz de la Torre and Chilean scientists Roberto Orellana and Salvador Donghi answer the main questions about this sanitation technique. In addition, they explain how a team of experts from three universities in the Valparaíso region has been researching since 2015, with the purpose of determining the most sustainable way to eliminate the hydrocarbons accumulated in that Viñamarino land during the 80 years of oil company operations. You can review the full article in the . Also, here you can find the transcript of the text: It was 2017 and a truck loaded with soil and sand extracted from the land of Las Salinas de Viña del Mar was trying to enter the small parking lot of the Biotechnology Center of the Federico Santa María University (USM), in the Los Placeres hill in Valparaíso. It was not easy, but it was finally achieved, according to the person in charge of the challenge, Roberto Orellana, PhD in Microbiology, an academic at the Universidad de Playa Ancha (UPLA) and associate researcher at the USM. “I had to call all the people who had cars parked in the place -even one that was in Concón- to move them as a kind of tetris to get the truck in. I had several gray hairs that day,” says Orellana, recalling all the logistics involved in moving the soil from the 16-hectare site located in the northern part of the Garden City, in front of Los Marineros beach. What was the effort for? In order to carry out with that land the pilot phase of a research aimed at determining the best way to eliminate the hydrocarbon contamination accumulated during the 80 years (from the second decade of the 20th century until the beginning of the 21st century) during which the oil installations of Copec, Shell, Esso and Sonacol operated in Las Salinas. Five “biopiles” were made with the soil transported in the truck in the courtyard of the USM Biotechnology Center, on the hill, in front of Caleta Portales. The name biopile is taken from the English word biopile, which could be translated as “bio-pile”. In other words, it is a mound of soil where biological processes will be developed; in this case, to carry out a bioremediation process, which in simple terms implies decontaminating the soil using the soil’s own bacteria and, eventually, some “guests” from other sites. The five biopiles installed at the USM site each contained 0.5 cubic meters of soil, i.e. 500 liters, so the piles were two meters long, one meter wide and 0.5 meters high. As the soil was contaminated with hydrocarbons as well as low concentrations of heavy metals and agrochemicals, the biopiles were placed “on a membrane to prevent the percolates from passing into the soil, and they were also covered with membranes to prevent volatilization”, explains Orellana. Once the biopiles were assembled, the “semi-industrial” stage of the research, which had already been in the laboratory for a couple of years, began.
“We had a first stage of microcosms, with smaller study units where there are more variables to measure; later we moved on to semi-industrial stages, a mesocosm level in the open air, with conditions that were not 5-star hotels -which is what we have in the laboratory-, but conditions closer to those that occur at the site where this is going to be applied,” says the doctor in Microbiology. “Then, we were able to replicate those approaches that were more promising than those detected in the microcosm test; what we had done at the level of one liter of soil, we were able to do at the level of 500 liters. In addition, the experiment we had done for 6 weeks was now done in 6 months, and we were able to have degradation kinetics ranging from 20 thousand parts per million to 3 thousand parts per million.” “Some treatments were slower, others a little faster, some with certain advantages and others with some disadvantages”, says Orellana in relation to what was done in each of the biopiles. In two of them, biostimulation was used with the addition of compost, one aerated and one non-aerated; in two others, bioaugmentation was used, one aerated and one non-aerated; and in the fifth, called landfarming, there was only a minor intervention, turning the soil and keeping it moist. Biostimulation basically consists of incorporating nutrients that stimulate a considerable increase in the bacteria already in the soil. Bioaugmentation is the addition of more bacteria, which can be of the same bacteria (autochthonous) cultivated in the laboratory, or brought from another place (allochthonous) and previously studied. In both cases, optimal conditions are provided so that the bacteria can enhance their functional capacity to oxidize hydrocarbons. In the case of the mesocosm biopiles created for this research, biostimulation was carried out with compost, “which has a series of nutrients, but the most important thing is that it has a microbial community that is adapted to break down polymers that are complex to break down”. Meanwhile, bioaugmentation was carried out with five types of strains: one autochthonous strain isolated from the site and four strains previously isolated from the mouth of the Aconcagua River and studied at the USM. “We applied 25 liters of bacteria per biopile, which is a super high amount of bacterial medium,” says Orellana. During the six months that the process lasted, the researchers carried out a permanent follow-up. “We started monitoring all the conditions to check the biodregeneration. The first thing is the contaminants, we also measured humidity, temperature, microbial density – how many of these bacteria were there, how many were growing, how many were not. We did molecular studies to follow up these communities; it is not studying how bacteria grow, but taking samples, extracting their DNA molecules, sequencing and analyzing them; it is a kind of census that allows us to know which groups are important for which stages and to see how these systems are regulating themselves”. When asked about any kind of inconvenience caused by the hydrocarbons or the manipulation of the bacteria, Orellana is categorical: “Not at all”.
“I was in charge of the team, working every day on this. In the tumbling process, small amounts of hydrocarbon are volatilized, especially at the beginning, but these are odors similar to those in a gas station (…) As for the bacteria, these are environmental bacteria, which do not see the human body as an opportunity; that is, there is no possibility of them being pathogenic for us”, he explains. “Our first responsibility is to ourselves as researchers and to our team,” adds Orellana, who did his doctoral thesis in the United States on remediation of soils contaminated with uranium, a radioactive element. The microbiologist emphasizes that behind this bioremediation project “there are dozens of people, students, postdocs, PhDs and researchers who have been working hard to, first, establish the approaches on which these projects are based, and that is, basically, to generate scientific evidence”. In this respect, he adds that in order to face a bioremediation process one must know the soil in which one is going to work very well and “in this case, we are talking about a chronic environmental liability, which has been contaminated for 80 years, something very different from an oil spill in the sea, for example, which is something punctual”. All the studies carried out aim, to a large extent, to determine “what are the factors that limit this environment from returning to its original condition”. Without these analyses, he says, “it would be as if a surgeon were to operate on a patient without having the proper diagnosis”. Regarding the origin of this research, Orellana tells that it dates back to 2015, when Las Salinas convened several academics from the Valparaíso Region to create a Committee of Experts in Sanitation, of which Orellana is part along with four other experts from various disciplines. This team motivated a “change of paradigm” emphasizes the doctor in Microbiology. With the same conviction that bioremediation is the most sustainable way to decontaminate a soil, says Spanish environmentalist Beatriz Ortiz de la Torre. She says that the first research on this technique emerged several decades ago in the United States and Europe, “when countries realized that industrialization had gone a little overboard with soil and water contamination”. “More traditional techniques, such as selective excavation of contaminated soil and removal to landfill, or more soil-aggressive techniques such as chemical oxidation, had been used for a long time, but the need to integrate sustainable remediation and protect soil health came in the wake of the European Soil Charter – in the 1970s,- when soil began to be seen as a finite and non-renewable resource,” says Ortiz de la Torre, who works as a consultant and decontamination and sustainable remediation technician for the IDOM Group (Consulting, Engineering and Architecture). In a colloquial way, the expert adds that “it was then when they said be careful, this soil that we are removing from the excavations, and all the structures and biological processes that we are carrying with the chemical oxidation have a repercussion, because we are running out of useful soil”. This is how they began to investigate minimally invasive techniques and biological techniques were born, which consist, “basically, in taking advantage of what the natural environment has in our favor to decontaminate the damage we have caused”.
Regarding bioremediation, he states that “it is a proven technique, it is harmless, and it is a fast process. The increase of bacteria is exponential when they have the optimum conditions, then they stabilize and that is when they degrade the long-chain heavy hydrocarbons. Once those hydrocarbons are gone, the bacteria plummet; the dormancy period can be 2 to 3 weeks. It is the re-inoculation that allows the bacteria to continue degrading the hydrocarbons for a few years, since the life span of a bacterium is not very long”, emphasizes the IDOM specialist, an entity that is advising Las Salinas on bioremediation. When the Spanish environmentalist speaks of optimum conditions she is referring, for example, to what is done in the biopile, “where the temperature, nutrients, humidity, oxygenation, etc., are controlled so that the bacteria are in their optimum growth environment and are capable of degrading at the highest possible speed and at the highest possible performance”. Regarding the type of microorganisms used, he comments that “there are many hydrocarbon-degrading bacterial species. The best known for their degrading capacity are, for example, the pseudomonads. I have worked with them, both at the indigenous level of pseudomonads that I have come across from a contaminated site, which I have removed myself, and at the commercial level.” The latter means that a sample is taken from a contaminated soil and then in the laboratory “we develop the bacterial consortium that is present in that soil, we observe which is the most defined species that degrades that contaminant and that is the species that we then commercialize. It is not that the commercial bacteria are different from the native ones; they may or may not be in the environment to be degraded”. At this point he explains that “it is true that pseudomonas have a variety that affects humans, but that variety is never related to the one applied to contaminated soils”. When asked about the possibility of these bacteria developing some kind of resistance to antibiotics, the environmentalist explains “the bacteria that are specified to degrade the hydrocarbon usually die as soon as the hydrocarbon runs out, so it would not matter how much resistance they acquire to the antibiotic. Moreover, these are bacteria that are not pathogenic to humans.” “One of the fundamental conditions for introducing bioremediation bacteria is that they are not human pathogenic, that they are innocuous, that they do not generate sporulation, that they do not mutate, that they do not have another food source; they are tremendously specific bacteria; and the tests -antibiogram- are done to determine if they generate resistance to some antibiotics”. “We have to take into consideration that they are bacteria that are already present in soils and have never pathogenically affected us humans. Their main food source is hydrocarbons, so unless we are made of recalcitrant hydrocarbons, I don’t think they will do anything to us”. Ortiz de La Torre emphasizes that bioremediation uses innocuous, natural products that do not harm the environment or human beings, and that conditions are generated that not only contribute to decontamination, but rather to remediation to re-integrate life back into the soil. This recovery of the soil, beyond the mere elimination of contaminants, is indispensable, says Salvador Donghi, a biologist at the Catholic University of Valparaíso (PUCV), who is also a member of the Committee of Experts in Sanitation.
“We must not forget that soil is the main metabolic machinery on a planetary level and the second scarcest natural resource in the world (…) Remediation should seek to clean up a soil that has been contaminated and return it to its native characteristics, allowing the functions, for example, of recycling all chemical compounds and, in addition, sustaining the entire vegetation cover responsible for fixing oxygen, gas exchange, etc.” There are several techniques for soil remediation, but not all of them are safe and sustainable, says Donghi, who is director of the consulting firm Simbiosis. “In Chile, soil confinement or the removal of contaminants to be treated elsewhere, which is called final disposal, has been used (…) Not only does it take the problem elsewhere, but the number of trucks used for the transfer means a huge carbon footprint.” “The confinement, meanwhile, does not take care of the problem; it allows habitability, but there is still an environmental liability buried there. In 100, 200 years, future generations are going to find themselves with a problem that we left unsolved. Within sustainable development this is a situation that is not permitted, environmental costs cannot be passed on to future generations (…), the environmental liabilities continue to exist, the same as the transfer of contaminants, the final disposal, is not framed within the framework of sustainable development”, explains Donghi. As an example, he mentions the situation in Germany with radioactive waste that was buried in old mines, but whose containers are being destroyed as a result of radiation. Another technique is chemical remediation, through the incorporation of chemicals to change the molecular state of the contaminants and render them inert or non-hazardous to human health. “This has side effects, because the chemical reaction generates byproducts that are going to be contaminants,” the biologist explains. “There are the thermal treatments, which destroy the contaminants through heat. It is tremendously expensive, effective with contamination, but it kills absolutely everything, not only the contaminants, but also all the biota, all the life that exists in the soils at the level of bacteria, protozoa, etc.” The PUCV academic says that this is widely used in China, where they do not have investment problems and pursue immediate goals, such as enabling sectors for housing, but not only does it destroy the entire composition of the soil in terms of life, but “to produce the heat an energy source is needed and they are probably using fossil fuels; which in the final equation ends up being polluting”. Donghi explains that recovering that soil, that ecosystem that has been generated as a result of very complex evolutionary processes, “after a process as harmful as the thermal one, is impossible”. “In short, the only remediation technique that manages to project itself in terms of sustainability is bioremediation,” he concludes. In the case of the Las Salinas site, he indicates that after 80 years of contamination “the soils have a lower amount of bacteria than those that exist in the Atacama Desert. This means that the soil cannot recover naturally, or it could do so in 250 to 300 years”. In this sense, he explains that without sanitation, it is currently impossible to use this land for human habitation or for other uses, such as a park.
“A first process that consisted of removing the first meter of contaminated soil ended between 2013 and 2014, that is, 8 years have passed and the vegetal recomposition is practically null. The soil cannot naturally recompose itself in the short term”. Regarding the economic costs of bioremediation, the biologist maintains that in Chile it is still expensive, mainly because of the research prior to the procedure. However, “in terms of social and environmental costs it is by far the best investment, because it pays off in the long term and has many other effects that help to increase the benefits in economic terms”. One of the benefits, in the case of Las Salinas, is the development of regional science. “As a result of the research, doctors have been trained and lines of research have been developed that are now published in prestigious scientific journals”. Likewise, he adds, “it gives the possibility of building positive alliances that allow, for example, private companies to invest in development hand in hand with local universities to solve local problems”. “The fact that in the Valparaíso region there are 3 universities that are working on a technique that is safe, recognized worldwide, is an enormous development for regional science. Moreover, it is one of the best records of decentralization: the region is taking charge of its problem with local knowledge (…) It has an enormous social, economic, scientific, educational, regional benefit, which far exceeds the investment that the private sector has to make in this case to be able to remedy”, concludes Donghi.
