It is known that sewage fluids from the city should not be discharged directly into the environment because they carry a certain pollutant load, and it is important to dispose of them before discharging them into a river, lake or sea. In the city of Allen, part of the province of General Roca, Río Negro, they are seeking to innovatively treat sewage effluent and put it to other uses.
The initiative is led by a group of researchers, led by Chemical Engineering Ph.D. Marcella Gatti, from the Kumaho National University College of Engineering. The project will consist of developing a combined treatment of effluent with the cultivation of aquatic plants or a biofilter and an anaerobic digester.
The main objective is for the effluent discharge to reach the river with a lower level of pollution. Then they try to develop other uses.
They have already achieved good results in the first stage. If it proves its benefits when it is more advanced, the innovative treatment of liquid waste can be transferred to other sites, where liquid purification plants are located, and further improve what is discharged into rivers, lakes or the sea.
Which consists
It involves the use of a biofilter for aquatic plants Limnobium lavigatumBrought from the city of General Roca. They were planted in processing canals in Allen, which were built to launch the initiative.
“The project consists of using aquatic plants and they are working very well. The idea is to take corrective action: Gatti explained that with these biofilters we seek to correct the effluent that comes out of the treatment lagoons in Allen. Rio Negro newspaper.
he The treatment concept is designed for cities that have effluent treatment lakes This purifies and attempts to store large amounts of mainly organic matter.
“This effluent still contains nitrogen and phosphorus components. It is nutrients for those plants,” the researcher said. It is proposed to enhance the growth of this biomass, under preferential conditions. By feeding them the nutrients that come from sewage effluents, he said They have a much lower pollution load.
“What reaches the river will not have the same important content when it leaves the lake. The new system seeks to utilize nitrogen and phosphorus. They are fixed by plant growth and their content in the lake’s liquid water is reduced.”
The aquatic plant used must be highly adapted to the region, because it must withstand high temperatures in summer and low temperatures in winter.
In this first stage of the process, the biofilter is purified. The treatment flow rate is now 4 cubic meters per day and the final flow will be 9.2 cubic meters per day. “A small scale is used to study and see what happens with that data and leave the laboratory scale,” he said.
Gatti pointed out that there were four canals built in parallel. In total, they have 9.2 cubic meters of capacity to subject liquid to processing. They are 12 meters long, each one is between 25 and 30 cm wide, and half a meter deep.
The fact that the municipality of Aline participated in the project allowed Aguas Rionegrinas to authorize the construction of canals next to the lake and thus the effluent was used in the project.
“Water enters through some sewers very slowly and stays there for two days. The idea is to increase the flow, but it has to start gradually because changes are slow in all types of biotechnological treatment,” he explained.
Sowing was done in September 2023 and so far the growth of the plants has been very significant and is well done. “The removal rate of organic matter was 60%, and nitrogen and phosphorus more than 80%.. He noted that it is a filter that allows for compliance with discharge limits.
The destination stations will be the second part of the initiative, which was selected as the Federal Innovation Project 2022, with funding from the Federal Council for Science and Technology of the Ministry of Science, Technology and Innovation.
The channels must be disinfected and then the plants are sent to an anaerobic digester, which allows the organic matter to decompose through waste and waste, without the presence of oxygen, and methane gas is formed.
“The idea is that in an anaerobic process where there is no oxygen, these plants turn into methane,” he added.
Methane is a commercially valuable fuel, and in areas where there is no natural gas it can be used for heating or converted into electrical energy.
The anaerobic digester has not been installed yet as it is in the construction phase.
It is being implemented by INTA researcher Lucas Zanovello, doctoral researcher Sandra Bartucci, and engineer Santiago Martinez.
At this point there will be a “nutrient cycle,” Gatti said. He explained, “What is in the water is transferred to the plants, and from there to a stage that produces methane gas, and in this way we can transform these wastes that we do not want to be in the water.”
It is planned that even with the use of purification lakes, another process can be carried out. “By having this data, it helps us expand, and thus study some factors that can be taken on a larger scale,” he explained.
UNCo is involved in this initiative. UNCo Regional Development Foundation -FUNYDER; Rio Negro Waters; RN Innova Agency; The municipality of Allen is the beneficiary.
The team led by Gatti consists of Conisit PhD fellow Margherita Cesano Sousa; Dr. Anahi Alvarez; civil engineer Sandra Otanio; Agronomist Valeria Diaz; Pablo Marigual, Head of the Environmental Promotion and Technical Training Department of the Municipality of Allen; Antonio Puerta, Environmental Management Director for Technical Training; Sergio Foglino, Director of the Sustainable Environment Agency; Luis Martinez, a master's degree in environmental risk, and agronomist Federico Horn from UNCo.
The future of the initiative
Members of this project have one year to develop it. It is likely that by June all the data collected will be available to see the results and evaluate their application in different locations.
The expected 12 months will allow researchers to analyze how the biofilter works in the four seasons of the year: spring (when the aquatic plants were transplanted), summer, fall, and winter.
This time period will allow us to determine whether “this plant filter allows us, at this size, to treat such a volume of water. And determine what size filter should be used for a densely populated site in Allen,” Dr. Gatti said.
Once these results are obtained, they can be extrapolated to other cities that use lakes or have the same residual effluent treatment.
The goal of this proposal is to achieve “pollutant reduction.” To reduce these contaminants, a multiple treatment was considered, which is the use of a biofilter (aquatic plants) through which the liquid wastewater can pass.
This filtered liquid meets the required discharge limits for waterways, or it can be reused to water trees, according to the expert, as a possibility in the future. It is called the “forest biofilter”.
Meanwhile, the goal is to decompose pollutants and utilize them by converting them into bulk biomass and methane.. “Since macrophytes (aquatic plants) consume carbon dioxide, they contribute to reducing the carbon footprint, which is a global problem for which a solution is being sought. He noted that methane gas obtained from biomass conversion can be used to heat nearby homes that do not It contains a supply network.
The aim is to promote sustainable production of methane – resulting from the transformation of pollutants from wastewater – so that it can be considered a sustainable alternative to fuel production.
The ultimate goal is to obtain technology that is socially and technically suitable for use in existing treatment plants in the region. It is concluded that those that use treatment lakes and those that use activated sludge are economically sustainable.
