2024-02-04 05:00:00
It is known that sewage liquids from a city should not be discharged directly into the environment since they carry a certain contaminant load, which is important to eliminate before discharging them into a river, lake or sea. In the city of Allen, which is part of the department of General Roca, Río Negro, they seek to carry out innovative treatment of sewage effluents and take advantage of them for other uses.
The initiative is led by a group of researchers, led by the doctor in Chemical Engineering, Marcela Gatti, from the Faculty of Engineering of the National University of Comahue. It will consist of developing a combined effluent treatment with aquatic plant cultivation or biofilter and an anaerobic digester.
The main objective is that the discharge of effluents reaches the river with a lower level of pollution. Then, they try to develop other uses.
They already had good results in the first stage. If they demonstrate their benefits when they are more advanced, the innovative treatment of effluents can be transferred to other locations, where there are liquid purification plants, and further improve what is discharged into rivers, lagoons or the sea.
What does it consist of
It involves the use of a biofilter of aquatic plants Limnobium smoothed, brought from the city of General Roca. They were planted in treatment 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: With these biofilters we seek to correct the effluents that are coming out of the treatment lagoons in Allen,” Gatti explained to Río Negro Newspaper.
He Remediation concept is designed for cities that have effluent treatment lagoons and that purify and try to buffer, mainly, the loads of organic matter.
“These effluents still have nitrogen and phosphorus components. For those plants they are nutrients,” said the researcher. It is proposed to promote the growth of this biomass, under preferential conditions. By feeding them the nutrient that comes from sewage fluids, they have a much lower pollution load, she said.
“What would reach the river would not have the same important content as when it leaves the lagoon. The new system seeks to take advantage of nitrogen and phosphorus. They are fixed through the growth of plants and their content in the lagoon effluent is reduced,” Gatti mentioned.
The aquatic plant used must be highly adapted to the area, because it must withstand high temperatures in summer and low temperatures in winter.
In this first stage of the process, the biofilter is being 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, see what happens with that data and leave the laboratory scale,” he mentioned.
Gatti indicated that there are four canals that were built in parallel. In total, they have 9.2 cubic meters of capacity to subject the liquid to treatment. They measure 12 meters long, each one of them is between 25 to 30 centimeters wide and half a meter deep.
The fact that the Municipality of Allen is involved in the project allowed Aguas Rionegrinas to authorize the construction of the canals next to the lagoon and thus the effluents were used for the project.
“The water enters through some spillways very slowly and remains there for two days. The idea is to increase the flow, but it must start gradually because changes are slow in all types of biotechnological treatment,” he clarified.
Sowing took place in September 2023 and so far the growth of the plants has been very important and purifies well. “The elimination of organic matter was 60%, nitrogen and phosphorus were above 80%.. It is a filter that allows the discharge limits to be met,” she noted.
The destination of the plants will be the second part of the initiative, which was selected as the Federal Innovation Project 2022, financed by the Federal Council of Science and Technology of the Ministry of Science, Technology and Innovation.
The channels must be purged and then the plants will be sent to an anaerobic digester, which will allow a process of decomposition of organic matter through the waste and waste, without the presence of oxygen, and methane is formed.
“The idea is that in an anaerobic process where there is no oxygen, these plants become methane,” he added.
Methane is a fuel that has commercial value and in areas where there is no natural gas it can be used for heating or converted into electrical energy.
The anaerobic digester is not yet installed because it is in the construction process.
Its execution is in charge of INTA researcher Lucas Zanovello, doctoral scholar Sandra Bartucci and engineer Santiago Martínez.
Gatti said that at this stage there will be “nutrient cycling.” “What is in the water is moved to the plants, and from these to a stage that produces methane and in that way, we can convert this waste that we do not want to have in the water,” he clarified.
It is intended that even with the use of purification lagoons, one more process can be carried out. “By obtaining this data it helps us scale, and thus study certain parameters that can be taken to a larger scale,” he clarified.
The UNCo intervenes in this initiative; the UNCo Foundation for Regional Development -FUNYDER; Rio Negro Waters; and the RN Innova Agency; and the municipality of Allen, which is the beneficiary entity.
The team led by Gatti is made up of Conicet doctoral fellow Margarita Cesano Sosa; Dr. Anahí Álvarez; civil engineer Sandra Otaño; the agricultural engineer Valeria Díaz; Pablo Marigual, who is the head of the Department of Environmental Promotion and Technical Training of the municipality of Allen; Antonio Puerta, who is the director of Environmental Management, Technical Training; Sergio Voglino, director of the Sustainable Environment Agency; Luis Martínez has a master’s degree in Environmental Risks and the agricultural engineer Federico Horne, from UNCo.
The future of the initiative
The members of this project have one year to develop it. It is likely that by June all the data collected will be available to know the results and evaluate its application in different locations.
The twelve months that are expected will allow researchers to analyze how the biofilter behaves in the four seasons of the year: spring (when the aquatic plants were planted), summer, autumn and winter.
This period of time will allow us to define whether “this plant filter allows us, with this size, to treat such a volume of water. And determine what size filter should be used for a location with Allen’s population density,” said Dr. Gatti.
Once these results are obtained, they can be extrapolated to other cities that use lagoons or have the same residual effluent treatment.
The objective of this proposal is to achieve a “reduction of pollutants”. To reduce these contaminants, multiple treatment was thought of, which is the use of a biofilter (aquatic plants) through which sewage effluents can pass.
This filtered liquid meets the discharge limits required for water courses, or can be reused for watering trees, according to the expert as a possibility for the future. It is called a “forest biofilter”.
Simultaneously, the aim is to degrade pollutants and take advantage of them by transforming them into macrophyte biomass and methane.. “As macrophytes (aquatic plants) consume carbon dioxide, they contribute to reducing the carbon footprint, a global problem that is being sought to be solved. The methane obtained from the transformation of biomass can be used to heat neighboring homes that do not have a grid supply,” he indicated.
The aim is to promote sustained production of methane – coming from the conversion of pollutants from sewage effluent – so that it can be considered a sustainable alternative for fuel production.
The ultimate goal is to obtain a technology that is socially and technically suitable for use in current treatment plants in the area. Both those that use treatment lagoons and those that use activated sludge, in an economically sustainable manner, he concluded.
1707030231
#sewage #obtain #energy #heating
