Brown containers arrives at Ourense schools thanks to the Ecoval Sudoe project

  • Ourense Town Council and Viaqua promote the participation of a school from Ourense in the ECOVAL project for the revalorization of organic waste
  • CEIP of Seixalbo will contribute the waste from its school dinning room to the pilot plant located at the Ourense WWTP

The Ecoval Sudoe project, strategies for the management, coordination and recovery of sludge and organic waste in the SUDOE region, enters a new phase in 2022. After successfully illustrating the technology for converting sewage sludge into volatile fatty acids, compounds that are converted into products such as paints, lubricants or adhesives in the chemical and petrochemical industry, the Ourense Wastewater Treatment Plant (WWTP) will now change its raw material to recover selectively collected organic waste taken from the containers recently installed at the Seixalbo school in Ourense.

In this way, the school canteen has become a supplier of the raw material to be used by the pilot plant to obtain volatile fatty acids. Moreover, the establishment is also involved in the environmental education campaign “Another container, a brown one!”, the goal of which is to raise the awareness of youngsters as to the importance of the correct separation of waste, with an emphasis on the fifth container and the characteristics of organic waste. The CEIP Seixalbo is a public school in the municipality of Ourense that is very involved in raising environmental awareness among its students, with the organization of workshops on the correct separation of waste, the creation of a school garden, composting activities and now participation in this European research project.

Representatives from Cetaqua, the leader of the project, from the Department of Education of the City Council of Ourense and Viaqua, came in person to the school to present the project and lay the foundations for collaboration. In adition to Cetaqua, representatives from the Ourense Town Council and Viaqua, official partners committed to supporting and promoting the initiative, also attended, positioning the town of Ourense and its waste treatment plant in particular as a reference benchmark in the commitment to the development of green technologies and the circular economy.

Castile and Leon, represented in the project by the Natural Heritage Foundation, together with the Palencia Town Council and Aquona, who also support the initiative, will also be involved in the supply of organic waste through schools as a means of raising awareness as to the importance of caring for the environment while promoting the biofactory model.

The importance of the Ecoval approach

Each individual in the Sudoe region, which encompasses the Spanish autonomous communities (with the exception of the Canary Islands), the south-western regions of France, the mainland regions of Portugal, Gibraltar and the Principality of Andorra, generates 136kg of organic waste a year. This results in the generation of 11 million tons of organic waste a year, 9 million of which are food remains. Currently, 65% of this organic waste is incinerated or dumped in landfills due to the limited use of selective collection processes.

Since the project was launched in November 2020, Ecoval has paved the way for the arrival of brown containers, which should have been installed in all European cities by late 2023. Thanks to the approach promoted by the project, bio-waste will be returned to the economic cycle, thereby contributing to the European Union goal to recycle 65% of municipal waste by the year 2035.

In addition to the aforementioned partners, Santiago de Compostela University, the Galician Business-University Foundation, the National Institute of Applied Sciences of Toulousse, Nereus, Aguas do Tejo Atlantico and the Municipal Environment Company of Porto are all taking part in this challenge. The joint venture, co-financed by the Interreg Sudoe Programme through the European Regional Development Fund, also enjoys the support of 31 associated partners.

What are volatile fatty acids?

Volatile fatty acids (VFAs) are organic compounds with six or fewer carbons in their structure. Although these terms are unfamiliar to the general public, they can be found in nature, usually as a result of bacterial processes such as anaerobic digestion. Given their high energy value, VFAs are a common part of animal metabolism, and such is their versatility that they can be found in vinegar production (acetic), food flavorings (butyric), or preservatives (propionic). At present, volatile fatty acids are almost entirely obtained from fossil resources, which has a very high environmental impact.

However, these VFA can be produced through biological processes that have been developed in recent decades and for which new, more efficient, and precise routes are still being found. Moreover, they belong to the category of intermediate products, i.e. they can be converted into a wide variety of end products (plastics, paints, lubricants, cosmetics, etc.) depending on the selected processes. This flexibility in production and conversion is one of the reasons why the demand for VFAs in the chemical sector is growing steadily.

The ECOVAL SUDOE project develops technologies for the production of these acids from sewage sludge and bio-waste generated in the urban environment. The project thus promotes the biorefinery or biofactory model, a new concept of facilities that generate high added-value by-products from waste. From these substrates, short carbon chains are obtained, volatile fatty acids, which in the case of ECOVAL are preferably acetic, butyric, and propionic.

The renewable origin in AGV production still represents a tiny fraction, so it is essential that the development of solutions based on the circular economy as proposed by ECOVAL, fully aligned with the objectives of the European Union to be the first climate-neutral continent in 2050.

Interesting, isn’t it? Here you can read how work has started in the project’s pilot plant.

Hands in the mud! Ecoval Sudoe completes work on pilot plant for the production of volatile fatty acids

One of the objectives of the Ecoval Sudoe project is to demonstrate the technical feasibility of producing volatile fatty acids (VFA) from urban sludge. To do this, at the Ourense Wastewater Treatment Plant (WWTP), Cetaqua has set up different tests to optimise the generation of acids such as acetic, propionic, or butyric acid from sewage sludge.

In order to determine the most suitable operating conditions for the pilot VFA production plant, different laboratory-scale tests were first carried out, such as batch tests on a 0.5L scale and the operation of semi-continuous reactors of 5L volume, which demonstrated the suitability of sewage sludge as a substrate with high potential for the production of high added value bioproducts with VFA.

The information provided at the laboratory scale has helped Cetaqua technicians to have a first approximation of the VFA production yields that can be obtained from sludge with and without pre-treatment. They were also able to analyse the effect of operating parameters such as pH, feed/microorganism ratio, hydraulic residence time, etc.

On a pilot scale, the technicians have optimised the fermentation process for the production of VFA, obtaining a stream that has to undergo solid-liquid separation, a unitary operation that has had to be perfected thanks to “jar tests” that have made it possible to determine the optimum doses of coagulant and flocculant for the division of the solid and liquid fractions. Thus, the objective of producing a liquid current rich in VFA for the partner NEREUS to study its clarification and concentration and a high-dryness solid cake that INSA will recover energetically has been achieved.

Following these tests, work is now continuing on the pilot plant which, after a start-up phase marked by hydraulic difficulties in operation and the necessary adjustments, is now operating more robustly. It will soon begin to be fed with biowaste.

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