2nd “Overcoming barriers in the recovery of WWTP sludge and bio-waste” workshop

The Ecoval Sudoe project is a shift in paradigm: from wastewater treatment plants to biofactories. A change of model, from linear to circular, and a change of concept: waste for resources. However, the testing of new technologies for the recovery of resources classified as waste up to now is not enough in itself. Innovation needs to go hand in hand with the acceptance of the business model. To this end, the project is organising a series of workshops in which different specialists answer the question: how can we overcome the barriers in the recovery of bio-waste and WWTP sludge?

The workshop held on January 18, the second in the project, was attended by 16 specialists from the Sudoe Region (Portugal, Spain and France), from sanitation and waste management entities, research centres, environmental authorities, legal consultants and sectoral associations. This event was organised by Águas do Tejo Atlântico with the collaboration of CETAQUA, Porto Ambiente, NEREUS, FEUGA and the Foundation for the Natural Heritage of Castile and Leon.

After the presentation of the project, experts from the three countries shared their experiences on the management of WWTP sludge and bio-waste, the use of value-added products (volatile fatty acids, for example) and waste declassification mechanisms. Forums were then created for each country, where the specific requirements of each Member State were addressed.

The session ended with an analysis of potential synergies in the Sudoe region and the presentation of the main conclusions of the first workshop.

The main barriers identified by the experts include:
– A lack of end-of-waste status criteria for volatile fatty acids produced from WWTP sludge and bio-waste.
– Complicated and time-consuming end-of-waste status processing.
– The absence of a common legal framework for all the Member States undermines the creation of an EU internal market.
– Difficulties in guaranteeing the quality of municipal biological waste from selective collection.

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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.