For decades, most of the wastewater from the Mahou San Miguel brewery in the northeastern Spanish city of Lleida was flushed down the drain.

Now the effluent is being used to generate power and heat for the brewery, which is taking part in a research project to make wastewater a reusable resource.

Bits for biogas

Mahou San Miguel, Spain's top beer producer, is using water to clean the Lleida brewery as well as to wash out fermentation tanks and old bottles before recycling and refilling them.

As a result, the wastewater is full of organic matter—so-called biomass—like old beer and bits of hops and grains that can be turned into biogas.

"You have energy in the wastewater in the form of biomass or heat, which you can recover," said Dr. Anne Kleyböcker, a researcher at the KWB water-research center in Berlin, Germany.

She said industrial wastewater also contains other materials such as nutrients that could be economically valuable as long as ways can be found to extract them.

Kleyböcker helps lead the EU-backed project, which brings together research organizations, universities and businesses from EU countries that also include, among others, Denmark, France, Greece and Italy. Outside the EU, participants come from Israel, Norway and the UK.

On-the-ground action

Called ULTIMATE, the 53-month project is coordinated by a Dutch water-research institute called KWR and is scheduled to run through October 2024.

It centers on pilot plants in the food-and-drink, petrochemical and biotechnology industries. The goal is to show the feasibility of laboratory-developed technologies at scale for extracting materials from wastewater, according to Dr. Gerard van den Berg, a project manager and team leader at KWR.

At a citrus-fruit processing center in Greece and an olive oil producer in Israel, pilot plants are extracting plant compounds such as polyphenols and antioxidants that can be used as dyes, food additives and supplements and chemical compounds for manufacturing.

Farther north, a chemical installation in France is exploring whether chemicals and metals such as sulfur and molybdenum can be recovered from water used to wash gases generated by the incineration of waste.

Even farther north is a demonstration plant at the Glenmorangie whisky distillery in the Scottish Highlands.

It extracts ammonia and phosphorus to use as fertilizers on local barley fields and harvests heat for reuse in this process from a reactor producing biogas from wastewater.

The wastewater is also purified so it can be reused to clean the distillery.

The cost-effectiveness of these activities varies and in some cases more work is needed to strengthen the economic benefits. In any case, the underlying importance of the actions is that they point the way towards a new and more sustainable method of industrial operations.

Industrial bonds

Kleyböcker said the project is pursuing 'industrial symbiosis'—the notion of different industries exchanging their waste products.

"Before we start to recover something, we already know who needs it," she said.

Europe has plenty of potential in this area because European countries have many diverse industries situated relatively close to one other, facilitating logistical questions, according to Kleyböcker.

Ultimately, however, the most efficient expression of this whole "circular economy" idea is when businesses extract and reuse materials from their own waste—as Mahou San Miguel is doing in Lleida, which is located about 150 kilometers west of Barcelona.

The use of biogas produced from the brewery's waste to generate electricity and heat for the site has been so successful that the company is expanding the bioreactor.

This will include a step tested under ULTIMATE to improve biogas production by encouraging the growth of a different type of microorganism—electroactive ones.

At present, around 2% of the energy needs of the brewery can be covered by the biogas system. In future, this share could rise to about 6%.