Cost-effective solutions to saline waste water

Salty effluents from the food and drink industry are difficult and expensive to clean. An EU-funded project is using a combination of bacteria and algae to treat waste water effectively and economically while generating commercially valuable biomass.

The food and drink industry produces vast amounts of waste water each year. Although the effluents are controlled by EU Directives, some parts of the sector – notably canned fish, meat processing, pickled vegetables, tanneries, aquaculture and others – produce very salty water with high levels of organic matter. Not only is this effluent harmful to the environment, but it is difficult and expensive to treat, especially for small businesses.

“Such costs are frequently deemed unaffordable for the smallest SMEs,” says Robert Reinhardt, technical manager of the EU-funded SALTGAE project. “Many focus on their core business and take some shortcuts with notable environmental impact regarding their waste-water treatment.”

The 20 partners in the three-year project are using a combination of technologies to develop cost-effective solutions to treating saline waste while, at the same time, generating useful products.

Algal-bacterial communities

In a conventional waste-water treatment plant, air is bubbled through the water to supply oxygen to bacteria which then consume any organic matter and release carbon dioxide. The process is expensive and does not work well for salty water.

SALTGAE researchers have opted for a mixture of bacteria and algae. Through photosynthesis, the algae produce oxygen for the bacteria while consuming the carbon dioxide, and requiring no active aeration. Algae are more tolerant to salt than bacteria so the project partners are investigating how algal-bacterial communities work in saline conditions.

Other partners are testing whether an alternative anaerobic process, whereby bacteria can convert organic matter into methane for biogas, can be adapted to process salty effluent.

Three demonstration schemes are now running, all based at existing plants: a site in Italy is treating effluent from the milk industry, a plant in Slovenia is dealing with tannery waste, while the site in Israel is processing waste from fish farming.

Not only will these technologies cut both energy consumption and carbon dioxide emissions but they will also produce large amounts of exploitable algal biomass. Project researchers are looking at several possible products ranging from feed for piglets to coatings and adhesives, protective edible coatings for fruit, bio-composites for use in 3D printing and high-value products such as beta carotene.

Opportunities for SMEs

Reinhardt estimates that the greenhouse gas released from treating various waste streams is equivalent to every EU citizen burning 100 litres of petrol each year. “Using technologies developed in the SALTGAE project we aim to lower these numbers significantly in our target market which is the food industry,” he says.

He expects that their work will be of particular interest to SMEs, making it possible for companies to treat their effluent more economically and effectively with the sale of biomass as a new source of revenue. Although SMEs make up only 5 % of the EU’s food and drink sector, they total 15 000 business with a combined turnover of EUR 64 billion, so the market is substantial.

“Within the consortium, we have a number of commercial SME partners that are eager to exploit the developed system,” he says. Any exploitation path for algal biomass is not limited to algae produced in salty waste water – most of these technologies can be applied in other situations.”

Reinhardt notes that SALTGAE is one of a network of EU-funded projects working together to explore the potential of waste water, algae and biogas. “For many of us who have seen more competitive business environments, this openness, cooperation, exchange of ideas and experience between projects and their partners is refreshing, creative and productive.”

Project details: 

Project acronym: SALTGAE
Participants: Spain (Coordinator), Italy, Slovenia, Israel, Ireland, Portugal, France, Belgium, Sweden
Project N°: 689785
Total costs: € 9 904 938
EU contribution: € 8 294 318
Duration: June 2016 to May 2019