Wastewater treatment company, Aquiris (subsidiary of Veolia Water), is running a pilot project at its Brussels-North Wastewater Treatment Plant. The project aims to use organic compounds from wastewater to produce bioplastics.
Making biodegradable plastics from sewage
Although it may sound surprising, wastewater contains all of the building blocks of biopolymers, thus it can be used as an important raw material for sustainable bioplastic production. “Until recently, the treatment of wastewater has always included the elimination of pollutants. Now we are able to both treat the wastewater and recover a byproduct that can be reused for bioplastic production in an existing plant. This is a revolutionary answer to the challenge of natural resource preservation,” explains Marc Rigal, the general manager of Aquiris.
The idea dates back to 2007, when the first successful laboratory trials were done at AnoxKaldnes – the Swedish subsidiary of Veolia Water. Swedish researchers observed that wastewater bacteria were creating polymers. The polymer producing strain was optimized to improve its efficiency. In 2011 in Brussels tests were performed which looked at the potential of wastewater to be used as an ingredient in the formation of bioplastics. Brussels with its 1,4 million inhabitants has the potential to produce 2.000 tons of wastewater-derived bioplastic each year.
How does it work?
Some bacteria (e.g. Bacillus Subtilis) used to degrade wastewater in depuration processes can accumulate carbon in the form of polyhydroxyalkanoates (PHAs). These PHA’s are biodegradable polyesters with comparable properties to some petroleum-based polyolefins. PHA production can be achieved in open, mixed microbial cultures and thus can be coupled to municipal wastewater treatment. The volatile fatty acids from the activated sludge serve as a carbon source for biopolymer synthesis. Laboratory- and pilot-scale studies have demonstrated the feasibility of municipal wastewater and solid waste treatment alongside production of PHA-rich biomass. PHA polymers can then be refined into bioplastics and similar products. Aquiris is now working to fine-tune the production process and optimize the biopolymer characteristics to ensure that they match the requirements of potential industrial customers.
What can be made out of wastewater bioplastics?
PHA biopolymers are highly biodegradable and biocompatible, therefore they are very attractive for the medical and pharmaceutical industries. They can be used to produce sutures, patches, stents, tissue regeneration scaffolds, nerve guides, grafts, implants, wound dressings, and other medical products. PHAs could also be useful in the automotive and bioplastics industries as well as in the packaging sector. Bioplastics have a great potential to fill a huge need in the “post-oil-era” when society begins to shift away from the use of fossil fuels. In 10 years from now, Veolia plans to be able to “refine” wastewater not only into bio-materials, but also into energy sources (biofuels, methane, hydrogen and ethanol) and fertilizers.
Image: Bacillus Subtilis (flickr.com)
