Sewage treatment plant in Brussels uses bacteria to create plastic polymers
Most plastic is made from petroleum products. As oil becomes harder to find, though, plastic manufacturers are seeking cheaper alternatives that are friendlier to the environment.
One solution is bioplastics. First, to clear up some common confusion, bioplastic does not mean it is biodegradable. It simply means the plastic is made from a renewable biological source. Both petroleum-based plastic and bioplastic products can be made biodegradable or non-biodegradable.
Plants such as corn are a common source of material for bioplastic, but a drawback for that is it takes resources away from food production.
Belgium-based wastewater treatment company Aquiris, a subsidiary of the conglomerate Veolia, has a pilot project at its Brussels-North Wastewater Treatment Plant to turn wastewater into plastic.
“Until now, the sanitation concept has always consisted in eliminating the pollution in wastewater. … We have the know-how to both treat the wastewater and recover a byproduct reusable as bioplastics in an existing plant. This is a revolutionary answer to the challenge of natural resource preservation,” Marc Rigal, the general manager of Aquiris, said in a statement.
Right now, the technology is in a pilot phase and Aquiris is looking for business partners to make the plan a reality. The waste water from Brussels, with a population of 1.1 million, has the potential make 20,000 tons of biolplastic a year. “The initial expenses are high, but that will come down once it goes into production,” Bernard Lambrey, who is heading up the project for Aquiris, told the press during a plant tour as part of the EU-sponsored Green Week. Some companies have shown interest in buying the process outright, but Aquiris is looking for investors to work with them in bioplastic production.
The process involves separating out volatile fatty acids from sludge and mixing is with wastewater and specially selected bacteria that convert the fatty acids into biopolymers. “We use a centrifuge to separate the fatty acids out,” Lambrey said, adding that the mix had to be heated to a proper temperature for the bacteria, which are the key part of the process, to digest the fatty acids and produce polymer chains.
The idea first came about in 2007 with a trial in Sweden, once it was discovered that some bacteria used in wastewater treatment were producing polymers. The bacteria strain was refined over time to be more efficient, and testing was moved to Brussels, where the first successes came in 2011. The bacteria used in the process are put through famine and feast phases, which makes them more productive than if they were fed a steady diet of fatty acids and wastewater.
The biopolymers are refined into bioplastics and similar products. The rest of the sludge can be used to produce biogas of energy. The treated wastewater is not suitable for drinking but is checked for levels of contamination before being released back into the environment.
While this particular process is new, bioplastics are not and there is an umbrella association to promote their use in Europe. Hasso van Pogrell, the managing director of European Bioplastics, told the Prague Post that the wastewater project is just one of several new technologies on the horizon, and European producers would likely embrace them when they became cost-effective and available.
“Right now, bioplastics made from corn are the most common. Plants that are high in sugar are good sources for bioplastics,” he said.
“Hemp can be used as well. It isn’t as high in sugar, but it also doesn’t take land away from use for growing food. A lot of consumers see that as an advantage,” he said.
At Green Week, his organization had a stand showing products that are already made from bioplastic. Flash drives, computer parts, toothbrushes, drinking cups and even car parts are already in mass production.
One item he liked was a not only bioplastic but also biodegradable. A bag for kitchen waste is supposed to break down over time. “People put biowaste in plactic bags, and these bags wind up in waterways and other places. Even though the biowaste could break down and go back into the environment, it won’t if it is sealed in a standard plastic bag,” he said. “The biodegradable bags break down and are also good for composting.”
Even though bioplastic is better for the environment than traditional fossil-fuel based plastic, it is still met with some resistance.
“Some people don’t want bioplastic if it is made from GMO corn,” he said. Even though there is no trace of genetic material or agricultural chemicals such as herbicides left in the bioplastic, some people still regard it with the same suspicion they take to all GMO products.
Van Pogrell speculated that some people might initially have the same suspicion over bioplasctic drinking cups, for example, made from wastewater. But over time this will likely change once awareness of the process becomes widespread and people understand that it is no different than any other plastic.
Consumers were initially concerned about the safety of all recycled products, and now that is no longer an issue.
He also pointed out the advantages of bioplastics, the main one being that they derived from renewable resources. Bioplastics will fill a huge need in the “post-oil era” when society shifts away from fossil fuels.
Since plants such as corn or hemp take carbon dioxide out of the atmosphere, bioplastics serve as a way to reduce greenhouse gases by storing that carbon. If the bioplastic items are recycled, the carbon is permanently removed from the atmosphere.
Bioplastics now account for roughly 1 percent of plastic production, but demand is rising, and demand is rising for food as well as the population worldwide increases.
Alternatives to bioplastics based on corn will reduce dependence on oil-based plastics while at the same time they will help keep agricultural land in the food production cycle.