Cork and plants used to remove pollutants from salt water

A research group from the Interdisciplinary Centre for Marine and Environmental Research (CIIMAR) is testing a system made of cork and plants to remove pollutants from salt water, more specifically in port areas.

With this pioneering project, whose prototype is installed in the marina of the Cruise Terminal of the Port of Leixões (APDL) in Matosinhos, besides improving the water quality, it intends to rehabilitate the ecosystems and promote local biodiversity, explained to Lusa CIIMAR researcher Cristina Calheiros, one of the responsible for the project.

To this end, the research group developed a biological treatment system, called "floating island", composed of three floating platforms of cork, interconnected with each other, with holes in which were placed four different species of plants.

These four species – Sarcocornia spp, Juncus spp, Phragmites spp and Halimione spp – were selected because they grow in wet lands, often flooded with salt water or saline of maritime origin, and so being adapted to variable salinity, said the researcher.

The floating islands, continued the responsible, are normally applied to lagoons which receive domestic or industrial wastewaters, being this part of a strategy of rehabilitation of rivers and other contaminated water bodies.

This is the first time that a system of this kind is applied in a marina, a place generally characterized by high levels of salinity and by the presence of different contaminants which result from the maritime traffic, such as hydrocarbons and heavy metals, as well as other conditions, like storms and the oscillations.

The platform, which has been in the test phase for about four months, was developed by Bluemater and Amorim Cork Composites, a nature-inspired engineering solution that imitates the physical-chemical and biological processes which naturally occur for water purification/depuration, through the actions of plant roots and associated microbiological processes, said Cristina Calheiros.

According to the researcher, the results obtained to date are "very promising" and show "a good adaptation of plants", which are surviving and developing.

"We are already checking all fauna associated with plants such as molluscs, bivalves and seaweeds, which are part of the ecosystem and promote water purification," she said, noting that to date there were no signs of plant survival under these salinity conditions.

It is predicted that "over time, the whole cork platform will be covered with vegetation, promoting biodiversity and enhancing the benefits that this ecosystem provides," as well as the expansion of the project to other marinas.

Cristina Calheiros believes that, in this way, the developed system can help to create margins and "a completely different dynamic" in areas such as seaports, normally without vegetation and "apparently without life"

The following stages of the project, developed by a multidisciplinary team, go through microbiological analysis, associated with techniques of molecular biology and chemistry.

"We are going to supervise the plants, what they can remove, as well as the action of the bacteria associated to the roots, through field studies and in the laboratory," identifying "superplants for these conditions," she said.

The researcher added that the development of these solutions is in line with the objectives for the sustainable development of the Agenda 2030 of the United Nations.

In the project also participate the CIIMAR researchers Ana Paula Mucha and Marisa Almeida, the latter also from Faculty of Sciences of the University of Porto.