BIOREMEDIATION OF THE PORT'S WATER
Topic of the practice
Bioremediation process consist of a biologic treatment or rather a cycle of microbial biodegradation in order to degrade the pollutant substances (generally organic compounds) and decrease their toxicity.
Good Practice Information
The aim of this project is to verify the efficacy of bacteria bio-fixed in a marine context and the possibility to use these systems to perform an ecologic decontamination or a biologic dredging in the case of stratified sediments polluted by organic compounds. An area within the Genova’s Porto Antico (bounded by the Acquarium and the Bigo) was chosen as sample survey. As a matter of facts, since this area is frequented by a large number of people, mainly tourists, it is quite important to reduce the torpidity levels and the smelly emissions of waters. Besides, the site is suitable for the survey because of its thick layer of polluted sediments.
The project is based on a step by step process: after the chemical characterization of the site (sampling and chemical analysis of sediments), micro-organisms more suitable and consistent with the features of the sediments were selected and sowed.
Monitoring of water quality
A weekly monitoring of surface water (approximately 50 cm of depth) was performed by a multiparametic probe in order to measure temperature, salinity, dissolved oxygen, pH, redox potential and a-chlorophyll concentration. Lab analysis were necessary to evaluate the concentration of nourishing substances (as ammonia, nitrates, nitrites, phosphates, etc.) present in the water, whereas the superficial transport properties and the surveying of meteorological-marine data were determined by using a floating apparatus.
Monitoring of sediments
A multistage sampling was performed:
1) chemical analysis to evaluate the relative humidity (%), dry fraction, concentration of hydrocarbons, oils and vegetable fats, etc.;
2) evaluation of biochemical composition of organic matter produced in the ecosystem by photosynthesis or coming from external sources (rains, rivers, waste water, etc.);
3) study of microbial composition (bacterial density and activity) that gives information about the potential degradative capacity of the sediments.
4) study about the meiofauna or rather the community of organisms specialized to live in particular habitat which is quite sensible to the alterations produced by pollution; the changes of the structure of this community are used as a sign of perturbation phenomena in aquatic ecosystems.
Evidence of success
• During the evolving of the project, a decrease of the thickness of the sediments of about 10 cm (due to decontamination process) was observed.
• Chemical analysis confirmed a consistent decreasing of the concentration of total organic compounds.
• Meiofauna presented an increased tassonomic diversity; the increased level observed in the first steps of the food chain is requested to start up the restoration and the preservation of the trophic relationships.
• As overall an final consideration, the environmental status of the sediments is strongly damaged but it is still able to effectively react with the bio-fixed micro-organisms.
Contact details to obtain further information on the practice
Dott. Stefania Maggi
Genova Port Autority
Annex completed on: 04-10-2012