» Microbial mercury remediation

© Logo: German Research Centre for Biotechnology
Mercury resistant microbes have evolved a mechanism to transform toxic ionic Hg2+ into non toxic elemental Hg0 using specialised transport proteins and the mercuric reductase enzyme. The elemental mercury diffuses out of the bacterial cells and can be collected in an appropriate bioreactor. On this basis, a novel biotechnology for clean-up of mercury polluted waste water has been developed, demonstrated and put into industrial practice at a chloralkali electrolysis factory by the GBF in cooperation with industrial partners. It was placed in a standard mobile container, controlled by telephone modem and proven to be efficient, robust, environmentally friendly and cost effective.

Container with pilot plant in operation at a German chloralkali electrolysis factory
Container with pilot plant in operation at a German chloralkali electrolysis factory

Facts about microbial mercury remediation:

Bioreactor volume 1 m3
Volumetric load 2 m3 wastewater/hour
Volume treated per year 18 000 m3
Average inflow concentration 4 mg Hg/l
Average outflow concentration < 50 µg Hg/l
Mercury collected per year 72 kg

» Novel integrated engineering solutions

© Logo: Technical University of Braunschweig
Biotechnological treatment options have to be integrated into a complete process scheme, which may include pre-treatment, process control, disposal of waste products, and other steps. Prof. Deckwer, Technical University of Braunschweig, will contribute his broad experience and scientific understanding of the processes of technical chemistry and so help to develop novel integrated solutions for mercury polluted waste water from various sources which are not only biologically feasible, but technically sound.

Flow scheme of the microbiological mercury remediation plant including pH adjustment, automated feeding and process control

Flow scheme of the microbiological mercury remediation plant including pH adjustment, automated feeding and process control

» Voltammetric electrodes

© Logo: The Hebrew University of Jerusalem
Prof. D. Mandler at the Hebrew University of Jerusalem has developed highly sensitive voltammetric electrodes which are applicable to monitor mercury levels in environmental samples or bioreactors and are much more cost effective than alternative measurement techniques. These electrodes have been shown to work reliably with chloralkali electrolysis factory wastewater. They might be integrated into bioremediation processes developed during the project to reduce overall costs and improve process control.

» Methylmercury analysis

© Logo: Jozef-Stefan-Institute
The most important mercury species are ionic mercury (Hg2+), elemental mercury (Hg0) organic mercury compounds, especially mono- and dimethylmercury. They have drastically different physical properties, environmental impact and toxicity to humans. Thus, their precise analytical determination is the basis for designing a biotechnological process and assessing its safety. It requires standardized protocols, which have been developed by Dr. Milena Horvat at the Josef-Stefan-Institute. Mercury speciation is measured by the use of atomic absorption, atomic fluorescence, and ICP ID MS as well as neutron activation (INAA and RNAA). The JSI has long experience in measurement of mercury speciation and is responsible for certification of reference materials for such analysis.

» Activated carbon filtration

© Logo: Technical University of Lodz
Activated carbon can be used both as a carrier material for a mercury reducing biofilm and as a final polishing step after mercury resistance based remediation. Professor Ledakovic from the Technical University in Lodz will investigate these possibilites and contribute his broad expertise in chemical engineering and biotechnology to the development of novel engineering solutions.

» Soil washing

© Logo: GEOtest Brno
A semi-industrial unit for soil remediation which is based on size fractionation and washing has been constructed by Dr. Jaroslav Reif from Geotest Brno and is operating at Vlora Hot Spot of Pollution, Albania. The microbial mercury remediation technology can be combined with the soil washing technology to remove solved ionic mercury from the soil wash water, to develop a new technology for clean-up of mercury polluted soils.