Writing in Water Research, Austrian researchers from TU Graz and the University of Graz discuss new materials that prevent damage from microbial induced concrete corrosion.
Wastewater systems are integral to infrastructure in every community. In an ideal world, they operate smoothly and are long-lasting. But biogenic transformation processes in sewage and water treatment systems are a “natural enemy” of conventional plants, frequently causing damage to concrete and metal elements that is expensive to repair.
In field tests researchers from TU Graz and Graz University investigated the damage caused by microbial induced concrete corrosion.
© TU Graz
As a result, it is not uncommon for wastewater systems to have a lifespan of under ten years, before they need to be refurbished or individual components replaced. Toxic gases released during biogenic processes, such as hydrogen sulphide, also pose a significant health risk, causing a range of symptoms from irritation to respiratory failure and death.
Writing in the journal Water Research, an interdisciplinary group of researchers from TU Graz and the University of Graz has outlined strategies aimed at preventing what is termed microbial induced concrete corrosion (MICC). The research team comprises two TU Graz staff members – Cyrill Grengg of the Institute of Applied Geosciences and Florian Mittermayr of the Institute of Technology and Testing of Construction Materials – as well as Günther Koraimann of the University of Graz’s Institute of Molecular Biosciences.
Microbial induced concrete corrosion: turning a blind eye not the answer
Cyrill Grengg of the Institute of Applied Geosciences at TU Graz explained: “MICC often corrodes the conventional types of concrete used in wastewater treatment plants at a rate of a centimetre or more per year. Accordingly, the concrete elements can be destroyed in a matter of only a few years, causing significant damage to wastewater systems.”
According to the researchers, there is often a lack of awareness of these processes and the resulting threat to wastewater infrastructure and human health. “Closing the manhole covers and looking the other way is not the answer,” Grengg added. In Germany alone, the economic impact of wastewater system repairs is put at around EUR 450 million per year. Although no data are currently available for Austria, the costs can be extrapolated and also applied to other European countries.
Microbial induced acid corrosion (MICC) in wastewater treatment facilities results from a sequence of biogenic sulphate reduction reactions, followed by reoxidation. Initially, sulphate in pressure pipelines or standing wastewater is reduced by bacteria under anaerobic – or oxygen-free – conditions, forming hydrogen sulphide. This pungent, highly poisonous gas escapes into the sewer air and diffuses into sewer pipes and manholes.
There reoxidation by autotrophic bacteria takes place on concrete walls that do not even come into contact with wastewater. These microorganisms produce sulphuric acid which reacts with concrete construction elements. As Günther Koraimann of the Institute of Molecular Biosciences at the University of Graz, who has studied these processes in detail, explains: “This leads to the vigorous formation of a biofilm on the surface of the concrete, a reduction of the pH value to below two, in other words highly acidic, and extensive formation of new minerals, mainly in the form of gypsum. The combination of these processes results in the rapid destruction of the concrete.”
The Graz-based scientists worked on a holistic solution using an interdisciplinary research approach. In-depth research into the microstructural and microbiological processes was followed by the development of new MICC-resistant materials in close collaboration with the Institute of Construction and Building Materials at TU Darmstadt. In this context, geopolymer concrete proved to be particularly well suited to withstand acid corrosion.
When developing this building material, resistance to acid was an extremely desirable property, as were highly antibacteriostatic surfaces, on which the research team made significant advances – microorganisms that trigger the initial oxidation process are unable to settle on such surfaces in the first place. In turn, this prevents the formation of sulphuric acid.
Florian Mittermayr of the Institute of Technology and Testing of Construction Materials at TU Graz commented: “We achieved some very promising results with materials that have a far greater lifespan than conventional types of concrete. Use of these long-lasting materials would allow operators to refurbish damaged wastewater systems, significantly extending their service life and reducing the financial burden on local government and wastewater associations.”
The researchers published their latest findings on MICC prevention in the current issue of the journal Water Research 134 (2018) 341 - 352: "Advances in concrete materials for sewer systems affected by microbial induced concrete corrosion: A review."
The province of Styria provided financial backing for the research, and is dedicated to raising awareness of this global problem among Styrian local authorities and regional wastewater associations.
Institute of Applied Geosciences | TU Graz
Rechbauerstrasse 12, A-8010 Graz
Mobil: +43 680 3169642
Tel. +43 316 873 6366
Institute of Technology and Testing of Construction Materials | TU Graz
Inffeldgasse 24, A-8010 Graz
Tel. +43 316 873 7159
Associate Professor Dr.
Institute of Molecular Biosciences | University of Graz
Humboldtstrasse 50, A-8010 Graz
Tel. +43 316 380 5626
Barbara Gigler | Technische Universität Graz
Dresden creates ground-breaking interface between technology and medicine
05.09.2019 | Technische Universität Dresden
Methane vanishing on Mars: Danish researchers propose new mechanism as an explanation
08.07.2019 | Aarhus University
How long the battery of your phone or computer lasts depends on how many lithium ions can be stored in the battery's negative electrode material. If the battery runs out of these ions, it can't generate an electrical current to run a device and ultimately fails.
Materials with a higher lithium ion storage capacity are either too heavy or the wrong shape to replace graphite, the electrode material currently used in...
To process information, photons must interact. However, these tiny packets of light want nothing to do with each other, each passing by without altering the...
Researchers from the Department of Atomically Resolved Dynamics of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg, the University of Hamburg and the European Molecular Biology Laboratory (EMBL) outstation in the city have developed a new method to watch biomolecules at work. This method dramatically simplifies starting enzymatic reactions by mixing a cocktail of small amounts of liquids with protein crystals. Determination of the protein structures at different times after mixing can be assembled into a time-lapse sequence that shows the molecular foundations of biology.
The functions of biomolecules are determined by their motions and structural changes. Yet it is a formidable challenge to understand these dynamic motions.
At the International Symposium on Automotive Lighting 2019 (ISAL) in Darmstadt from September 23 to 25, 2019, the Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, a provider of research and development services in the field of organic electronics, will present OLED light strips of any length with additional functionalities for the first time at booth no. 37.
Almost everyone is familiar with light strips for interior design. LED strips are available by the metre in DIY stores around the corner and are just as often...
Later during this century, around 2060, a paradigm shift in global energy consumption is expected: we will spend more energy for cooling than for heating....
19.09.2019 | Event News
10.09.2019 | Event News
04.09.2019 | Event News
20.09.2019 | Life Sciences
20.09.2019 | Life Sciences
20.09.2019 | Life Sciences