Periodic Reporting for period 1 - NOBILIS (Novel Biobased Low-carbon Infrastructure Solutions)
Okres sprawozdawczy: 2022-02-01 do 2024-01-31
As population grows and gathers in urban conurbations, there will be an increasing need to build on unsuitable ground (contaminated or too weak for construction). This will require improvement of the ground so that construction can go ahead. Ground improvement will also be needed for the maintenance and repairs of old infrastructure earthworks. Current methods for firming up ground can be disruptive and costly, have environmental side-effects and generate carbon emissions. This project develops instead a nature-based process to produce biomimetic cement (biocement) which not only firms up the ground by producing cements naturally but can also absorb carbon dioxide in the process. The overarching objective of this research was thus to develop and prove these new, exciting bio-based processes in the laboratory and develop the technology towards site application as a method of improving existing railway infrastructure earthworks.
The project is in line with climate action policies and is beneficial for the society as upon industrial application the techniques can allow infrastructure to be provided in an economical and environmentally responsible manner, reducing material use, embedded carbon and other impacts on the natural environment and ecosystems.
The project is in line with climate action policies and is beneficial for the society as upon industrial application the techniques can allow infrastructure to be provided in an economical and environmentally responsible manner, reducing material use, embedded carbon and other impacts on the natural environment and ecosystems.
With the site application in mind, we isolated microorganisms from the railway embankment site, where the field demonstation of the technique would take place. We screened these microorganisms in terms of their ability to produce a specific enzyme, carbonic anhydrase, which helps catalysing chemical reactions involving CO2. For the proposed techniques, the enzymes produced by the micoorganisms can be harvested and used on their own (free enzymes) or the microorganisms will be producing the enzyme while in the soil, at the site that requires ground improvement. Either method has advantages and limitations, therefore we researched both options. Regarding the first option, for the first time, we bound the enzyme on some synthesised carriers in the form of nano-flowers, so that the enzyme does not degrade while in the environment, and also as a method of recovering and reusing the enzyme, hence reducing the costs of the technique. For the latter method, using the microorganisms to produce the enzyme on site, while in the soil, we used 2 different ways of doing this, with the native bacteria in the soil: a) we inceased the population of the microorganisms favourable for the process and introduced them back into the soil (bioaugmentation) and b) we stimulated instead the microorganisms already in the soil to produce the carbonic anhydrase enzyme (biostimulation); we performed modelling of the biocementation process using experimental data, as modelling validated by experimental data can help generalise future predictions without the need to repeat many lengthy tests. To grow the microorganisms for the bioaugmentation process we used successfully food waste from our university canteen, thus considerably reducing the costs of the process, with the industrial upscaling in mind. Considering the field application, we had to think of a practical way to implement the treatments into soils under existing infrastructure, where it is critical not to disturb the structural health of the infrastructure works. Treatments in this context refer to nutrients for the microorganisms (including the microorganisms, when bioaugmenting) and the required salt solutions that help us producing the cements naturally. As a large part of the materials we dealth with were of very low permeability, we decided to send the treatments to the soil using low DC voltage (electrokinetic treatment); this way the treatments can be conveyed under the existing structure many times faster than without the application of the electric current, and without building up high fluid pressures inside the soil. We performed site visits, consulted Ground Investigation reports and existing literature with some own modelling, to understand the causes of movement of the railway earthworks that needed to be treated with our proposed techniques (biocements combined with the electrokinetic method). We proposed a site treatment set up for the pilot field testing, and assessed the environmental impact and sustainability of the proposed techniques, towards further optimisation of the processes in the future.
Biocementation for ground improvement has drawn the vivid interest of the international community in the past decade. However, the process used from most research groups worldwide, urea hydrolysis, is producing undesirable ammonia byproducts. Also, the process was used mostly for sand soils. As highlighted above, for the first time we realised biocementation with native microorganisms from the site soil, which are able to consume CO2 while generating biocement, and this process does not generate undesirable byproducts. As opposed to other groups, we applied the technique to fine-grained soils with organic content rather than sands, as well as to coal ash from locomotives in the late 19th and early 20th centuries, a material which has been historically placed on the top of UK railway embankments and which is very prone to erosion. We have proven the process in combination with electrokinetic implementation for the first time and assessed its sustainabilty using life cycle assessment tools. The field pilot of electrokinetic biocementation for an actual railway embankment will be the first of its kind.
The project was designed to develop innovative techniques for our industry partners and other identified end-users, who are looking for improved techniques for unsuitable soil treatment. For companies offering ground improvement services (e.g. one of our industry partners), these techniques can be further developed to high TRL and create new business expertise widening their market for biocementation. Our railway industry partners, who are end-users of the techniques, are suffering from very high maintenance & remediation costs of their railway earthworks. The branch of the company partnering NOBILIS, are spending up to £1 m/year delay minute costs for 80 km railway founded on problematic soils we tested for biocementation; biocementation of the problematic soft soil will help them improve the soil thus reducing the engineering problems and related costs they face. Upon proof of the technique through long-term field monitoring they could apply it to numerous other locations across the UK, promoting the industry use of the techniques in the wider geotechnical, transport and civil engineering sector. The techniques are in line with the European Green Deal and the objective to help the civil engineering sector become more competitive, resource efficient and sustainable. We address timely environmental, economic and societal concerns, in line with the EU policies and actions aimed at investigating new processes towards a low-carbon and resource-efficient economy, with good management of natural resources and processes.
The project was designed to develop innovative techniques for our industry partners and other identified end-users, who are looking for improved techniques for unsuitable soil treatment. For companies offering ground improvement services (e.g. one of our industry partners), these techniques can be further developed to high TRL and create new business expertise widening their market for biocementation. Our railway industry partners, who are end-users of the techniques, are suffering from very high maintenance & remediation costs of their railway earthworks. The branch of the company partnering NOBILIS, are spending up to £1 m/year delay minute costs for 80 km railway founded on problematic soils we tested for biocementation; biocementation of the problematic soft soil will help them improve the soil thus reducing the engineering problems and related costs they face. Upon proof of the technique through long-term field monitoring they could apply it to numerous other locations across the UK, promoting the industry use of the techniques in the wider geotechnical, transport and civil engineering sector. The techniques are in line with the European Green Deal and the objective to help the civil engineering sector become more competitive, resource efficient and sustainable. We address timely environmental, economic and societal concerns, in line with the EU policies and actions aimed at investigating new processes towards a low-carbon and resource-efficient economy, with good management of natural resources and processes.