A tribological approach for environmental remediation
Current methods of water treatment – such as chlorination and UV radiation – lead to undesired by-products, can be only locally effective and are sensitive to water composition. Moreover, their universal applicability to a range of microorganisms is under discussion. Additionally, the degradation of the persistent organic pollutants polychlorinated biphenyls PCBs requires navigation towards its maximum potential. The EU-funded triboREMEDY project aimed at approaching these two separate targets, the inactivation of microorganisms in water and the degradation of the PCBs, through a similar tactic, the application of tribolysis. This method focuses on controlling the friction and wear generated between two surfaces when interacting to achieve more optimal outcomes.
Implementing novel tribological strategies for water treatment
triboREMEDY developed a system that could provide safe water while working with low energy consumption, without material or chemical usage during operation, easy to maintenance, and installable in remote regions. The resulting prototype has shown an ability to generate extreme tribological conditions – such as a high shear rate leading to inhibition of the proliferation of bacteria and viruses – while being additionally supported by generated secondary effects, such as heat. Although the inactivation was not the same for all types of microorganisms, it was demonstrated that the inactivation levels were comparable to the rest of the competing technologies, while offering the benefits of chemical-free and material-free consumption during operation. However, for further efficiency increase and wider applicability, even harsher operating conditions are foreseen as necessary.
A persistent problem in storage
As part of the project, the tribological concept was also utilised to avoid contamination spread from untreated stockpiles of PCBs. Although the production of PCBs has been largely abandoned around the world, equipment and materials containing or being contaminated by PCBs still exist – especially in developing countries. Materials are treated as hazardous waste if the PCB content is as low as 500 ppm (mg/kg). Millions of tonnes of waste await the development of technology that can process especially high concentrations of PCBs to prevent leakages during storage and to avoid risks during their transportation to incineration facilities, which could result in the production of even more harmful chemicals such as dioxins. “We were able to demonstrate that the hypothesised tribological reactions can be triggered in PCB-like model compounds,” explains project coordinator Francesco Pagano. “Complete dechlorination of the target molecule was obtained when diluted in hydrocarbon-like contaminated oil, or in neat form like concentrated PCB stockpiles.”
Environmental treatments of the future
The technology related to the dehalogenation of PCBs can be applied also to the decontamination of other halogenated POPs or generally difficult-to-be-remediated halogenated waste, being a future focus of the project partners. The triboreactor provided proof of concept at laboratory level, but further optimisation and scaling up is necessary for implementation of this technology at an industrial level. The project consortium will further pursue this aim.
Keywords
triboREMEDY, water treatment, safe water, human health, environmental health, water remediation, tribolysis
