The fate of biodegradable groundwater monitoring well
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Accumulation of plastics worldwide has already aroused public concern due to its persistence in the natural environment, threatening environmental and human health in the coming decades. The utilisation of groundwater monitoring wells made of conventional plastic in groundwater and soil investigation projects aggravates plastic pollution in the subsurface. The development of biodegradable groundwater monitoring wells (‘Biowell’) provides an alternative. However, the biodegradation performance of a biowell placed in the soil has not been investigated in-depth and has led to the central research question: "What is the fate of the biodegradable monitoring well?” In the first step, external interviews with the producer, converter and researcher were held to provide background information. On the other hand, internal surveys were performed to gain deeper insight into the optimal conditions to utilise biowell. The results showed that the biowell is the best solution for short-term monitoring projects when sustainability is a critical request from clients and the government. However, deficiency of legislation and certification pose barriers to promote biowell on a large scale. Besides, biodegradation performances of biowell in natural field conditions have notbeen investigated previously due to the deficiency of realistic cases. Two years ago,one biowell was installed underground in Utrecht. This used biowell is further chemically and physically analysed by visual inspection and Py GC-MS test. The results illustrated that biowell experienced slow-speed biodegradation under the natural field unsaturated condition. Studies concentrating on the ultimate biodegradation under laboratory conditions are still scarce, which requires further investigation. Soil burial tests were designed under twelve different laboratory settings to investigate biodegradation performances. Results demonstrated that the biodegradation rate has a positive relationship with temperature while no obvious effects were noticed from soil humidity and bioaugmentation. The first-order kinetic model was further used to estimate the final biodegradation time, which anticipates that it would take approximately 3000 days and 3500 days under 20 ℃ and 40 ℃, respectively. Briefly summarised, the biowell proves to be a more sustainable option in short-term soil & groundwater investigations providing appropriate implementation. Regarding the fate of biowell, it indicates that approximately 10 years is required to approach ultimate biodegradation in the natural soil environment.