Experimental Investigation on Microplastics Biofouling Rate in an Aquatic System

Microplastics (MPs), small plastic particles under 5 millimeters, are a growing environmental concern in freshwater and marine ecosystems. They originate from numerous sources, can easily move due to their small size, and hold the potential to transport pollutants through their movements in marine and freshwater ecosystems. Hence, formulating the distribution and movement of these microplastics within aquatic environments is very important. However, MP distribution and mobility in water are complex processes which depend on many environmental and physical factors. One of the factors contributing to the dynamic nature of microplastics is biofouling. Biofouling, a process where MPs undergo surface changes and accumulate microorganisms, is a key factor influenced by factors like size, shape, and environmental conditions. Water quality in Lake Ontario is impacted by urban and wastewater discharge and across the lake MPs are reported at different levels. The wastewater effluent influences biofilm formation on MPs and in turn, affects their movement in the lake. Despite increased research on microplastic biofouling in freshwater, a significant research gap still exists especially in experimental works. To address this gap, in this study, a series of lab-based experiments, simulating Lake Ontario conditions, were conducted to analyze bacterial growth and biofilm formation on different microplastic sizes. The study investigated factors such as bacteria type, nutrient availability, shaking speed, microplastic size, and flow rate on MP biofouling formation and growth.

This study highlights the significance of biofouling on microplastics, focusing on how bacterial competition, nutrient supply, and the rate of water flow affect the formation of biofilms. This understanding is crucial for addressing hydro-environmental issues related to biofouling and microplastics, providing insight into mitigation measures.