Browsing by Subject "Microplastics"

Microplastic pollution is a globally increasing issue in both terrestrial and aquatic environments. One of its pathways to ecosystems is urban wastewater, as the treated effluent has been observed to contain remarkable quantities of plastic particles. In addition, as the treatment process separates the nutrients and solids into a sludge, the particles have been found in the sludge as well. The aim of this thesis is to investigate the costs of removing microplastic particles from the wastewater, and to assess the total microplastic pollution mitigation potential of selected wastewater treatment and sludge management methods. To examine this, I conducted a cost-effectiveness analysis, in which I constituted five different technology scenarios and calculated their incremental cost-effectiveness ratios. The ratios were then compared against a business-as-usual baseline scenario and each other to define the lowest cost of removing microlitter. The cost-effectiveness analysis was conducted for four different wastewater treatment plant sizes. The technology scenarios constituted of combinations of three wastewater treatment and two sludge management methods. The wastewater treatment methods were conventional activated sludge, rapid sand filtering and membrane bioreactor, and the sludge management methods were anaerobic treatment followed by land application as a fertilizer, and sludge incineration. The cost data on the selected wastewater treatment and sludge management methods were obtained from various documented sources, whereas two studies on the microlitter content in wastewater (Talvitie et al., 2017a & 2017b) comprised the effect data. To achieve an overview of the magnitude and the mitigation capacity of the issue, I compared the costs and the quantity of released microlitter of each technology scenario to the baseline scenario. In addition, to assess the impact of changing economic attributes and wastewater quality on the cost-effectiveness ratios, I performed a univariate sensitivity analysis. The results of the analyses prove that removing microplastics from wastewater is both feasible and cost-effective. The membrane bioreactor combined with sludge incineration resulted the most economical scenario in all circumstances and in each wastewater treatment capacity.

Oceans, seas, lakes and other waterbodies are increasingly suffering from too much plastic waste. Numerous sources are contributing to this plastic waste problem. Additionally, conventional fishing nets, made out of nylon, are causing environmental damage by disintegrating into microplastics. The breakdown process stops there, as these microscopic particles are non-biodegradable. Microplastics remain in waters for years causing harm to marine organisms that ingest them. Linen fishing nets are a valid alternative and more ecological production of nets. This study aims to compare the costs of these new linen nets with conventional nets. These costs can be related to the environmental benefits of these alternative nets. The research objective is to study the question under which conditions it would be optimal to choose linen nets over conventional (nylon) fishing nets. The conditions examined are economic and policy, environmental and technological. This research question is put into the wider context of microplastics. A rotation model, typically used in forest economics, is applied to analyze the optimal lengths of periods to renew both a linen and a nylon fishing net. A comparison of the costs is conducted and a subsidy-based policy instrument is determined for the fishers using linen nets. A subsidy-based policy could be applied to make fishing enterprises in Finland use ecological fishing gear. The results suggest that the costs of such a policy would be reasonable, estimated between €1.1 and €4.5 million in this study. Importantly, an increase in the use of ecological nets would lead to a decrease in the total microplastic load in waterbodies.