Macroalgae Management in Coastal Regions in the Aspect of the Sustainable Development Strategy

The article discusses the problem of excessive growth of one-year filamentous algae, contributing to the disturbance of ecological balance in the Puck Bay. The aim of the study is to estimate the possibility of restoring this balance through the use of macroalgae as a co-substrate for biogas and fertilizer production in the regional biological wastewater treatment plant (WWTP). Effectiveness of biogas production from aquatic plants, including free-floating filamentous algae, was examined. Tests have shown that the biogas potential of seaweed constitutes the level of 162 m3/Mg of organic dry solid substances of algae. It was estimated that using the summer intense algal growth, removing 65,000 Mg of algae, 800,000 m3 of biogas can be obtained from the area covering the inner Puck Bay. After biogas conversion, 2,320 MWh of electricity and 2,100 MWh of heat energy could be produced. Harvesting free-floating algae enables the annual removal of 100-150 Mg of phosphorus and 200-400 Mg of nitrogen from Puck Bay and, thus, reduces the level of its eutrophication. Macroalgae management at a certain stage of growth also prevents the presence of algae on beaches and contributes to the improvement of fishing conditions and boosts the tourism value of the region.