Prioritizing the Valorization Strategies of an Invasive Fern (Azolla) in a Wetland

Wetlands play a vital role as one of the most important natural habitats on our planet. However, the survival of these natural wetlands is threatened by various factors. The arrival of invasive and non-native aquatic ferns is one of these challenges. In this regard, Azolla filiculoides has become a severe problem for the Anzali wetland. Azolla, as an aquatic fern, has created numerous issues in aquatic habitats and paddy fields in recent decades. However, the valorization of Azolla can contribute to the establishment of a collection system for this invasive fern, which can consequently reduce the negative impact of this fern on the wetland, and it can serve as a free and available source of biomass. In this respect, a fuzzy multi-criteria decision-making approach was used to rank the valorization strategies of this invasive fern. Initially, through an in-depth literature review and expert opinions, four criteria were designated as indicators for research evaluation: 1) technical, 2) economic, 3) social, and 4) environmental. Six management options for Azolla were considered: 1) no collection, 2) collection and landfilling, 3) direct use as livestock and poultry feed, 4) composting, 5) biogas generation, and 6) biodiesel generation. The results revealed that "biodiesel generation," "biogas generation," and "composting" were ranked as the most effective management strategies for Azolla in the investigated wetland. This study suggests that bioenergy generation and compost production from Azolla are promising strategies towards mitigating the negative impact of this fern on the Anzali wetland.