Investigating Biofilm Resilience in Constructed Wetland: Responses to Hexachlorocyclohexane

Constructed wetlands represent an innovative approach to wastewater treatment, particularly in environments challenged by industrial pollution. This study investigates the impact of hexachlorocyclohexane (HCH), chlorobenzenes (ClB) and metals (Fe, Mn) on bentic diatoms and microbial communities within the biosorption/biodegradation module, and an aerobic wetland system. Results on biofilm composition heterotrophs vs autotrophs, upstream and downstream. Bentic diatoms emerged as the dominant phyla across all sites, highlighting their resilience in diverse environmental conditions. Their species richness and the Shannon diversity index within the sites varied, with a general increase in the direction of water flow. The diatoms found in all samples were Achnanthidium minutissimum, Rhopalodia parallela, Nitzschia palea. Their relative abundances varied across the monitored sites. Metabolic activity within the biofilms varied, with lower efficiency observed at sites with higher pollutant loading and increased turbidity caused by iron colloids. The chlorophyll a concentration of the biofilm community functioned as a proxy for the autotrophic biomass and increased along the wetland, underscoring the influence of water treatment processes on primary production was positive only in the end of wetland. Microbial community analysis revealed distinct clustering patterns, indicating module-specific variations in abundance and composition. The main taxa which were detected in all samples is Sediminibacterium and the members of family_Rhodobacteracea and family_Comomonadacea. These findings contribute to the understanding of biofilm responses to pollution in constructed wetlands, offering insights for enhancing ecological resilience and water treatment efficiency in polluted environments.