Which biofilm reactor is suitable for degradation of 2,4-dimethylphenol, focusing on bacteria, algae, or a combination of bacteria-algae?

Effectively treating phenolic substances is a crucial task in environmental protection. This study aims to determine whether bacterial-algae biofilm reactors offer superior treatment efficacy compared to traditional activated sludge and biofilm reactors. The average degradation ratios of 2,4-dimethylphenol (40, 70, 150, 300, and 230 mg/L) were found to be 98 %, 99 %, 92.1 %, 84.7 %, and 63.7 % respectively. The bacterial-algae biofilm demonstrates a higher tolerance to toxicity, assimilation ability, and efficacy recovery ability. The cell membrane of Chlorella in the bacteria-algae biofilm is not easily compromised, thus ensuring a stable pH environment. High concentrations of tightly bound extracellular polymers (TB-EPS) enhance the efficacy in treating toxic pollutants, promote the stable structure. Intact Chlorella, , bacilli, and EPS were observed in bacterial-algal biofilm. The structural integrity of bacteria-algae consistently enhances its resistance to the inhibitory effects of high concentrations of phenolic compounds. Cloacibacterium, , Comamonas, , and Dyella were the main functional bacterial genera that facilitate the formation of bacterial-algal biofilms and the degradation of phenolic compounds. The dominant microalgal families include Aspergillaceae, , Chlorellales, Chlorellaceae, , and Scenedesmaceae have certain treatment effects on phenolic substances. Chlorellales and Chlorellaceae have the ability to convert NH4+-N. 4 +-N. The Aspergillaceae is also capable of generating synergistic effects with Chlorellales, , Chlorellaceae, , and Scenedesmaceae, , thereby establishing a stable bacterial-algal biofilm system.