Effect Of Bioactivity Inhibitors On Generation Of H₂O₂ And Degradation Of Sodium Dodecyl Benzene Sulfonate In Natural Biofilm Systems

As a common complex biosystem in natural water, N utural biofilm possesses the environmental behavior of accumulation, adsorption and transformat ion of heavy metals and organic pollutants, and the migration and transformation of pollutants in natural water can be obtained indirectly through the exploration of the interaction between biofilm and organic pollutants. In natural water, the active group（ROS） generated by the dissolved organics under light is an important factor to affect the degradation of organic pollutants. The effects of irradiation and diurnal variation on biofilm for organic pollutants degradation have been explored, and the preliminary study showed that it was the ROS produced by photosynthesis that facilitated the degradation of organic pollutants. However, the mechanisms of ROS generated by photosynthesis of biofilm under light and their degradation of organic pollutants are not clear yet. Thus, it is very necessary to investigage the interaction laws and their mechanism between the metabolism of biofilm and typical organic pollutants, which is helpful to further understand the impact of metabolism of biofilm on the migration and transformation of oganic pollutants in natural water.Here, we take water/natural biofilm as simulated experimental system, and non-persisted, non-volatile sodium dodecyl benzene sulfonate（DBS） in natural water represents organic pollutants. The suitable bioactivity inhibitors were chosen by pre-experiment, and the implement conditions of bioactivity inhibitors in DBS degradation experiment of biofilm system were determined by different concentration and pre-effect time of the bioactivity inhibitors. Besides, we investigated the effects of metabolism of biofilm（mainly photosynthesis and respiration） on H₂O₂ generation and DBS degradation by adding various photosynthetic inhibitors, photorespiratory inhibitors, and respiratory inhibitors.The results showed that the bioactivity inhibitors chosen by pre-experiment were applicable in DBS degradation experiment of biofilm system under irradiation firstly. Secondly, the larger the concentration and the longer the pre-effect time of the bioactivity inhibitors, the greater the impact of biofilm system on H₂O₂ generation and DBS degradation, and the optimal concentration and pre-effect time of the bioactivity inhibitors was 20.0 μmol/L and 1.5 h, respectively. Ultimately, the amounts of H₂O₂ generation and DBS degradation decreased significantly of biofilm after adding the photosynthesis inhibitors compared with the system without them, and the effect of photorespiratory on H₂O₂ generation and DBS degradation can be ignored, which occurred with the photosynthesis simultaneously. In addition, there was no stronger inhibitory effect when adding respiratory inhibitors compared with photosynthesis inhibitors, which means no favourable physiological processes for the degradation of organic pollutants were inhibited except photosynthesis. The results further indicated that other physiological processes contributed little to H₂O₂ generation and DBS degradation apart from photosynthesis, and photosynthesis was the main pathway to produce H₂O₂ of ROS, and it was also the main factor affecting the degradation of organic pollutants.