ABSTRACT
So far, many types of carriers (such as artificial mat, industrial soft carriers) have been widely used in removing pollutants, purifying water quality via the periphyton attached on the surface of these carriers. In the presence of periphyton, the distribution of redox zone at different water layers is directly or indirectly associated with the removal rate of pollutants. Therefore, it is more practically significant to study the distribution of redox zone at different water layers and the microbial diversity in the presence of periphyton. In this study, the pilot experiment was performed in a simulated water column bioreactor. Firstly, the eutrophic water collected from XuanWu Lake was added into the simulated water column bioreactor. The industrial soft carriers were then suspended into the water column in order to enhance the growth of periphyton. After periphyton gained a steady growth state, the oxidation reduction zones (redox zones) and the responsible microorganisms at different water layers were monitored. The results showed that five sequent redox zones (i. e. oxygen reduction, nitrate reduction, iron reduction, methanogenic and sulfate reduction zones, respectively) appeared in different water layers from top-down in the presence of periphyton and their responsible terminal electron acceptors were O2, NO3(-), Fe3+, CO2 and SO4(2-) respectively. The indicators of the different zones were DO, NO2(-), Fe(2+), HCO3(-) and sulfide, and the highest concentrations were 11.290 mg x L(-1), 4.950 mg x L(-1), 38.326 mg x L(-1), 120.000 mg x L(-1) and 12.180 mg x L(-1), respectively. The results of microbiological characteristics tested by Biolog EcoPlate technology revealed that there were significant differences in the composition, metabolic activity, carbon utilization of periphyton at different water layers, causing the difference in the distribution of redox zones at different water layers. These findings implies that study on the distribution of redox zones and microbiological characteristics in the presence of periphyton provides a better understanding that periphyton is capable of improving water quality at different layer, and also provides some theoretical basis for the development of technology for purifying water quality based on periphyton.
