The Role of Biofilm in Clogging Process in Vertical Flow Constructed WeTland

This article explores the cause of substrate clogging in the absence of suspended solids or very low suspended solids (<<10mg/L, Water quality integrated wastewater discharge standard (GB189918-2002) level 1A emissions standards) in the influent during the operation process. Both the growth and detachment of biofilm were found to play positive roles in the clogging process under commonly used hydraulic loading in vertical constructed wetland. In addition, the existence of the biofilm enabled the suspended solids to combine much easier, which accelerated the settlement and interception of the solids. The biofilm secreted extracellular polysaccharides, which added to the adhesion property of the substrate. Thus, more solids were captured, and the occurrence of clogging was accelerated. Finally, the conceivable clogging process mainly caused by biofilm was conceptually described. However, the quantitative effects of the biofillm on clogging are still desirable to be studied.