Abstract: The effects of nutrients including C₆H₁₂O₆, KNO₃ and NaH₂PO₄ on the dehydrogenase activity and polysaccharide content of the substrate biofilms in the integrated verticalflow constructed wetland were studied by means of the orthogonal array design. Results show that C₆H₁₂O₆ and KNO₃ were the main factors to influence the dehydrogenase activity and polysaccharide content, respectively. The different combinations of the three nutrientsin different concentrations had different effects on the dehydrogenase activity and polysaccharide content of biofilms, and there existed the optimal combinations. For the dehydrogenase activity, the optimal combination of the nutrients was 0.2 g/L C₆H₁₂O₆, 0.8 g/L KNO₃, 0.05 g/L NaH₂PO₄. And for the polysaccharide content, the optimal combination was 0.2 g/L C₆H₁₂O₆, 0.4 g/L KNO₃, 0.2 g/L NaH₂PO₄. The corresponding dehydrogenase activity and polysaccharide content were 5.40 μg TF/g substrate, 12 h and 3 454.6 μg/g substrate, respectively.

Key words: biofilms, nutrient, dehydrogenase activity, polysaccharide content, integrated verticalflow constructed wetland