Effect of substrate on operation performance of ecological floating bed for treating simulated tailwater from wastewater treatment plant

Abstract

ABSTRACT Ecological floating bed (EFB) with assembling substrate can effectively enhance the removal of nitrogen. However, the influence of the substrate on the operation process of the EFB remains unclear. In this study, EFBs with zeolite, sponge iron and complementary substrates (zeolite and sponge iron) were established to explore the effects of different substrates on nitrogen removal efficiency, physical and chemical properties and plant growth. Complementary substrates could efficiently and stably remove nitrogen from tailwater. The concentration of ammonium nitrogen (NH4 +-N), nitrate nitrogen (NO3 --N) and total nitrogen (TN) in the effluent during the operation were lower than 1, 1 and 1.5 mg/L, respectively. Additionally, complementary substrates had no inhibitory effect on plant growth, and those substrates had little influence on the distribution of dissolved oxygen (DO), the oxidation–reduction potential (ORP) and the pH value. The zeolite increased the NH4 +-N removal and promoted the growth of plant stems and roots. However, sponge iron could effectively remove the NO3 --N in the water body and inhibit the growth of plants. These results can provide a basis for the EFB in the reuse of the tailwater of wastewater treatment plant.