Experimental study on segregation purification for nitrogen pollution by floating bio-film constructed wetlands

Combined floating bed and bio-film constructed wetlands (FBCW) simulation system was built to treatment sanitary wastewater with filamentous of palm and non woven and Trifolium repens L. TN,NH 3 -N, NO 3 -N,NO 2 -N and pH were investigated for upper, middle and under layer wetland system by intermission operation continued 118 days under natural conditions. Results demonstrated that system into the stable phase of the high removal rate after 48 days with 2m 3 /(m 2 .d) of hydraulic loading and 10 hours of the hydraulic retention. Average removal rate of TN and NH 3 -N were 64.4% and 60.6%, the highest removal rate reach 79% and 77%, respectively. Segregation effect was clearer. The purification ability of upper layer was higher than middle. Middle layer was higher than under layer. TN and NH 3 -N removal rate of upper layer were 1.96 and 1.45 times and 1.36 and 1.12 times higher than that of middle and under layer, respectively. And the system has a good buffering capacity. pH of inflow water changes have a greater impact on the lower, while the upper pH values stabilized at 7.38-7.74.