Effect of Matrixes and Plants on the Removal of Nitrogen and Phosphorus in Paddy Fields Drainage Ditch

Under the laboratory condition, use the mixture of coal cinder and soil, the mixture of fine sand and soil , and simple soil as the matrixes; use the Acorus calamus, the Typha angustata Bory et Chaub, and the Scirpus validus Vahl as the plants. Three groups of ditch systems are built to study the effect of different group of ditches in removing nitrogen and phosphorus pollution of paddy fields drainage ditch. The results show that the plants significantly improve the purification performance of ditches, the removal rate to TN of the ditch system based on the mixture of fine sand and soil and the Acorus calamus is 50.9% which is higher than other groups; the removal rate to TP of the ditch system based on the mixture of coal cinder and soil and the Acorus calamus is 48.1% which is higher than other groups.

Diversity and Abundance of Ammonia-Oxidizing Bacteria in Horizontal Subsurface-Flow Constructed Wetlands with Different Vegetation and Substrate

The diversity and abundance of ammonia-oxidizing bacteria was investigated in three different types of horizontal subsurface flow constructed wetlands, reed (Phragmites australis)/gravel bed (W1), hybrid vegetation {reed, cattail (Typha latifolia), bulrush (Scirpus validus)}/gravel bed (W2) and reed/hybrid substrates bed (gravel, zeolite, slag) (W3). The investigation of community structures of ammonia-oxidizing bacteria revealed that the types of macrophytes , substrate and space distributions had significant influence on the microbial community. The ammonia-oxidizing bacteria detected were all inculturable, and belonged to Nitrosomonas spp.