The impact of Aerationtime on the Nutrient Removal in Polluted Water by Canna Indica Ecological Floating Bed

摘要

In order to study the effect of aeration time on nutrient removal by plant ecological floating bed in water,Canna indica ecological floating bed was regarded as the object.Four groups were designed in the experiments,which were control,aeration time 4,8,and 12 h/d.According to the pre-experiment,the aeration rate of 2.4m3/(m2·d) was chosen.The heights of Canna indica were measured on Day 0,3,5,7,18 and 28 and DO,ρ(TN),ρ(TP),ρ(CODCr),ρ(NH3-N)and ρ(NO3-N) in water were tested as well.After the experiment,the total numbers of rhizosphere bacteria was accounted.The results showed that: ①the aeration time of groups 4h/d and 8h/d had significant difference from the control group; ②in aeration time 4h/d group the plant grew best in height,with109cm on Day 28; ③the DO reached peak with the best nutrient removal effect in the group aeration time 4h/d.On day 28,the concentration of DO reached 11.29mg/L and the removal rates of TN,TP,CODcr,NH3-N and NO3-N reached 75.10％,69.32％,65.75％,73.29％ and 78.79％ respectively; ④On day 28,the total amount of rhizosphere bacteria in aeration time 4h/d group accounted to 1.01 × 106(cells/mL) which was significantly more than that of other three groups,compare with 4.12× 105,9.07× 105,7.77× 105 (cells/mL) in control group,the aeration time 8,and 12 h/d group.In conclusion,when the aeration rate was designed as 2.4m3/(m2·d),the aeration time of 4 h/d was helpful for cleaning the polluted water.