| Urban landscape water body has the functions of reducing dust,improving environmental comfort and living quality.However,it is more likely to occur eutrophication because of high nitrogen and phosphorus concentration and poor mobility in urban landscape water body.At present,it is still inadequate for the sampling,analysis and evaluation of water quality of urban landscape water.Therefore,it is very important to explore the efficient,energy saving,small footprint equipment for the purification of urban landscape water.This paper firstly explored to determine the optimum sampling time and depth in different seasons of Xi'an moat.Then,the method of single factor evaluation of eutrophication level was developed based on the optimum sampling method.Finally,the effect of two different fast filter columns on the quality of landscape water was studied.The main conclusions were as follows:1)During the monitoring period,the mean values of total nitrogen(TN),total phosphorus(TP),ammonia(NH4+-N)and orthophosphate phosphorus(PO43--P)concentration increased gradually with the increase of water depth.Moreover the above parameters changed obviously with the seasons.The algae density and chlorophyll a(Chla)concentration decreased with the water depth.The correlation between the algae density and Chla concentration was 0.97 by Pearson correlation analysis.2)In this paper,the mixed water samples referred to the samples of 0.5m below the surface and the sample of 0.5m above the bottom of the moat.It was found that the mean values of the mixed water samples were closer to the mean values of whole day than the water samples only collected at 0.5m below the surface for the water quality parameters through the water quality monitoring in Xi'an moat.The water quality parameters in the afternoon were also closer to the average value of the whole day.Therefore,the mixed water samples and water samples collected in the afternoon were more representative.3)The correlation between ?DO and Chla concentration in water was studied under the condition of light and dark ratio being 1: 1,temperature being 25? and light intensity being 2000 lux.The results showed that Chla concentration and ?DO were positively correlated in Microcystis aeruginosa,Chlorella and Pseudomonas sp.The Pearson correlation coefficients of Chla concentration and ?DO were 0.95,0.96 and 0.97,respectively.It showed that ?DO was a meaningful index for evaluation of eutrophication as a single factor in an actual monitoring when compared with DO concentration.Based on the comprehensive nutritional level index,the degree of eutrophication could be determined according to the range of ?DO as follows: being poor nutrient when ?DO?0.35mg/L;being middle nutrient when 0.35mg/L<?DO?0.77mg/L;being mild eutrophic when 0.77mg/L<?DO?1.5mg/L;moderate eutrophic when 1.5mg/L<?DO?3.37mg/L;being severe eutrophic when 3.37mg/L<?DO? 8mg/L;being extreme eutrophic when ?DO>8mg/L.4)The effect of two kinds of fast filter columns on landscape water purification was studied.The results showed that the mean removal of TP,PO43--P,chlorophyll a and turbidity in the influent by sponge iron filter were 88.8%,96.2%,73.8% and 83.4%,respectively.On the other side,the average removal of TP,PO43--P,chlorophyll a and turbidity were 91.7%,95.4%,66.4% and 80.7%,respectively.In addition,the maximum adsorption capacity of sponge iron and activated alumina through Langmuir curve was 362mg/kg and 73.8mg/kg,respectively,which revealed the adsorption capacity of sponge iron was about 4.9 times of activated alumina and it had a large adsorption capacity for low concentration of phosphorus.Furthermore,it was also found 0.1M KCl+0.1M NaOH had a good effect on the regeneration of saturated sponge iron through the regeneration experiment. |
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