Study Of Slightly Polluted Water Treat By Suspended Algae

In order to study the characteristics of suspended algae remove pollutants form slightly polluted water, this experiment researches the low of suspended algae growth and pollutants removing in different pollutant level. This paper also researches the difference of suspended algae growth and pollutants removing in different value pH.Experiments in formal group, starting ammonia nitrogen concentrations are 4.8mg/l,8.4 mg/l,15.6mg/l separately. At the end of experiment ammonia nitrogen remove rate are 95.2%, 83.3%, 94.2% separately. The starting total phosphorus concentrations are 0.35mg/l,0.52 mg/l,0.89mg/l separately. At the end of experiment total phosphorus remove rate are 77.1%, 96.1%, 20% separately. Suspended algae in this experiment grow keep to Logistic growth model, and the increase ratio keeps to Gaussian model. According to Gaussian model fit curve, the increasing rate of 1# algae comes to the peak, being 1.814, while the increasing rate of 3# algae is the lowest, and being 0.941. The peak duration of algae's increasing rate in experiments in this group is between 2.074 days and 20788 days. Suspended algae can absorb phosphorus completely. The lowest concentration of total phosphorus in this experiment comes to 0.02mg/l. In the late stage of algae's quick increasing, the changing trend of the ratio of nitrogen and phosphorus will distinguish from each other according to the water condition of slightly polluted water.Experiment in the latter group, under the following conditions: the starting ammonia nitrogen concentration is 20.5mg/l, the starting total phosphorus concentration is 0.94 mg/l, and in different pH value, in neutral condition, the final density of algae cell is 2.6 times than in the condition of acidity-tendency. Through the cushioning effect of carbonate in water as well as the self-adoption of algae species group's biology and chemical adjusting function. Algae can make water's PH value tend to close up to the neutral range to grow. Suspended algae get high absorbing rate of total phosphorus up to 94.6%, when the water is neutral, but when the water is alkaline, the rate is 34%, being the lowest. The neutral condition can help suspended algae to remove ammonia nitrogen. Neutral, alkaline-tendency and acidity-tendency, in such 3 different conditions, suspended algae can remove ammonia nitrogen at different rate: 91%, 82% and 58%. Water can remove total phosphorus at the rate of 67% and 34% under acidity condition and alkaline condition. The concentration changing trend of CODcr is 4.2mg/l and the removal rate comes to 83.8% at last, the removing process of CODcr keep to zero order reaction.The result of this experiment show that suspended algae can remove pollutant in slightly polluted water efficiently. When the PH value is different, it affects the removal rate of ammonia nitrogen and total phosphorus seriously, but it affect the removal rate of CODcr slightly.