| The alga-bacteria symbiotic system is a kind of wastewater treatment method, which is formed by alga photosynthesis and bacterial metabolism. It is an effective method to solve water eutrophication and heavy metal pollution. The algae and associated germs exist prevalently in natural aquatic environments, could be used to solve water eutrophication and remove heavy metal cadmium in waste water. Based on measure the polysaccharide, ATP of the biofilm, made a study of the relationship between the effect of alga-bacteria biofilm remove the heavy metal cadmium from the sewage and the influence of temperature,PH,the initial concentration of cadmium are also discussed. In addition, the influence factors of the nitrogen and phosphorus removal efficiency of the symbiotic biofilm were studied. The results showed that:1. By growing the freshwater algae and their associated bacteria in the lake water of Changle Lake in Xi'an City, and their growth characteristics were studied. The whole growth period lasts about 30 d. 0d~10d, which is adapted to the culture medium environment and the growth is slow, The culture liquid is gradually turned into light yellow by the milk white; After the 10d~20d, the culture liquid is changed from light yellow to light green; the 20d~30d medium is dark green, and remains unchanged. Bacteria and algae have good adaptability to the p H,Temperature,salinity etc environmental condition. In the process of culture, the absorbance and chlorophyll a of the culture medium were determined, and the growth of the bacteria was good.2. In the experiment, the bacteria and algae were enriched in a lot of culture, and the growth and maturity of the bacteria was immobilized on the membrane. In this paper, the semi soft packing is used as a carrier to form the biofilm, and the biofilm is extracted and determined by EPS and ATP. The data show that the amount and activity of the biofilm are good.3. This research is to remove cadmium by using the cultured and immobilized bacteria algae. The experimental results show that the suitable temperature of fresh water algae and its associated bacteria can effectively remove the heavy metal cadmium in wastewater, the optimum temperature is 25?~40?,the optimum temperature is 30?, and the p H value of 6~9 is better, and the optimum p H is 6. When the initial concentration of cadmium ion was less than 20mg/L, the removal rate of in the biofilm was positively correlated. the coefficient of association R2 is between 0.9093~0.9459. Low concentrations of heavy metal cadmium and heavy metal removal rate were high in the treatment of lowconcentration of heavy metal by using bacteria and algae.4. In this study, the effect of nitrogen and phosphorus removal from fresh water by using algae and its associated bacteria on domestic wastewater was studied. The results showed that the removal of nitrogen and phosphorus in the symbiotic system of bacteria was obvious. Algal-bacterial symbiotic system after immobilized, the removal effect of ammonia nitrogen and total phosphorus was much higher than that of the non-immobilized bacteria algae symbiotic system. After starvation,it is beneficial to make a proper hunger processing algal-bacterial symbiotic system of nitrogen and phosphorus removal in wastewater, the more hungry days denitrification and phosphorus removal effect is better,in this experiment, hunger after 4 days denitrification and phosphorus removal rate can reach more than 90%. The optimum temperature of the immobilized bacteria was 28?,and the optimum p H was 7. Because of the different physiological requirements of the nutrient substances of nitrogen and phosphorus, the effect of nitrogen and phosphorus on the removal of nitrogen and phosphorus in artificial wastewater was studied. The results showed that when the ratio of nitrogen to phosphorus was 20:1, the removal of nitrogen and phosphorus in the symbiotic system was the best. After treatment of sewage TP,NH4+-N, 3.35mg/L,7.35mg/L, respectively, the corresponding removal rate was 92.3%,95.6%. |
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