Study On Algae Screening And The Removal Of Nitrogen And Phosphorsus By Algae Biofilm

Algae biofilm technology is a new type of biological denitrification and phosphorus removal method.In recent years,the researchers have done plenty of works to the effect of wastewater treatment and the purification mechanism of algae biofilm while the study of algae screening,biological activity and the correlation between activity and purifying effect are still very limited.The screening experiments were first investigated with three species of algal biofilm (Oedogonium sp.,Anabaena flos-aquae, Chlorella pyrenoidosa) under the condition of continuous light of3500lx and PVC as their carrier, then the impacts of nitrogen and phosphorus ratio (N/P ratio) and hunger degrees on algae biofilm were carried out, including purifying capacity, algae cell number and exopolysaccharides(EPS),and then to analyz the relation between algae biofilm’s activity and its purifying effect.The major conclusions obtained in experiments were as follows:(1)The fittest algae for forming biofilm was screended by comparing their (Oedogonium sp., Anabaena flos-aquae,Chlorella pyrenoidosa) value of TP,NH3-N,EPS and DHA.The results showed that the removal efficiency,EPS and DHA of Anabaena flos-aquae were better than others,the removal rates of TP and NH3-N were90.25%,85.19%respectively, the value of EPS and DHA were18.333mg/L,0.069ug TF/mLh respectively.(2) The purifying capacity of algal biofilm was investigated with Anabaena flos-aquae under the different N/P ratio and hunger degrees.The results showed that the removal rates of TP,NH3-N and COD were maximum when N/P ratio is20:1,resching87.32%,90.57%,82.56%respectively;the removal rates of TP,NH3-N and COD were the maximum when the hunger degrees is2days, resching88.80%,84.29%,91.63%respectively;the value of EPS was highest when N/P ratio is5:1,reaching66.667mg/L;At the end of the hunger degrees experiment, the value of EPS was:1d>0d>7d=2d>4d.(3) The experiments to analyze the change in dehydrogenase activity (DHA) of Anabaena flos-aquae wree carried out under the conditions of N/P ratio and hunger degrees.The results showed that the value of DHA was highest when N/P ratio is20:1,reaching0.092ugTF/mLh; the value of DHA was highest when hunger degrees is2days, reaching0.240ugTF/mLh.There were positive correlation between algae activity and purification ability according to the linear fitting equation.