| Phenol contained in waste water comes from industrid departments such as coking factory,gasworks,petrochemical works,insulant factory mainly,is considered as a category of organic pollutants with the widest distribution and the largest effect in the water environment.Phenolic compounds are various in styles, such as phenol,cresol,phenyl phenol,naphthol,chlorine phenol,etc.The most prominent phenolic compounds in pollution are phenol and cresol.Algae are the primary producer in aquatic ecosystem.There are a great variety of algae in the environment and their generation time is short.Not only the influence of chemical substances on the primary producers in aquatic ecosystem can be reflected by the results,but some kinds of algae have very good degradation to organic pollutants.Chlorella vulgaris (C.vulgaris) bought from Institute of Hydrobiology Chinese Academy of Sciences was selected as the test organism and phenol was selected as the test chemical.The investigations were carried out on the heterotrophic growth ability of C.vulgaris,the comparison among culture systems and the biodegradation of phenol by C.vulgaris under the condition of different cultures.tudied the heterotrophic growth ability of C.vulgaris under five cultures of which glucose concentrations in 5g/l,10g/l,15g/l,20g/1,and the results showed that the 10g/1 was the best glucose concentration for the growth of C.vulgaris.The maximal biomass concentrations (dry weight) of C.vulgaris growing under heterotrophic culture obtained were 6.9g/1,9.8g/1,11g/l,14.1g/l,13.8g/1 respectively,the specific growth rates were 0.36d-1,0.39d-1,0.27d-1,0.31d-1,0.3d-1 respectively, and the dry weight and growth rates was 0.6g/1 and 0.09d-1.Those results show that glucose is a good C-source for promoting the growth and heterotrophic growth was suitable for mass culture.The ratio of dry weight (DW) of cell,optical density (OD) of medium and cell density assumes a very good linearity relation.Due to the exception of illumination,the chlorophyll content of C.vulgaris in heterotrophic cultivation was lower than in autotrophic cultivation.At the end of mixtrophic cultivation and sequential heterotrophic-a-utotroph ic cultivation,the maximum dry weight of C.vulgaris were 14.1g/l,12.9g/l re spectively,and the specific growth rate were 0.707d-1 and 0.686 d-1 Compared with autotrophic cultivation,heterotrophic cultiv-ation is a better way for culti vating C.vulgaris.When selected the adju-sted SK medium,it was shown that the part of autotrophic cultivation make a good effect for increasing the cell d ensity, dry weight and ch-lorophyll content.This research,phenol was setted in the following two concentrate-ons: 20 Omg/1 and 400mg/1,with the 96h-EC50,310rag/1(mixtrophic cult-ivation),337mg /1 (sequential heterotrophic-autotrophic cultivation).Three parameters were select ed as toxicity indexes:algal growing rate,optic-al density and chlorophyll cont ent,and were determined every 24h dur-ing a growth period.At the same tim e,the culture of algae with thre-e different concentration of Phenol was calcul ated.Then the kinetic eq-uations of Phenol biodegradation by C.vulgaris were established.C.vul-garis appeared to have a certain capability to degrade Phenol.The bio-degradation rates of phenol by C.vulgaris with its initial concentratio n being 200,310,400mg/l(mixtrophic cultivation) were 96%,53.5%and23.5% after 144h,respectively,while in sequential heterotrophic-autotrophic cultivation wer e 96%,63.2%and20.5%. |
PDF Full Text Request