| Human activities affect the aquatic environment, and the aquatic environmentalso affectc the quality of life of people. The combined pollution of algae andsynthetic organic compounds is one of the environmental problem posed by humanactivities. Prior research on this issue showed a poor coverage of the kinds oforganics and the species of algae, insufficient mechanism and lack of therelationship to the actual water treatments. In this paper, the combined pollution ofnitrobenzene(NB), a wide used chemical, and Microcystis aeruginosa, a species ofcyanobacteria which can cause water blooms, was investigated to fill in the blank ofthe prior studies.The concentrations of NB in the combined pollution of NB and M. aeruginosaat different incubation time were monitored. The results showed that M. aeruginosacan increase the elimination rate of NB, and a high algal density and a high initialconcentration of NB favor the bio-reaction. The results of kinetic analysis indicatedthat the elimination of NB in a solution without algae appeared to be apseudo-first-order reaction with respect to the NB concentration, whereas afirst-order model was too oversimplified to describe the elimination of NB in asolution with algae. Assuming that different algal cells have the same effect on thebio-reaction under the same conditions, the bio-reaction can be described asdC k0CmNBACnNBdt. When algae were in the exponential growth phase, the expressof kinetic model is dC1.68711050.72482.5407NBCACNBdt. With the help of kineticanalysis, the effect of pH and humic aid on the bio-reaction were studied, and theresults showed that a low pH value and a high concentration of humic aid arefavorable to the bio-reaction ability of algae, but unfavorable to the alga l growth.The actural elimination rate of NB is confirmed by the bio-reaction ability and thealgal density.The concentration of NB in algal cells were mesured, and the results showedthat the biosorption of NB by M. aeruginosa is responsible to the elimination of NBin the aqueous phase, but not the primary cause. Both the inactivation of M.aeruginosa and the illumination condition can affect the bio-reaction ability, and NBcan be metabolised by M. aeruginosa as a sole carbon source, which indicated thatM. aeruginosa have the ability to biodegrade NB. The analysis of the intermediateand the enzyme activity showed that NB can be reduced to aniline(AN) by NBreductase produced by M. aeruginosa, but cannot be further bio-degraded. Due tothe photodegradation of AN, the concentration of AN increased at firt and thendecreased. The elimination of NB in the algal solution is the result of the interaction of volatilization, reduction of NB and photodegradation of AN.The presence of NB inhibited the growth of M. aeruginosa, however, M.aeruginosa with a high algal density showed a strong endurance. NB enhanced theproductivity of disinfection byproducts formation potential by M. aeruginosa andresult in an increased disinfection risk, which is related to the enhanced proteinproductivity and the bio-degradation intermediate of NB. The presence of NB alsoinhibited the productivity of MC-LR by M. aeruginosa, which is related to thedecreased cell activities.The treatment efficiency of combined pollution of NB and M. aeruginosa andthe sole pollution of M. aeruginosa by pre-oxidation and coagulating sedimentationwere investigated. The results showed that the combined pollution increased thesoluble THMFP concentration and increased the disinfection risk of the treatedwater.As the complex interaction of NB and M. aeruginosa, the influence on watertreatments is a complex issue and should be carefully considered. A thoroughunderstanding on the issue of combined polllution of algae and synthetic organiccompounds can help us to take the advantage of the interaction and to ensure thedrinking water quality safety. |
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