Study On Detection Of Harmful Substances In Industrial Wastewater Based On Luminous Bacteria Method

In our country, the monitoring and evaluation of industrial wastewater mainlyfocuses on the analysis of physicochemical indexes at present. But only theconcentration level of one or one kind of contaminants in wastewater is given simply bythis physical-chemical analysis. It can not reflect the bioavailability and theenvironmental damages of wastewater accurately. Traditional physicochemiacal analysishas such certain limitations that it can not meet the request of water environmentsecurity management anymore. Industrial wastewater has wide varieties of pollutantsand complicated compositions. Because of the commen existence of compoundpollution interacting by several pollutants in wastewater, the studies of joint toxicities ofthem are more pratical significance for ecological risk assessment of industrialwastewater. As a convenient, sensitive, accurate and rapid biotoxicity testing method,luminous bacteria test has been widely applied to the studies on comprehensive toxicityof industrial wastewater and combined toxicity of pollution factors.The single acute toxicities of16kinds of contaminating materials to Vibrio fischeriwere determined respectively by Microtox Model500toxicity detector in this paper.And the toxicities of different materials were compared by EC50values at the same time.The results showed that, there were certain differences among the acute toxicities of6heavy metals such as Cd, Cr, Cu, Hg, Pb and Zn. The EC50values were in the range of0.107mg/L~33.031mg/L and the toxicity order of6heavy metals was: Hg> Pb> Zn> Cu> Cd> Cr. The EC50value of formaldehyde to Vibrio fischeri was7.720mg/L.The EC50values of6kinds of benzoic compounds ranged from20.448mg/L to108.431mg/L and the toxicity order was: phenol> nitrobenzene> benzene> aniline>chlorobenzene> toluene. It could be inferred that the contribution order of differentsubstituents to the acute toxicities of benzoic compounds was:-OH>-NO2>-H>-NH2>-Cl>-CH3. The EC50values of NO3-, NO2-and NH4+were35.451g/L,3.287g/L and3.277g/L. The toxicities were relatively weak and the toxicity order of different nitrogenforms was: NH4+≈NO2-> NO3-.On the basis of single toxicities, the joint toxicities of several mixtures to Vibrio fischeri were studied by the equitoxic ratio analysis method. Toxic Unit and AdditionalIndex were adopted to evaluate the joint toxic effects of mixtures. The results indicatedthat, the joint toxicity types of “Cd+Pb”,“Cd+Cu+Pb+Zn” and “Zn+benzene”were antagonistic effect, the types of “benzene+chlorobenzene”,“Zn+toluene” and“Zn+chlorobenzene” were synergistic effect, and the types of other mixtures werepartial additive effect when Toxic Unit was used. Compared with that, when AdditionalIndex was used, the types of all mixtures were antagonism except that “benzene+chlorobenzene”,“Zn+toluene” and “Zn+chlorobenzene” were synergism. For adefinitive mixture, results might be different using different methods evaluated, but thetrends were the same in general. The differences of evaluation results were caused bythe different hierarchies of different evaluation standards.The influences of different forms of nitrogen on the bio-toxicity effects of Zn toVibrio fischeri were researched under the determined nitrogen concentration condition.The results indicated that, there was certain antagonism of3forms of nitrogen to thebio-toxicity effects of Zn and the antagonism of NO3-was stronger than NO2-or NH4+.The toxicity of Zn in water body was reduced obviously.Physicochemical indexes and comprehensive toxicities of industrial wastewatersamples collected from17enterprises in Anshan City were determined and therelationship between them was studied. I found that, there were some differencesbetween physicochemical indexes and comprehensive toxicities in wastewater fromdifferent industries or different enterprises. Mineral Processing B had severe toxicity toVibrio fischeri, Petroleum Processing Q had medium toxicity, Beverage ManufacturingH, Textile K and Chemical N had low toxicity, and others had no toxicity.Comprehensive toxicities were the result of various pollutants and had no directcorrelation with a certain class of pollutants in this paper. Physicochemical indexes andcomprehensive toxicities were both the reflection of wastewater quality and accuratejudgments to wastewater quality could be made out only by combined analysis.