Study On Screening High-efficiency Predominant Bacteria And Their Characteristics In The Treatment Of Phenol And Heavy Metal Ions Complex Wastewater

Wastewater discharged from industries such as leather, smelting,electroplating results in serious pollution of heavy metals and organic compoundin water environment. When heavy metals accompany with organic pollutants inthe wastewater, they usually form new pollutants with organic pollutantsthrough complexation and/or chelation. As high biological toxicity of thesecompound pollutants, it makes the composition of the wastewater become morecomplicated and increases treatment difficulty of the wastewater. So, how toimprove efficiency of biological treatment system has caused extensive socialattention. In this study, the complex wastewater including heavy metals such asFe³⁺, Cd²⁺, Zn²⁺and Pb²⁺and organic pollutant such as phenol was used as thetreatment target. A series predominant bacteria, which have good removal effectof single or combind pollutants, were obtained by domestication, screening andpurification. The removal efficiency of the complex wastewater wereinvestigated in the predominant bacteria treatment system. The effect ofhydraulic retention time（HRT）, strain concentration, initial concentration ofpollutants on the removal of heavy metal and phenol were all discussed.Furthermore, the removal mechanism of pollutants was preliminary concludedby assaying the key enzymatic activity of these bacteria.（1）When the complex wastewater including phenol and Fe³⁺was treatedby Pseudomonas fluorescens, low concentration of Fe³⁺could be obviouslybenefit for improving the removal rate of phenol. The removal rate of phenoland Fe³⁺could obtain99.6%and57.9%respectively with initial concentrationof Fe³⁺and phenol were10mg/L and20mg/L. Compared with the systemwithout Fe³⁺salt, the removal rate of phenol could be improved about75%.Buthigh concentration of Fe³⁺would inhibit the removal rate of phenol of the strain.Based on the analysis result of key enzymatic activity, the degradation of phenolin this system was accomplished by the action of the catechol-1,2-dioxygenaseenzyme. （2）When the complex wastewater including phenol and Cd²⁺、Zn²⁺，apredominant strain, which had high degradation efficiency of phenol withtolerant Cd²⁺and Zn²⁺salt, was successfully isolated from an internalcirculation（IC） reactor. The results of morphology test together with16SrDNAgenetical sequence analysis indicated that bacteria belonged to the branch ofPseudomonas putida. It is showed that under the condition of pH and reactiontime of8.0, and24h respectively, the removal rate of phnol, Cd²⁺and Zn²⁺couldobtain about100%,19.7%and10.3%with initial phenol, Cd²⁺and Zn²⁺of lowerthan200mg/L,10mg/L and20mg/L respectively.（3）When the complex wastewater including phenol and Cd²⁺、Pb²⁺，apredominant bacteria with high removal ability of Cd²⁺and Pb²⁺in the complexwastewater including phenol was obtained by separation and purification fromsludge.The results of morphology test together with16SrDNA geneticalsequence analysis indicated that bacteria CP-3belonged to the branch ofStenotrophomonas acidaminiphila. It is showed that under the condition of pH,temperature and reaction time of6,35℃and24h respectively, the removal rateof Cd²⁺and Pb²⁺could obtain about45.1%and92.1%with initial phenol, Cd²⁺and Pb²⁺of50mg/L, lower than20mg/L and100mg/L respectively. Moreover,even if the initial phenol concentration is higher than200mg/L, the bacteriumcan still survive in the wastewater.