Study On Biodegradation Of Triphenylmethane Dyes Wastewater

As far as consumption is concerned, triphenylmethane dyes are classed as the third dyes, following after azo and anthraquinone dyes. The wastewater from manufacturing and utilization operations is imbued with high-color and poor biodegradation, resulting in environmental pollution.Accounting for the conditions prescribed above, a microorganism, which can biodegrade Crystal Violet (CV, one of triphenylmethane dyes ) efficiently, was screened and sorted from the textile waste water and active sludge in the wastewater treatment plant. The bacteria strain was identified as Kingella and named as Kingella H, the effluence of external factors on the dyes biodegradation were studied to optimize the biodegradation conditions, and under the optimal conditions , the cometabolism kinetics of CV was studied intensively. By means of the check of biodegradation intermediates of CV through Ultra Spectrograph, the possible biodegradation pathway of CV was discussed. The biodegrability of triphenylmethane dyes were studied systematically .Main conclusions can be drawn as follows:(1) The biodegrading enzyme of Kingella H can be found in the cells or on cell wall, and the gene which control the strain's capability of biodegradation was allocated in the plasmid. The CV can be cometabolized by Kingella H in the presence of oxygen.(2)Biodegradation of CV by Kingella H was carried out under aerobic condition, in which the optimal decolorization were as follows: temperature 35℃, pH7.0, shaking rate 150rpm and concentration of glucose 6g/L.Some salts containing heavy mental ion have inhibitory effects on the growth of Kingella H and decolorization of CV differently. The sequence was as follows: HgSO4>AgSO4>K2CrO4>CuSO4> MnSO4> Pb(Ac)2> ZnSO4.When the temperature is below 45℃,the relationship between temperature and CV biodegradation rate complied with the Arruenius equation with the activity energy 63.26kJ·mol^-1 and k0 9.041×l0⁷s^-1.(3) The process of glucose biodegradation by Kingella H can be described by the Monod equation, where the maximum specific biodegradation rate coefficient kg is 0.234g/g.min,half-velocity constant Kg is 0.0809g/L and biomass yield coefficient 0.200g/g. CV exerted non-competitive inhibition on the glucose biodegradation, with the inhibition coefficient KIg15.2mg/L. CV is the self-inhibitory non-growth substrate, the inhibitory kinetics can be described by the Andrews model, with the maximum specific biodegradation rate coefficient kc=2.20mg/g.min, half-velocity constant Kc=9.80mg/L and inhibition coefficient KIc=3.93mg/L. Additionally, glucose can accelerate the biodegradation rate of CV. An available kinetics model for cometabolism have been developed.(4) Ketonic group was found in the CV biodegradation intermediates by means of Ultra Spectrograph, and then the possible pathway of CV biodegradation was deduced.(5) The biodegradation rate constant k of triphenylmethane dyes was evaluated comprehensively. The complexity and number of substitution groups can effect the dyes biodegradation . The QSBR model was developed which indicated that the molecular weight is the most important factor that influences the Kingella H's ability of degrading the triphenylmethane dyes.Overall, while the triphenylmethane dyes biodegradation was studied systematically, the character of Kingella H was investigated preliminarily. So it is meaningful in both practical application of triphenylmethane dyes biodegradation and the foundation for further study.