| Para-nitrophenol?PNP?,as a kind of nitro aromatic compounds,is mainly used in the production of synthetic medicine,dyes,organophosphorus pesticides and industrial solvents.The phenol-containing wastewater formed by it has high toxicity and contains The characteristics of large amount of salt and complex composition restrict the process of biological method for treating phenol-containing wastewater.This experiment explored the characteristics of degradation of p-nitrophenol by the halophilic bacteria Halomonas sp.H17 and the halotolerant bacteria Staphylococcus sp.CL at different temperatures,initial p-nitrophenol concentration,initial pH,salinity and inoculation amount;the effect of the degraded carbon source?glucose?on the degradation of p-nitrophenol by two strains;the inoculum of the two strains were prepared and the effect of degrading p-nitrophenol was investigated.The main results and conclusions obtained are as follows:?1?When the temperature is from 15-40oC,the initial p-nitrophenol concentration is from 100-800 mg/L,the initial pH is from 5-10,and the salinity is from 0%-20%,the degradation rates of p-nitrophenol of H17 and CL both increases first and then decreases;when the inoculation volume is from 0.5%-5.5%,the degradation rate of p-nitrophenol of H17 and CL increases first and then stabilizes.H17 and CL have the highest degradation rate at a temperature of 30oC,p-nitrophenol concentration of 200 mg/L,pH of 7,salinity of 10%,inoculation volume of 3.5%and 2.5%,respectively.?2?At temperature of 20oC and 25 oC,p-nitrophenol concentration of100 mg/L,pH partial acid or base,salinity 10%-20%and inoculation volume 3.5%-5.5%,the degradation rate of H17 is significantly higher than CL;when the concentration of p-nitrophenol is 400-800 mg/L,salinity is0%-3%and inoculation volume is 0%-2.5%,the degradation rate of CL is significantly higher than H17.?3?Increasing the glucose concentration from 0 g/L to 1.0 g/L reduced the degradation rates of H17 and CL from 79.2%and 76.7%to 30.7%and32.3%,respectively.The increase of urea concentration from 0 g/L to 0.2g/L increased the degradation rate of H17 and CL from 78.9%and 78.2%to 82.3%and 81.1%,respectively.?4?When the initial p-nitrophenol concentration is 100-800 mg/L,adding glucose is reduced the degradation rates of H17 and CL from30.5%-80.3%and 33.6%-76.8%to 17.3%-52.1%and 16.6%-45.2%.Adding urea can increase the pH of H17 and CL culture fluid from 4.6-5.5and 4.4-5.3 to 6.7-7.0 and 6.5-6.9,effectively alleviating the inhibitory effect.?5?The degradation of p-nitrophenol by H17 and CL conforms to the Haldane model.The maximum specific degradation rate of H17 is higher than CL(0.34 h-1 and 0.31 h-1);H17 has stronger affinity for p-nitrophenol than CL?the corresponding saturation constants are 51.65 mg/L and 87.88mg/L?;the inhibition effect of p-nitrophenol on H17 is less than that of CL?the corresponding inhibition constants are 581.22 mg/L and 293.45 mg/L?.The addition of glucose increases the inhibitory effect of the substrate on H17 and CL;the addition of urea reduces the inhibitory effect and increases the rate of phenol lowering of H17 and CL.?6?When the initial p-nitrophenol concentration is 100-800 mg/L,the degradation rates of H17 and CL bran agents are higher than their respective wheat bran agents and rice straw powder agents.At 200 mg/L,the highest degradation rate of H17 and CL bran agents are 78.4%and70.1%.?7?When the initial p-nitrophenol concentration is 100-800 mg/L,the degradation rates of H17 and CL bacterial solutions are higher than those of their respective bran agents.Glucose and urea can improve the phenol-reducing effect of H17 and CL bacterial solutions and agents,and the phenolic reducing ability of the bacterial agent is better than that of their respective bacterial solutions.When the concentration of p-nitrophenol is200 mg/L,the degradation rates of H17 and CL bacterial solutions and bran agents reached the maximum at 85.9%and 82.6%,89.8%and 88.6%,respectively. |
PDF Full Text Request