The Construction Of Engineering Bacteria For Degradating Erythromycin And Application In Source Water BAF Pretreatment

In recent years, the new micro-pollutants phannaceuticals and personal care products (PPCPs) for drinking water quality impact has aroused world attention. How to avoid PPCPs into the drinking water is the top priority of the present study. It is an economical, safe and easy way that using Biological pretreatment for raw water to reduce or even remove PPCPs in the front processing of drinking water. In this study, bioaugmentation technology and biological aerated filter technology were combined to pre-treat the micro-polluted source water. Degradation strain of erythromycin was selected and used in the BAF, the research of its application provided a theoretical basis to the application of practical projects, has important practical significance.In this study, the method of solid phase extraction-high performance liquid chromatography was established to detect the erythromycin in solution, moreover, the conditions of solid phase extraction and liquid chromatography were optimized. The optimal conditions of solid phase extraction were as follows:the water sample pH was 7.0; extraction speed was 5mL/min; elution volume was 6mL; the ratio of methanol was 100%. Under these conditions, the enrichment of erythromycin showed good results, the average recovery was 97.90%, RSD of 1.81%(n=7). The optimal conditions of HPLC were as follows:Agilent ZORBAX Eclipse XDB-C18 cartridge (150×4.6mm,5μm), mobile phase of phosphate buffer solution(0.02mol/L potassium hydrogen phosphate solution adjusted to pH 7.0 with phosphoric acid):acetonitrile=35:65 (V:V); detection wavelength was 210 nm; flow rate was 0.6mL/min; column temperature was 50℃; injection volume 20μL. Under these conditions, erythromycin peak time is about 5min, erythromycin concentration and peak area showed good linear relationship, erythromycin concentration standard curve equation was y=2.263x+0.521(y indicates the peak area, x indicates the concentration of erythromycin). the linear correlation coefficient R was 0.9994, linear relationship was good. When the signal to noise ratio is 3, the method detection limitation was 0.8μg/L.Selected crythromycin as the target pollutants, the efficient degradation bacteria of erythromycin which was called Ery-E was isolated from activated sludge of sewage treatment plant in Songjiang Shanghai. According to the colony morphology of strain, physiological and biochemical characteristics and 16S rDNA gene sequence analysis, strain Ery-E is Pseudomonas putida. The degradation characteristics of strain Ery-E to crythromycin showed the best degradation conditions were as follows: The range of pH was from7.0 to 7.5; temperature was 30℃; initial erythromycin concentration was 30mg/L. Under these conditions, erythromycin degradation rate was 76.6%, when strains Ery-E had grown 5 clays in the inorganic medium solution which used erythromycin as the sole carbon source. Moreover, tests showed that add additional carbon source could contribute to the degradation of erythromycin. When the carbon sources were yeast, beef extract and glucose, the degradation rate of erythromycin could be increased. Especially when the carbon source was yeast, the degradation rate of erythromycin was 83.9% in 5 days.The degrading bacteria and activated sludge were mixed, added to two kinds of filler (bio-ceramic and volcanic rocks) BAF to form biofilm. Research the removal effect of the degrading bacteria to trace erythromycin within the BAF. When the range of water temperature was from 14.8℃to 19.6℃, the range of pH was from 6.46 to 7.81, experiments show that Bio-ceramic BAF Biofilm cycle was 12 days, the volcanic rock filter BAF was 13 days, the bio-ceramic BAF attached with engineering bacteria was 12 days, the volcanic rock filter BAF with engineering bacteria was 12 days. BAF optimum conditions were as follows:the gas-water ratio was 4:1, HRT was 4h. Under these conditions, the average removal efficiency of bio-ceramic BAF to ammonia, CODMn, turbidity were 87.1%,26.2%,89.8;the average removal efficiency of volcanic rock filter BAF to ammonia, CODMn, turbidity were 89.1%,25.6%,88.4%; the average removal efficiency of bio-ceramic BAF attached with engineering bacteria to ammonia, CODMn, turbidity were 86.8%,26.1%,89%; the average removal efficiency of volcanic rock filter BAF attached with engineering bacteria to ammonia, CODMn, turbidity were 89.4%,26%,88.2%. Four groups of BAF had reached a good removal efficiency. When Adding erythromycin concentration was 50μg/L, the average removal efficiency of bio-ceramic BAF to erythromycin was 27.3%; the average removal efficiency of volcanic rock filter BAF to erythromycin was 29.2%; the average removal efficiency of bio-ceramic BAF attached with engineering bacteria to erythromycin was 61.2%; the average removal efficiency of volcanic rock filter BAF attached with engineering bacteria to erythromycin was 69.4%. The removal efficiency of volcanic rock filter BAF to erythromycin was better than bio-ceramic BAF. Experiments show that dosing specific engineering bacteria to BAF, so that the specific pollutants could be degraded, was simple, effective and feasible.