Control Technology And Mechanism Of Geosmin And 2-Methylisoborneol

At present, along with the development of industry and enlargement of citizenpopulation, more and more waste was abandoned randomly which induce more toxicchemicals into drinking water source. Eutrophication was one of popularenvioronmental problems happened in waters, blooming agae consume dissovledoxygen in water, release some components toxic, smelle disgusting, and ruin thequality of water.Simple and accurate analysis methods for detecting micro pollutants such asendocrine disrupting chemicals, taste and odor chemicals were established. For thefirst time, a one-year-long investigation on micro pollutants in water source ofShanghai was carried out including the microbiology source of 2-MIB. Theconventional water treatment processes used in our country were valuated in thispaper. In broad, for the first time, products analysis of 2-MIB and GSM were carriedout by GC-MS, no obvious compounds were found, so it is possible that 2-MIB andGSM were directly mineralized; the removal of 2-methylisoborneol and geosmin bycoagulation-PAC-UF membrane was studied. Under the circumastances that the PACwas satured, the process can effectively remove most of 2-MIB and GSM.The results of research showed that liquid-liquid miroextration-gaschromatography-mass spectrum was adopted to analyze 2-methylisoborneol andgeosmin. The recoveries of 2-methylisoborneol and geosmin can reach 70%～80%,the detection limits were 5ng/L, 1ng/L, respectively. Investigation on musty and eathysmelling chemicals in drinking water of Shanghai started from Jan, 2006 to Dec, 2006,the results indicated that there was almost no pollution arosed by geosmin, theconcentration of geosmin in the year was under the threshold, while2-methylisoborneol had sharp variation with a highest concentration 139.27ng/L inHuangpu River detected in August, in the same time, 54.82 ng/L in Changjiang River.During July, August and September, the concerntration of 2-methylisoborneol in rawwater reached its peak. The investigation brought Microscopy showed thatOscillatoria was the main microorganism which produced 2-methylisoborneol. Variation of 2-methylisoborneol and geosmin in raw water of YangshupuWaterworks had the similar trend with that obtained from Songpu. In the finishedwater, the highest concentration of 2-methylisoborneol was detected in August,average concentration of a year reached 29.57ng/L, far above the threshold. Aerationprocess had the ability to remove these two taste and odor chemicals by a degree of32.4%～48.0%; preoxidation by potassium, prechlorination and enhanced coagulationhave little effect on removal of 2-methylisoborneol and geosmin;Activated carbon adsorption process and advanced oxidation process areeffective in removing 2-methylisoborneol in drinking water. For PAC, pH value hadapparent influence on adsorption capacity and rate, along with the increase of pH,adsorption capacity and rate were elevated; Negative ions almost had no influence onPAC adsorption of 2-methylisoborneol, while some positive ions can partly affect theadsorption process, because their hydrolysis led the solution to be acid. The sequencewas Na⁺＜K⁺＜Ca²⁺＜Mg²⁺＜Fe³⁺＜Al³⁺ according to the influence; In seasonswhen taste and odor problem burst, in order to decerease the concentration of2-methylisoborneol to the under threshold level, 53mg/L PAC at least should beadded. To avoid the affection brought by coagulants and oxidation agents, theaddition point should be selected seriously.The degradation of 2-methylisoborneol and geosmin in water by UV, UV/H₂O₂followed first-order kinetics model. The initial concentration of 2-methylisoborneoland geosmin had little effect on the degradation rate, and the removal efficiency couldbe greatly enhanced by increasing the intensity of UV radiation and dosage H₂O₂ in acertain range in the solution.Proper pH value and some organics or other inorganicions in real water can accelerate or restrain the reaction rate, in the same condition,the 2-methylisoborneol and geosmin can more rapidly degrade in tap water than inpure water.