| At present,the occurrence of drinking water odor issues leads to negative impacts on both the quality of customers’ daily life and the image of water supply corporates.During the real production and operation process in water plants,due to the insufficient understanding of earthy-musty odorants in water sources,and the lack of obtain accurate judgment or achieve effective early warning,once odor issue occurs,water plants have to spend a long time on screening analysis of odor issues,which greatly affects the aging of treatment and disposal.Aiming at the issues above,this paper takes Shiyan reservoir and Tiegang reservoir,which are water resource reservoirs of one drinking water odor issue prone area in Shenzhen,as the research object,and chooses Shenzhen reservoir as the control.Comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry(GC×GC-TOFMS)was used to screen 54 common odorous substances in raw water,combining with flavor profile analysis(FPA)olfactory sensory evaluation method and odor activity value(OAV),the primary odorant types of drinking water in Shenzhen were determined,which is earthy-musty,and the main earthy-musty odorants are 2-methylisoborneol(2-MIB)and Geosmin(GSM).According to the daily monitoring needs of water plants,headspace solid phase micro-extraction combined with gas chromatography mass spectrometry method(HS-SPME-GC/MS)method was developed for the determination of earthy-musty odorants,2-MIB and GSM.The method evaluation showed that the detection limits of 2-MIB and GSM were 1.73 ng/L and 1.21 ng/L,respectively.The limits of quantification were 6.93 ng/L and 4.85 ng/L,respectively.The recoveries were in the range of 91.17~105.98% with relative standard deviations less than 15%,which meets the testing requirements.In order to determine the change of the content of earthy-musty substances in the reservoir,a one-year testing and analysis of 2-MIB and GSM in the three reservoirs was conducted.The results showed that the average content of GSM in the three reservoirs was less than 10 ng/L.2-MIB in Shiyan reservoir and Tiegang reservoir was > 40 ng/L,and 2-MIB was not detected in Shenzhen reservoir.Compared with GSM,2-MIB has a greater contribution to the intensity of earthy-musty odorants,and it should be the key research object.At the same time,to determine the biological source of 2-MIB,the main water quality parameters of three reservoirs and algae were tested and analyzed for one year.The data of algae species and abundance in the reservoir were obtained.The analysis of algal biomass and 2-MIB content showed that 2-MIB also had a high content of water while algae biomass was high.Potential for producing snake algae isolated and purified culture,its olfactory abilities were verified,and determined Anabaena is the main source of 2-MIB in water source.Based on the above research results,a molecular biological method for detecting the 2-MIB-controlled synthetic gene was established.The potential of 2-MIB in algae was predicted to provide early warning for water plants.The results showed that the 2-MIB gene could be successfully detected by the established real-time quantitative polymerase chain reaction(q PCR)method.When the number of genes was in the range of 2.46 × 103 ~ 2.46 × 109 copies/μL,R2 is 0.9988,which satisfies the testing requirements.At the same time,on the basis of the research results of this paper,reasonable suggestions were provided for establishing a relatively odor problems warning and emergency detection scheme in water plants,and come up with a new thought for water plants to detect odor issues. |
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