| Urban drinking water is very important to the safety of residents.Progresses are made greatly in society and technology.However,drinking water safety problem has not been thoroughly solved.Drinking water safety incidents occurred frequently in the past worldwide.Water is crucial to human life and used by every person and each family and every day.Once it is suddenly contaminated,mass damage would be badly made.Understanding the possible sources of toxins and establishing its monitoring and alarming system are essential for prevention of drinking water sudden contamination accidents.This paper aims to explore the production of toxoflavin by Burkholderia gladioli under different culture conditions,to develop a luminol-hydrogen peroxide-copper oxide nanoparticles flow injection chemiluminescence technology system for monitoring the sudden pollution of toxoflavin in drinking water,to screen the toxin removal agent powdered activated carbon(PAC)as the emergency treatment detoxification material,and to design an online monitoring and early warning processing system based on the Lab VIEW software.The main results are as follows:1.Toxoflavin was easily produced by Burkholderia gladioli.The production of toxoflavin cultured at the Luria-Bertani(LB)liquid medium was more than that in nematode growth medium(NGM)liquid medium,reaching 1.677 mg/L.Among the natural media of ground and unground rice,glutinous rice,tremella and corn,the unground corn medium was the most suitable one for the bacterial strains to produce toxin,and the yield could reach 5.29 μg/g after 6days of culture,followed by the ground tremella medium,which contained 1.35 μg/g of toxoflavin.The yield of toxoflavin in rice and glutinous rice media was very little.The results showed that the production of toxoflavin could reach higher yield under the conditions of slightly acidic environment(p H=6)and room temperature(26-34 ℃).2.A noval flow injection chemiluminescence monitoring method was established based on the inhibitory effect of toxoflavin on luminol-hydrogen peroxide-copper oxide nanoparticles system.The results of one-way test and response surface optimization experiment showed that the linear range of the method was 0.005 ～ 5.000 mg/L,the detection limit was 0.001 mg/L,the recovery rate was 84 ～ 114%,and the relative standard deviation was 0.28% for 0.05 mg/L toxoflavin.This method had high precision,wide linear range,and was fast and convenient,could be applied to the on-line early warning of sudden pollution caused by toxoflavin poisoning in drinking water.3.PAC made from coconut shell showed great effect on removal of toxoflavin.Regarding the detoxification effect,ultraviolet irradiation was better than incandescent lamp irradiation,and heating at 60 ℃ was better than ultraviolet irradiation,but the detoxification of the above were not as effective as PAC.The material sources of PAC had great effect on its dsorption to teh toxoflavin.PAC made from coconut shell showed better adsorption effect than bamboo.With the same material,powder of 325 mesh had more efficient adsorption capacity than the 40 mesh’s.The results showed that at room temperature,when 250 mg/L PAC was added into 5 mg/L toxoflavin solution,the removal rate reached almost 100%.The follow-up test verified that the325 mesh coconut shell PAC with 50 times of toxoflavin concentration could achieve almost100% removal rate,and the removal efficiency was very high,indicating that PAC could meet the emergency treatment needs of drinking water sudden pollution.4.A water quality online monitoring and early warning system was developed by using Lab VIEW software,which was composed of database,early warning monitoring system,risk identification system,prediction and evaluation system and simulation evolution system.The software was combined with flow injection chemiluminescence method,and the drinking water safety level was divided according to the established safety threshold-safety,basic warning,intermediate warning and senior warning.Corresponding treatment measures were set for each state,and the water quality could be evaluated every 30 days.Based on this,the follow-up water treatment work arrangements of all departments were determined.It made the application from theoretical research to practical management and successfully established the online monitoring and emergency early warning system to deal with the sudden pollution of drinking water toxoflavin poisoning.In conclusion,toxoflavin was easy to be cultured,concentrated and extracted from the cheap corn seeds to become a hazard affecting drinking water safety.The newly established flow injection chemiluminescence system and early warning system could be used for online monitoring of the sudden pollution of toxoflavin.PAC made from coconut shell could effeciently remove toxoflavin from drinking water,so mass production of PAC could be made as reserve materials for drinking water emergency application. |
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