The Removal Of Taste And Odor Substances In Water By Powdered Activated Carbon Adsorption And Enhanced Coagulation

With the increase in population and the rapid development of the city’s industry,many harmful pollutants and chemicals were indiscriminately into rivers, lakes and other water bodies, causing serious pollution of drinking water sources,which caused the water bodies in the state of eutrophication. And in eutrophic water bodies, a lot of algae can produce secondary metabolites with musty earth, which are easy to cause odor problems in water bodies.In recent years, the incidents of drinking water sources suddenly polluted by odor occur repeatedly,which making that the issues of drinking water safety were widespread attention.Generally,the conventional process of waterworks is difficult to remove the odor substances.So it is necessary to explore a fast and efficient method to remove the odor substances, to respond to the sudden odor pollution of drinking water.This test took geosmin(GSM) and 2-Methylisoborneol(2-MIB) which are mainly odor substances in the water as the research object。The analysis methods of GSM and 2-MIB in the water were studied,and the study focused on the removal of activated carbon adsorption and enhanced coagulationin to odor substances(GSM,2-MIB).The result showed that headspace solid phase micro extraction-GC-MS can effectively determinate othe odor substances in the water.The standard curve of GSM and 2-MIB were established through the test.The correlation coefficient can reach0.99 or more, and are below the detection limit of 10ng/L. The method is simple,sensitive and accurate, and the detection limit is low, realistic the testing requirements of water sample.During the experiment, the adsorption isotherms of activated carbon were respectively fitted by Freundlich and Langmuir models,the result showed that Freundlich adsorption isotherm model could better describe the adsorption process of the activated carbon to odor substances and the correlation coefficient can reach more than 0.9.In the powder charcoal of wood, coal,and coconut shell, and the adsorption capacity and adsorption rate of Wood charcoal to GSM and 2-MIB is biggest,followed by the Coal charcoal, coconut shell charcoal.Through the study of adsorption kinetics, obtained that the fastest time of activated carbon adsorption was former 30 min,between 90~120min,adsorption achieved homeostasis. Within a certain range, the temperature was less affected to the process of activated carbon adsorption,but looked from the overall situation,low-temperature was better foractivated carbon adsorption.Under alkaline conditions, the removal of activated carbon to GSM and 2-MIB was higher.With the enhancement of hydraulic conditions,the removal of activated carbon to odor substances was higher.Natural organic matter in water could compete with the odor substances, the higher content of natural organic,the lower the removal rate of activated carbon for odor substances.The removal rate was low of conventional processes to odor substances, the removal rate of GSM and 2-MIB were only 13.91%,19.91%.The removal rate of activated carbon adsorption enhanced coagulation to odor substances(GSM,2-MIB)were higher,the rate could reach 90% and 77% respectively, the removal rate of activated carbon adsorption was the major proportion in this process.Changes in the type and dosage of coagulant could not effectively improve the removal rate of odor substance. The removal of PAC to turbidity and UV254 in the water which was casted into carbon was best.Increasing the dosage of activated carbon and prolong adsorption time could effectively improve the removal rate of odor substance.Different types and degrees of odor pollution in the water, the dosage required for activated carbon are also different.The removal rate of potassium permanganate enhanced coagulation to odor substances(GSM,2-MIB) were lower,the rate was only about 20% and30%.Increasing the dosage of potassium permanganate and prolong oxidation time could not effectively improve the removal rate of odor substances.The removal of activated carbon combined with potassium permanganate to enhanced coagulation for odor substances(GSM, 2-MIB) were better,but the removal rate is lower than that of activated carbon adsorption enhanced to coagulation alone.