| Industrial wastewater such as pulping wastewater,dyeing wastewater,soybean protein wastewater which belongs to the organic wastewater of high concentration,often used IC,UASB to treat anaerobic matter.Macromolecular organic matter through anaerobic treatment is metabolism as low molecular organic acids.VFA(volatile fatty acid)is an important intermediate in the anaerobic digestion process,a high concentration of VFA has inhibitory effect on methane bacteria produce methane,and the accumulation of VFA can not only reflect the state of the methane bacteria is not active,at the same time also can explain operating conditions of the deterioration of the reactor is an important index of anaerobic device running status.So for the detection and control of the VFA is very necessary.Method of detecting VFA usually with colorimetric method,chromatography,titration and distillation.Based on the determination of distillation VFA concentration,and the results were very similar with the real value of recovery rate were higher than90%,and is smaller than the real value.When the VFA is less than 300 mg/L,recovery rate is as high as 99%,recovery rate increased as the standard to reduce.Thus determination of VFA in anaerobic wastewater treatment using distillation is more feasible and reasonable.This paper study the influence of the chloride for detecting VFA,respectively to simulate wastewater samples and water samples and the actual blank cic to add certain amount of sodium chloride standard solution,waste water detection of VFA.Results show that under the condition of blank samples,200 ~ 800 mg/L chloride's influence on the measured value difference is not big,when more than 1000mg/L chloride,it can be seen that there has been a marked increase VFA.Theoretical density of 208.80,417.60,626.40,835.20,1044.00,acetic acid preparation standard water samples,both to join 2200 mg/L of sodium chloride,VFA values are increased and the incremental data range from 29.6 ~ 40.6 mg/L,the maximum is about the minimum of 1.37 times.Anaerobic reactor effluent water,add 200.0,400.0,600.0,400.0 mg/L of sodium chloride solution,the determination of the VFA value increases,when the VFA = 96.75 mg/L respectively increment of 4.24 ~ 52.95 mg/L,when the VFA = 166.28 mg/L increment in 3.34 ~ 59.08 mg/L,VFA = 302.63 mg/L increment in 5.95 ~ 58.96 mg/L,VFA = 432.58 mg/L increment in 7.36 ~ 53.28 mg/L.In addition this paper may cause VFA distillation titration test interference of other factors in the analysis and test,respectively in view of the bicarbonate ions,different acidity and sodium ion in the test,by eliminating the bicarbonate found in wastewater treatment,before and after the removal of VFA is 2.53 mg/l.from incremental add 10 ml,respectively,after 20 ml of phosphoric acid acidification,VFA increment from 1.2 ~ 1.8 mg/L.By sodium ion replacement and removal,VFA still increased.Through the above results show that the determination of chloride ion of VFA indeed had an impact,and has nothing to do with other factors.According to the test results,to better achieve the accuracy of the determination of VFA,the laboratory should consider to remove chloride ion,normally used to remove chloride ion laboratory way is divided into four kinds: salt precipitation method,ion exchange method,separation of intercept method,oxidation-reduction method.In this paper,by comparing these four kind of way,the final choice silver ion precipitation method to remove chloride ion,and the removal rate is as high as 93.0%,the removal effect is good.According to the result of experiment and analysis,this article also aimed at the laboratory to remove chloride ion in water samples test are proposed. |
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