Experimental study of the influence of the high-concentrated chloride ion on the aerobic bacteria activity in pharmaceutical sewage

In this paper,we would like to introduce the findings of our experimental study of the effect of aerobic bacteria activities on the high-concentrated chloride ion in pharmaceutical sewage.As is known,there always exists high concentrated chloride ion in the pharmaceutical sewage,which may strongly affect the biochemical pool of aerobic bacteria.Coming from this need,we have arranged a series of experiments with the original pharmaceutical sewage with content of chloride ion in it.For our research purpose,we have made corresponding experiments by using the standard mercury salt method for measuring COD and the national standard silver nitrate method for measuring Cl-concentration,so as to observe better the changing regularities of chloride ion in correspondence with the COD,DO,SV30% and spawn quantity.The experimental data indicate that in the process of NaCl experiment,the COD value tends first to increase and then decrease.When the experiment comes to the stable stage,it can be found that the COD value tends to increase ceaselessly,and finally turns the process into four stages: DO value tends to be stable,then dropping,and then rising.And,in the last stage,when the chlorine ion concentration increased to 3 175 mg/L,the anaerobic bacteria would be brought up into a domestication stage.With the increase of chlorine ion concentration,the aerobic bacteria for sewage processing tends to gradually decline.Entering the stage of domestication and restoration,the concentration of chlorine ion tends to increase in a range from 4 294 mg/L to 5 146 mg/L,that is to say,the aerobic bacteria may grow to a stable stage,in which,when the concentration of chloride ion is 489 mg/L and the COD of sewage is 456 mg/L,the dissolved oxygen would begin to decrease to the lowest(DO value is 6.4 mg/L),SV30% is 25 mg/L.Thus,the result shows that the activity of aerobic bacteria is best with the treating capacity turning to be best at the moment.And,when the concentration of chlorine ion grows between 5 146-7 911 mg/L,the density of aerobic bacteria would begin to decrease gradually,whereas the sludge may come to the loose drift mud state gradually.And,now,the supernatant becomes gradually turbid with the increase of gradually dissolved oxygen.Thus,it would bring the microbial gradually into the biological decay.In the end,it can be concluded from the experiments that the highest water concentration of chloride ion in pharmaceutical sewage is 4 898 mg/L,which can provide useful parameters for the high chlorine sewage from the pharmaceutical industry,thus making high chlorine sewage treatment a useful operation reference for the pharmaceutical industry.