Study On Treatment Of Sorbic Acid Wastewater

Sorbic acid, 2, 4 - hexadiene acid in chemistry, is considered as an antiseptic with the lowest toxicity. It has been applied widely to foodstuff, medicine, light industry and cosmetic, etc. As a result of the sorbic acid widespread application, massive sorbic acid wastewater from production process produces is coming. This kind of wastewater is extremely complex, which contains organic acids, aldehydes, ketones, lactones and other substances, difficulty to do biological treatment. If sorbic acid wastewater discharged without any disposal, it will exercise a terribly bad influence on environment.This experimental topic originated from "Research of Sorbic Acid Wastewater Treatment" the Jilin Province science and technology agencies subsidization project. Hydrolysis acidification integrated with membrane bio-reactor was applied in the experiment to treat sorbic acid wastewater which came from Hong Kong new business International Corporation in Jilin economy and technology developing area.At the first stage of the experiment, we cultured anaerobic sludge for hydrolysis acidification and aerobic sludge for membrane bio-reactor.The experimental stage started from mid-August; the connection installed the good test equipment, raises in the domesticated hydrolysis acidification stage and the membrane bio-reactor sludge.The hydrolysis acidification sludge was taken from the sewage treatment plant tires of the oxygen pond, initially was grayish brown flocculent, the settlement good performance. Confined sludge placed inside temperature of 35℃for training, Changed water every day to join the microorganisms essential nutrients, and to observe the pattern of sludge. One week after sludge became darker in color, larger particles and air bubbles generated. Note sludge has been a certain amount of acid production of methane-producing bacteria. Wastewater COD1500-2500mg/L each part once, in operation for 12 days, effluent quality basic stability and achieved 1800mg/L. After the continuous had run four weeks, the COD elimination rate stabilized about 30% moved this sludge to the hydrolysis acidification pond.Aerobic sludge was taken from Changchun Western suburbs Sewage treatment plant aeration tank. After the sludge reception was put in directly the test installation, 100:5:1 joined the nutrients and the trace element according to the C: N: P proportion entered the water. COD was gradually enhanced from 300mg/L to 1500mg/L along with the time variation. To determine the sludge train situation, the COD of testing, activated sludge was on a daily basis for examination. At the beginning of the vaccination microscopy observation was significantly sludge floc, microbial species, but the number was small. A few days later sludge particles became larger, the color was from brown to yellow and increasingly densed granular sludge. We could see a large number of microorganisms exist, and then moved to the sludge membrane bio-reactor. Activated Sludge acclimation operated for a week, domesticated aerobic activated sludge removal rate of COD was above 90%.By changing the acid hydrolysis of the residence time (HRT), dissolved oxygen (DO), pH, temperature reaction conditions to identify the optimal operating conditions, commission acid hydrolysis stage for the first stage of research, the aspects of acid hydrolysis were as follows.(1)Measured the changes of BOD5/COD before and after acid hydrolysis. After acid hydrolysis, BOD5/COD value rose from 0.3 to 0.45.Biochemical Properties markedly improved.(2)Concentration in the wastewater, the pH, temperature and other conditions were certain circumstances, influent flow rate adjustment would change the acid hydrolysis of the hydraulic retention time (HRT), the measured COD removal, acid hydrolysis to identify the best HRT. After the test, the best HRT was 6 hours.(3) In all other conditions under certain conditions, changed the pH of wastewater, in order to determine the best operating pH. After the test, the best pH was 5-6.(4) Other conditions under certain conditions changed the wastewater temperature to determine the best reaction temperature. Through testing, the temperature maintained above 10°C , acid hydrolysis temperature of the treatment had little effect on the conclusions.Done experiment of the membrane bio-reactor stage, so in the following respects.(1) In the influent concentration, composition, temperature and other conditions under certain conditions, changed membrane bio-reactor pH. The optimal pH of aerobic biological experiments was 6.5-8.5.(2) Other conditions were in a certain situation, and changed the membrane bio-reactor temperature to work out the best operating temperature. After the trial concluded: temperature was 20°C and above, the removal of COD with increasing temperature had no obvious enhancement.This experiment studied the best conditions via changing HRT of hydrolysis acidification, DO in aerobic sludge, pH, temperature, etc. Under the best conditions, the removal rate of COD was more than 95%, and that of NH₄⁺-N was about 90%. After treatment, every aspect of discharged water can reach the first class standards of《Integrative Discharge Standards of Sewage》.