| People are paying more and more attention on the safety of antisepsis with the improving of living standard and development of food industry. Traditional aseptic, including sodium benzoate and sodium nitrite, are harm to people's liver, even as a carcinogen. But they have a good effect on keeping food fresh. Sodium benzoate will transform to benzoic acid which is toxic slowly in the stomach, and it will make people have a headache and letdown the memory. The sodium nitrite is color fixatives for foods and antiseptic, and it has comparability with salt at the character and taste. When people absorb more than 0.3g to 0.5g sodium nitrite, it will be an obvious poisoning symptom. As an aseptic of food,restorative leechdom,tobacco and top grade cosmetic, sorbic acid is recognized as one of the safe aseptic by the World Health Organization and the Food and Agriculture Organization. The effection of sorbic acid is 5 to 10 multiple of the sodium benzoate and it will change to CO2 and H2O in the body whth no rudimental. That is the reason that the output of sorbic acid became larger and larger.It produced lots of waste water in the producing of the sorbic acid,containing organic acid,aldehyde,ketone and lactone. The waste water, which was come from a sorbic acid produce factory in Jilin city Jilin province, had a very high CODCr reach 13000mg/L,with a low pH and pungent smell. The CODCr of the wastewater still can reach 2200mg/L after the antacid and dilute,pH value 5-6 and the wastewater can be bio-chemical treatment only after beforehand dealing with. The process flow in that factory was Crotonaldehyde- ketene process.The paper introduced the condition of sorbic acid and itspresent state of the wastewater treatment. The content and purpose of the experiment was also important discussed. Considering the water quality of the wastewater,I decided to use the hydrolysis acidification—aerobic combinatorial process. The hydrolysis acidification was chosen to improve the anaerobic biodegradability of the wastewater and provide advantageous condition for the aerobic treatment. The experiment proved that the best HRT was lower than the dynamics equation. The removal efficiency of CODcr and BOD5 was more than 95% and 96%, respectively. Thus the out-coming water reached the standard stipulated in the national regulation GB8978-96. The wastewater into the hydrolysis acidification set after adjusting the pH. The removal efficiency reached about 12%, pH value was 4.3-5.6, BOD5/CODcr raised by 66%, the suitable temperature was 25℃. At the aerobic set, the C:N:P supplement ratio is 150:5:1.Experimentation conclusion:1. The temperature was not strict at the hydrolysis acidification phase. There were lots of air bubbles accreting at the wall of the trough, proving that part of the hydrolysis acidification phase turned into the anaerobic phase. Big air bubbles appeared at the sludge layer which was float at the top of hydrolysis acidification trough.2. BOD5/CODcr increased by 66% obviously, and it proved that the anaerobic biodegradability of the wastewater was improved.3. It was very dangerous to feed the microorganism with single nutrition as the C or N, and will easily occur the sludge bulking.4. The acidification-aerobic combinatorial process was proved to be a effective method to treat the sorbic acid wastewater. The wastewater's CODCr and BOD5 removal efficiency was highly about more than 95% and 96%.5. The best running condition of the experiment: temperature: 25℃±10℃, pH: 5.5～6.5 at acidification process and 5.5～7.5 at the aerobic process, HRT: 12hours.The article also discussed the solution of sludge bulking. The sludge bulking was caused by maladjustment of nutrition. I took some measure to solve this problem, such as swing in FeCl3 and H2O2, improving aeration mode, changing the proportion of nutrition maladjustment. After taking the measure, the out-coming water was accord with the emission control regulations.
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