化学机械法棉秆制浆废液的生物转化条件及转化物的安全性

Biotransformation and safety of cotton stalk alkaline peroxide mechanical pulping waste liquor

【目的】系统研究棉秆制浆废液用于培养具有生物防治功能的枯草芽孢杆菌的适宜条件和转化液的安全性。【方法】以初始p H值、温度、曝气量和接种量作为单因素,通过实验优化培养条件,并以大鼠和大耳兔作为测试动物,对转化液的安全性进行分析。【结果】结果表明,APMP棉秆制浆废液培养枯草芽孢杆菌的最适条件为:初始p H7.0,温度30℃,曝气量16 L/h,接种量0.8 g/L,反应器内加入填料,装填率为30%,在此培养条件下菌株的活芽孢数为6.27×109CFU/m L,废液COD转化率达70.4%。生物转化后,转化液的成分含量与转化前相比均有不同程度的下降。经4种毒性试验检测表明,未发现转化液的生物致病性。【结论】APMP棉秆制浆废液可为枯草芽孢杆菌的生长和代谢提供必要的营养,可用于生物转化,且转化液为无刺激性、无毒性物质。

[Objective] We studied the conditions of culturing Bacillus subtilis SY1 to treat cotton stalk alkaline peroxide mechanical pulping waste water,and evaluated afterwards the safety of its release to plants and animals. [Methods]The culture conditions were optimized through single factor tests,including temperature,initial p H,oxygen,and inoculation size. We used rats and big ear rabbits to test the safety of treated waste water. [Results] The optimal condition was as follows： initial p H7. 0,hydraulic retention time 30 h,temperature 30 ℃,filling rate of aeration 16 L / h,the dosage of Bacillus subtilis SY1 0. 8 g a liter water,and the stuffing volume accounting for 30% of the effective volume of the reactor.Under these culture conditions,the live spore number of Bacillus subtilis SY1 reached 6. 27 × 10^9 CFU / m L. The removal rate of COD reached 70. 4%. Results of the acute dermal toxicity test,dermal irritation test,eye irritation test and skin sensitization test after treated by the fermentation showed no clinical signs or changes conditions,and no deaths during the test period of 21 days. Animal body weight had a tendency to increase and had no abnormalities in the major organs,the Lethal Dose 50（ Abbreviated LD50） values was equal or greater than 10. 5 g/（ kg body weight） in acute dermal toxicity experiments. LD50 values were equal or greater than 2500 mg /（ kg body weight） in dermal irritation experiments. No rabbits exhibited chemosis eye at any time during the test period. The results of skin sensitization test showed no erythema or edema. The skin sensitization value was less than 0. 5. [Conclusion] Pulping waste water of APMP cotton stalk fermented by Bacillus subtilis SY1 had reduced COD and no obvious toxicity to animals.