Research On The Immobilization Of Bacillus Subtilis And Its Application In Synthetic Wastewater Treatment

The aim of this research was to find some good immobilization methods of Bacillus Subtilis and also to get some results of its application in synthetic wastewater treatment. Following results were obtained:1.The effective concentration of B.subtilis cultivated by bran could arrive at 3×10¹⁰ cfu/g.Then packed by polypropylene nonwoven,immobilized B.subtilis can be get.2.Some experiments on the release rule of embedded B.subtilis has been done.It has been proved that the summation number of B.subtilis diffused in the experimented water and kept in the novwoven pack could get the largest number of 36 billion after 6-8 hours the embedded B.subtilis added,4.5 times of the original level of 8 billion. After that,the number of B.subtilis in the water or the pack began to decrease slowly.It gradually level off after 48 hours that the summation number stayed at 14 billion.Then,the number of B.subtilis dropped.There were 8 billion B.subtilis after 5 days in the whole system,equal to the original number.The microorganism could release slowly in water in this embedded way and proliferated at the same time.So a long water purification time could be promised.3.Compared the water purification effect of the immobilized solid-state B.subtilis with the ambulatory B.subtilis powder,the following results have been found. Under aerated condition,there was no big difference between throwing different quantitative B.subtilis when treating synthetic wastewater of low-concentration organic matter.There was no difference between the immobilized solid-state B.subtilis and the ambulatory B.subtilis powder too.When treating synthetic wastewater of high-concentration organic matter,the purification effect was the best at the concentration of 7.5×10⁵ cfu/mL.The COD_Mn removing effect of immobilized solid-state B.subtilis is better than directly adding B.subtilis powder. The experiment of continuely supplying organic matter to the water purification process showed that the immobilized solid-state B.subtilis could play a longer-time role and decompose the organic matter in the water faster.Under no aeration condition,this immobilized way could also play well at a low DO level that the COD removing rate could arrive at 75.22%after 48 h,compared with 40.21%of using direct disposal way.4.Through the experiment of optimizing the components of the culture medium,it showed that the output of the exopolysaccharides could get more than 2 mg/L with combination of 3%saccharose,1%ammonium sulfate and 0.5%beef extract.And OD₆₀₀ of B.subtilis could get 3.16.