Development Of Photosynthetic Bacteria Agent And Its Application In Anaerobic Digestion Of Dairy Products Dross

Photosynthetic bacteria are a group of facultative anaerobic bacteria that do not produce oxygen.Because of its unique physiological characteristics and its own rich nutrients,it is widely used in many fields and industries.In this paper,the biological characteristics and the optimum growth conditions of homemade photosynthetic bacteria were studied,and the feasibility of the anaerobic digestion of the scum was investigated under the medium temperature(37 degrees C).The experimental study shows that:1.From the sediment of the river and river bed of the Yangzi campus of Yangzhou University,the strong and fast growing photosynthetic bacteria compound bacteria were domesticated and named as photosynthetic bacteria agent(YDEM1).6 strains(PZ-1-6)were isolated and purified from YDEM1 according to colony and individual morphological characteristics,and their proportion in YD EM1 accounted for more than 99%.By comparing the sequence of 16S rDNA bases,it was found that PZ-1,PZ-2,PZ-3,PZ-4,PZ-5 and PZ-6 were the most similar to the faecal bacteria,the fecal bacteria,the photosynthetic bacteria(red bacilli),the bacillus,and testosterone from the DNA database,respectively.The similarity was divided into 99.5%,99.8%,99.5%,99%,99.4%,99.3%.Although the colony and individual morphological characteristics of PZ-1 and PZ-2 are different,16S and rDNA base sequence alignment showed that PZ-1 and PZ-2 were the same as E.faecalis.The results showed that the YDEM1 of the photosynthetic bacteria complex consisted mainly of 5 strains.2.In order to realize the large-scale production of photosynthetic bacteria bacteria,the optimum conditions for YDEM1 expansion were further studied.The experiment show:a)The best medium of photosynthetic bacteria bacteriums is DL-malic acid 3 g/L,sodium bicarbonate 1.0 g/L,ammonium chloride 1 g/L,Magnesium Sulfate 0.2 g/L,sodium chloride 1 g/L,potassium dihydrogen phosphate 0.3 g/L,hydrogen phosphate two potassium 0.5 g/L,calcium chloride 0.05 g/L,sodium propionate 0.3g/L,yeast ointment 1.5 g/L.b)The optimal culture conditions for photosynthetic bacteria inoculum were initial pH 7-8,temperature 30,inoculum 15%and light intensity 2000-3000Lux.3.The effect of thermothermal pretreatment and time on the biodegradability of slag in 60?80 C was studied.The test show:a)The fluidity of the scum heated at 80 degrees Celsius increased,the viscosity decreased,and a clear supernatant layer was formed,b)When the 2h was thermally treated,the dissolution rate of SCOD was 40.8%,and the dissolution rate of NH3-N was 7.6%.After the increase of heat treatment time,the concentration of SCOD and NH3-N increased obviously.When the heat pretreatment time reached 16h,the dissolution rate of SCOD and ammonia nitrogen reached 112.6%and 27.4%,respectively.Considering the cost and efficiency,it is suggested that the thermal pretreatment time in actual engineering practice is 2h.4.Self made photosynthetic bacteria YDEM1 was used as a microecologic preparation to treat dairy products dross under anaerobic digestion at medium temperature.After 30 days anaerobic digestion,the removal rate of TS in dairy scum was 36.8%,the removal rate of VS was 52.0%,and the removal rates of TCOD and SCOD were 75.8%and 86.6%respectively,the scum disposal of dairy products has obvious effect of reduction,stabilization and harmlessness.