| Microbial flocculants are a class of green water treatment agents with flocculation activity,high efficiency biodegradability and no secondary pollution after degradation.The use of microbial flocculants is of great practical significance to human health and the natural environment.In order to accelerate its development,this study developed a new high-efficiency microbial flocculant based on the isolation of cellulose decomposing bacteria from cattle and sheep and the determination of its flocculating effect.The preliminary exploration of its production and application has been carried out,and the environmental significance for wastewater purification has been analyzed.In this paper,three strains of flocculant producing bacteria with better flocculant activity were isolated from the screening and identification of microbial flocculant producing bacteria.Through molecular biology and systematic physiological and biochemical identification,strain P40-2 was identified as a new species of Cellulomonas taurus,and named as Cellulomonas taurus.Strains P71-1and P99-1 were identified as Cellulosimicrobiums.The experiment determined that the carbon and nitrogen sources of MBF-P40,MBF-P71 and MBF-P99 medium were glucose,yeast extract and urea.The optimal culture conditions were as follows: initial p H value 7,culture temperature 30-36 ?,revolution 120-130 r/ min,culture time24-48 h.It was confirmed by toxicological experiments and observed that after intragastric administration of MBF-P series products,there was no chromosome aberration in blood cells of mice.The qualitative analysis of Molish,biuret and ninhydrin reactions showed that the microbial flocculants were mainly composed of carbohydrates and proteins.LC-MS quantitative analysis showed that MBF-P was mainly composed of eight monosaccharides,MBF-P40 was mainly composed of ribose,MBF-P71 was mainly composed of glucose and ribose,and MBF-P99 was mainly composed of rhamnose,xylose,glucose and ribose.LC-MS/MS quantitative analysis of MBF-P40 identified 956 proteins,MBF-P71 identified 382 proteins and MBF-P99 identified 1420 proteins.Zeta potential measurement and infrared spectroscopy analysis showed that MBF-P series products have negative charge and the presence of polysaccharide characteristic peaks represented by hydroxyl,amino,carboxyl,acyloxy and other functional groups,indicating that its flocculation mechanism is mainly bridging and adsorption,microbial catabolism and potential neutralization.In the actual application of MBF-P series products in treating sewage and wastewater,it was found that the purification effect is more ideal for sewage near farms,domestic sewage treatment plants,ships and ports.Among them,the highest flocculation rate of pig farm wastewater reached 96.07%,and the highest COD removal rate was 89.72%.The flocculation rate of the domestic sewage treatment plant reached 95.64%,the COD removal rate reached 50.37%,and the ammonia nitrogen removal rate reached 64.16%.MBF-P99 treated sewage near ship ports with the flocculation rate of 93.76%,the COD removal rate reached 83.62%,the ammonia nitrogen removal rate reached 93.86%,and the total nitrogen removal rate reached92.33%.MBF-P40 and MBF-P71 have a shelf life of 6 months(4?),and MBF-P99 have a shelf life of 9 months(4?).SEM observation test of sewage treatment effect found that after the addition of MBF-P series products,the sedimentation in sewage formed large flake floccule with closer texture.By comparing the water quality test report before and after sewage treatment and user feedback evaluation,it can be seen that MBF-P series products have certain market development value and can be applied to large-scale production and promotion. |
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