Isolation Of Flocclant Producing Strain And Its Application For Swine Wastewater Clarification

In the past few decades,with the rapid development large-scale farming industry in our country,the environmental pollution becomes increasingly serious.Where swine wastewater is a major source of pollution,swine wastewater containing high concentrations of organic matter,suspended solids and ammonia.At present,the anaerobic-aerobic technology was mainly used for the treatment of swine wastewater.Although anaerobic treatment can degrade most of organic pollutants in wastewater,but the digested swine wastewater remain high concentrations of suspended solids,especially no ammonia is removed.The SBR technology was most widely used in further treatment of anaerobic digestion of swine wastewater.Usual,high concentration of suspended solid will increase the processing load and shock loads of microorganisms,resulting in poor effect of swine treatment.In this case,the flocculation technology which efficient removal of suspended solids gradually attracted people’s attention,the chemical flocculant have been widely used for their efficient and inexpensive,but they have increased the harm to human health and environmental risks.Compared with traditional chemical flocculants,microbial flocculants are safe,non-toxic,biodegradable,lack of secondary pollution.So,people pay more attention in studies on microbial flocculant in recent years.In this study,we aimed to screen flocclant producing strain which had a good flocculation activity through purification of the separation of swine wastewater and swine wastewater sludge microorgnism.Strain was identified using molecular biology methods,optimization of the culture condition to production flocculant,and optimization medium carbon and nitrogen sources to reduce the cost of flocclant.Prepared flocculant to study the effect of its flocculation piggery wastewater suspended solids by application test.1.Isolation,screening and identification of the flocclant producing strain.In order to obtain an flocculant producing bacteria which efficient flocculation swine wastewater,the strains of swine wastewater sludge of swine wastewater treatment in sedimentation tank were isolated by using diluted plate count and selective medium,swine wastewater was used to measure flocculating activity of fermented broth in screening.Furthermore,they were identified by morphological and molecular biology.Results showed six strains have good flocculation on swine wastewater were screened from sewage and sludge samples,strain of FD-14 had the best flocculating performance and its flocculation rate reached 80.1%.The sequences length of strain FD-14 was 1463 bp,FD-14 has closest relationship with Bacillus spp.,the homology with Bacillus amyloliquefaciens(KP059106.1)was 99%.Mega 4.0 software was used in strain of phylogenetic analysis,FD-14 was belonged to Bacillus amyloliquefaciens.2.Optimization of the culture condition of flocclant producing strains.In order to optimize strain FD-14 culture conditions,determination of growth curve,the experiment explored culture time,temperature,initial p H,rotating speed influence on the yield of flocclant through single factor and orthogonal test.The relationship between cell growth and flocculating activity of Strain FD-14 indicated that the strain fermentation dynamics belonged to type II,as fermentation time and product synthesis partially coupled.The ptimum culture conditions of strain FD-14 was 33℃,initial p H 6.5,rotating speed of 150 r/min,culture 42 h.Temperature,initial p H,rotating speed on FD-14 effects were significant(P<0.01).3.Optimization of carbon and nitrogen sources of flocclant producing strains.In order to reduce the cost of flocclant,the fermentation medium was optimized.The bran,corn powder and starch were selected as cheap carbon sources.The soybean meal,ammonium chloride and urea were used as cheap nitrogen sources.The results show that strain FD-14 use starch as an alternative to the fermentation medium cheap carbon,flocculation rate of 80.80 %,was not significantly different(P> 0.05)with the original standard medium;Substitution effect of cheap nitrogen source are poor,the best of ammonium chloride,flocculation rate was 67.38%,significantly lower than the original standard medium(P <0.05).4.Application of bioflocclant in production.For the study of bioflocculant application conditions,the experiment explored the adding amount of fermented broth and coagulant aid calcium chloride influence on the flocculation swine wastewater through single factor.And prepared fermented broth for three tons scale production test in swine wastewater treatment station,to study the effect of microbial flocculant application in production.Results show that flocculation rate can reach79.0%;Microbial flocculant treatment swine wastewater with high efficiency,and flocculant might be used for flocculation of swine wastewater.