Research On Development And Application Of Microbial Agent Based On Potato Starch Wastewater

Potato starch wastewater(PSW)are rich in nutrients,is a rare and water resources,using the plant grows,the preparation of microbial fermentation agent,is an effective approach to realize the recycling use,can reduce environmental pollution,reduce the pressure of wastewater treatment,and can realize resource recycling,is a major research trend in recent years.In this study,the effects of direct irrigation of potato starch wastewater(PSW)on soil environmental factors and microbial community structure of cultivated land were firstly explored,so as to provide a theoretical basis for the preparation of microbial agents.The experiment adopted the method of flood irrigation with heavy irrigation(IN)of 900 m3/hm2.Three treatments were light irrigation(IR)of 600 m3/hm2 and no irrigation(CK).Potato starch wastewater,wastewater sedimentation sludge and production well water were used as bacterial sources to screen functional microorganisms.Response surface optimization was used to carry out the COD degradation fermentation experiment of single strain,and on this basis,the complex bacterial community was constructed to ferment starch wastewater to make microbial agents,and its application research was carried out in the facility.Taking eggplant as the research object,the orthogonal experiment of four factors and three levels was adopted.Different fertilizer application amount,drip irrigation frequency,fertilization period and chemical fertilizer reduction were taken as factors,and three levels were set for each factor.The test results are as follows.1.PSW direct irrigation can increase soil organic matter(SOC),total nitrogen(TN),available phosphorus(AK),available potassium(AP),total salt(EC)content,and reduce soil bulk density(VW)and pH;irrigation improves The relative abundance of Proteobacteria,unidentified_Bacteria and Bacteroides in the soil,and at the same time increased at the genus level the genus Sulfomonas,Flavobacterium,Pseudomonas,Toxoplasma,and Acidotropa The relative abundance of genus Marseilles;Spearman correlation analysis shows that SOC,AK,AP,pH and EC are significantly positively correlated with a variety of bacterial genera(P<0.01);Redundancy analysis(RDA)shows that AK is the influence The key factor of microbial community structure,soil environmental factors significantly affect the relative abundance of Arcobacter.2.Using PSW as the source of bacteria,after enrichment,separation,purification,and re-screening,a COD-degrading strain PWF015 was obtained.Through morphological characteristics and 16S rDNA sequence analysis,the strain was Bacillus amyloliquefaciens(accession number:MT150951).On the basis of single factor optimization,response surface optimization was carried out to explore the best fermentation conditions for strains to degrade COD.The results showed that when the pH,temperature and dosage were 8.07,29.81℃ and 1.95%(volume fraction),the COD degradation rate reached The largest is 71.65%,which is 11.27%higher than before optimization.3.Using PSW,starch wastewater sedimentation sludge and well water used in production as bacterial sources,the functional strains that can degrade starch wastewater were screened from them.After isolation and screening,a total of 3 strains of bacteria,Lactobacillus paracasei,Pichia pastoris and Rubrivivax gelatinosus.The accession numbers are:MW750370,MW750418 and MW750413,respectively.Using the three isolated strains plus Bacillus amyloliquefaciens preserved in the laboratory,the degradation test of a single strain of starch wastewater by a single strain was carried out,and its degradation ability was obtained from strong to weak as follows:Bacillus amyloliquefaciens>Lactobacillus paracasei>Pakistan Pichia desseri>Rhodotorula colloidalis;on the basis of the single-strain degradation test,the strains are combined with the starch wastewater treatment test,and The results showed that the compound combination of 4 strains had the strongest ability to degrade PSW,so 4 strains were selected for inoculant fermentation.4.The results of orthogonal experiment of fertilizer efficiency showed that the order of the four experimental factors on eggplant growth was drip irrigation amount>fertilization period>organic fertilizer+chemical fertilizer reduction>drip irrigation frequency;and the optimal combination was A1B3C1D1,which is potato starch juice water bacterial fertilizer The total fertilization rate is 75m3/hm2,applied every 7 days,20%in the seedling stage,40%in the flowering and fruiting stage,40%in the fruiting stage,and 1200 kg/hm2 of bio-organic fertilizer as the base fertilizer+diammonium phosphate to reduce the amount by 30%,it has the best impact on the growth and development of eggplant and the rhizosphere soil environment;from the perspective of the microbial community structure,the soil microbial diversity is relatively reduced with the increase of fertilization,and the dominant bacteria phyla after fertilization include Proteobacteria and unknown Bacteria,Actinobacteria,Acidobacteriota.After comparison,PSW fermentation increased the soil bacteria(phyla level)22 phylums and soil microbial diversity and microbial populations compared with pre-fermentation.