The Study Of Flocculation Mechanism Of Glycoprotein Flocculant And Domestic Sewage Flocculant

Compared with traditional chemical flocculants,microbial flocculants have advantages that is green-produced,non-toxic and can be safely used for water and wastewater treatment.However,the environmental applications of microbial flocculants are relatively limited as its low flocculation efficiency and high production cost.At present,it is still mainly at the laboratory research stage.Therefore,trying to improve flocculation efficiency and reduce the production cost have become the main research objectives.The main research content of this study is the flocculation performance of microbial flocculant and its flocculation mechanism.The study focuses on the different between the structure,properties and flocculating performance of the flocculant of the MBF-NIII2 glycoprotein flocculant and that of porcine eye-derived glycoprotein flocculant,in order to obtain acid glycoprotein that is an ideal domestic sewage treatment flocculant.Strains were screened by sewage and animal tissues as microbial sources and get the high flocculating activity one.Their fermentation process parameters were measured and figure out the flocculant properties of the produced glycoprotein flocculants.The main conclusions are as follows:（1）As the structure determines the nature,flocculation is an important characteristic of glycoproteins and it is of great significance to study the primary structure of the flocculation mechanism.Therefore,the structure of two glycoprotein flocculants was studied.The DNS method was used to eliminate errors caused by the turbidity of the agent itself in the experiment and studied the total sugar content of the two flocculants.The Folin-phenol method was used to determine the protein content.The molecular weight of the flocculant was determined using the viscosity method.The terminal amino acid species were determined by the terminal group method and its primary structure was calculated.（2）The effects of different flocculation systems on flocculation were studied.It shows that the flocculation rate reaches the highest when the dosage of MBF-NIII2 and porcine eye-derived glycoprotein flocculant is 0.4 mL and the flocculation rate is 70.18%and 77.60%,respectively.The cation of alkaline metal ions(Ca²⁺)will improve flocculants activity;which increases from 85.60%to 87.90%.MBF-NIII2 flocculant and porcine eye-derived glycoprotein flocculant are both present a certain degree of thermal stability.The flocculation rate of MBF-NIII2 flocculant is 85.3%under neutral conditions,while the flocculation rate of pig’s eye-derived glycoprotein flocculant is91.2%under acidic conditions.In summary,the flocculation efficiency of acid glycoprotein is higher than that of neutral glycoprotein.（3）The flocculation mechanism of glycoproteins was studied from the viewpoint of destroying the double layer and hydrated layer of glycoprotein colloids.By changing the pH conditions,different concentrations of neutral salt solution and water-soluble ethanol in the flocculation system,thereby affecting the stability of the colloid,de-stabilizing the colloidal particles,flocculating agent molecules and contaminating particles to coagulate to achieve the flocculation effect.Then the protease adds into the flocculation system,it will break the peptide chain in the glycoprotein,so the flocculation rate decreased.It draws a conclusion that the protein played a important role in the flocculation process.The longer the glycoprotein flocculant peptide chain and the greater the molecular weight are beneficial to flocculation.（4）In order to obtain more efficient flocculation of acidic glycoproteins,the sewage from the 4th sewage treatment factory of Xi’an City and chicken stomach were used as microbial sources to separate and screen them.Finally,the strain C3 has the highest flocculating ability of 86.3%flocculation rate of and the composition and properties were studied.（5）The glycoprotein produced by the selected C3 strain was extracted by ethanol extraction.The product was characterized and its primary structure was studied.The flocculation performance of the MBF-C3 glycoprotein flocculant was measured with the wastewater from the 4th sewage treatment factory of Xi’an City.It is concluded that the flocculation efficiency in different systems is higher than that of MBF-NIII2 neutral glycoprotein flocculant,which has a good flocculation effect on domestic sewage.