Study On Production Of Single Cell Protein Using The Glutamic Acid Ion-exchanged Wastewater

Glutamic acid wastewater comes into being in the process of producing glutamic acid. It is a kind of high concentrated organic wastewater featured by high CODcr,high NH₃-N,high BOD,highSO₄^2- and low pH. It is mainly composed of fermented waste mother liquor, ionic exchange tail liquid and waste liquor which came from washing and regenerating ion exchange resin.This dissertation took glutamic acid ion-exchanged wastewater as initial sample liquid. It mainly analyzed its wastewater ingredient and predicted percentage of wastewater. The CODcr, density, solid content, total ash, water-insoluble ash, acid-insoluble ash content of glutamic acid ion-exchanged wastewater were respectively 50250mg/L, 1.0744g/mL, 0.1376g/mL, 0.0027g/mL, 0.0008g/mL, 0.0003g/mL. Its residual sugar was mainly reducing sugar and its content was 0.0041g/mL. Besides, the contents of residual glutamic acid, ammonium sulphate, residual bacterial protein and fat were respectively 0.3g/100mL, 0.1009g/mL, 0.0057g/mL, 0.0043g/mL.Choosing chitosan and xanthan, through single factor and orthogonal experiments, the author can identified the best action condition of chitosan: the dosage of chitosan was 4g/L, pH was 8, temperature was 20℃, in this condition, we agitate it for 5 minutes, eventually the thalli residue was 0. The best action condition of xanthan was: the dosage of xanthan was 2g/L, pH was 3, temperature was 30℃, the time of agitating was 5 minutes. Xanthan could remove other ingredients owing to its thickening power as dealing with bacterial protein. Therefore, we chose chitosan as flocculating agent in subsequent processing and determined that the density, solid content of processed glutamic acid wastewater were 1.0594g/mL, 10.95%, and the content of ammonium sulphate, residual glutamic acid, fat, reducing sugar, total ash were respectively 8.86%, 0.41%, 0.36%, 0.26%.With 100mL flocculated sample liquid, we did single factor experiment of pH, adjusted pH to 3, 3.5, 4, 4.5, 5, 5.5, 6, and 80mL water was gotten through vacuum concentration, and the quality of ammonium sulphate through crystallization was determined. It was easiest to crystallize when pH of wastewater was 4.3. the author determined that the ingredients of processed sample were: density 1.0895g/mL, solid content 47.71%, the residual glutanic acid content 4.48%, the ash 0.91%, residual reducing sugar 2.07%, crude fat content 2.28%, ammonium sulfate content 35.28%. And the residual glutanic acid content was still high. The analysis holds that when glutanic acid isoelectric point was 3.22 and pH was 4.3, if we carried on concentration crystallization, we could have few extracts.This experiment selected Candida tropicalis, saccharomyces cerevisiae, baker's yeast, carried on primary screening in NO.1 medium, selected big single colony to carry on bevel preservation, obtained three strains each 10 separately and numbered them separately. This experiments also selected No.1-1 Candida tropicalis, No.1-11 saccharomyces cerevisiae, No.1-21 baker's yeast, determined its growth curve separately in NO. 1 medium with weight method, and then determined that the generation intervals of the three strains were respectively 4.58h, 2.13h, 2h. Under the same circumstance, the dry weight of three strains which were cultivated for 18h were determined by centrifugal. This experiment also determined residual sugar and residual ammonium sulphate content in supernatant fluid, compares and selects heavy, less residual sugar and residual ammonium sulphate thallies, and eventually determined strain aiming at Candida tropicalis.We carried on strain secondary screening for 10 Candida tropicalis, selected the relatively big single colony, and eventually got 10 strains. We cultivated the 10 strains on even ground, and selected the heaviest dry weight --- No.1-1-2 Candida tropicalis with a dry weight of 0.49g/100mL as objective strain in subsequent experiment.Taking NO.1 medium as starting medium, ammonium sulfate, glucose, corn pulp additional amount as experimental factors, did single factor experiment, and obtained the best additional amounts which were respectively ammonium sulfate 0.15%, glucose 1%, corn pulp 0.6%.