Experimental Study On The Treating Of Fermentation Mother Liquid Of Monosodium L-glutamate

The most refractory wastewater in monosodium L-glutamate industry is fermentation mother liquid which contains high concentration of organic acid, the COD concentration can reach to the range 100,000~200,000mg/L; chloride ion, or sulfate ion concentration is generally up to 100,000mg/L. Treat of fermentation mother liquid is a hard and emergency study of monosodium L-glutamate industry.Focusing on the high COD and high chloride ion concentration status of fermentation mother liquid, this study, of which in order to develop a reasonable and economic process route, had carry out in two aspects: iron-carbon micro electrolysis pre-treatment and anaerobic bio-treatment.Fermentation mother liquid contains sufficient electrolyte and its acidity also suitable for micro electrolysis reaction, so that this wastewater can flow into the micro electrolysis reactor directly without go through any adjustment. The reactor reacted on sequencing batch. After the micro electrolysis reaction, powder Ca(OH)2 was put into the wastewater, Fe(OH)2 and Fe(OH)3 were generated then come into flocculation reaction. Three signal factor experiments were carry out to determine the suitable Fe-carbon mixture dosage, the necessity of aeration, and the proper reaction time separately. Then a orthogonal experiment used L9(34) orthogonal table was carried out to determine the optimum condition of micro electrolysis reaction. The result indicated that aeration could increase the redox potential of micro electrolysis reaction while flocculation effect can also be improved through aeration process; Eorthogonal experiment determined optimum factor company is: beginning pH=2.0, ending pH=10.0, mFe: mC=0.5:1, reaction time=3h, considering the practical condition, ending pH can be regulate to 9.0 while engineering apply. The COD removal rate can up to 53% under optimum conditions.Study of anaerobic treatment of fermentation mother liquid of monosodium L-glutamate wastewater which come through the micro electrolysis pretreatment was carry out by using a reactor of laboratory scale UASB reactor. After 18days acclimation, the start up of reactor was mainly completed. It is concluded that there was no evident inhibition performance when the Cl- concentration was under 4,500mg/L, microorganism do not need a long time to fit the high Cl- environment on this level. After the start up experiment, let the influent COD maintained at a steady level, then the influent Cl- was raised gradually. When the Cl- concentration rose to 5,000mg/L, inhibition performance was observed. COD removal rate had decreased when Cl- concentration higher than 5,000mg/L. A test about oganic loading impact under high Cl- concentration was carried out, the results indicated that the anaerobic microbe was very susceptible to impact load and the change of VLR, so it can be concluded that in anaerobic bio-treatment of Fermentation mother liquid, the VLR should not be higher than 4kgCOD/ (m3·d).