Full-Scale Study Of Anaerobic/Facultative Process For Treatment Of Monosodium Glutamate Wastewater

The sewage discharge was not up to the country standard because of somedesign flaws and the complex quality in the Chrysanthemum MonosodiumGlutamate Corporation, Harbin. Based on the comprehensive investigation on thesimilar wastewater treatment processes and the on-site condition, the originalprocess was improved all-around. After commissioning and operation of 153days, the effluent concentration of COD, TN, TOC and NH₄⁺-N maintained in50mg/L, 15mg/L, 6mg/L and 8mg/L and the removal efficiency were above99.5%, 98.8%, 99.9% and 99%, respectively. All indexs could meet and excel theFirst Grade Standard of"Integrated wastewater discharge standard"(GB 8978-1996).This study investigated regularity of the two-phase anaerobic system and thefacultative tank which were the key improvement. The mechanism and theinfluence factors of the transformation and migration of nitrogen were alsostudied.There was better linear relationship between the organic loading rate and theCOD removal rate. The cell activity in the two-phase anaerobic system was0.7003gCOD/(gVSS·d). The results showed that 2.1566 g/LCaCO3 alkalinity wasgenerated during release of 1.0g/LNH₄⁺-N.Protein and aminoacid, as the main nitrogen source of monosodium glutamatewastewater, were in the form of organic nitrogen. The NH₄⁺-N/TN ratio changedfrom 0.5 in the hydrolysis-acidification tank to 0.8 in UASB reactor, whichindicated that ammonium had already become the leading form in the UASBreactor. In the late period of the full-load operation, the TN and NH₄⁺-Nconcentration declined by 1000mg/L without great variation of concentration ofnitrate and nitrite. There were two possible reasons, one was denitrification andanother was the effect ofAnaerobicAmmonia Oxidation.Theâ–³COD/â–³TN ratio obtained from the sections of 3.0-5.0m and 5.0-10.0mwere 22.2:1 and 12.0:1, respectively, which indicated that nitrogen loss farexceeded the maximum theoretical value of 50:1. The mean sludge concentration of these sections was 8943.3mg/L and 2698.7mg/L, especially in the section of5.0-10.0m where the mean sludge concentration was 2698.7mg/L whereas thereduction of TN concentration was 244.5mg/L that was almost 45% of the totalreduction in the UASB reactor. However, it couldn't be explained by cellsynthesis and should be explored further.