Study On Monosodium Glutamate Wastewater Treatment With SHARON-ANAMMOX Process

Monosodium glutamate wastewater is one of high ammonia-containing industrial wastewaters which are difficult to be treated by biologic processes. The wastewater has been mostly treated by traditional biological processes, and the treatment cost is very high. SHARON-ANAMMOX (Single reactor for High activity Ammonia Removal over Nitrite- Anaerobic Ammonium Oxidation) process is a novel biological process for nitrogen removal that has been developped in recent years. Compared with traditional biological processes for nitrogen removal, SHARON-ANAMMOX process does not require additional organic electron donor, needs less energy supply for aeration, consumes less neutralized chemicals. The feasibility and performance to treat monosodium glutamate wastewater with SHARON-ANAMMOX process is investigated and the results are summarized as follows.1) The monosodium glutamate wastewater is acidic, which is not suitable to be nitrifed directly. Therefore, some chemicals need to be added to neutralize the wastewater. Among the four tested neutralization chemicals, lime and sodium hydroxide are better to adjust pH than sodium carbonate or sodium bicarbonate. Because of alkalinity consumption in nitrification process, it must be balanced in time. If lime or sodium hydroxide serves as the alkalinity-supplied chemical, it is required in a relatively small amount. However, pH value will be beyond the range for nitrobacteria to grow and metabolize if it is added once for all. So it should be added by several times or in several sections. If sodium carbonate or sodium bicarbonate serves as the alkalinity-supplied chemical, pH value is within the range for nitrobacteria to grow and metabolize. Therefore it can be added once for all. Taking alkalinity, pH and cost into account, sodium carbonate can be regarded as the most suitable chemical. As long as the effluent alkalinity is kept about 50 mg/L, pH value will stay between 7.5 and 8.0, which satisfies the growth and metabolism of nitrobacteria. The effluent NH₄^--N contributes to effluent alkalinity indirectly, not directly.2) Volumetric total nitrogen removal potential in the SHARON reactor was about 1196 mg/(L?d) via increasing substrate concentration. When influent ammonium concentration came to 800 mg/L, the nitrite accumulation rate was increased up to 94.7%. Volumetric total nitrogen removal potential of the SHARON reactor was up to 1825 mg/(L? d) via shortening HRT. Under combined control of pH, DO, temperature, substrate concentration and load, the performance of short-cut nitrification is good and stable. The nitrite accumulation rate is about 87.0±6.5%. NO2"-N/NH4+-N in effluent is 1.33±0.20, fit to ANAMMOX process. Nitrogen loss by denitrification is found to be one of the important factors leading to nitrogen loss.3) With anaerobically-digested sludge as the seeding sludge, two kinds of ANAMMOX reactors, sequence batch reactor (SBR) and biofilm reactor, were started up. The comparison of their performance showed that volumetric total nitrogen removal potential in SBR was near to that in the biofilm reactor (about 2000 mg/(L?d)), which was far higher than that in the traditional nitrification and denitrification process. The biomass accumulation in SBR was higher than that in the biofilm reactor. However, SBR tolerated smaller shocking in substrate concentration and hydraulic loading rate than the biofilm reactor.4) Volumetric total nitrogen removal potential in the ANAMMOX reactor was up to 457 mg/(L?d), which was higher than that in the traditional nitrification and denitrification process when used to treat monosodium glutamate wastewater. The sludge activity in the reactor was about 0.30 mg N/(mg VSS?d), which is higher than that in the literatures [0.18±0.02 mg N/(mg VSS-d)]. It is difficult to recover by itself when the reactor was inhibited by nitrite. Reducing the substrate concentration to the critical value can relieve inhibition. The nitrite concentration tolerated by ANAMMOX is 96.5-129 mg/L. The effect of NO2"-NinflUent/NH4+-NinflUent on ANAMMOX reactor performance is obvious. With increase of NO2^-NjnflUent/NH4+-Ninfiuent, the nitrite in effluent mounted up. The effluent NO2"-N/NH4+-N in short-cut nitrification should be controlled between 1.0 and 1.4, namely ammonium conversion rate in short-cut nitrification should be from 50% to58%.