Study On The Process Of Biochemical Treatment Of Methionine Fermentation Wastewater And Process Design

The bio-pahmaceutical industry is one of the major complex industries and it generates amino acid fermentation wastewater that can affect the environment and human health adversely.The excessive first investment and high costs of daily operating is the main problem about that wastewater treatment.It affects the economic efficiency of companies.Based on the traditional anaerobic and aerobic biological treatment process,this study developed a combination of biological treatment process for the experimental wastewater,which has low treatment cost and can be used to treat the fermentation wastewater with extremely high concentration.The experiment is carried out to determine and optimize the treatment steps of the process parameters,and made a simple engineering design for the main equipment of this process.The results of single-stage anaerobic digestion and aerobic treatment showed that the maximum influent COD could be 15660 mg/L in the medium temperature anaerobic reactor(ASBR)with 8d of HRT and 10 g/L of sludge loading.The volume load was 1.96 kgCOD/(m3·d)and the maximum COD removal rate was 75.8%.In the subsequent aerobic study,the effect of the recycling effluent on the operation of the aerobic process was studied.The results showed that the concentration of influent ammonia nitrogen(compared with the influent COD and TP)was the main factor of the reflux ratio.It should not be higher than 150 mg/L.And then in the selected reflow ratio is not higher than 3.0 operating conditions,the effluent meets the standard of GB 21903-2008.In order to further improve the capacity and efficiency,the process has been improved.Using two-stage anaerobic process to improve COD removal,followed by short-cut nitrification and denitrification process to remove ammonia nitrogen,and finally with conventional aerobic process to remove residual pollutants.The results showed that the two-stage anaerobic digestion(ASBR + UASB)could shorten the HRT to 5d(2d + 3d).The influent COD was 20880 mg/L while reached 93.8%of COD removal and 4.37 kgCOD/(m3·d)of the volume load.Compared with the single-stage anaerobic digestion,the capacity of two-stage anaerobic treatment has a significant increase.The short-cut nitrification and denitrification process reached more than 90%of ammonia nitrogen removal in the condition of influent ammonia nitrogen 600 mg/L,25?30?,DO 0.6?1.0 mg/L,HRT 8h.Next,during aerobic treatment,glucose or methanol can be used as an additional carbon source with HRT of 6.5h and 8.5h,respectively.The addition amount is in accordance with COD/TN = 10.The effluent could meet the standard of GB 8978-1996,level I.