Pilot Studies On Fermentation Wastewater Treatment By EGSB-A/OMBBR-O₃-OMBBR Process

Fermentation wastewater belongs to high concentration organic wastewater,which is difficult to be treated by conventional biochemical treatment.In this work,a pilot-scale expanded granular sludge bed(EGSB)-anoxic/aerobic moving bed biofilm reactor(A/OMBBR)-ozone oxidation(O3)-aerobicMBBR(OMBBR)combination process was applied to treat yeast fermentation wastewater,and the practical pollutants removal efficiencies as well as the optimal operation parameters of this process were investigated.The yeast wastewater was firstly treated by EGSB,and the experimental results showed that EGSB had a good performance in removing COD from wastewater.When the influent organic volume load were 2.15 kgCOD/(m3 d),1.76 kgCOD/(m3 d)and 0.95 kgCOD/(m3 d),all the COD removal efficiencies could reach over 70%,the highest removal rate arrived at 82.7%with a influent load of 0.95 kgCOD/(m3 d),and the removal rate is not affected by the water quality variation.The total nitrogen concentration of EGSB effluent increased slightly and the nitrate concentration decreased obviously.A/OMBBR-O3-OMBBR combination process could remove 27%of total nitrogen and 98%of ammonia nitrogen in the influent,the growth rate of nitrate nitrogen was 772%,and the removal rate of COD was about 93%.COD was degraded at different degrees in all three MBBRs,although it could not be significantly reduced by ozone oxidation unit,the biodegradability of wastewater was improved after ozone oxidation unit,resulting that the COD removal rate in the second aerobic MBBR was higher than that of the first one which were 21%and 12%,respectively.The removal of total nitrogen was mainly achieved in the anoxic MBBR reactor,and the growth rates of nitrate nitrogen in the two aerobic MBBRs were 310%and 11 1%,respectively.The microbial community structure of the processing unit was analyzed by using high throughput sequencing technology.The results showed that during the stable operation period of the reactor,microbial diversity is improved compared to that in the inoculated sludge,and the microbial diversity in anaerobic system is higher than that in aerobic system.In EGSB,Proteobacteria,Firmicutes and Bacteroidetes occupied the dominant position working as the main functional flora,and were responsible for most of the degradation of COD.In anoxic MBBR,Proteobacteria was the main functional bacteria,which was responsible for the removal of total nitrogen and part of COD.In aerobic MBBR,Betaproteobacteria and Gammaproteobacteria occupied the dominant position and were responsible for the removal of organics.The cost analysis showed that the treatment cost of the combined process was 1.20 yuan/ton if only electricity and pharmacy cost were considered,which was lower than most existing data and was worthy of promotion.