| The effluent of the hybrid anaerobic expanded granular sludge bed (EGSB)-aerobic membrane bioreactor (MBR) system for food yeast fermentation wastewater treatment requires advanced treatment, due to its still high COD, TOC, UV254, chromaticity and poor biodegradability. Taking food yeast fermentation wastewater after EGSB-MBR (E-MA/O effluent) as the research object, this article investigated the advanced treatment efficiency of COD, TOC, UV254, and chromaticity and the main influencing factors during AC catalytic ozonation process treating food yeast fermentation wastewater. Furthermore, the degradation of organics before and after the AC/O3 process was analyzed through the ultraviolet-visible wavelength scanning, FT-IR, the three dimensional fluorescence spectrum (3DEEM) and GC-MS method. A field pilot-scale experiment was carried out on the basis of the lab studies to explore the real treatment efficiency of the combined process of EGSB-anaerobic/aerobic MBBR-O3 oxidation-aerobic MBBR.The results showed that the adsorption efficiencies of COD, TOC, UV254 and chromaticity were relatively low in the AC adsorption process with only 10.6%,8.9%,14.0% and 12.0%. Moreover, AC catalytic ozonation process had an obvious higher organic removal efficiency than ozonation-alone process, especially in the early stage of the reaction (0-10 min). After a 10 min reaction, the removal efficiencies of COD, TOC, UV254 and chromaticity in AC catalytic ozonation increased 16.4%,8.5%, 9.4% and 10.6% than those in single ozonation process. After a 30 min reaction, the removal efficiencies of COD, TOC, UV254 and chromaticity in AC catalytic ozonation reached 57.0%,31.2%, 83.5% and 95.0%, respectively, and the value of BOD5/COD increased from 0.113 to 0.389, which indicated the biodegradability of the wastewater was improved obviously. Moreover, the experiment results showed that the optimal ozone dosage was 10.14 mg/L, the best pH value was 7 in the reaction system, and optimal AC dosing quantity was 1.0 g/L. And the catalytic performance of sludge-based activated carbon (SAC) was also investigated and there was no significant difference between SAC and commercial AC. In addition, the reactions of AC catalytic ozonation, in (0-2), (2-10) and (10-30) min period followed the first order kinetics reaction, and the reaction rate decreased gradually. The spectrum analysis and GC-MS analysis showed that AC catalytic ozonation had high removal efficiency for the aromatic compounds, organics with conjugated double bond and chromaticity in the wastewater. In addition, AC catalytic ozonation played a preferable role in the degradation, transformation and removal of aromatic compounds such as acids, alcohols, aldehydes and other organics. Meanwhile, the AC/O3 process could translate large molecules including alkane, halogenated hydrocarbons, alcohols, esters and ketones into small molecule organics, such as alkanes and esters.The start-up and continuous running test of the complete set of field pilot-scale instrument were carried out based on the lab experiment. The start-up of the field pilot-scale instrument lasted about 20 days or so, and preliminary test results showed that the removal of COD in the process of EGSB, anoxic/aerobic MBBR system and 03/aerobic MBBR advanced processing system was rising gradually, maintaining at about 60%,28% and 38% respectively, and the total removal efficiency of COD reached around 80%. In the stage of improving inlet load (20-47 d), organic load increased from 0.75 kgCOD/(m3·d) to 1.25 kgCOD/(m3·d), with the improvement of COD removal to 90% consequently. |
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