Abstract
Propylene glycol methyl ether was removed from wastewater in a trickling bed bioreactor under different liquid distribution conditions. A 0.3 m diameter column filled with two heights of 0.7 m and 1.4 m with 2 cm plastic spheres were used. The wastewater flow rate varied from 0.184 to .0918 kg/m₂.s. The effect of the initial liquid distribution was examined using two types of liquid distributors: a multipoint liquid distributor and a central single point liquid distributor. Over 96 hours of treatment period, the BOD₅ was reduced by 85% and 65% under the most uniform liquid distribution condition and the poor liquid distribution condition, respectively, achieved in this study. Increasing the liquid flow rate from 0.184 to 0.198 kg/m₂.s, it increased the dynamic liquid holdup by 53% and the apparent BOD₅ removal rate constant by 23% at 1.4 m bed height using the multipoint liquid distributor. Moreover, with the use of the multipoint liquid distributor, the apparent reaction when the liquid flow rate was increased from 0.184kg/m₂.s to 0.918 kg/m₂.s. In addition, it was found that the effect of an increase in the bed height on the percentage BOD₅ removal was not significant when initial liquid distribution was uniform. Under the uniform initial condition, only 4% increase in the percentage BOD₅ removal was observed when the bed height increased from 0.7 to 1.4 m whereas when the initial distribution was extremely non-uniform, the percentage of BOD₅ removal was increased by 20% with increasing bed height. The local distribution of the BOD₅ removal was not uniform across the bed cross-section and it was affected by the liquid flow distribution across the bed cross-section.
Highlights
MC propylene glycol methyl ether (PGME) ppm Biological Oxygen demand Chemical oxygen demand Liquid hourly space velocity, volume of liquid fed to reactor per hour per volume o f reactor Maldistribution Coefficient Propylene glycol methyl ether Part per million
Liquid distribution was m easured for single point liquid distributor at the range o f liquid flow rates varied from 0.184 kg/m^.s to 0.918 kg/m^.s.The liquid distribution profile o f single point liquid distributor at different liquid flow rate can be found in A ppendix A (Figure A .l)
The results showed that the percentage BOD5 removal for 1.4m bed height was greater than that of the 0.7 m bed at any liquid flow rate (Figure 4.30)
Summary
Treatment tipne was 72 hours and the initial concentration o f the PGM E was SOOppm. ..82. Kg/m^.s.Treatment time was 72 hours and the initial concentration of the PGME was Figure 4.28: Comparison of the performance o f the single delivery point distributor and ^. Figure 4.31; Effect of liquid distribution on the local BOD; removal for the single delivery point distributor with the liquid flow rate was 0.184 kg/m^.s and the initial. Figure A?l: Effect of liqilicf flow rate on liquid distribution profile at the 1.4 m bed height — Figure A.IZ: B iodc grad at'ibn 'of PGME in the trickling filter with the initial concentration:. :. Figure ' : Effect o f ihitWl 'dbhce'nfratioh o f the PGME on the percentage COD removal after hours offreadmeh'f'àt 'llqüid flow rate of 0.551 kg/m^.s with e m ultipoint delivery. MC PGME ppm Biological Oxygen demand Chemical oxygen demand Liquid hourly space velocity, volume of liquid fed to reactor per hour per volume o f reactor Maldistribution Coefficient Propylene glycol methyl ether Part per million
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