Anaerobic Digestion of CHLOrphenolic Wastes


1 School of Civil Engineering (MCE-NUST), Risalpur Cantt, Pakistan

2 Department of Civil and Environmental Engineering, UET Taxila, Pakistan


Feasibility of methanolic wastes treatment containing chlorophenol in experimental UASB reactors i.e. R-I and R-II working side by side constantly for a couple of almost 32 weeks were studied. UASB reactor R-I was initiated by utilizing the digested sludge alone, whereas, the UASB reactor R-II was startedup by adding an activated carbon of an effective size 1.5-2.5mm to the digested sludge with the volume-volume ratio of 3:2. At low loading rates d” 0.5g-TOC/L-d for R-I and d” 2.6g-TOC/L-d for R-II, it was observed that the effect of HRT on the TOC reduction was not prominent, and in both the reactors the TOC reduction effectiveness was noticed to be above 80%. An optimum OLR to accomplish 80-85% TOC and chlorophenol reduction effectiveness (at HRT e” 12hours) was observed to be 2.6g-TOC/L-day and 10.8g-TOC/L-day for reactor R-I and R-II, respectively. It was also observed that to attain more than 80% TOC removal efficiency at a constant OLR of 6.5g-TOC/L-day and at a HRT of 18-20hours, the maximum influent chlorophenol concentration should stay below 21mg/L and 29mg/L for reactor R-I and R-II, respectively. The average VFAs effluent concentration observed was 357mg/L and 230mg/L for the reactor R-I and R-II, respectively. Comparatively the production of biogas in reactor R-II was less. The overall gas conversation rate observed at greater than 80% TOC removal efficiency for R-I and R-II was found to be 0.28L/g-CODremoved and 0.17L/g-CODremoved, respectively, with 60-62% of methane content for both the reactors. The results of this study suggested that the use of methanol as a medium to biodegrade chlorophenol in the presence of an activated carbon in a UASB reactor is an effective and feasible method at mesophilic temperature and neutral pH.