The effect of
carbon sources and
shock loadings have been studied using two sets of sequential upflow anaerobic sludge blanket (UASB) and rotating
biological contactor (RBC) reactors viz., UASB-I followed by RBC-I and UASB-II followed by RBC-II for the removal of two different priority
pollutants, 2-CP and 2,4-DCP present in simulated
wastewaters.
Sodium formate,
sodium propionate,
glucose and
methanol were used separately as four different
carbon sources in the feed as co-substrate.
Methanol was found to be the best
carbon source for UASB reactors showing 95% 2-CP and 81.1% 2,4-DCP removals. The
carbon sources
formate and
propionate were not found suitable in UASB reactors as only 22.6-46.8% 2-CP and 41.9-42.8% 2,4-DCP removals were observed. With
glucose as
carbon source 93.7% 2-CP and 79.6% 2,4-DCP removals were observed in UASB reactors. For all the four
carbon sources more than 97.6% 2-CP and 99.7% 2,4-DCP removals were observed in sequential reactors. Although all the four
carbon sources could not serve as good
carbon source for UASB reactor alone but could be successfully used by the sequential reactors for the removal of
chlorophenols. The Performance of sequential reactors was also evaluated at five different chlorophenolic
shock loadings. During
shock loading study the concentration of
chlorophenols in the
wastewaters was increased to 45, 60, 75, 90 and 105 mg/l as compared to the normal feed containing 30 mg/l 2-CP or 2,4-DCP. During
shock loading study complete removal of 2-CP and more than 99.6% removal of 2,4-DCP was observed in sequential reactors. Sequential reactors successfully withstood all the
shock loadings and produced high quality effluents.