Abstract
The effects of biogenic substrate (peptone) concentration on reactor performance, yield coefficient (Y) and degradation kinetics were evaluated in an instantaneously fed sequencing batch reactor (SBR) receiving a mixture of 4โchlorophenol (4โCP) and 2,4โdichlorophenol (2,4โDCP). High chemical oxygen demand (COD) removal efficiencies (90โ95%) and complete removal of chlorophenols were observed even in the absence of peptone (i.e. chlorophenols served as sole carbon and energy sources). During the degradation of 4โCP, 5โchloroโ2โhydroxymuconic semialdehyde (CHMS, the meta cleavage product of 4โchlorocatechol) accumulated but was subsequently completely removed. 2,4โDCP competitively inhibited 4โCP degradation, as 4โCP degradation only commenced after complete removal of 2,4โDCP. It was concluded that decreasing peptone concentration did not affect chlorophenol degradation profiles in the reactor. The chlorophenol degradation kinetic studies suggest that competent biomass alone was responsible for chlorophenol degradation. Consequently, it was thought that competent biomass concentration was constant even though peptone concentration in the feed was varied, as competent biomass grows on chlorophenols only. Models developed using this assumption agreed well with experimental data, which also confirmed that a biogenic substrate has no impact on chlorophenol degradation profiles in an SBR with instantaneous feed. Copyright ยฉ 2006 Society of Chemical Industry