Abstract
In the presence of sufficient dissolved oxygen, sediment oxygen demand (SODtT) results from various chemical and biochemical reactions. The first objective to clarify the mechanism of SODtT is to differentiate biochemical (SODto) from chemical sediment oxygen demand (SODtc).
The scope of this paper is to estimate the effectiveness of SODto inhibition by toxicants (i.e. mercuric chloride, formaldehyde and phenol) from the view point of the kinetic studies.
At lower concentration of organic matter in the BOD bottle, these toxicants show the best inhibiting effect for holding oxygen demand at a nearly constant level after 1 day of incubation, but these toxicants lost their potency with increasing of organic matter concentration.
The mercuric chloride- and formaldehyde- treated sample did not appear to affect the rate-constants of bacterial growth (ki=1.6 day-1) and endogenous respiration phase (ke=0.10 day-1), but it did appear to suppress the amount of the ultimate oxygen demand of both the phases.
The ki and ke values determined from the phenol-treated sample are 0.20 day-1 and 0.10 day-1, respectively. And this inhibitor introduced the delay of bacterial growth reaction. Information on ultimate oxygen demand is similar to the result found in mercuric chloride- and formaldehyde- treated SODtT.
