River water quality model no. 1 (RWQM1): II. Biochemical process equations

In this paper, biochemical process equations are presented as a basis for w ater quality modelling in rivers under aerobic and anoxic conditions. These equations are not new, but they summarise parts of the development over th e past 75 years. The primary goals of the presentation are to stimulate com munication among modellers and field-oriented researchers of river water qu ality and of wastewater treatment, to facilitate practical application of r iver water quality modelling, and to encourage the use of elemental mass ba lances for the derivation of stoichiometric coefficients of biochemical tra nsformation processes. This paper is part of a series of three papers. In t he first paper, the general modelling approach is described; in the present paper, the biochemical process equations of a complex model are presented; and in the third paper, recommendations are given for the selection of a r easonable submodel for a specific application.