COMBINED INFLUENCE OF TEMPERATURE AND PROCESS LOADING ON THE EFFLUENT CONCENTRATION OF BIOLOGICAL TREATMENT

摘要

The influence of temperature on biological wastewater treatment is generally quantified by an exponential model for maximum growth (μ_(max)) of bacteria or maximum conversion (v_(max)) for specific substrates. This "maximum" influence is also applied for reactor design, although recent experiences with nitrogen removal show little temperature effect on the effluent concentrations. The new parameter "process temperature influence" (dc_e/dT) on the effluent concentration is defined and quantified including the "kinetic temperature influence" plus process loading and reactor configuration. These interrelations are modelled and presented graphically. Also, dc_e/dT is expressed as "apparent temperature coefficient" θ_a for easy comparison with the kinetic coefficient. θ_a depends strongly on the degree of process loading and never reaches the magnitude of the kinetic coefficient. Especially at lower loadings this coefficient is almost equal to one proving very little temperature effect dc_e/dT. The derived model is verified by computer simulation. Hence, effluent concentrations of biological treatment are much less sensitive to temperature changes than quantified by the kinetic temperature coefficients θ. This significantly reduced temperature influence should be incorporated into the design of reactor volumes to ensure a realistic design (procedure) and reduce unnecessary investment cost. The presented model is a valuable tool in this respect.