Explaining widely varying biofilm-process performance with normalized loading curves

The goal of the research was to evaluate whether the method of normalized loading curves could explain the performance differences among three steady- state biofilm processes that had nearly identical loadings and process configurations. Three methanogenic fluidized-bed biofilm reactors were challenged with a range of surface loadings of three distinctly different organic substrates: acetate, phenol, and glucose. Normalized loading curves were generated from the four fundamental parameters (S(min), S(min)*, K*, J(R)) and compared to the experimental performance. The curves and the fundamental parameters explained why effluent concentrations of acetate and phenol were sensitive to loading, while the glucose concentration was insensitive; why effluent concentrations were much lower for phenol than for glucose at similar surface loads; and why acetate required a much higher surface loading to give similar performance trends.