Kinetic study of organic matter removal in an integrated anaerobic reactor high rate algal pond system
The objective of this study was to build an empirical model for the design of wastewater plants by using an integrated system comprising an anaerobic reactor and a high rate algal pond. This model is based on the kinetics of elimination of organic matter in the reactors, and, in contrast to the Oswald approach based on the algal energy balance, this model was constructed according to an engineering concept taking into consideration the design parameters of the reactors (flow, charges, etc.). This new approach is characterized by the introduction of a parameter that is indicative of symbiosis between algae and bacteria. In fact, the model is based on the growth of algae-bacteria biomass as a major aspect of depollution in the high efficiency algal channel. The limits of validity of this model have been verified on experimental data collected at the Rabat pilot station located in the Agronomic and Veterinary Hassan II Institute, and from the wastewater treatment plant of the city of Ouarzazate. This work reflects the importance of biological parameters in the conception of an algal bioreactor. The factor γ, which is the algae/bacteria ratio, was evaluated by Oron and collaborators to be around 1/100, a result confirmed using experimental data from the Rabat pilot station. This design approach was verified for a retention time of 1.5 to 2 days in the anaerobic reactor and raw organic loads entering the system around 600 mg•L-1. One can consider that the combination of a retention time of two days in the anaerobic reactor and four days in the High Rate Algal Pond could be a good basis for the design for such systems in Morocco.