Model-based design of a pilot circulating bed membrane bioreactor for sewage treatment
Population growth in developing countries leads to overloading existing sewage treatment plants. Additionally, suburban residential complexes are sometimes constructed and inhabited before their sewage treatment facilities are ready for various reasons. Therefore, there is a need for locally developed package units which should be robust, modular, and require minimum maintenance. The following article describes the conceptual design of a hybrid bioreactor of such a unit intended to treat 120 m3 of sewage per day. The design makes use of published literature in this regard over the last three decades. The proposed bioreactor consists of an upstream circulating bed compartment (CBC) with plastic biofilm carriers and a downstream microfiltration membrane compartment (MMC). Each of these two compartments has a nominal effective volume of 29 m3. The CBC is mainly anoxic whilst the MMC is aerobic (oxic) making the reactor an A/O arrangement. Following implementation, an initial experimental phase is envisaged to tune the reactor with respect to functionality and maximization of nitrogen removal. Details of this tuning phase are also given in the article.