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Technical Description Nitrogen removal in the Bio-Pure process is considerably greater than that offlowthrough and single- tank, sequencing-batch reactor systems. The Bio-Pure system achieves an average of 96% total nitrogen removal. This high nitrogen removal is achieved through simple modifications of the timing (batching) cycle in the controlling microprocessor. '— AERATION DETENTION The Bio-Pure system's superior low-sludge-producing performance is obtained,in part,by combining the complete-mix hydraulic design with the detention times of the extended-aeration designs. This combination effectively produces a low RM ratio and a subsequent high MCRT. This promotes the development of specific, high-process microorganisms. The growth curve of the cell life cycle is related to the effectiveness of BODS removal within the treatment process. In all cases, removal of BODS is dependent upon aerator detention time. Growth and predominance of microorganisms are controlled by a variety of circumstances,including type offood matter,metabolic rate,and microorganism size.Because a definite type of microorganism lives best under certain conditions, it is possible to relate treatment efficiency to microorganism type. This is a determining factor for good batch process detention design. As the BOD remaining in the batch decreases, ciliated protozoa increase in number. A general guide as to relative predominance of protozoa and efficiency in the process may be characterized in the following chronological order: TYPE PROCESS EFFICIENCY 1. Sarsodina Plant startup or recovery 2. Holophytic flagellates High organic overloading 3. Holozoic flagellates Decreasing organic overloading 4. Ciliates Lowering efficiency 5. Stalked ciliates Elevating efficiency 6. Rotifers High BOD efficiency, rapid oxidation High rotifer concentration will occur when the BODS removal efficiency is high;therefore,additional detention capacity is required. The aerator size required to achieve this efficiency is based upon F:M ratio criteria between 0.1 and 0.5 pound BOD/pound MLVSS. A second method of determining retention time is a microscopic examination of the stalked ciliates. Groupings of 3 to 4 stalks indicate a healthy sludge;less or more groupings indicate either too young or too old a sludge. The quantity of microorganisms can be represented by the quantity of MLVSS. Ideally, the living or active microorganisms would simply be counted, but this is not feasible; studies show the MLVSS is a good approximation of microorganism concentrations in the NILSS. Data obtained are calculated using a moving seven-day average. 12 a.