Title: Probabilistic Modeling of Two-Stage Biological Nitrogen Removal Process: Conditions for Enhanced Process Certitude
Abstract: In a conventional two-stage biological nitrogen removal (BNR) process, the extent of uncertainty associated with different operating parameters (e.g., solids retention time, internal recirculation ratio, anoxic hydraulic retention time [HRT], total HRT, and sludge recycle ratio) was evaluated by simulation with Activated Sludge Model no 1. Variability in the values of kinetic parameters was incorporated in performing stochastic simulations by adopting the influent biodegradable chemical oxygen demand–to–total kjeldahl nitrogen (COD:TKN) ratio of 10, an important determinant of BNR performance. Simulation results predicted maximum level of certitude for effective nitrogen removal at 3-h anoxic HRT (and 12-h total HRT). Appreciable rise in process certitude for nitrogen removal was indicated as solids retention time was increased from 5 to 20 days. No noticeable rise in confidence level could be achieved for meeting stipulated treatment targets by increasing internal recycle (for nitrate recirculation) beyond 300%. Process certitude remained virtually unaffected by increase in either sludge recycle ratio or total HRT of the system. Such an approach for reducing treatment uncertainty, related to variability in biokinetic parameters by studying the effect of operating parameters on the system, could be regarded as a valid objective in BNR process design and operation. This would ultimately lead to the development of ranges in operating conditions for enhanced process certitude.
Publication Year: 2010
Publication Date: 2010-12-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 1
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