Wastewater treatment modelling: dealing with uncertainties

Abstract

This paper serves as a problem statement of the issues surrounding uncertainty in wastewater treatment modelling. The paper proposes a structure for identifying the sources of uncertainty introduced during each step of an engineering project concerned with model-based design or optimisation of a wastewater treatment system. It briefly references the methods currently used to evaluate prediction accuracy and uncertainty and discusses the relevance of uncertainty evaluations in model applications. The paper aims to raise awareness and initiate a comprehensive discussion among professionals on model prediction accuracy and uncertainty issues. It also aims to identify future research needs. Ultimately the goal of such a discussion would be to generate transparent and objective methods of explicitly evaluating the reliability of model results, before they are implemented in an engineering decision-making context.

A Final Touch for the Environmental Engineering Students at the Onset of their Profession: Senior-Year Graduation Design Project – Case Study for 2014-2015

“…Use of certain safety factors/coefficients in process calculations and WWTP design is a common and precautionary practice which enables reaching the set effluent standards even under conditions of continuously fluctuating influent overflow rates and pollution loads [17]. On the other hand, use of inflated safety factors should be avoided to prevent overestimation of reactor volumes/footprints and overdesign of the WWTP, which eventually jeopardizes the feasibility aspect of the project.…”

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“…There are several types of uncertainty relevant to the modeling and operational optimization of WWTPs (Belia et al 2009). First, the future influent, or wastewater, flowing into the plant is inherently uncertain, both in terms of flow (the amount flowing into the plant), and chemical composition.…”

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“…The definitions of source and level of uncertainty are taken from the synthesis of Guillaume et al (2010, which is in turn based on extensive literature on uncertainty typologies in the environmental modelling community Norton et al, 2006;Refsgaard et al, 2007;Belia et al, 2009;Matott et al, 2009;Warmink et al, 2010).…”