Mathematically formulated key performance indicators for design and evaluation of treatment trains for resource recovery from urban wastewater

Maria O Van Schaik,Seda Sucu,Hans J Cappon,Wei-Shan Chen,D Brett Martinson,Djamila Ouelhadj,Huub H.M Rijnaarts

doi:10.1016/j.jenvman.2020.111916

Abstract

While urban wastewater infrastructure is aging and no longer adequate, climate change and sustainability are urging the transition from pollution management to resource recovery. Lacking evidence-based quantitative evaluation of the potential benefits and consequences of resource recovery from wastewater hinders the negotiation amongst stakeholders and slows down the transition. This study proposes mathematical formulations for technical, environmental, economic, and social key performance indicators (KPIs) that can be used to quantify the benefits and the risks of resource recovery. The proposed formulations are derived from the literature and validated with stakeholders. Each KPI is mathematically formulated at treatment train level by considering: (1) the characteristics of individual unit processes (UPs) in the treatment train (TT), (2) the context in which the TT is installed, and (3) the resources to be recovered. The mathematical formulations of the KPIs proposed in this study enable a transparent, consistent and informative evaluation of existing treatment trains, as well as support the (computer aided) design of new ones. This could aid the transition from urban wastewater treatment to resource recovery from urban wastewater.

Highlights

A recent evaluation of the European Urban Waste Water Treatment Directive emphasised that compliance with the Directive requires continuous investment to replace or improve inadequate wastewater treatment plants (WWTPs) (European Comission, 2019)
This study focuses on key performance indicators (KPIs) that evaluate the technical, social, eco nomic and environmental impacts of all the unit processes (UPs) in the treatment train (TT) but only within the immediate surrounding
The capital expenditure (CAPEX) of a UP in the TT (CAPEXj, euros) represents the one time expenditure for purchasing the UP and the operation and maintenance expenditure (OPEX) is the total yearly expenditure for energy, chemicals, replaced components and required labour to operate and maintain a UP (OPEXj, euros/year). When both KPIs are used at the same time, they should be expressed in the same currency

Summary

Introduction

A recent evaluation of the European Urban Waste Water Treatment Directive emphasised that compliance with the Directive requires continuous investment to replace or improve inadequate wastewater treatment plants (WWTPs) (European Comission, 2019). The recovery of resources from wastewater requires a different approach towards wastewater management and treatment facility design (Diaz-Elsayed et al, 2019; Mehta et al, 2015; Puchong kawarin et al, 2015). To design sustainable resource recovery facilities, technical, environ mental, economic, and social performance indicators need to be considered in an integrated and comprehensive way (Plakas et al, 2016; Regmi et al, 2019). Only a few studies involved stakeholders in selecting indicators for evaluation of resource recovery from wastewater (Cornejo et al, 2019; Foxon et al, 2002; Molinos-Senante et al, 2014)

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Discussion

Conclusion