Balancing effluent quality, economic cost and greenhouse gas emissions during the evaluation of (plant-wide) control/operational strategies in WWTPs.

The objective of this paper was to show the potential additional insight that result from adding greenhouse gas (GHG) emissions to plant performance evaluation criteria, such as effluent quality (EQI) and operational cost (OCI) indices, when evaluating (plant-wide) control/operational strategies in wastewater treatment plants (WWTPs). The proposed GHG evaluation is based on a set of comprehensive dynamic models that estimate the most significant potential on-site and off-site sources of CO₂, CH₄ and N₂O. The study calculates and discusses the changes in EQI, OCI and the emission of GHGs as a consequence of varying the following four process variables: (i) the set point of aeration control in the activated sludge section; (ii) the removal efficiency of total suspended solids (TSS) in the primary clarifier; (iii) the temperature in the anaerobic digester; and (iv) the control of the flow of anaerobic digester supernatants coming from sludge treatment. Based upon the assumptions built into the model structures, simulation results highlight the potential undesirable effects of increased GHG production when carrying out local energy optimization of the aeration system in the activated sludge section and energy recovery from the AD. Although off-site CO₂ emissions may decrease, the effect is counterbalanced by increased N₂O emissions, especially since N₂O has a 300-fold stronger greenhouse effect than CO₂. The reported results emphasize the importance and usefulness of using multiple evaluation criteria to compare and evaluate (plant-wide) control strategies in a WWTP for more informed operational decision making.

[1]  M. V. van Loosdrecht,et al.  Methane emission during municipal wastewater treatment. , 2012, Water research.

[2]  C. Grady,et al.  An Updated Process Model for Carbon Oxidation, Nitrification, and Denitrification , 2008, Water environment research : a research publication of the Water Environment Federation.

[3]  Meyer Steinberg,et al.  Hynol—An economical process for methanol production from biomass and natural gas with reduced CO2 emission , 1993 .

[4]  M C M van Loosdrecht,et al.  Modelling nitrous and nitric oxide emissions by autotrophic ammonia-oxidizing bacteria , 2013, Environmental technology.

[5]  George Tchobanoglous,et al.  Wastewater Engineering Treatment Disposal Reuse , 1972 .

[6]  P. Vanrolleghem,et al.  Evaluating mathematical models for N2O production by ammonia-oxidising bacteria: towards a unified model , 2012 .

[7]  Sally Brown,et al.  Calculator tool for determining greenhouse gas emissions for biosolids processing and end use. , 2010, Environmental science & technology.

[8]  W. Gujer,et al.  Release of nitrous oxide (N2O) from denitrifying activated sludge: Verification and application of a mathematical model , 1996 .

[9]  H. Siegrist,et al.  Isotope signatures of N₂O in a mixed microbial population system: constraints on N₂O producing pathways in wastewater treatment. , 2013, Environmental science & technology.

[10]  Mogens Henze,et al.  Activated sludge models ASM1, ASM2, ASM2d and ASM3 , 2015 .

[11]  Ingmar Nopens,et al.  Wastewater treatment models in teaching and training: the mismatch between education and requirements for jobs. , 2009, Water science and technology : a journal of the International Association on Water Pollution Research.

[12]  L. Corominas,et al.  Comparison of different modeling approaches to better evaluate greenhouse gas emissions from whole wastewater treatment plants , 2012, Biotechnology and bioengineering.

[13]  J. B. Copp,et al.  Benchmark Simulation Model No 2: finalisation of plant layout and default control strategy. , 2010, Water science and technology : a journal of the International Association on Water Pollution Research.

[14]  Riccardo Gori,et al.  Effects of soluble and particulate substrate on the carbon and energy footprint of wastewater treatment processes. , 2011, Water research.

[15]  Ulf Jeppsson,et al.  Benchmarking of Control Strategies for Wastewater Treatment Plants , 2014 .

[16]  Ulf Jeppsson,et al.  Dynamic influent pollutant disturbance scenario generation using a phenomenological modelling approach , 2011, Environ. Model. Softw..

[17]  L. Corominas,et al.  Including greenhouse gas emissions during benchmarking of wastewater treatment plant control strategies. , 2011, Water research.

[18]  Peter A Vanrolleghem,et al.  Evaluating four mathematical models for nitrous oxide production by autotrophic ammonia‐oxidizing bacteria , 2013, Biotechnology and bioengineering.

[19]  B. De Baets,et al.  Influence of sampling strategies on the estimated nitrous oxide emission from wastewater treatment plants. , 2013, Water research.

[20]  O. Edenhofer,et al.  Intergovernmental Panel on Climate Change (IPCC) , 2013 .

[21]  Gustaf Olsson,et al.  ICA and me--a subjective review. , 2012, Water research.

[22]  W. Salas,et al.  Methane and Nitrous Oxide Emissions from Natural Sources , 2010 .

[23]  Ulf Jeppsson,et al.  An ASM/ADM model interface for dynamic plant-wide simulation. , 2009, Water research.

[24]  M. V. van Loosdrecht,et al.  Nitrous oxide emission during wastewater treatment. , 2009, Water research.

[25]  Magnus Arnell,et al.  Dynamic modelling and validation of nitrous oxide emissions from a full-scale nitrifying/denitrifying sequencing batch reactor treating anaerobic digester supernatant , 2013 .

[26]  J Colprim,et al.  A hybrid supervisory system to support WWTP operation: implementation and validation. , 2002, Water science and technology : a journal of the International Association on Water Pollution Research.

[27]  P. Vanrolleghem,et al.  Towards a benchmarking tool for minimizing wastewater utility greenhouse gas footprints. , 2012, Water science and technology : a journal of the International Association on Water Pollution Research.

[28]  F. Blumensaat,et al.  Modelling of two-stage anaerobic digestion using the IWA Anaerobic Digestion Model No. 1 (ADM1). , 2005, Water research.

[29]  Günter Langergraber,et al.  Guidelines for Using Activated Sludge Models , 2012 .

[30]  Alejandro Rivas,et al.  Model-based optimisation of Wastewater Treatment Plants design , 2008, Environ. Model. Softw..

[31]  Ulf Jeppsson,et al.  Practical use of wastewater treatment modelling and simulation as a decision support tool for plant operators - case study on aeration control at Linköping wastewater treatment plant , 2013 .

[32]  A. Hospido,et al.  A methodology to estimate greenhouse gases emissions in Life Cycle Inventories of wastewater treatment plants , 2012 .

[33]  Ignasi Rodríguez-Roda,et al.  Systematic Procedure to Handle Critical Decisions during the Conceptual Design of Activated Sludge Plants , 2007 .

[34]  P Grau,et al.  Supervisory control strategies for the new WWTP of Galindo-Bilbao: the long run from the conceptual design to the full-scale experimental validation. , 2006, Water science and technology : a journal of the International Association on Water Pollution Research.

[35]  Peter A. Vanrolleghem,et al.  Calibration and validation of an activated sludge model for greenhouse gases no. 1 (ASMG1): prediction of temperature-dependent N2O emission dynamics , 2014, Bioprocess and Biosystems Engineering.

[36]  Jurg Keller,et al.  Development of a model for assessing methane formation in rising main sewers. , 2009, Water research.

[37]  Ulf Jeppsson,et al.  Calibration and validation of a phenomenological influent pollutant disturbance scenario generator using full-scale data. , 2014, Water research.

[38]  Zhiguo Yuan,et al.  Nitrous oxide emissions from wastewater treatment processes , 2012, Philosophical Transactions of the Royal Society B: Biological Sciences.