Techno-economic characteristics of wastewater treatment plants retrofitted from the conventional activated sludge process to the membrane bioreactor process
1. College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 101408, China 2. Yanshan Earth Critical Zone and Surface Fluxes Research Station, University of Chinese Academy of Sciences, Beijing 101408, China 3. State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China 4. Department of Energy, Environment and Climate Change, School of Environment, Resources and Development, Asian Institute of Technology, Klong Luang, Pathumthani 12120, Thailand 5. School of Civil Engineering, Guangzhou University, Guangzhou 510006, China 6. College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China 7. Research and Application Center for Membrane Technology, School of Environment, Tsinghua University, Beijing 100084, China
• Retrofitting from CAS to MBR increased effluent quality and environmental benefits.
• Retrofitting from CAS to MBR increased energy consumption but not operating cost.
• Retrofitting from CAS to MBR increased the net profit and cost efficiency.
• The advantage of MBR is related to the adopted effluent standard.
• The techno-economy of MBR improves with stricter effluent standards.
While a growing number of wastewater treatment plants (WWTPs) are being retrofitted from the conventional activated sludge (CAS) process to the membrane bioreactor (MBR) process, the debate on the techno-economy of MBR vs. CAS has continued and calls for a thorough assessment based on techno-economic valuation. In this study, we analyzed the operating data of 20 large-scale WWTPs (capacity≥10000 m3/d) and compared their techno-economy before and after the retrofitting from CAS to MBR. Through cost-benefit analysis, we evaluated the net profit by subtracting the operating cost from the environmental benefit (estimated by the shadow price of pollutant removal and water reclamation). After the retrofitting, the removal rate of pollutants increased (e.g., from 89.0% to 93.3% on average for NH3-N), the average energy consumption increased from 0.40 to 0.57 kWh/m3, but the operating cost did not increase significantly. The average marginal environmental benefit increased remarkably (from 0.47 to 0.66 CNY/g for NH3-N removal), leading to an increase in the average net profit from 19.4 to 24.4 CNY/m3. We further scored the technical efficiencies via data envelopment analysis based on non-radial directional distance functions. After the retrofitting, the relative cost efficiency increased from 0.70 to 0.73 (the theoretical maximum is 1), while the relative energy efficiency did not change significantly. The techno-economy is closely related to the effluent standard adopted, particularly when truncating the extra benefit of pollutant removal beyond the standard in economic modeling. The modeling results suggested that MBR is more profitable than CAS given stricter effluent standards.
C Brepols, H Schäfer, N Engelhardt (2010). Considerations on the design and financial feasibility of full-scale membrane bioreactors for municipal applications. Water Science & Technology, 61(10): 2461–2468 https://doi.org/10.2166/wst.2010.179
pmid: 20453318
2
Y T Chang, N Zhang, D Danao, N Zhang (2013). Environmental efficiency analysis of transportation system in China: A non-radial DEA approach. Energy Policy, 58: 277–283 https://doi.org/10.1016/j.enpol.2013.03.011
3
J DeCarolis, S Adham, W R Pearce, Z Hirani, S Lacy, R Stephenson (2007). Cost trends of MBR systems for municipal wastewater treatment. Proceedings of the Water Environment Federation, 2007(15): 3407–3418 https://doi.org/10.2175/193864707787973734
4
M Djukic, I Jovanoski, O M Ivanovic, M Lazic, D Bodroza (2016). Cost-benefit analysis of an infrastructure project and a cost-reflective tariff: A case study for investment in wastewater treatment plant in Serbia. Renewable & Sustainable Energy Reviews, 59: 1419–1425 https://doi.org/10.1016/j.rser.2016.01.050
5
R Färe, S Grosskopf, C A K Lovell, C Pasurka (1989). Multilateral productivity comparisons when some outputs are undesirable: A nonparametric approach. Review of Economics and Statistics, 71(1): 90–98 https://doi.org/10.2307/1928055
A Fenu, J Roels, T Wambecq, K De Gussem, C Thoeye, G De Gueldre, B Van De Steene (2010). Energy audit of a full scale MBR system. Desalination, 262(1–3): 121–128 https://doi.org/10.1016/j.desal.2010.05.057
8
S Gabarrón, G Ferrero, M Dalmau, J Comas, I Rodriguez-Roda (2014). Assessment of energy-saving strategies and operational costs in full-scale membrane bioreactors. Journal of Environmental Management, 134: 8–14 https://doi.org/10.1016/j.jenvman.2013.12.023
pmid: 24463730
9
T Gao, K Xiao, J Zhang, X Zhang, X Wang, S Liang, J Sun, F Meng, X Huang (2021). Cost-benefit analysis and technical efficiency evaluation of full-scale membrane bioreactors for wastewater treatment using economic approaches. Journal of Cleaner Production, 301: 126984 https://doi.org/10.1016/j.jclepro.2021.126984
10
X D Hao, J Li, M C M van Loosdrecht, T Y Li (2018). A sustainability-based evaluation of membrane bioreactors over conventional activated sludge processes. Journal of Environmental Chemical Engineering, 6(2): 2597–2605 https://doi.org/10.1016/j.jece.2018.03.050
11
F Hernández-Sancho, M Molinos-Senante, R Sala-Garrido (2010). Economic valuation of environmental benefits from wastewater treatment processes: An empirical approach for Spain. Science of the Total Environment, 408(4): 953–957 https://doi.org/10.1016/j.scitotenv.2009.10.028
pmid: 19903571
12
F Hernández-Sancho, M Molinos-Senante, R Sala-Garrido (2011). Energy efficiency in Spanish wastewater treatment plants: A non-radial DEA approach. Science of the Total Environment, 409(14): 2693–2699 https://doi.org/10.1016/j.scitotenv.2011.04.018
pmid: 21549411
13
F Hernández-Sancho, R Sala-Garrido (2009). Technical efficiency and cost analysis in wastewater treatment processes: A DEA approach. Desalination, 249(1): 230–234 https://doi.org/10.1016/j.desal.2009.01.029
14
X Huang, K Xiao, Y Shen (2010). Recent advances in membrane bioreactor technology for wastewater treatment in China. Frontiers of Environmental Science & Engineering in China, 4(3): 245–271 https://doi.org/10.1007/s11783-010-0240-z
15
R Iglesias, P Simón, L Moragas, A Arce, I Rodriguez-Roda (2017). Cost comparison of full-scale water reclamation technologies with an emphasis on membrane bioreactors. Water Science & Technology, 75(11): 2562–2570 https://doi.org/10.2166/wst.2017.132
pmid: 28617275
16
S J Judd (2016). The status of industrial and municipal effluent treatment with membrane bioreactor technology. Chemical Engineering Journal, 305: 37–45 https://doi.org/10.1016/j.cej.2015.08.141
17
P Krzeminski, L Leverette, S Malamis, E Katsou (2017). Membrane bioreactors: A review on recent developments in energy reduction, fouling control, novel configurations, LCA and market prospects. Journal of Membrane Science, 527: 207–227 https://doi.org/10.1016/j.memsci.2016.12.010
18
B Lin, K Du (2015). Energy and CO2 emissions performance in China’s regional economies: do market-oriented reforms matter? Energy Policy, 78(3): 113–124 https://doi.org/10.1016/j.enpol.2014.12.025
19
H Lin, J Chen, F Wang, L Ding, H Hong (2011). Feasibility evaluation of submerged anaerobic membrane bioreactor for municipal secondary wastewater treatment. Desalination, 280(1–3): 120–126 https://doi.org/10.1016/j.desal.2011.06.058
20
S Longo, A Hospido, J M Lema, M Mauricio-Iglesias (2018). A systematic methodology for the robust quantification of energy efficiency at wastewater treatment plants featuring Data Envelopment Analysis. Water Research, 141: 317–328 https://doi.org/10.1016/j.watres.2018.04.067
pmid: 29804018
21
M Mohsin, I Hanif, F Taghizadeh-Hesary, Q Abbas, W Iqbal (2021). Nexus between energy efficiency and electricity reforms: A DEA-Based way forward for clean power development. Energy Policy, 149: 112052 https://doi.org/10.1016/j.enpol.2020.112052
22
M Molinos-Senante, F Hernández-Sancho, R Sala-Garrido (2010). Economic feasibility study for wastewater treatment: A cost-benefit analysis. Science of the Total Environment, 408(20): 4396–4402 https://doi.org/10.1016/j.scitotenv.2010.07.014
pmid: 20667582
23
M Molinos-Senante, F Hernández-Sancho, R Sala-Garrido (2011). Cost-benefit analysis of water-reuse projects for environmental purposes: A case study for Spanish wastewater treatment plants. Journal of Environmental Management, 92(12): 3091–3097 https://doi.org/10.1016/j.jenvman.2011.07.023
pmid: 21856067
24
R Pretel, B D Shoener, J Ferrer, J S Guest (2015). Navigating environmental, economic, and technological trade-offs in the design and operation of submerged anaerobic membrane bioreactors (AnMBRs). Water Research, 87: 531–541 https://doi.org/10.1016/j.watres.2015.07.002
pmid: 26206622
25
R Sala-Garrido, M Molinos-Senante, F Hernández-Sancho (2011). Comparing the efficiency of wastewater treatment technologies through a DEA metafrontier model. Chemical Engineering Journal, 173(3): 766–772 https://doi.org/10.1016/j.cej.2011.08.047
K Xiao, S Liang, X Wang, C Chen, X Huang (2019). Current state and challenges of full-scale membrane bioreactor applications: A critical review. Bioresource Technology, 271: 473–481 https://doi.org/10.1016/j.biortech.2018.09.061
pmid: 30245197
28
K Xiao, Y Xu, S Liang, T Lei, J Sun, X Wen, H Zhang, C Chen, X Huang (2014). Engineering application of membrane bioreactor for wastewater treatment in China: Current state and future prospect. Frontiers of Environmental Science & Engineering, 8(6): 805–819 https://doi.org/10.1007/s11783-014-0756-8
29
T Young, M Muftugil, S Smoot, J Peeters (2012). MBR vs. CAS: Capital and operating cost evaluation. Water Practice and Technology, 7(4): 1–8 https://doi.org/10.2166/wpt.2012.075
30
D Yu, J Wang, L Zheng, Q Sui, H Zhong, M Cheng, Y Wei (2020). Effects of hydraulic retention time on net present value and performance in a membrane bioreactor treating antibiotic production wastewater. Frontiers of Environmental Science & Engineering, 14(6): 101 https://doi.org/10.1007/s11783-020-1280-7
31
P Zhou, B W Ang, H Wang (2012). Energy and CO2 emission performance in electricity generation: A non-radial directional distance function approach. European Journal of Operational Research, 221(3): 625–635 https://doi.org/10.1016/j.ejor.2012.04.022
