Water-energy nexus of the wastewater treatment plants

  • Shalini Nakkasunchi

Student thesis: Doctoral Thesis


Water-Energy (W-E) Nexus of wastewater treatment plants (WWTPs) is one of the crucial research areas of the present decade. WWTPs consume about 3-5% of the global energy and contribute to indirect greenhouse gas (GHG) emissions into the environment. Although responsible for significant energy consumption and aerial emissions, WWTPs have the potential for energy recovery (sector specific renewable energy) from wastewater (WW) and sludge in addition to the energy generation from renewables like solar and wind (non-sector specific renewable energy). Considering these, a review was undertaken on W-E nexus at WWTPs from broad range of research articles collected from different scientific resources such as Scopus, Elsevier etc, and technical and government reports published in last 10 years. The main aim of this review is to identify the energy saving and low carbon measures and tools (modelling) to assess the carbon reduction potential of the WWTPs. From the literature review, it is identified that no models/tools provide the flexibility to assess (a) the energy demand of the WWTP and (b) feasibility of the renewable energy system integration to the WWTP on a single platform. Considering this, a methodological framework was developed specifically for the WWTPs called Water-Energy Nexus Tool (WENT) in a Microsoft Excel environment. This framework provides the flexibility to assess the energy demand of the WWTPs and possibility of renewable energy generation at the plant. The developed framework was applied to WWTPs in Spain (Molina and Alicantarilla WWTPs in Murcia), Italy (Ponte Metauro WWTP in Fano) and Northern Ireland (North coast WWTP) to assess their carbon emission reduction potential. Based on the results obtained from this assessment and carbon emission reduction measures
reported in the literature recommendation of low carbon solutions and pathways are proposed for the WWTP managers to reduce the carbon emissions associated with the energy consumption at the WWTPs. The low carbon solution involves (i) most viable operational strategies like repair and replacement of the faulty equipments, online or automatic control of the processes, (ii) assessment of the techno-economic feasibility of the sector specific renewable energy technologies like anaerobic digester, heat pumps, and hydropower turbine, and (iii) techno-economic feasibility of the non-sector specific renewable energy technologies
like solar PV and wind turbines.
Date of AwardMar 2022
Original languageEnglish
SponsorsDepartment for the Economy
SupervisorNeil Hewitt (Supervisor) & Caterina Brandoni (Supervisor)


  • Energy recovery
  • Renewable energy
  • Carbon emissions
  • Energy assessment
  • Techno-economic feasibility

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