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Optimizing the Energy and Carbon Footprint in Wastewater Treatment Plants

A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "B: Energy and Environment".

Deadline for manuscript submissions: closed (31 December 2023) | Viewed by 10945

Special Issue Editors


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Guest Editor
Department of Water Resources and Environmental Engineering, School of Civil Engineering, National Technical University of Athens, Athens, Greece
Interests: biological processes; emerging contaminants; mathematical modelling; resources recovery; water quality; wastewater treatment; wastewater and sludge reuse
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Guest Editor
Soil and Water Resources Institute, Hellenic Agricultural Organisation-DIMITRA, Thermi, 57001 Thessaloniki, Greece
Interests: environmental biotechnology; waste and watewater treatment; anaerobic digestion
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The Guest Editors are inviting submissions to a Special Issue of Energies on the subject area of “Optimizing the Energy and Carbon Footprint in Wastewater Treatment Plants”. Municipal wastewater treatment is a significant energy consumer. It is estimated that in developed countries, approximately 1–3% of the total electrical energy consumption on a country level is allocated to wastewater treatment. Furthermore, it is expected that these energy requirements will increase over time due to population growth and the employment of advanced treatment technologies to achieve the increasingly stringent treated effluent limit values. Therefore, the optimization of the energy footprint of wastewater treatment plants (WWTPs) is a major driver toward the achievement of zero-energy or energy-positive plants.

This Special Issue will focus on studies targeted at novel processes which aim at a decrease in energy consumption and/or increase in energy production either directly from wastewater or through sewage sludge treatment, thus promoting the optimization of the total energy footprint of WWTPs.

Topics of interest for publication include but are not limited to:

  • Novel low energy footprint wastewater treatment processes (e.g., chemical enhanced primary sedimentation; high rate activated sludge systems, deammonification processes);
  • Direct energy production through wastewater treatment (e.g., anaerobic MBR, UASB, microbial fuel cell technology, hybrid systems);
  • Advanced techniques aiming at an increase in biomethane production through sewage sludge anaerobic treatment;
  • Co-processing of industrial waste streams with sewage sludge studies;
  • Novel processes for biogas upgrade to pure methane;
  • National surveys on the energy profile of WWTPs;
  • Development of methodologies for the assessment of the energy efficiency of WWTPs;
  • Mathematical modeling studies with a focus on optimization of the energy footprint in WWTPs;
  • Investigating GHG emissions in WWTPs;
  • Optimizing GHG emissions (N2O, CH4, CO2) in bioprocesses;
  • Thermal processes for sewage sludge treatment.

Prof. Dr. Constantinos Noutsopoulos
Prof. Dr. Panagiotis G. Kougias
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Energies is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • energy footprint
  • wastewater treatment
  • biomethane production
  • greenhouse gas emissions
  • sewage sludge treatment

Published Papers (5 papers)

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Research

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10 pages, 1630 KiB  
Article
Evaluating the Operation of a Full-Scale Sequencing Batch Reactor–Reverse Osmosis–Evaporation System Used to Treat Landfill Leachates: Removal of Pollutants, Energy Consumption and Greenhouse Gas Emissions
by Konstantinos Tsompanoglou, Olga P. Koutsou and Athanasios S. Stasinakis
Energies 2023, 16(19), 6872; https://doi.org/10.3390/en16196872 - 28 Sep 2023
Cited by 2 | Viewed by 1178
Abstract
Limited information is available in the literature regarding the energy consumption and the greenhouse gases emitted during landfill leachates treatment. A full-scale landfill leachates treatment system that included primary sedimentation, biological treatment in sequencing batch reactors, reverse osmosis and mechanical vapor recompression evaporation [...] Read more.
Limited information is available in the literature regarding the energy consumption and the greenhouse gases emitted during landfill leachates treatment. A full-scale landfill leachates treatment system that included primary sedimentation, biological treatment in sequencing batch reactors, reverse osmosis and mechanical vapor recompression evaporation was monitored and evaluated for the removal of major pollutants, energy consumption and greenhouse gas emissions. Samples were taken during a period of two years from different points of the system, while the actual power consumption was calculated considering the available mechanical equipment and the hours of operation. The quantities of greenhouse gases emitted were estimated using appropriate equations and based on the operational characteristics of the system. According to chemical analyses, biological treatment resulted in partial removal of COD and total nitrogen, while the removal of BOD5 and NH4-N was significant, reaching 90 and 98%, respectively. Use of reverse osmosis increased the removal of all pollutants, satisfying the requirements of the legislation on wastewater discharge into the environment. Power consumption was calculated to be 35.3 KWhr per m3 of treated leachate, while mechanical vapor recompression evaporation was responsible for 60.5% of the total energy required. The contribution of other processes to energy consumption was as follows, in decreasing order: sequencing batch reactors > reverse osmosis > primary treatment. The roots blower vacuum pump used for mechanical vapor recompression evaporation, and the blowers providing air to the sequencing batch reactors, were the most energy-intensive pieces of apparatus, contributing 44.2% and 11.3% of the required energy, respectively. The quantity of greenhouse gases emitted was estimated to be 27.7 Kg CO2eq per m3 of treated leachates. Among the different processes used, biological treatment and mechanical vapor recompression evaporation contributed to 45.7% and 44.1% of the total emissions, respectively. The findings of this study reveal that an integrated landfill leachate treatment system that combines biological treatment and reverse osmosis can assure the protection of the aquatic environment by producing high-quality effluent; however, further research should be conducted regarding the sustainable management of reverse osmosis concentrate. Mechanical vapor recompression evaporation contributes significantly to the environmental footprint of the landfill leachates treatment system due to both high energy consumption and elevated emissions of greenhouse gases. Full article
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14 pages, 2848 KiB  
Article
Techno-Economic Analysis of Succinic Acid Production from Sugar-Rich Wastewater
by Hyunjin Kim, Byoung-In Sang, Panagiotis Tsapekos, Irini Angelidaki and Merlin Alvarado-Morales
Energies 2023, 16(7), 3227; https://doi.org/10.3390/en16073227 - 03 Apr 2023
Viewed by 2057
Abstract
Succinic acid (SA) is a valuable platform chemical that can be converted into biodegradable plastics, resins, solvents, etc. The emerging biological routes for SA production are gaining more attention because they exploit the natural abilities of bacteria to fixate carbon dioxide (CO2 [...] Read more.
Succinic acid (SA) is a valuable platform chemical that can be converted into biodegradable plastics, resins, solvents, etc. The emerging biological routes for SA production are gaining more attention because they exploit the natural abilities of bacteria to fixate carbon dioxide (CO2). On the other hand, an inexpensive organic carbon source that can fulfill the energetic requirements of the microbial strain is also a significant challenge for industrial SA production. The current work presents a holistic techno-economic analysis of SA production using sugar-rich residual streams and biogas as raw materials. Simulation results showed that by establishing an integrated process, high SA production can be simultaneously achieved with biogas upgrading. The CO2 provided from biogas and carbohydrates, which are provided from organic by-products is converted into two products: biomethane (CH4 > 95%, a clean biofuel), and SA. The mass and energy balances and techno-economic indicators were simulated and calculated using SuperPro Designer®. The total capital investment and the total production cost for a facility producing 1000 tSA/year were estimated to be EUR 5,211,000 and EUR 2,339,000 per year, respectively. The total revenue was calculated to be EUR 2,811,000 per year, while the revenue due to biomethane produced, namely, 198,150 Nm3 corresponded to EUR 205,284 per year. The return on investment, payback period, and internal rate of return of the project were found to be 11.68%, 8.56 years, and 11.11%, respectively. Full article
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11 pages, 3012 KiB  
Article
Residual Forest Biomass in Pinus Stands: Accumulation and Biogas Production Potential
by Alexandros Eftaxias, Evangelia Anna Passa, Christos Michailidis, Christodoulos Daoutis, Apostolos Kantartzis and Vasileios Diamantis
Energies 2022, 15(14), 5233; https://doi.org/10.3390/en15145233 - 19 Jul 2022
Cited by 5 | Viewed by 1266
Abstract
Lignocellulosic biomass is an abundant resource that can be valorized for the production of bioenergy. However, studies aiming to quantify the amount of biogas production potential per km forest road are scarce in the literature. In this study, fresh pine needles, pine needle [...] Read more.
Lignocellulosic biomass is an abundant resource that can be valorized for the production of bioenergy. However, studies aiming to quantify the amount of biogas production potential per km forest road are scarce in the literature. In this study, fresh pine needles, pine needle litter, pine branches, and pine bark were digested in batch reactors under mesophilic conditions after a grinding/milling pre-treatment. All samples were collected from a low-altitude Mediterranean Pinus forest (North Greece) adjacent to a category G forest road with a gentle slope. The methane yield of fresh pine needles was between 115 and 164 NmL g−1 volatile solids (VS), depending on the Pinus tree size. Pine needle litter produced a significantly lower methane yield (between 58 and 77 NmL g−1 VS), followed by pine bark (85 NmL g−1 VS) and pine branches (138 NmL g−1 VS). Considering the quantity of pine needle litter accumulated on adjacent forest roads (600 ± 200 g m−2), it was possible to calculate the biomethane production potential per km of forest road (up to 500 Nm3 km−1) if the biomass collected was disposed of at an anaerobic digestion facility. The results of the study demonstrate that residual forest biomass represents an additional resource for bioenergy production. Moreover, harvesting residual forest biomass can decrease the incidence of devastating summer forest fires and their disastrous consequences for the environment, the economy, and the local populations. Full article
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15 pages, 2185 KiB  
Article
A 2D Modelling Approach for Predicting the Response of a Two-Chamber Microbial Fuel Cell to Substrate Concentration and Electrolyte Conductivity Changes
by Theofilos Kamperidis, Asimina Tremouli, Antonis Peppas and Gerasimos Lyberatos
Energies 2022, 15(4), 1412; https://doi.org/10.3390/en15041412 - 15 Feb 2022
Cited by 3 | Viewed by 1685
Abstract
Bioelectrochemical systems have been the focus of extensive research due to their unique advantages of converting the chemical energy stored in waste to electricity. To acquire a better understanding and optimize these systems, modelling has been employed. A 2D microbial fuel cell (MFC) [...] Read more.
Bioelectrochemical systems have been the focus of extensive research due to their unique advantages of converting the chemical energy stored in waste to electricity. To acquire a better understanding and optimize these systems, modelling has been employed. A 2D microbial fuel cell (MFC) model was developed using the finite element software Comsol Multiphysics® (version 5.2), simulating a two-chamber MFC operating in batch mode. By solving mass and charge balance equations along with Monod–Butler–Volmer kinetics, the operation of the MFC was simulated. The model accurately describes voltage output and substrate consumption in the MFC. The computational results were compared with experimental data, thus validating the model. The voltage output and substrate consumption originating from the model were in agreement with the experimental data for two different cases (100 Ω, 1000 Ω external resistances). A polarization curve was extracted from the model by shifting the external resistance gradually, calculating a similar maximum power (47 mW/m2) to the observed experimental one (49 mW/m2). The validated model was used to predict the MFC response to varying initial substrate concentrations (0.125–4 g COD/L) and electrolyte conductivity (0.04–100 S/m) in order to determine the optimum operating conditions. Full article
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Review

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56 pages, 4296 KiB  
Review
A Comprehensive Review on Pretreatment Methods for Enhanced Biogas Production from Sewage Sludge
by Georgia-Christina Mitraka, Konstantinos N. Kontogiannopoulos, Maria Batsioula, George F. Banias, Anastasios I. Zouboulis and Panagiotis G. Kougias
Energies 2022, 15(18), 6536; https://doi.org/10.3390/en15186536 - 07 Sep 2022
Cited by 11 | Viewed by 3711
Abstract
The treatment of municipal wastewater is considered a cornerstone for the protection of public health and environment. However, a major issue derived from this process is the large quantities of produced sewage sludge. Although anaerobic digestion is a widely applied method in Wastewater [...] Read more.
The treatment of municipal wastewater is considered a cornerstone for the protection of public health and environment. However, a major issue derived from this process is the large quantities of produced sewage sludge. Although anaerobic digestion is a widely applied method in Wastewater Treatment Plants (WWTPs) aiming to stabilize the sludge and to recover energy in the form of methane, it is usually limited due to the reduced decomposition efficiency and slow biodegradation rate of this recalcitrant substrate. For this reason, various pretreatment methods have been proposed aiming to modify the sludge structure, solubilize the organic matter, and decrease the crystallinity of sludge so as to accelerate hydrolysis and consequently enhance methane production. The current research is a comprehensive collection of recent advances in pretreatment technologies that can be potentially applied in wastewater treatment facilities. The critical review analysis presented herein reveals the several advantages and drawbacks, as well as the technical opportunities of the pretreatment methods and provides an assessment of their feasibility/applicability from an energetic, environmental, and economic point of view. Full article
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