Special Issue "Design, Operation and Economics of Wastewater Treatment Plant"

A special issue of Water (ISSN 2073-4441). This special issue belongs to the section "Wastewater Treatment and Reuse".

Deadline for manuscript submissions: 30 June 2021.

Special Issue Editors

Assoc. Prof. Gikas Petros
E-Mail Website
Guest Editor
Technical University of Crete, School of Environmental Engineering, Chania, Greece
Interests: wastewater; biosolids; sewage sludge; waste to energy; gasification; anaerobic digestion; integrated water management
Dr. Phillimon T. Odirile
E-Mail Website
Guest Editor
Department of Civil Engineering, Faculty of Engineering & Technology, University of Botswana, Gaborone, Botswana
Interests: water quality; wastewater treatment; biosolids
Dr. Dachao Ma
E-Mail Website
Guest Editor
Department of Environmental Engineering, School of Resources, Environment and Materials, Guangxi University, Nanning City, China
Interests: Sewage sludge; Biosolids; Waste to green products; Hydrothermal Conversion;Wet oxidation; Pyrolysis; Pollutant imigration

Special Issue Information

Dear Colleagues,

Wastewater treatment is a necessity for any modern society. Until a few decades ago, the primary aim of any wastewater treatment plant (WWTP) design attempt was the construction of a plant able to treat wastewater so as to achieve the imposed discharge standards. Today, the primary aim of the consulting engineers is to design the “optimum” WWTP, so as to achieve the imposed discharge limits at minimum capex and opex. Contrary to past designs, which were dominated by various versions of the “activated sludge” process, a large spectrum of technologies is now available to select the most appropriate one. The availability of modern materials (e.g., membranes), the improvement of aeration processes (e.g., microbubbling), the development of new wastewater treatment devices and processes (e.g., microsieves, wet oxidation), new processes for biosolids management (e.g., waste to energy, hydrothermal carbonization), nutrient recovery (e.g., phosphorus), and the employment of novel online monitoring systems have opened new design horizons in wastewater treatment. Moreover, the potential for water reuse and the increasing requirement to control the level of micropollutants at the effluent have enforced the use of novel designs.

The present Special Issue aims at presenting the new trends in WWTP design, operation, and economies. Performances of new materials and techniques for wastewater treatment and biosolids management, studies on WWTPs operation and economics, and well-documented case studies are welcome. Critical review articles are strongly encouraged.

Assoc. Prof. Gikas Petros
Dr. Phillimon T. Odirile
Dr. Dachao Ma
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 papers will be 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. Water 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 2000 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

  • Wastewater
  • Biosolids
  • Sludge
  • Economics
  • Design
  • Operation
  • Wastewater treatment plant
  • Sewage

Published Papers (9 papers)

Order results
Result details
Select all
Export citation of selected articles as:

Research

Article
Research on the Utilization of Saline Alkali Water Resources Based on Two-Phase Flow
Water 2020, 12(11), 2994; https://doi.org/10.3390/w12112994 - 26 Oct 2020
Viewed by 513
Abstract
In order to reasonably use solar energy to solve problems such as land desertification and soil salinization in Southern Xinjiang, this paper proposes a system combining photothermal and flash evaporation technologies, which use local saline water for desalination treatment to achieve secondary utilization [...] Read more.
In order to reasonably use solar energy to solve problems such as land desertification and soil salinization in Southern Xinjiang, this paper proposes a system combining photothermal and flash evaporation technologies, which use local saline water for desalination treatment to achieve secondary utilization of water resources. Firstly, we introduce the whole system of the photovoltaic desalination plant. As an important heat-collecting element of the system, the solar tube is the key to whether this plant can work efficiently. Then, we carry out the detection and theoretical derivation of data along the tube. We establish a two-phase flow model of saline water in the tube, considering convective heat transfer, and define the formula of the heat collecting efficiency factor. Finally, based on iterative calculation, the temperature trend of the tube and the change law of the two-phase flow are obtained, and the ecological and economic benefits and energy efficiency of the system are analyzed. Full article
(This article belongs to the Special Issue Design, Operation and Economics of Wastewater Treatment Plant)
Show Figures

Figure 1

Article
Treatment of Textile Wastewater by CAS, MBR, and MBBR: A Comparative Study from Technical, Economic, and Environmental Perspectives
Water 2020, 12(5), 1306; https://doi.org/10.3390/w12051306 - 05 May 2020
Cited by 5 | Viewed by 1310
Abstract
In this study, three different biological methods—a conventional activated sludge (CAS) system, membrane bioreactor (MBR), and moving bed biofilm reactor (MBBR)—were investigated to treat textile wastewater from a local industry. The results showed that technically, MBR was the most efficient technology, of which [...] Read more.
In this study, three different biological methods—a conventional activated sludge (CAS) system, membrane bioreactor (MBR), and moving bed biofilm reactor (MBBR)—were investigated to treat textile wastewater from a local industry. The results showed that technically, MBR was the most efficient technology, of which the chemical oxygen demand (COD), total suspended solids (TSS), and color removal efficiency were 91%, 99.4%, and 80%, respectively, with a hydraulic retention time (HRT) of 1.3 days. MBBR, on the other hand, had a similar COD removal performance compared with CAS (82% vs. 83%) with halved HRT (1 day vs. 2 days) and 73% of TSS removed, while CAS had 66%. Economically, MBBR was a more attractive option for an industrial-scale plant since it saved 68.4% of the capital expenditures (CAPEX) and had the same operational expenditures (OPEX) as MBR. The MBBR system also had lower environmental impacts compared with CAS and MBR processes in the life cycle assessment (LCA) study, since it reduced the consumption of electricity and decolorizing agent with respect to CAS. According to the results of economic and LCA analyses, the water treated by the MBBR system was reused to make new dyeings because water reuse in the textile industry, which is a large water consumer, could achieve environmental and economic benefits. The quality of new dyed fabrics was within the acceptable limits of the textile industry. Full article
(This article belongs to the Special Issue Design, Operation and Economics of Wastewater Treatment Plant)
Show Figures

Figure 1

Article
Development of Decay in Biofilms under Starvation Conditions—Rethinking of the Biomass Model
Water 2020, 12(5), 1249; https://doi.org/10.3390/w12051249 - 27 Apr 2020
Cited by 1 | Viewed by 819
Abstract
The study investigates the decay of heterotrophic biomass in biofilms under starvation conditions based on measurements of the oxygen uptake rate (OUR). Original incentive was to understand the preservation of active biomass in SBR-trickling filter systems (SBR-TFS), treating event-based occurring, organically polluted stormwater. [...] Read more.
The study investigates the decay of heterotrophic biomass in biofilms under starvation conditions based on measurements of the oxygen uptake rate (OUR). Original incentive was to understand the preservation of active biomass in SBR-trickling filter systems (SBR-TFS), treating event-based occurring, organically polluted stormwater. In comparison with activated sludge systems, the analyzed biofilm carrier of SBR trickling filters showed an astonishing low decay rate of 0.025 d−1, that allows the biocenosis to withstand long periods of starvation. In activated sludge modeling, biomass decay is regarded as first order kinetics with a 10 times higher constant decay rate (0.17–0.24 d−1, depending on the model used). In lab-scale OUR measurements, the degradation of biofilm layers led to wavy sequence of biomass activity. After long starvation, the initial decay rate (comparable to activated sludge model (ASM) approaches) dropped by a factor of 10. This much lower decay rate is supported by experiments comparing the maximum OUR in pilot-scale biofilm systems before and after longer starvation periods. These findings require rethinking of the approach of single-stage decay rate approach usually used in conventional activated sludge modelling, at least for the investigated conditions: the actual decay rate is apparently much lower than assumed, but is overshadowed by degradation of either cell-internal substrate and/or the ability to tap “ultra-slow” degradable chemical oxygen demand (COD) fractions. For the intended stormwater treatment, this allows the application of technical biofilm systems, even for long term dynamics of wastewater generation. Full article
(This article belongs to the Special Issue Design, Operation and Economics of Wastewater Treatment Plant)
Show Figures

Figure 1

Article
Energy Consumption and Internal Distribution in Activated Sludge Wastewater Treatment Plants of Greece
Water 2020, 12(4), 1204; https://doi.org/10.3390/w12041204 - 23 Apr 2020
Cited by 2 | Viewed by 1101
Abstract
The high-energy consumption of wastewater treatment plants (WWTPs) is a crucial issue for municipalities worldwide. Most WWTPs in Greece operate as extended aeration plants, which results in high operational costs due to high energy needs. The present study investigated the energy requirements of [...] Read more.
The high-energy consumption of wastewater treatment plants (WWTPs) is a crucial issue for municipalities worldwide. Most WWTPs in Greece operate as extended aeration plants, which results in high operational costs due to high energy needs. The present study investigated the energy requirements of 17 activated sludge WWTPs in Greece, serving between 1100–56,000 inhabitants (population equivalent, PE), with average daily incoming flowrates between 300–27,300 m3/d. The daily wastewater production per inhabitant was found to lie between 0.052 m3/PE·d and 0.426 m3/PE·d, with average volume of 0.217 ± 0.114 m3/PE·d. The electric energy consumption per volume unit (EQ (kWh/m3)) was between 0.128–2.280 kWh/m3 (average 0.903 ± 0.509 kWh/m3) following a near logarithmic descending correlation with the average incoming flowrate (Qav) (EQ = −0.294lnQav + 3.1891; R2 = 0.5337). A similar relationship was found between the daily electric energy requirements for wastewater treatment per inhabitant (EPE (kWh/PE·d)) as a function of PE, which varied from 0.041–0.407 kWh/PE·d (average 0.167 ± 0.101 kWh/PE·d)) (EPE = −0.073ln(PE) + 0.8425; R2 = 0.6989). Similarly, the daily energy cost per inhabitant (E€/PE (€/PE·d)) as a function of PE and the electric energy cost per wastewater volume unit (E€/V (€/m3)) as a function of average daily flow (Qav) were found to follow near logarithmic trends (E€/PE = −0.013ln(PE) + 0.1473; R2 = 0.6388, and E€/V = −0.052lnQav + 0.5151; R2 = 0.6359), respectively), with E€/PE varying between 0.005–0.073 €/PE·d (average 0.024 ± 0.019 €/PE·d) and E€/V between 0.012–0.291 €/m3 (average 0.111 ± 0.077 €/m3). Finally, it was calculated that, in an average WWTP, the aeration process is the main energy sink, consuming about 67.2% of the total electric energy supply to the plant. The large variation of energy requirements per inlet volume unit and per inhabitant served, indicate that there is large ground for improving the performance of the WWTPs, with respect to energy consumption. Full article
(This article belongs to the Special Issue Design, Operation and Economics of Wastewater Treatment Plant)
Show Figures

Graphical abstract

Article
Methodology for Energy Optimization in Wastewater Treatment Plants. Phase II: Reduction of Air Requirements and Redesign of the Biological Aeration Installation
Water 2020, 12(4), 1143; https://doi.org/10.3390/w12041143 - 16 Apr 2020
Cited by 1 | Viewed by 976
Abstract
Phase I of the proposed energy optimization methodology showed how the selection of best management criteria for the biological aeration process, and the guarantee of its control at the wastewater treatment plant (WWTP) in San Pedro del Pinatar (Murcia, Spain) produced reductions of [...] Read more.
Phase I of the proposed energy optimization methodology showed how the selection of best management criteria for the biological aeration process, and the guarantee of its control at the wastewater treatment plant (WWTP) in San Pedro del Pinatar (Murcia, Spain) produced reductions of around 20% in energy consumption by considerably reducing the oxygen needs of the microorganisms in the biological system. This manuscript focused on phase II of this methodology, which describes the tools that can be used to detect and correct deviations in the optimal operating points of the aeration equipment and the intrinsic deficiencies in the installation, in order to achieve optimization of the oxygen needs by the microorganisms and improve the efficiency of their transfer from the gas phase to the liquid phase. The objectives pursued were: (i) to minimize the need for aeration, (ii) to reduce the pressure losses in the installation, (iii) to optimize the air supply pressures to avoid excessive energy consumption for the same airflow, and (iv) to optimize the control strategy for the actual working conditions. The use of flow modeling and simulation techniques, the measurement and calculation of air transfer efficiency through the use of off-gas hoods, and the redesign of the aeration facility at the San Pedro del Pinatar WWTP were crucial, and allowed for reductions in energy consumption in Phase II of more than 20%. Full article
(This article belongs to the Special Issue Design, Operation and Economics of Wastewater Treatment Plant)
Show Figures

Figure 1

Article
Experimental Investigation of Substrate Shock and Environmental Ammonium Concentration on the Stability of Ammonia-Oxidizing Bacteria (AOB)
Water 2020, 12(1), 223; https://doi.org/10.3390/w12010223 - 13 Jan 2020
Viewed by 850
Abstract
A wastewater treatment plant (WWTP) frequently encounters fluctuation in ammonium concentration or flow rate (Q), which may affect the stability of ammonium oxidizing bacteria (AOB). In this study, two continuous stirred tank reactors (CSTRs) were operated for 588 days and ammonium concentration was [...] Read more.
A wastewater treatment plant (WWTP) frequently encounters fluctuation in ammonium concentration or flow rate (Q), which may affect the stability of ammonium oxidizing bacteria (AOB). In this study, two continuous stirred tank reactors (CSTRs) were operated for 588 days and ammonium concentration was varied at various steady-state conditions. There was no inhibition observed in CSTR operation and AOB acclimated once at a certain ammonium concentration. Cells at an acclimated steady-state concentration (200 mgTAN/L from R(A) and 1000 mgTAN/L from R(B)) were extracted to perform a batch test at operating conditions, and self-inhibition behavior was observed in the batch reaction. In CSTR operation, the environmental ammonium concentration was varied and the specific oxygen uptake rate (SOUR) value was estimated from daily profile data and compared with batch reaction. In the CSTR operation as a substitute for self-inhibition, the SOUR was shifted towards the maximum specific oxygen uptake rate (SOURmax) and no self-inhibition was observed. For further justification of the CSTR’s stability, several total ammonium nitrogen (TAN) concentrations (range from ~−106 to ~+2550 mgTAN/L) were directly added to interrupt the stability of the process. As a substitute for any effect on the SOUR, the CSTRs were recovered back to the original stable steady-state conditions without varying the operational conditions. Full article
(This article belongs to the Special Issue Design, Operation and Economics of Wastewater Treatment Plant)
Show Figures

Figure 1

Article
Operational Improvement of Main Pumps for Energy-Saving in Wastewater Treatment Plants
Water 2019, 11(12), 2438; https://doi.org/10.3390/w11122438 - 21 Nov 2019
Cited by 2 | Viewed by 1016
Abstract
Efforts towards energy independence in wastewater treatment plants (WWTPs) constitute important policy in Japan. Energy-saving strategies consist of operational improvements and the installation of energy-saving devices. The energy consumed by the main pumps is equal to approximately 14% of the energy consumed by [...] Read more.
Efforts towards energy independence in wastewater treatment plants (WWTPs) constitute important policy in Japan. Energy-saving strategies consist of operational improvements and the installation of energy-saving devices. The energy consumed by the main pumps is equal to approximately 14% of the energy consumed by WWTPs in average in Japan. The main pumps, which are simple machines, do not have the innovative, energy-saving devices associated with other equipment used in WWTPs; therefore, realizing energy savings through operational improvement is extremely important. In recent years, variable frequency drives (VFDs) have increasingly been used to control the rotation speed of main pumps in order to save energy. However, there are many cases where power consumption increases due to the excessive rotation speed control ignoring pump characteristics. In this study, improvement of the operating method based on the power consumption analysis is examined for A WWTP. Differences in characteristics between water pumps and wastewater pumps are discussed, and simulation results without rotational speed control show a reduction in power consumption of 10%. Daily operational report data of the WWTP are used for the power consumption analysis, and additional data acquisition is not necessary. Thus, the power consumption analysis method used in this study can be easily applied to other WWTPs. Full article
(This article belongs to the Special Issue Design, Operation and Economics of Wastewater Treatment Plant)
Show Figures

Figure 1

Article
Effects of Short-Term Uncertainties on the Revenue Estimation of PPP Sewage Treatment Projects
Water 2019, 11(6), 1203; https://doi.org/10.3390/w11061203 - 09 Jun 2019
Cited by 3 | Viewed by 1062
Abstract
Many sewage treatment facilities in China have been developed and operated using the Public-Private Partnerships (PPP) model. However, a big challenge faced by these PPP projects is that the subsidy requested from the government during the operation is normally higher than what was [...] Read more.
Many sewage treatment facilities in China have been developed and operated using the Public-Private Partnerships (PPP) model. However, a big challenge faced by these PPP projects is that the subsidy requested from the government during the operation is normally higher than what was estimated originally, thus often exceeding the budget that the government can afford. This leads to a high risk of project failure or insufficient operation. This problem is largely caused by the uncertainties exhibited in the existing models, such as the Black-Scholes (BS) model. While being used in the budget estimation, these models cannot sufficiently account for the short-term uncertainty that may be incurred during the operation of projects. In this study, a method to account for this short-term uncertainty has been proposed to improve the BS model. This allows for investigations to address issues related to how the real option value of a government subsidy is affected. A Monte Carlo simulation was performed to take into account the noise in the estimation. A sensitivity analysis further revealed that this discrepancy is largely affected by the values of the relevant parameters in the short-term uncertainty model. We found that the short-term uncertainty has a significant effect on private revenue and government subsidy and that the changes of the latter are more sensitive to the change of short-term uncertainty. The value of the relevant variables of short-term uncertainty determined the fluctuation of the revenue. The mean value and revenue had a positive correlation. The reverting speed and revenue showed a negative correlation. The short-term volatility had a positive correlation toward the fluctuation range of the revenue. The simulation results indicate that this enhanced method can produce more accurate information for a better assessment of the PPP project under a wide range of uncertainty scenarios, allowing for the best decision making by the government. Full article
(This article belongs to the Special Issue Design, Operation and Economics of Wastewater Treatment Plant)
Show Figures

Figure 1

Article
Performance Simulation and Assessment of an Appropriate Wastewater Treatment Technology in a Densely Populated Growing City in a Developing Country: A Case Study in Vientiane, Laos
Water 2019, 11(5), 1012; https://doi.org/10.3390/w11051012 - 15 May 2019
Cited by 8 | Viewed by 1675
Abstract
The fast-growing population in Vientiane, the capital of Laos, has resulted in increasing domestic wastewater generation, which directly impacts the urban water environment due to the lack of a suitable wastewater treatment system. This study aims to assess six wastewater treatment alternatives based [...] Read more.
The fast-growing population in Vientiane, the capital of Laos, has resulted in increasing domestic wastewater generation, which directly impacts the urban water environment due to the lack of a suitable wastewater treatment system. This study aims to assess six wastewater treatment alternatives based on two technologies—trickling filter and activated sludge—used for on-site, decentralized, and centralized wastewater treatment systems to support decision-making for selecting the most suitable and practical alternative for wastewater treatment in Vientiane. To determine the most appropriate treatment system, the wastewater treatment process simulation with BioWin and the technique for order preference by similarity to ideal solution (TOPSIS) method are applied to assess the removal efficiencies for biochemical oxygen demand (BOD), chemical oxygen demand (COD), and total suspended solids (TSS), as well as to rank the six wastewater treatment technologies based on the following four environmental criteria: (1) land requirement, (2) electricity use, (3) sludge production, and (4) CO2 emissions. The BioWin results illustrate that the capacity of each alternative is similar in terms of domestic wastewater treatment efficiency, while differing in terms of environmental impacts. In addition, the alternative ranking shows that a centralized wastewater treatment system with a trickling-filter process is more suitable than on-site and decentralized wastewater treatment systems based on their environmental impacts. This finding provides evidence for decision-makers to select a suitable alternative for wastewater treatment in order to promote access to safe sanitation and sustainable urban wastewater management in Vientiane, Laos. Full article
(This article belongs to the Special Issue Design, Operation and Economics of Wastewater Treatment Plant)
Show Figures

Figure 1

Back to TopTop