Sustainable Wastewater Treatment Systems Research Articles

Enhancing Decision Fusion for Wastewater Treatment System Selection Using Monte Carlo Simulation and Gray Analytic Hierarchy Process

This research presents an innovative data fusion model that utilizes Monte Carlo simulations (MC) and the Gray Analytic Hierarchy Process (G-AHP) to address the complexity and uncertainty in decision-making processes, particularly in selecting sustainable wastewater treatment systems. The study critiques and extends the Dempster–Shafer and Yager’s theories by incorporating a novel MC algorithm that mitigates the computational challenges of large numbers of experts and sensors. The model demonstrates superior performance in synthesizing diverse expert opinions and evidence, ensuring comprehensive and probabilistically informed decision-making under uncertainty. The results show that the combined MC algorithm produces satisfactory results, and thus, offers wide applicability in decision-making contexts. To determine its effectiveness, an extensive empirical study was conducted to identify an appropriate wastewater treatment system for the busy city of Tehran, incorporating the insights and perspectives of respected experts in the field. The selection was based on three technical, economic, and environmental–social criteria. Due to the large dimensions of each of the defined criteria, sub-criteria were also defined to achieve better results for each of the criteria. The in-depth analysis conducted revealed that enhanced aeration activated sludge (EAAS) emerged as the best choice for Tehran’s most urgent needs among various competitors, with a remarkable priority rating of 34.48%. Next, the Gray Analytic Hierarchy Process (G-AHP) was used to determine the most important sub-criterion, based on which resistance to hydraulic shock is most important in the enhanced aeration activated sludge system. Due to its versatility in different fields and industries, this method is a powerful tool for managers to optimize system efficiency and identify defects and risks and eventually to minimize costs.

Investigating the sustainability of biogas recovery systems in wastewater treatment plants- A circular bioeconomy approach

Advanced wastewater treatment options offer a unique opportunity to recover valuable resources such as energy (biogas), nutrients, and minerals embedded in the wastewater streams. However, considerable challenges remain when designing and planning sustainable wastewater treatment systems. This study aims to evaluate the sustainability of waste-to-energy (WtE) recovery in the form of biogas in a wastewater treatment plant (WWTP). The study investigates the performance of a biogas recovery system in different scenarios and applications from 2018 to 2040, considering the city of Tbilisi in Georgia. The study results reveal a significant biogas production potential, with an average annual energy (heat and power) generation of 137 GWh when biogas is recovered from the wastewater (WW) and sewage sludge (SS). The WWTP-based WtE systems can avoid up to 38,500 tCO2eq emissions every year. The combined recovery (from WW and SS) scenario is financially feasible with a net present value of 14.88 million EUR and a levelized cost of biogas of 0.08 EUR/m³. Recovered biogas can help avoid the usage of 172.34 million m³ of natural gas worth 42.4 million EUR. Sensitivity analysis shows that the quality of wastewater, price of energy, and capital cost of the anaerobic digestion plant are the key factors in determining the economics of WtE recovery systems. This research also demonstrates the interlinkages between sustainable development goals and various benefits of resource recovery systems. This study could be helpful for decision-makers involved in planning and deploying resource recovery systems in a circular bioeconomy approach in WWTPs globally.

The Design of a Sustainable Industrial Wastewater Treatment System and The Generation of Biohydrogen from E. crassipes.

Water scarcity is a significant global issue caused by the prolonged disregard and unsustainable management of this essential resource by both public and private bodies. The dependence on fossil fuels further exacerbates society's bleak environmental conditions. Therefore, it is crucial to explore alternative solutions to preserve our nation's water resources properly and promote the production of biofuels. Research into the utilization of E. crassipes to remove heavy metals and generate biofuels is extensive. The combination of these two lines of inquiry presents an excellent opportunity to achieve sustainable development goals. This study aims to develop a sustainable wastewater treatment system and generate biohydrogen from dry, pulverized E. crassipes biomass. A treatment system was implemented to treat 1 L of industrial waste. The interconnected compartment system was built by utilizing recycled PET bottles to generate biohydrogen by reusing the feedstock for the treatment process. The production of biological hydrogen through dark fermentation, using biomass containing heavy metals as a biohydrogen source, was studied. Cr (VI) and Pb (II) levels had a low impact on hydrogen production. The uncontaminated biomass of E. crassipes displayed a significantly higher hydrogen yield (81.7 mL H2/g glucose). The presence of Cr (IV) in E. crassipes leads to a decrease in biohydrogen yield by 14%, and the presence of Pb (II) in E. crassipes leads to a decrease in biohydrogen yield of 26%. This work proposes a strategy that utilizes green technologies to recover and utilize contaminated water. Additionally, it enables the production of bioenergy with high efficiency, indirectly reducing greenhouse gases. This strategy aligns with international programs for the development of a circular economy.

Sustainable municipal wastewater treatment using an innovative integrated compact unit: microbial communities, parasite removal, and techno-economic analysis

BackgroundThe upflow anaerobic sludge blanket (UASB) reactors rely on bacterial communities to break down pollutants in wastewater (municipal or industrial).Methods and resultsIn this study, a novel combination of UASB followed by aerobic treatment has been proposed for the treatment of municipal wastewater focusing on bacterial communities using high-throughput sequencing and parasite removal in this novel combination of reactors. Moreover, economic estimation of the compact unit composed of two overlapping UASB reactors, followed by a downflow hanging non-woven fabric (DHNW) reactor, the anaerobic baffled reactor (ABR), and chlorine unit was investigated in this study based on community populations of 1000 and 10,000 inhabitants, with a municipal plant capacity of 54,000 and 540,000 m3/year. Cost estimation was conducted based on two scenarios, one considering the contingency cost and auxiliary facility, and the other excluding them. Non-metric multidimensional scaling (nMDS) revealed that the treatment stages structured the microbial communities. Proteobacteria was the most prevalent phylum in all treatment stages, followed by Bacteroidota in most stages. Firmicutes and Actinobacteria were also present in significant amounts. The treatment system achieved from 40 to 66.67% removal of parasites (parasitic nematode, Cryptosporidium, and microsporidia). Redundancy analysis (RDA) indicated a strong positive correlation between chemical and biological oxygen demand (COD/BOD) with Campylobacterales and could be used as a bioindicator of treatment performance.ConclusionThese findings can inform the development of more efficient and sustainable wastewater treatment systems that take into account microbial ecology and economic considerations.

A state-of-the-art review and guidelines for enhancing nitrate removal in bio-electrochemical systems (BES)

Excess unmanaged nitrogen pollutes the environment. A sustainable wastewater treatment system must achieve better pollutant removal efficiency at a lower cost, and the feasibility of integrating biological nitrogen removal into bio-electrochemical systems (BES) has been reported as a tool in green technology. Nitrogen in the form of nitrate (NO3) is a common pollutant in both surface and ground waters, and a high level of NO3 makes water unsuitable for drinking water. This analysis and review of BES for treating NO3 polluted water investigate BES's components and operational factors and their importance on the NO3 removal efficiency to design more powerful but economic systems. The NO3 removal efficiencies were analyzed by the influence of electrode materials, working mode, number of chambers, type of inoculum, capacity, and microbial community structure. Overall, the electrode materials, significantly influence the NO3 removal rate. The operational parameters, such as working mode, the number of chambers, inoculum type and the systems' capacity, were deemed important and have significantly influenced the NO3 removal efficiencies when analyzed by the random forest classification algorithm. Proteobacteria and Firmicute were the prominent phyla observed in BES treating NO3 polluted water. Besides the denitrification (abundance of narG, nirS, nirK, nosZI, and nosZII genes) process in BES, there is evidence of electrochemical support for anaerobic ammonium oxidation (ANAMMOX) (abundance of hzsB or ANAMMOX-specific 16S rRNA genes) and dissimilatory NO3 reduction to ammonium (DNRA) (abundance of nrfA genes) processes. Our analysis suggest that BES, as a continuous two-chamber system with cathode and anode materials as granular carbon and carbon paper, respectively, with denitrifying microbes as inoculum type, would contribute to optimum NO3 removal efficiencies.

Role of constructed wetlands in mitigating the challenges of industrial growth and climate change impacts in the context of developing countries

One of the most persistent issues affecting individuals in developing countries is the lack of access to safe drinking water and sanitary facilities. The adoption of centralized water, energy, and cost-intensive technology has proven ineffective in addressing the complex water-related challenges that have arisen as a consequence of growing urbanization in developing nations. Constructed wetlands have emerged as an effective wastewater treatment solution with natural applications. The fundamental goal of this study is to offer a complete overview of the wide variety of practices, uses, and investigations of constructed wetlands systems for eliminating different pollutants from wastewater in developing countries leading to placing them in the context of climate change, environmental resource planning, and sustainable wastewater treatment systems. CWs offer significant levels of treatment performances with hybrid systems achieving contaminant removal efficiencies up to 93.82% for total suspended solids, 85.65% for chemical oxygen demand, and 80.11% for ammonia nitrogen which is adequate with respect to other viable alternatives. In terms of Biological Oxygen Demand (BOD5), the highest elimination (84.06%) was achieved in hybrid systems when compared to Free water surface CWs (65.34%), Horizontal sub-surface CWs (75.1%), and Floating treatment wetland (55.29%). The maximum power density generation through the microbial fuel cell-based constructed wetlands ranges between 50 and 86 mW/m2in Bangladesh (integrated tidal flow) and 852 mW/m3in China (vertical flow), and the production of bioenergy has been evidenced up to 1,836.5 GJ/hector/year. Annually, wastewater treatment plant systems (WTPs) generate around a hundred times more Methane (CH4), Nitrous oxide (N2O), and carbon dioxide (CO2) than CWs. In metropolitan cities, WTPs may lead to a considerable increase in upstream land use, which could be minimized by promoting CWs in these areas. The potential utility of different CWs in protecting and preserving estuarine quality within the present regulatory framework is finally addressed in the study, emphasizing that it can balance the impacts of industrial expansions in developing countries for subsequent mitigation and adaptation to climate change.

Selective separation of volatile fatty acids, nitrogen and phosphorus from anaerobic acidogenic fermentation via forward osmosis membrane process

Selective separation and recovery of volatile fatty acids (VFA) and other valuable resources promotes a sustainable wastewater treatment system, but its cost-effective separation approaches are poorly understood. This study investigated the feasibility of applying a forward osmosis (FO) dewatering process for the selective separation of VFA, ammonium and phosphate from anaerobic acidogenic fermentation. Limited VFA rejection of fermentation broth, i.e., less than 20 %, was observed under acidic conditions, while the rejection rate was significantly increased to ∼90 % at neutral pH. The transfer of ammonium across the membranes was remarkably impacted by the feed solution pH. Lower pH (∼4) values resulted in higher rejection rates of ammonium (∼96 %), and the rate gradually declined as pH increased. The rejection of phosphate, which remained higher than 98 %, was less sensitive to pH variations. The increase in water flux promoted the rejection of VFA, ammonium and phosphate, and the membrane orientation significantly impacted the transfer of nutrients in the FO process. The active layer facing the feed solution (AL-FS) mode exhibited higher rejection rates of VFA, ammonium and phosphate than the active layer facing the draw solution (AL-DS) mode, which was ascribed to the internal concentration polarization effect. Furthermore, approximately 80 % of water could be effectively reduced from a real acidogenic fermentation liquor during the FO process; ammonium and phosphate were 3.72-fold and 4.10-fold concentrated in feed solution, respectively, and VFA was selectively separated in draw solution. The work confirmed the feasibility of utilizing FO processes in separating and enriching VFA, ammonium and phosphate from anaerobic fermentation liquors, providing meaningful information on promoting FO-based processes in treating wastewater.

Investigating public awareness towards wastewater management in a small community

<p>A critical element for the successful management of wastewater is the active participation of residents in all stages of treatment in order to ensure public acceptance. The primary purpose of this study is to identify and analyze the specific views and attitudes of the inhabitants of Leros Island, Greece, regarding (a) the performance of the wastewater treatment plant (WWTP) operating on Leros Island and (b) their level of awareness on and (c) their willingness to accept a natural wastewater treatment system. This study also emphasizes the significance of a participatory approach to construct sustainable wastewater treatment systems in small communities. Results show an apparent lack of information regarding natural wastewater treatment systems for all respondents, and it turns out that a high level of education does not necessarily mean higher awareness of alternative wastewater treatment methods nor greater acceptance of innovative wastewater treatment systems. Age showed a significant correlation with social acceptance of alternative ways of waste treatment, with people over the age of 56 shown to be most willing to apply a natural wastewater treatment system in remote areas of the Leros island. Environmental awareness policies could contribute to more sustainable community wastewater management.</p>

Insights on microbial fuel cells for sustainable biological nitrogen removal from wastewater: A review.

Microbial fuel cells (MFCs) have emerged as a promising technology for energy-efficient wastewater treatment. The feasibility of integrating biological nitrogen removal into MFC systems has been reported. However, better pollutant removal efficiency and power production need to be achieved at a lower cost for a sustainable wastewater treatment system. The objective of this paper is to critically review the nitrogen removal process in various MFC configurations, factors that influence this process, and challenges that should be overcome in future studies. Based on the results of the review, shortcut nitrification-autotrophic denitrification in an MFC is an option as it minimizes the aeration energy and C/N ratio requirement; however, it is necessary to evaluate the N2O emission further. Another attractive option is the heterotrophic anodic denitrification process as it demonstrates the potential for free-buffer MFCs, but the nitrogen removal efficiency at low C/N ratios needs improvement. Bacteria population in MFC system also plays an essential role in both contaminant removal and electricity generation. It can be concluded that MFCs can be a low cost, sustainable solution for the treatment of wastewater and removal of nitrogen. Moreover, selection of MFC configuration will depend on the nature of the wastewater.

Recent Advances in Polymer-based 3D Printing for Wastewater Treatment Application: An Overview

The introduction of Industrial Revolution (IR) 4.0 has signalled a transformation of traditional manufacturing landscape to intelligent production systems and advanced technologies. Additive manufacturing (AM) is a vital element in this latest revolution due to its remarkable potential in providing a green fabrication alternative with advanced design flexibility that surpasses the traditional manufacturing methods. At present, polymer-based additive manufacturing has drawn considerable interest in wastewater research due to its notable design freedom in manufacturing of novel, geometrically complex, and porous structures used in membrane modules and spacers, adsorption, advanced oxidation process, bioreactor, and microfluidic technology. In this work, recent advances of additively manufactured polymeric materials and 3D printing techniques used for various wastewater research are reviewed. Furthermore, the challenges in the fabrication techniques are assessed, alongside with the discussion on future perspectives of polymer-based AM technologies to develop a versatile and sustainable wastewater treatment system at commercial scale.

Removal of triclocarban from treated wastewater using cell-immobilized biochar as a sustainable water treatment technology

Triclocarban (TCC), an emerging endocrine disruptor, has been commonly found in municipal treated wastewater. Pseudomonas fluorescens MC46 (MC46), an effective TCC-degrading bacterium, could be applied to remove TCC from wastewater. In addition, application of a cell immobilization technique could possibly enhance its removal performance. This study examined microbial cells immobilized on waste biochar (from wood vinegar production) as a highly effective advanced wastewater treatment unit for TCC removal. TCC removal was investigated from real wastewater samples using the following treatments: biochar only, cell-immobilized biochar, and free cell systems in batch (short-term) and semi-batch (long-term) modes. The TCC adsorption capacities of original and potassium hydroxide-modified biochars (no cells) were 8.43 and 9.17 mg/g, respectively. During the batch experiment, the cell-immobilized modified biochar exhibited the highest TCC removal, 79.80%, in the model TCC solution. Five-cycle semi-batch experiments were utilized to investigate the reusability and performance of the treatment systems. After five cycles, the cell-immobilized modified biochar still achieved stable TCC removal (52%) due to the integration of adsorption and biodegradation. Free MC46 cells and biochars (no MC46 cells) only removed 32% and 2% of TCC, respectively, due to cell washout/death and sorbent exhaustion. This important work clearly demonstrates the significant potential for the future utilization of cell-immobilized biochars in a sustainable wastewater treatment system. Furthermore, the use of renewable agro-industrial wastes aid in the development of a strong circular bio-based economy.

Sustainability Study of In-situ Hydroponic Vetiver System for Urban Wastewater Management in Developing Countries: A Theoretical Review

Urban wastewater management is a crucial challenge in the small and medium towns situated in the developing countries worldwide. These towns are also facing an increasing gap between infrastructure and population growth. A conventional approach to curb these problems is the application of cost-intensive electro-mechanical sewerage technologies, as adopted in developed countries. The first part of this paper derives a set of indicators to framework a sustainable urban wastewater treatment system by reviewing the current state of wastewater management in developing countries, for example, the sample case study being India. The second part evaluates the potential performance of the proposed alternative in-situ hydroponic vetiver system (HVS) against those set of sustainability indicators by reviewing the worldwide performance of the HVS. The objective of this paper is to assess the potential viability of the HVS as a sustainable and cost-effective alternative for developing countries. The current analysis can aid in mainstreaming the use of HVS in policy making and urban planning.

An efficient oxic-anoxic process for treating low COD/N tropical wastewater: Startup, optimization and nitrifying community structure

In this study, we assessed and optimized a low-dissolved-oxygen oxic-anoxic (low-DO OA) process to achieve a low-cost and sustainable solution for wastewater treatment systems in the developing tropical countries treating low chemical oxygen demand-to-nitrogen ratio (COD/N) wastewater. The low-DO OA process attained complete ammonia removal and the effluent nitrate nitrogen (NO3–N) was below 0.3 mg/L. The recommended hydraulic retention time and sludge retention time (SRT) were 16 h and 20 days, respectively. The 16S rRNA sequencing data revealed that long SRT (20 days) encouraged the growth of nitrite-oxidizing bacteria (NOB) affiliated with “Candidatus Nitrospira defluvii”. Comammox made up 10–20% of the Nitrospira community. NOB and comammox related to Nitrospira were enriched at long SRT (20 days) to achieve good low-DO nitrification performance. The low-DO OA process was efficient and has simpler design than conventional processes, which are keys for sustainable wastewater treatment systems in the developing countries treating low COD/N wastewater.

Ensuring sustainability of conventional aerobic wastewater treatment system via bio-augmentation of aerobic bacterial consortium: An enhanced biological phosphorus removal approach

Enhanced biological phosphorus removal (EBPR) is an inevitable need of sustainable waste water treatment systems (WWTS). In this regard, this study aimed to investigate the potential of an aerobic continuously stirred tank reactor (CSTR), enriched with selected bacterial consortium, for enhanced phosphorus removal. The CSTR biomass was bioaugmented through addition of 12 distinct phosphorus accumulating and solubilizing strains. The medium and high strength synthetic waste water, having the phosphorus concentration in the range of 1.4–40 mg/L, was fed to the CSTR throughout this study. With respect to medium strength feed, total phosphorus (TP) removal efficiency reached up to 90% at an influent concentration of 20 mg/L, followed by a declining trend of removal efficiency as 62 and 30%, at the TP concentration of 30 and 40 mg/L, respectively. Contrary, the EBPR activity was observed to be inhibiting (lesser accumulation of phosphorus in biomass) at lower influent TP value of 10 mg/L, when the CSTR was operated with high strength waste water. Further, ammonical nitrogen and chemical oxygen demand removal performance of the system was observed to be independent of influent TP concentration. Detailed experimental investigations revealed that the inoculated bacterial consortium favored the transformation and storage of influent TP into intracellular storage of polyphosphate (poly-P). Overall, the results indicated that the sustainability of existing WWTS can be ensured through bioaugmentation of non-EBPR sludge to aerobically cultivated EBPR performing sludge.

Sustainable Wastewater Treatment Systems (2018–2019)

An important part of the environmental degradation suffered by the planet is caused by the discharge of untreated or poorly treated wastewater. Industrial, urban, and agricultural wastewater contain many different types of pollutants such as biodegradable and nonbiodegradable organic matter, suspended solids, turbidity, nutrients, heavy metals, pesticides, pathogens, etc. All of these pose a threat to the environment and human health, so the selected treatment techniques must be adapted to their nature in order to optimize their removal. In addition to efficiency, wastewater treatment methods must be sustainable, not only from an environmental point of view, but also economically and ethically. As a result, no technological dependence should be generated in less developed countries or communities. Therefore, this Special Issue deals with improvements in various aspects of wastewater treatment including different aspects of water treatment such as the development of mathematical models, the application of life cycle techniques, or the experimental optimization of wastewater treatment methods. Thirteen articles were accepted covering some of the most relevant fields of wastewater treatment: activated sludge, nanoparticle treatment, constructed wetlands, energy–water nexus, nutrient recovery, eco-friendly sorbents, and reverse osmosis.

Development and adoption of wastewater treatment system for peri-urban agriculture in Multan, Pakistan.

The present research was conducted to assess the feasibility of biological treatment of a typical wastewater (WW) stream in Multan, Pakistan, using daily trends of WW characteristics and to design a wastewater treatment (WWT) system for that stream. The pH (5.8-6.2), temperature (24-30 °C), biological oxygen demand (BOD5: 128-265 mg/L), ultimate BOD (BODu: 227-438 mg/L), BOD/total Kjeldahl nitrogen (BOD5/TKN:5.9-11.2), BODu/BOD5 (1.6-2.0), carbonaceous BODu/nitrogenous BODu (CBODu/NBODu:1.6-2.8) of the WW was found to support the biological WWT. The inclusion of NBOD also indicated the need for nitrification-denitrification. The linear regression analysis of volatile suspended solids (VSS) with total suspended solids (TSS) indicated the high content of organic solids, which also made the WW suitable for biological treatment. The BOD/COD (chemical oxygen demand) <0.8 indicated the requirement for biomass acclimation. The major process units of the WWT system developed included a primary clarifier, cascade aeration, trickling filter, adsorption filter and chlorination contact tank. During the validation of design procedures, considerable removal of TSS (91%), TDS (46%), BOD5 (88%), COD (87%) was observed over the 15 week operational period of the secondary WWT system. The WWT system developed was appropriate as a sustainable WWT system that consumed less energy and had lower operational costs.

Membrane Distillation Biofouling: Impact of Feedwater Temperature on Biofilm Characteristics and Membrane Performance.

Membrane distillation (MD) is a temperature driven membrane separation technology that holds great potential for decentralized and sustainable wastewater treatment systems. Yet, similarly to all membrane based systems, microbial fouling (biofouling) might be a critical hurdle for MD wastewater treatment applications. In this study we determined the impact of increasing feedwater temperatures (47 °C, 55 °C, and 65 °C) on biofilm growth and MD performance via dynamic biofouling experiments with Anoxybacillus sp. as a model bacterium. Our results indicated that cell growth was reduced at 47 °C, resulting in moderate distillate water flux decline (30%). Differently, extensive growth of Anoxybacillus sp. at feedwater temperature of 55 °C caused severe distillate water flux decline (78%). Additionally, biofouling induced membrane wetting, which facilitated the passage of bacteria cells and endospores through the membrane structure into the distillate. Although bacterial growth was impaired at feedwater temperatures of 65 °C, excessive production of EPS (compared to bacterial abundance) crippled membrane separation due to severe pore wetting. These results underline the importance of optimized operating conditions and development of antibiofouling and antiwetting membranes for successful implementation of MD in wastewater treatment with high biofouling propensity.

Integrating bioelectrochemical systems for sustainable wastewater treatment

Current wastewater treatment processes such as activated sludge process and other aeration technologies are resource-consuming and are unsustainable. Novel and integrated processes are crucial to the development of sustainable wastewater treatment systems. In this context, anaerobic treatment technologies provide numerous opportunities for minimization of energy and resource consumption and maximization of beneficial products. Further, integration of anaerobic digestion augmented by co-digestion, fermentation, dark fermentation or photo-fermentation and other bioelectrochemical systems may result in resource-efficient waste management and environmental protection. This mini-review discusses various possibilities and highlights recent developments of integrated aerobic and anaerobic technologies with bioelectrochemical systems for sustainable wastewater treatment.

Adaptable wind/solar powered hybrid system for household wastewater treatment

Sustainable and cost-effective water treatment systems are critical elements to developing nations. In India, the human population is escalating while the water availability is lagging behind. An adaptable, affordable, and sustainable wastewater treatment system powered by wind/solar energy is proposed based on proven theory and technology. A household in India is singled out to illustrate the workings of the proposed system, where the wastewater is recirculated through a hybrid of water purifiers powered by solar/wind energy. The system demonstrated here is specifically designed for small-scale applications, i.e., for a single household. The solar still has been divided into four stages. Partial vacuum is created inside the still so as to obtain boiling point temperatures of 70°C, 67°C, 62°C and 50°C in the four stages. Dhanbad, India 23.79°N, 86.43°E, with an average solar intensity of 850W/m2 for 6h a day, has been used for this study. A lumped parameter mathematical model was developed for this study. With an aperture area of 2.5m2, the total amount of water distilled is found to be 43.3kg/day. The system proposed is more efficient than existing systems as it is able to achieve efficiencies as high as 53%. The effect of wind speed on distillate output yield has also been discussed.

Comparative Study of Photocatalytic Fuel Cell for Degradation of Methylene Blue under Sunlight and Ultra-Violet Light Irradiation

Photocatalytic fuel cell is considered as a sustainable wastewater treatment system which could degrade organic pollutants and generate electricity simultaneously. In this study, a single-chambered photocatalytic fuel cell based on immobilized ZnO/Zn photoanode was evaluated under sunlight and UV light irradiation, respectively. Methylene blue was used as the dye pollutant in the photocatalytic fuel cell. The fabricated ZnO/Zn photoanode was characterized using scanning electron microscopy and X-ray diffraction. Significant difference in degradation efficiency of methylene blue was observed under UV and sunlight irradiation, respectively. Results showed that the decolorization efficiency and electricity generation of methylene blue in PFC and photolysis were higher under sunlight irradiation compared to those of the UV light irradiation. The decolorization trend of methylene blue was unstable under photolysis using UV light irradiation. Under sunlight irradiation, about 85% of methylene blue was decolorized by PFC, but only 35% of decolorization was observed under UV light irradiation. The maximum power density of the PFC under sunlight irradiation (0.0032 mW/cm2) was almost two times of that under the UV light irradiation (0.0017 mW/cm2).