In this study, the environmental impacts were assessed for five municipal solid waste (MSW) treatment processes with energy recovery potential. The life cycle assessment (LCA) tool was used to ...quantify the environmental impacts. The five processes considered are incineration, gasification, anaerobic digestion, bio-landfills, and composting. In addition, these processes were compared to recycling where applicable. In addition to environmental impacts quantification, the energy production potentials for the five processes were compared to provide a thorough assessment. To maximize the future applicability of our findings, the analyses were based on the waste treatment technologies as they apply to individual waste streams, but not for a specific MSW mixture at a particular location. Six MSW streams were considered; food, yard, plastic, paper, wood and textile wastes. From an energy recovery viewpoint, it was found that it is best to recycle paper, wood and plastics; to anaerobically digest food and yard wastes; and to incinerate textile waste. On the other hand, the level of environmental impact for each process depends on the considered impact category. Generally, anaerobic digestion and gasification were found to perform better environmentally than the other processes, while composting had the least environmental benefit.
•Five municipal solid waste treatment processes were investigated.•The life cycle assessment (LCA) tool was used to quantify the environmental impacts.•The energy potential of the treatment processes was also studied.•Processes are incineration, gasification, anaerobic digestion, bio-landfills, and composting.•Anaerobic digestion and gasification were found to perform better environmentally.
•Timeline of MD’s growth and development with major milestones.•Systematic map review of MD publications between 1960 and 2016.•MD practitioners’ survey on future application and research ...areas.•Alignment between MD researchers and industry for MD commercialization examined.
Research on membrane distillation (MD) experienced a slow growth from the 1970s through 90s but has gained revived interest recently. Despite recent developments, MD still has to overcome several hurdles to pave its path to successful commercialization. This article presents a systematic map review of all research publications available in the ScienceDirect database from 1970 to 2016 focusing on the key aspects of MD publication trends, applications, research topics and the studied membrane materials and configurations. The gathered information was compared with MD implementation trends to assess the alignment of academia and industry towards MD commercialization. A select group of MD experts, both from academia and industry, were then surveyed for their perspective on the future for MD commercialization. While desalination is the most studied MD application so far, brine concentration was unanimously identified as the most likely future application for MD. Industry experts believe topics of practical significance, such as fouling and wetting, deserve more research focus. On the contrary, improving energy efficiency in MD was the top pick by academic experts. The most researched topic, development of novel MD membranes, was at odds with the key research topics identified by the industry and research experts for MD’ growth and development.
Utilizing low enthalpy geothermal resources in various applications, including desalination, has triggered continuously growing interest in the past decade. This work offers a preliminary ...techno-economic evaluation of coupling a low-enthalpy geothermal resource, commonly found in regions such as the Arabian Gulf countries, and a suitable desalination technology. The desalination processes chosen, multiple effect distillation (MED) and reverse osmosis (RO), were designed as integrated energy–water systems and were compared and assessed in terms of their levelized cost of water produced. It was found that geothermal RO could potentially be a more cost-effective option for seawater geothermal desalination in the Gulf Cooperation Council (GCC) countries, based on our model results. A number of parameters, which can potentially alter the results of the analysis, were chosen to investigate their effect on the LCOW of the proposed schemes. These parameters include feed water quality, operational lifetimes of both the geothermal and desalination systems, quality of the geothermal resource, cost of well-drilling and finally, reinjection temperature of the utilized geofluid. By varying their values, the robustness of our initial model results was assessed.
•Techno-economic analysis of RO and MED using low enthalpy geothermal energy•A cost model was developed for estimation of the LCOW of each scheme.•RO is more cost-effective than MED when driven by the same geothermal source.•Sensitivity analysis conducted to study the effect of several parameters on LCOW•Quality and utilization efficiency of the geothermal resource affect LCOW the most.
Membrane distillation (MD) has become an area of rapidly increasing research and development since the 1990s, providing a potentially cost effective thermally-driven desalination technology when ...paired with waste heat, solar thermal or geothermal heat sources. One principal challenge for MD is scaling and fouling contamination of the membrane, which has gained growing attention in the literature recently as well. The present paper surveys the published literature on MD membrane fouling. The goal of this work is to synthesize the key fouling conditions, fouling types, harmful effects, and mitigation techniques to provide a basis for future technology development. The investigation includes physical, thermal and flow conditions that affect fouling, types of fouling, mechanisms of fouling, fouling differences by sources of water, system design, effects of operating parameters, prevention, cleaning, membrane damage, and future trends. Finally, numerical modeling of the heat and mass transfer processes has been used to calculate the saturation index at the MD membrane interface and is used to better understand and explain some of trends reported in literature.
•Review: temperature, flow rate, SI, feed type, specific salt effects in MD fouling•Module type, and temperature and concentration polarization greatly affect fouling.•High temperature prevents MD biofouling.•Particulate fouling can be easily avoided by microfiltration.•Reducing feed pH, membrane superhydrophobicity, and antiscalants prevent MD scaling.
In this study, we examined the current status of food waste management in the hospitality sector, taking the United Arab Emirates, in general, and Abu Dhabi, in particular, as examples. We ...specifically studied the for-profit subdivision of the hospitality sector, comprising primarily of hotels and restaurants. First, we surveyed the management staff of 45 hotels/restaurants, in order to understand how much food waste is generated and how food service operations can impact food waste production within these establishments. Then, we carried out materials flow analyses to investigate how the amounts of food waste generated varied at the different steps of the food service chain, and what factors contributed most significantly to these amounts. Water and carbon footprints of the disposed food waste at some of the events monitored were also calculated for benchmarking. We found that the factors contributing most significantly to food waste generation include serving style and timing, type of food served, and the prediction accuracy of the number of expected customers. To account for the interplay of these various parameters, a performance indicator, named the FRESH number, was introduced to rate the sustainability of food service within the hospitality sector. Finally, based on our findings, we recommended a number of minimization strategies for food waste in the hospitality sector. Simple but effective strategies, which involve the cooperation of the hotel/restaurant staff and the guests, can lead to a drastic decrease in global food waste generation.
•Current status of food waste management for the UAE hospitality sector was examined.•Materials flow analysis for a variety of events was carried out.•The carbon and water footprints of the event food waste were calculated.•Waste from serving dishes tends to be the greatest component of event food waste.•A performance indicator for the food waste sustainability at events was developed.
Thermoplasmonic effects notably improve the efficiency of vacuum membrane distillation, an economically sustainable tool for high‐quality seawater desalination. Poly(vinylidene fluoride) (PVDF) ...membranes filled with spherical silver nanoparticles are used, whose size is tuned for the aim. With the addition of plasmonic nanoparticles in the membrane, the transmembrane flux increases by 11 times, and, moreover, the temperature at the membrane interface is higher than bulk temperature.
In this work, a new protocol was developed for creating charge-tuned, hydrophilic hybrid ultrafiltration (UF) membranes with high flux, rejection rate, and fouling resistance. The membranes were ...fabricated using a combination of sulfonated poly(ether sulfone) (SPES) and aminated graphene (GO-SiO2-NH2) nanohybrid via the non-solvent-induced phase separation (NIPS) method. The GO-SiO2-NH2 nanohybrid was first synthesized using GO nanosheets and 3-aminopropyl triethoxysilane (APTES) through the covalent condensation reaction at 80 °C and was thoroughly characterized. Then, 2–8 wt% of the nanohybrid was incorporated into the matrix of SPES for the fabrication of the hybrid membranes. The resulting membranes were characterized using an electrokinetic analyzer, a contact angle goniometer, and Raman, field emission scanning electron microscopy-energy-dispersive X-ray spectrometry (FESEM-EDX), and atomic force microscopy experiments. The porosity, charge density, and surface morphology were altered, and the hybrid membranes became more hydrophilic after the incorporation of the nanohybrid. The pure water flux of the hybrid membranes systematically increased with the loading amount of the nanohybrid. The pure water flux of the hybrid membrane containing 6 wt% GO-SiO2-NH2 nanohybrid at a 2 bar feed pressure was 537 L m–2 h–1, about 3-fold that of pristine membrane (186 L m–2 h–1). The fouling resistance of the hybrid membranes was evaluated and confirmed using several representative foulants, including bovine serum albumin, humic acid, sodium alginate, and a synthetic solution of natural organic matter (NOM). The fabricated membranes were capable of removing more than 97% of NOM, without a compromise of their rejection rate.
Conventional water resources in many regions are insufficient to meet the water needs of growing populations, thus reuse is gaining acceptance as a method of water supply augmentation. Recent ...advancements in membrane technology have allowed for the reclamation of municipal wastewater for the production of drinking water, i.e., potable reuse. Although public perception can be a challenge, potable reuse is often the least energy-intensive method of providing additional drinking water to water stressed regions. A variety of membranes have been developed that can remove water contaminants ranging from particles and pathogens to dissolved organic compounds and salts. Typically, potable reuse treatment plants use polymeric membranes for microfiltration or ultrafiltration in conjunction with reverse osmosis and, in some cases, nanofiltration. Membrane properties, including pore size, wettability, surface charge, roughness, thermal resistance, chemical stability, permeability, thickness and mechanical strength, vary between membranes and applications. Advancements in membrane technology including new membrane materials, coatings, and manufacturing methods, as well as emerging membrane processes such as membrane bioreactors, electrodialysis, and forward osmosis have been developed to improve selectivity, energy consumption, fouling resistance, and/or capital cost. The purpose of this review is to provide a comprehensive summary of the role of polymeric membranes and process components in the treatment of wastewater to potable water quality and to highlight recent advancements and needs in separation processes. Beyond membranes themselves, this review covers the background and history of potable reuse, and commonly used potable reuse process chains, pretreatment steps, and advanced oxidation processes. Key trends in membrane technology include novel configurations, materials, and fouling prevention techniques. Challenges still facing membrane-based potable reuse applications, including chemical and biological contaminant removal, membrane fouling, and public perception, are highlighted as areas in need of further research and development.
Polyvinylidenefluoride (PVDF) membranes were fabricated using non-solvent assisted phase inversion technique (NIPS) to ultimately create a membrane distillation (MD) membrane. No pore forming ...additives were employed, in order to maintain the pore size distribution (PSD) as narrow as possible. Instead, a 2-stage coagulation bath system was used. The effects of the CB temperature, immersion time, polymer solution concentration, and thickness of the casted PVDF membranes were investigated. Prospective membranes with a uniform and open structure on the surface and an asymmetric interconnected pore structure all through the thickness of the membranes were obtained. A narrow PSD (0.14–0.2 µm) along with a high liquid entry pressure (LEP) range of 420–570 kPa and porosity values ranging from 57% to 79% were observed in the fabricated membranes, with a contact angle variance from 100° to 127°. The synergy of hydrophobicity, mechanical strength, high LEP and a very narrow PSD made the fabricated membranes suitable candidates for MD applications. Direct Contact (DCMD) and Vacuum MD (VMD) testing using these membranes were then carried out to analyze and understand their operational MD performance. The membranes were found to yield acceptable water vapor flux in MD and a narrower PSD than commercial PVDF membranes with similar nominal pore size. The salt rejection achieved was lower than expected, which was explained based on pore wetting.
•PVDF membranes were fabricated using DIPS technique to create MD process membranes.•A 2-stage coagulation bath (CB) system with water and ethanol was used.•Narrow PSD, high LEP, mechanical strength, CA and porosity membranes were obtained.•Membranes were tested in MD giving good flux in both VMD and DCMD.
In this work, we first show the findings of autopsy performed on the membranes used in the Scarab AB® membrane distillation (MD) system at the solar MD pilot plant in Plataforma Solar de Almeria ...(PSA) in Spain. The fouling and the damage endured by the MD membranes during intermittent long-term (2010–2013) solar-powered operation in the pilot plant were assessed and characterized. Different cleaning strategies were used to remove the fouling layer and restore the membrane properties. Data regarding relevant membrane characteristics for the MD process, such as contact angle, gas permeability, porosity, liquid entry pressure, mechanical strength, etc., and their relationship with the membrane performance under MD operation were discussed and analyzed. Scanning electron microscopy (SEM) was employed to study the morphology of the fouled and cleaned membranes and characterize the membrane damage. The identified best cleaning procedure was then applied in the MD plant system at PSA. Results suggested that cleaning effectively removed a great part of the fouling and reduced the wetting of the membranes. However, this improvement was offset by the effect of inactive periods during which wetting processes were favored.
•Effects of long-term field operation on MD membranes were studied.•Changes in key membrane features due to fouling were assessed.•Different cleaning protocols were tested to restore the membrane properties.•Application of the best cleaning protocol in the field (PSA MD plant – Spain).•Cleaning proved to be effective, but inactive periods led to membrane re-wetting.
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