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Solar pond is one of the latest technologies that have been used to produce fresh water in different countries. The studied solar pond consists of a metal floor and glass walls. In this research, a mathematical model is presented with the aim of estimating salt deposition. The results show that proposed model has high accuracy. Results show that sum of square error and relative error of proposed equation are equal to 3.048E−14 and 0.11214, respectively. In addition, the p-value and square error of proposed model have been validated. Results show that p-value of temperature and shear stress has a significant contribution in salt deposition. This research shows that R-Squared of proposed model is equal to 0.9359. This value indicates good validity of the proposed model. [ABSTRACT FROM AUTHOR]

The rising global energy demand necessitates innovative solutions for harnessing renewable energy sources. Solar ponds have received attention as they present a viable means to address this challenge by absorbing and storing solar radiation. This article provides a comprehensive review of solar pond technology, including its principles, applications, heat extraction mechanisms, and approaches to optimize performance, with special attention to the salt-gradient solar pond. Additionally, the article identifies challenges that currently hinder the large-scale adoption of solar pond technology and offers recommendations for future research. By providing a detailed analysis of the current trends and future research directions, this paper seeks to contribute to the ongoing efforts to improve these systems, exploring various approaches to increase their efficiency and make them more economical and environmentally sustainable. [ABSTRACT FROM AUTHOR]

Electrogen is a microbial group that plays an important role as anodic biocatalyst of microbial fuel cells (MFCs), one of the most extensively studied microbial-based technologies for bioelectricity generation. The aims of this research were to isolate potential electrogenic bacteria from aquaculture pond sediments and conduct a thorough evaluation on the MFCs' electricity production and efficiency parameters. A total of 18 electrogenic bacteria having various electrochemical abilities was successfully isolated using thioglycollate solid media enriched with Fe3+. Five isolates (namely KCf1, KCf2, KCf4, KCf10, and KCf14) were non-pathogenic electrogens and able to produce relatively stable and high open-circuit voltage values (690–810 mV) on glucose-fed MFCs. Further evaluations on electricity production in close-circuit mode (fixed resistor technique, polarization tests, and analysis of power overshoot phenomenon) and efficiency parameters (Coulombic and energy efficiencies) showed that KCf2, molecular identified as Bacillus altitudinis AC11.2, was the most potential MFC biocatalyst among all isolates. It produced an MPP value of 67.11 mW m−2, current density of 333.03 mA m−2, and Coulombic and energy efficiency of 53.86% and 63.27%, respectively. Efforts to increase the MFC's electrical output have been done by assembling four reactors in series and parallel circuits, obtaining the maximum total voltage of 1.6–2.0 V (for series configuration). This potential output was higher than a portable zinc–carbon battery (1.5 V) and a Ni–Cd battery (1.2 V). However, the voltage reversal suffered in series circuits was another challenge in the development of MFCs for bioelectricity production, since the existence of this phenomenon due to biological factors (microbial metabolism dynamics) are not easy to be controlled. [ABSTRACT FROM AUTHOR]

The cheapest and pollution-free method of producing drinkable water is solar distillation utilizing solar stills. However, the solar stills operate at lower-than-optimal efficiency, presenting significant room for improvement. Researchers have identified various techniques, modifications, and improvements to enhance efficiency in solar distillation. Notably, a solar pond is integrated with the solar still to boost performance, with the solar pond dramatically enhancing solar efficiency. In this research, four factors were identified as significantly influencing the performance of the solar stills: the concentration of sodium chloride (NaCl) in the solar pond, mini solar pond zones connected to the solar still, and the angles of internal and external reflecting mirrors. Three levels for each parameter were chosen for our study. The Taguchi method was utilized to identify the optimum level of these four parameters that maximizes performance. The best combination for maximizing efficiency was identified as connecting the solar still to the lower converting zone of the mini solar pond, using water containing 4 kg of NaCl, setting the internal reflecting mirror at 0°, and fitting the external reflecting mirror above the solar pond at 140°. This combination achieved a daily efficiency increase to 57.14%. Theoretical values were compared with experimental outcomes, showing that the solar still operated most efficiently between 12:00 and 14:00 h. The findings suggest not only immediate applications for improving solar still designs but also a pathway for future research into cost-effective desalination processes. [ABSTRACT FROM AUTHOR]

Design of economical and effective solar ponds which are useful thermal energy storage devices, remains a huge challenge. The present work aims at investigating the thermal performance of low cost mini salt gradient solar pond. The portable pond was fabricated as a rectangular configuration having a volume of 0.5m³. Polystyrene and high density polyethylene sheets were employed for insulating the walls. The top of the pond was covered with a slender glass so that the dust accumulation could be prevented without affecting the absorption of solar radiation. Sodium chloride salt was used as the medium and the three salt gradient regions namely lower convective, non-convective, and upper convective regions were established through injection filling technique. The temperature and salt gradient data were observed experimentally for a period of 20 days at Coimbatore, India. The pond could absorb significant amount of available radiation (around 65%) and the maximum temperature of the pond was observed to be 49 °C. Frequent washing of the water surface is necessary to maintain stable salt gradient. Nevertheless, portable pond fabricated with low cost materials exhibited good potential of storing solar energy for solar thermal applications. [ABSTRACT FROM AUTHOR]

This research focuses on the influence of water turbidity on the thermal efficiency of solar ponds, innovative devices designed for the concurrent collection and storage of solar energy utilizing salinity gradients. A three-dimensional simulation approach is employed to analyze solar ponds under varying turbidity conditions, namely clear, slightly turbid, and very turbid water. The findings reveal that increased turbidity levels lead to reduced solar radiation penetration, consequently decreasing the temperature in the pond's bottom storage zone. Notably, the presence of a temperature profile across horizontal planes in solar ponds, as identified in this study, challenges the adequacy of conventional onedimensional models in explaining certain phenomena. This insight casts doubt on the widely accepted concept of distinct upper and lower convective zones within solar ponds, suggesting a need to re-evaluate this hypothesis. Moreover, the ground beneath solar ponds is posited as a potential secondary heat storage zone. The study proposes the strategic placement of heat exchangers in the central circular ground plane, just beneath the bottom of the pond. This positioning is recommended to optimize heat extraction efficiency while circumventing the placement of exchangers in the corrosive Lower Convective Zone (LCZ), thereby reducing maintenance costs. The findings underscore the necessity of considering three-dimensional aspects in solar pond analyses for a more comprehensive understanding of their thermal behavior. [ABSTRACT FROM AUTHOR]

The increasing demand for renewable and environmentally friendly energy sources is a top priority for many countries around the world. It is obvious that renewable solar energy will help to meet most of the energy demand in the coming years. A solar pond is a huge Salt artificial Lake that serves as a solar energy collection system. However, site selection is a critical factor that affects the effectiveness and lifetime of a solar pond. Here, we present an innovative methodology for site selection based on three environmental factors, including direct solar irradiance (DNI), temperature, and wind speed. Our approach uses Python programming and clustering analysis with several libraries, including Pandas, Geopandas, Rasterio, Osgeo, and Sklearn, to analyse and process data collected over a 30-year period from NASA power. This method was applied to the geographic boundaries of Egypt, but the methods can be applied to any spatial context if the same dataset is available. The results show that Egypt has a potential land area of 500 km2 suitable for solar ponds construction along the border with Sudan throughout the year, including 2000 km2 in winter (between January and March), 800 km2 in spring (between April and June), 900 km2 in summer (between July and September), and the largest area of 3700 km2 (between October and December), most of which is located in the south of the Eastern Desert and around the Nile River. Notably, the northwestern region, close to the Mediterranean Sea on the border with Libya, exhibits suitability for solar pond development, with consistent performance throughout the year. Our results provide an efficient way for GIS and data processing and could be useful for implementing new software to find the best location for solar ponds development. This could be beneficial for those interested in investing in renewable energy and using solar ponds as an efficient water treatment plant. [ABSTRACT FROM AUTHOR]

This study is an endeavour to introduce a novel approach to enhance the performance of solar collectors. The sun emits sufficient power of solar radiation to meet the demand of energy. Harvesting the renewable solar energy needs advanced technologies and requirements. Solar ponds including salinity gradient solar ponds (SGSPs) are common solar collectors. These ponds are one of the solar energy applications used for many industrial and domestic purposes. However, challenges of the conventional SGSPs such as evaporation, salt diffusion, temperature discrepancy, and layer mixing profoundly and significantly affected their expansion globally. A novel experimental solar collector configuration to overcome the challenges of the conventional solar ponds (solar collectors) is investigated, there is no water body and no salinity gradient to build; it is entirely a collector with no water body. The experimental unit was constructed in an arid area. It is basically a cylindrical tank with a total depth of 1.4 m with three zones or layers to store heat namely, paraffin wax layer (10 cm thickness). The paraffin layer was covered with a layer of coal with a thickness of 30 cm. On the top of coal layer, an air gap with a thickness of 80 cm was left. A clear plastic cover with a thickness of 0.2 cm was utilized to cover the constructed layers and making the air gap. The experimental unit was monitored, and temperature measurements were collected for the period of 17/7/2021-30/9/2021. The results demonstrated that temperature of the paraffin wax layer reached more than 48 °C in a short period and with a small day and night discrepancy (1 °C). Temperature of the paraffin layer remained constant around 43 °C even in night-time during the period of the study. Furthermore, the results showed that temperatures of coal layer and air gap reached the maximum at the daytime of 53 °C and 71 °C respectively with a clear discrepancy between day and night. The results of the present study are encouraging for more investigations in this new direction of solar collectors. [ABSTRACT FROM AUTHOR]

In this research, the efficiency of a solar distillation system as a passive technique in the process of water distillation from wastewater was investigated. The solar distillation process is proposed as a desalination process with zero discharge (ZD), in order to prevent salt water from entering to the sea and using salt water. In this study, three solar ponds with three different floors were used. Laboratory data show that the density of wastewater varies between 1.09 and 1.27 g/cm3 when using simple flooring. The amount of density changes when using floor covering made of nanozinc oxide is between 1.05 and 1.21 g/cm3. Laboratory data show that changes in density when using flooring made of nanoaluminum oxide are between 1 and 1.17 g/cm3. The laboratory results show that heat capacity of the wastewater decreases with increase in the depth of the effluent. Results show that flooring made of nanoaluminum oxide increases the rate of evaporation by about 17% and flooring made of zinc oxide by about 11%. [ABSTRACT FROM AUTHOR]

Featured Application: The present paper evaluates 10 alternative shoreline pond electrode station designs using frames in a linear arrangement of electrodes for HVDC interconnections, against the typical design, according to CIGRE B4.61/2017 (parallel arrangement of electrode frames, with respect to the longitudinal axis of the breakwater), studying it from the point of view of electric field analysis (with emphasis on the near-field). During the design of a shoreline electrode station for High-Voltage Direct Current (HVDC) interconnections, the location of the electrodes plays a critical part, especially in the development of the near-electric field. The basic structure is their linear placement, in the form of successive frames, parallel to the longitudinal axis of the breakwater, as proposed by CIGRE and implemented in existing projects. However, this arrangement requires a considerable breakwater length, which may not be permissible, as in the case of Stachtoroi, one of the two electrode stations being built for the 1 GW, ±500 kV HVDC interconnection between Crete and mainland Greece. This troubled the preliminary study team of the electrode stations, which investigated other possible configurations. In this paper, configurations of linear placements of electrode frames are studied and compared at the preliminary study level in terms of electric field effects (especially the near-field), using an analytical simplified model and the superposition method, to determine the most appropriate arrangement of electrodes that will cover the respective requirements of CIGRE directives B4.61/2017. These arrangements are practically evaluated for two different electrode station locations at Korakia in Crete and at Stachtoroi in Aegina for the Crete–mainland-Greece interconnection, resulting in interesting alternative solutions. [ABSTRACT FROM AUTHOR]

A study has created a solar pond model. The pond's performance in terms of heat storage and electric power generation using TEG is analyzed using this model. The impact of various parameters, such as covering the pond's surface with plastic and using reflectors to focus on the intensity of solar radiation, will be investigated. A pyramidal pond with a base size of 0.64 square meters was used to validate the model. And it has a 6.25 square meter surface area. There's also a 1.35-meter depth. The walls are inclined at a 60-degree angle. TEG was also used to determine the pond's electrical capacity. The addition of a plastic cover and reflectors enhanced the efficiency of the pond's operation from 12.1% to 27.5%, according to the findings. At a lower layer temperature of 60 degrees Celsius, the electrical capacity reached 104 watts with a TEG operating efficiency of 8.9%. [ABSTRACT FROM AUTHOR]

There has been a practice of converting saltwater into potable water using solar stills for more than a century. Their production is only 2,000–5,000 mL/m² ·d, considering all the modifications. The process of production is expensive and inconvenient. The double basin solar stills are the only recommended solution to this problem. In this work, the performance of a double basin solar still with exterior reflectors, lower basin with flat plate collector (FPC) and mini solar pond has been examined and it was executed in Francis Xavier Engineering College, Tirunelveli, Tamil Nadu, India (latitude 11.9089° N, longitude 79.7589° E) with 09.00 to 19:00 h on a daily basis for a period of 20 d. Further, it has been examined whether the modifications have an impact on the effectiveness of double basin. Even in double basins, the 100 cm² × 100 cm² upper basins have a 5-step tray inside the lower basins for stability. There is a total of 25 compartments in each tray, having five portions each section. Materials, such as granite, for storing the heat is present in each unit. The yield of distilled water has been increased to 5,650 mL/m² ·d, when the external reflectors were installed. The yield has further increased to 6,249 mL/m2 ·d when the double basin solar still is connected to the FPC and small solar ponds. The overall yield due to the modifications has been increased by 127.5%. [ABSTRACT FROM AUTHOR]

A salinity gradient solar pond (SGSP) is capable of storing a significant quantity of heat for an extended period of time. It is a great option for providing hot water at a reduced energy cost. Additionally, SGSP is used in low-temperature industrial applications such as saltwater desalination, space heating, and power generation. Solar pond thermal performance is dependent on a variety of operational variables, including the soil conditions, the climate of the particular site, the thickness of the solar pond layers, the depth of the water table, and the salt content of the pond. As such, this study examines the thermal performance of a solar pond under a variety of operational conditions. The solar pond model is used to test the thermal performance by simulating two-dimensional heat and mass transport equations. The equations are solved using the finite difference technique utilizing MATLAB® scripts. Salt distributions and temperature profiles are computed for a variety of factors influencing SGSP's thermal performance. The main distinguishing variables influencing the thermal performance of SGSP are soil conditions, such as soil texture, types, the moisture level in soil, and water table depth. The final findings indicated that the fine sand dry soil performed better than the other soil types owing to its poor heat conductivity. The economic results indicated that the period of return (POR) of the intended system is around 2 years. The solar pond construction costs such as excavation, transportation, salt and lining, were considered based on the local prices. This modeled study extracted the greatest possible energy is 110W/m2, with the fine sand dry at 62.48°C lowest temperature. This study suggested that the climatic conditions of Lahore is better than climatic conditions of Islamabad. Additionally, deeper water tables are suggested for improved thermal performance of the pond. [ABSTRACT FROM AUTHOR]

Dunaliella salina (Chlorophyceae), Phormidium versicolor (Cyanophyceae), and Cylindrotheca closterium (Bacillariophyceae) were isolated from three ponds in the solar saltern of Sfax (Tunisia). Growth, pigment contents, and photosynthetic and antioxidant enzyme activities were measured under controlled conditions of three light levels (300, 500, and 1000 µmol photons m−2 s−1) and three NaCl concentrations (40, 80, and 140 g L−1). The highest salinity reduced the growth of D. salina and P. versicolor NCC466 and strongly inhibited that of C. closterium. According to ΦPSII values, the photosynthetic apparatus of P. versicolor was stimulated by increasing salinity, whereas that of D. salina and C. closterium was decreased by irradiance rise. The production of carotenoids in D. salina and P. versicolor was stimulated when salinity and irradiance increased, whereas it decreased in the diatom. Catalase (CAT), Superoxide dismutase (SOD), and Ascorbate peroxidase (APX) activities were only detected when the three species were cultivated under E1000. The antioxidant activity of carotenoids could compensate for the low antioxidant enzyme activity measured in D. salina. Salinity and irradiation levels interact with the physiology of three species that have mechanisms of more or less effective stress resistance, hence different resistance to environmental stresses according to the species. Under these stress-controlled conditions, P. versicolor and C. closterium strains could provide promising sources of extremolyte for several purposes. [ABSTRACT FROM AUTHOR]

Solar ponds are characterized by high storage capacity and the ability to provide a stable and continuous power source. Careful selection of the extraction rate helps to maintain supply temperature in a range suitable for the operation of an absorption unit. This study proposed a system in which a solar pond is coupled with an absorption chiller to investigate the resulting advantages. The chiller is cooled by using water of the upper convective zone, which ensures that the limit of deterioration of its performance is not reached and eliminates the need for an expensive cooling system. The key parameters in terms of ambient temperature, solar radiation, pond specifications, and cooling and refrigeration temperatures are investigated to optimize the proposed system design. The prediction of the model showed good agreement with the experimental results. By choosing the appropriate place to implement the system, such as the Dead Sea area, which enjoys favorable climatic conditions, it was found that a pond with an area of 3000 m2 can produce a heat rate at a temperature of 80 °C that can drive a chiller with 126.3 kW cooling capacity, with overall COP of 0.183. Based on this study, it appears that this type of system is feasible and suitable for cooling production, especially in hot regions. [ABSTRACT FROM AUTHOR]

Solar crystallizer ponds are characterized by high population density with a relatively simple community structure in terms of species composition. The microbial community in the solar saltern of Santa Pola (Alicante, Spain), is largely dominated by the hyperhalophilic square archaeon Haloquadratum walsbyi. Here we studied metatranscriptomes retrieved from a crystallizer pond during the winter of 2012 and summer of 2014 and compared Hqr. walsbyi's transcription patterns with that of the cultured strain Hqr. walsbyi HBSQ001. Significant differences were found between natural and the cultured grown strain in the distribution of transcript levels per gene. This likely reflects the adaptation of the cultured strain to the relative homogeneous growth conditions while the natural species, which is represented by multiple ecotypes, is adapted to heterogeneous environmental conditions and challenges of nutrient competition, viral attack, and other stressors. An important consequence of this study is that expression patterns obtained under artificial cultivation conditions cannot be directly extrapolated to gene expression under natural conditions. Moreover, we found 195 significantly differential expressed genes between the seasons, with 140 genes being higher expressed in winter and mainly encode proteins involved in energy and carbon source acquiring processes, and in stress responses. [ABSTRACT FROM AUTHOR]

In the direct contact membrane distillation (DCMD) system, the temperature polarization due to boundary layer formation limits the system performance. This study presents the experimental results and heat transfer analysis of a DCMD module coupled with a salinity gradient solar pond (SGSP) under three different flow channel configurations. In the first case, the feed and permeate channels were both empty, while in the next two cases, the feed and permeate channels were filled with a porous spacer material. Two different spacer geometries are examined: 1.5 mm thick with a filament angle of 65°, and 2 mm thick with a filament angle of 90°. The study considers only the heat transfer due to conduction by replacing the hydrophobic membrane normally used in a DCMD module with a thin polypropylene sheet so that no mass transfer can occur between the feed and permeate channels. The Reynolds number for all three configurations was found to be between 1000 and 2000, indicating the flow regime was laminar. The flow rate through both the feed and permeate sides was the same, and experiments were conducted for flow rates of 5 L/min and 3 L/min. It has been found that the highest overall heat transfer coefficient was obtained with the spacer of 2 mm thickness and filament angle of 90°. [ABSTRACT FROM AUTHOR]

A simple, miniature saltless Solar Pond (SP) was designed and constructed in the present work. It consisted of a Plexiglas container with a square cross-section, within which cruciform baffles were suspended in the upper half of the pond, and copper coil tubing was fitted in the middle of the lower zone to function as a heat exchanger without disturbing the pond's inertia. Different variables' effect on the water's temperature rise at various vertical locations within the pond were investigated. These variables included the presence of the cruciform baffles, the inclination of a mirror fixed to the top rim of the pond, a glass transparent cover (GC), and the presence or absence of a gel thickening material to increase the water viscosity inside the SP, the climatic conditions, and the presence of glass wool (GW) in the lower section of the SP. For an experiment, an estimated energy balance was performed, and the thermal storage efficiency was calculated. The best obtained thermal storage efficiency was 32.58% in the presence of the cruciform baffles, a 45° inclination of a mirror fixed to the top rim of the SP, at an ambient temperature of 30 °C on a calm, sunny day with a wind speed of 7 km/h. [ABSTRACT FROM AUTHOR]

The performance of solar ponds is influenced by a number of factors. The purpose of this study is to investigate the effect of the solar pond layers, as well as the climate conditions, on the temperature in the ponds bottom layer. Several analyzes were performed for this purpose employing the Taguchi method. The lower zone temperatures obtained were in a good agreement with the literature data, with an average deviation of 7.9%. The results showed that the thickness of the various layers of the solar pond, as well as the climate conditions, had a variety of effects on the operation of salinity gradient solar ponds. Furthermore, the optimum thickness of the solar pond's middle layer was calculated to be 190 cm under various conditions. Finally, using the Taguchi analysis results, equations were presented to estimate the temperature of the solar pond's lowest layer concerning the thickness of each the three layers in different climatic conditions. According to the findings of this study, the thickness of the upper layer of the solar pond had the least effect, while the thickness of the middle layer had the most effect on the maximum temperature and the annual average temperature of the lower layer. [ABSTRACT FROM AUTHOR]

Solar ponds are systems that store solar energy in salt water as heat energy. In order to store heat energy for a long time in solar pond, the heat insulation should be done well. In this study, the effect of phase change materials was investigated to improve the insulation of the pond and to store the heat energy for a longer time. The melting temperature is a key parameter in the selection of phase change materials. The temperature distribution of the solar pond was examined and phase change materials with melting temperatures in the range of the pond average temperature ±10 °C were selected. Three different phase change materials were used in the walls of the solar pond for insulation. The temperature and enthalpy changes of the system were calculated numerically for a year. The heat storage ratio of the solar pond was determined by using the obtained enthalpy and solar radiation data. Consequently, the heat storage ratio of the pond with glass-wool is maximum 20.95% in July and minimum 7.92% in January. The heat storage ratio of the solar pond which paraffin C18, capric acid and paraffin 44 are used as phase change materials is maximum 32.22%, 34.85%, and 47.81% in December, respectively. It is observed that the appropriate selection of phase change materials is provided a longer storage time for solar ponds. [ABSTRACT FROM AUTHOR]

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An experimental analysis was carried out with basin-type vertical multiple-effect diffusion solar still coupled with solar pond (BVMEDS-SP) to evaluate 24 hours overall performance of still by varying feed flow rate and temperature in addition to other affecting parameters. A solar pond was utilized to harness solar energy diurnal and the same energy was provided to basin water nocturnal in batch mode to produce distillate throughout the day. It can be seen that the daily energy and exergy performance of BVMEDS-SP having four effects was improved by 21.74% and 16.83%, respectively, when the feed flow rate was reduced from 0.32 g/m2/s to 0.13 g/m2/s. As the temperature of feed water was enhanced from 25.65°C to 32.4°C, the daily energy and exergy efficiency of BVMEDS-SP correspondingly increased by 41.76% and 46.62%. In addition, increasing the number of effects from 2 to 5 improved the overall energy and exergy efficiency to 93.15% and 171.80%, respectively. The cost analysis revealed that cost of distillate for 2-effect still was Rs. 4.64/kg and it reduced to Rs. 3.11/kg for 7-effect still. A productivity correlation was furthermore developed and estimated that the experimental database of current research was in good agreement with the error band of −5% to +10%. [ABSTRACT FROM AUTHOR]

Solar energy has intermittent heat collection due the atmospheric phenomena, even the clarity index is widely evaluating the approximation for modelling the solar energy always is a function of the time. Solar ponds are a technology for solar energy accumulation, this technology has evaluations for tilt angles and salt concentration temperature variation and has availability with small variation along 24 hours a day. This technology may supply constant heat load to a thermodynamic cycle for temperature upgrade from the solar pond temperature level. Absorption heat transformer is a Type II heat pump to take a heat source part of the thermal energy to increase the temperature of the half heat source, in this case, from a solar pond. This article shows the data for several operating conditions of an absorption heat pump operating whit Carrol © / water solution. The main result is the gross temperature lift from solar pond technology with an AHT operating with condensation into the same solar pond to increase the Coefficient of Performance. [ABSTRACT FROM AUTHOR]

A universal strategy that integrates PAA grafting, ion exchange, and in-situ chemical reactions to synthesize photothermal materials for enhanced solar-driven interfacial evaporation and gradient materials for electricity generation, respectively. [Display omitted] • A universal strategy is proposed for the preparation of SDIE and FFIPG materials. • Synthesized nanoparticles or nanoplates are evenly spread on SDIE fabric fibers. • A combination of one-way flow and suspension mode is used for fluid evaporation. • All SDIE fabrics achieve excellent evaporation rates at 0.5 cm suspension height. • The fluid flow can constantly generate a potential difference across the FFIPG fabrics. In our contemporary society, addressing the increasingly pressing global resource shortage, particularly the scarcity of vital water resources and energy, is critical for human survival. This paper presents a strategy that integrates PAA grafting, ion exchange, and in-situ chemical reactions to synthesize photothermal materials for enhanced solar-driven interfacial evaporation and gradient materials for electricity generation, respectively. The obtained photothermal material demonstrates exceptional light absorption and photothermal conversion performance. By employing a unique combination of unidirectional flow and suspension mode for water evaporation, remarkable evaporation rates are achieved, with all samples exceeding 2.03 kg m-2h−1. The hybrid mode is also applied to saltwater treatment, where it is found that the evaporation rate is not significantly affected, regardless of the salt concentration. No change in the evaporation rate is observed even after 12 h of continuous treatment with 10 % brine, indicating the robustness and stable performance of the evaporative materials. For the synthesized gradient materials, the flowing fluid can establish a potential difference at both ends of the gradient fabric. The magnitude of open circuit voltage and short circuit current can be controlled by adjusting the measurement distance, the deposited nanoparticles with different polarity and the amount of charge carried. We acquire a maximum output of 209.7 mV using the gradient Cu-S/PAA-cotton fabric, which can be connected in series to power small electronic devices like a digital watch. This research not only advances the design and practical application of high-performance solar evaporators but also illuminates a novel pathway for developing electricity-generating materials. [ABSTRACT FROM AUTHOR]

To study the partitioning of solar radiation over the melting Arctic sea ice and address the lack of systematic measurements of the optical properties of melt ponds and the underlying ice, four experiments in non-Arctic regions were designed to explore the distribution of solar irradiance on pond surface, pond bottom, and underlying ice. These experiments also investigated the influence of different pond depths (H p), underlying ice thicknesses (H i), and melt pond sidewall conditions (i.e., the black sidewalls, ice sidewalls, and pond horizon size) on the apparent optical properties (AOPs) of melt ponds. The black sidewalls with a small pond radius (barrel experiment) showed the greatest influence on the AOPs, significantly lowering the albedo and transmittance, and increasing the energy absorbed by the pond (Ψ p) and underlying ice (Ψ i). Different sidewall types, such as the black and ice sidewalls, did not affect the AOPs' trend, but affected their values. The AOPs were also influenced by pond size. The albedo linearly decreased and Ψ p linearly increased with the increase of pond radius. The albedo and Ψ p were almost independent of pond radius as pond radius larger than 0.58 m and 1.25, respectively. The black sidewalls experiment, in which the pond radius was 2.5 m, and the pond size experiment showed that solar energy was mainly absorbed by the melt pond. Ψ p increased from 19% to 62%, which corresponded to H p increasing from 5 cm to 35 cm in the pond size experiment. The results of the four experiments were consistent with the values obtained from numerical simulations and in situ measurements in the Arctic. The experiments conducted in this study were shown to be effective tools to complement and verify the optical measurements of Arctic melt ponds. They allow us to obtain the key information in Arctic pond measurements, which is difficult to achieve due to the severe weather conditions and marine environment. • The experiments vary a number of pond parameters and observe the change of optical properties of melt ponds. • The experiments can help confirming pond models. • The results separate the distribution of solar irradiance in the pond. [ABSTRACT FROM AUTHOR]

Varying salt density solar pond is a method that is best suited to absorb and store solar energy. This examination includes the test enhancement of the permeable and nonpermeable sunlight-based ponds dependent on its exhibition in different conditions. This experiment was done in Salem, Tamil Nadu, India. This particular topographical area has a high level of solar radiation and is a tropical district. Readings for a period of 30 days were taken; the temperature circulation, a measure of heat energy stored and concentration of salt density was assessed. For examination, two comparable solar ponds of volume 0.02 m3 and a height of 0.32 m was built. Black granite pieces, broken glass pieces, and welding spatter were used as a permeable medium in the lower convective zone (LCZ) in one of the two solar ponds. The temperatures of the permeable solar pond and non-permeable solar pond reached the highest values of 42.3°C and 40.6°C respectively. The solar pond with a permeable medium demonstrated an increase of 4.18% in temperature. The difference in amounts of stored thermal energy is 4.54 kJ. From the obtained parameters, the optimization is done and the permeable medium solar pond is found to store more amount of heat energy than the non-permeable solar pond. For the optimization of the mixed medium, criterion parameter ßelk has been acquired in the solar pond. [ABSTRACT FROM AUTHOR]

In this paper, in order to guide the lithium salt production from solar ponds in salt lakes, the two ternary systems (Li2SO4 + LiB5O8 + H2O) and (LiCl + LiB5O8 + H2O) at 298.15 K and 101.325 kPa were studied using the isothermal dissolution experimental method. The solubilities, densities and refractive indices were measured experimentally. From the experimental data, the phase diagrams and the diagrams of physicochemical properties, including density and refractive index, against composition Li2SO4 and LiCl in each ternary system were established. The phase diagrams for the two ternary systems at 298.15 K all have one invariant point, two univariate solubility curves and two crystalline regions corresponding to lithium pentaborate pentahydrate (LiB5O8·5H2O), lithium sulfate monohydrate (Li2SO4·H2O, in the former system) and lithium chloride monohydrate (LiCl·H2O, in the later system). In addition, both ternary systems are of the hydrate type I, neither double salt nor solid solution were found. The variations of density and refractive index against the concentrations of lithium sulfate in the former system and lithium chloride in the later system are similar. On the basis of empirical formulae for density and refractive index, the calculated data agree well with the experimental values, which indicate that all data obtained are reliable. [ABSTRACT FROM AUTHOR]

van Haren, H., 2020. High-resolution temperature observations of a shallow lagoon in the South Pacific (Bora Bora). Journal of Coastal Research, 36(3), 536–544. Coconut Creek (Florida), ISSN 0749-0208. The daily cycle of heating and cooling of the near-surface ocean may be quite different in the open ocean compared with a shallow lagoon with a seafloor that is a few meters deep and can be heated directly by the sun. This solar radiation can affect the local benthic communities. To study the physical processes associated with the daily cycle of the South Pacific lagoon surrounding Bora Bora, a vertical string of five high-resolution temperature sensors is moored at a 2-m-deep site for 3 weeks. Besides standard ocean warming (mostly during the day) and cooling (mostly at night), the sensors show relatively highest temperature near the lagoon floor during the warming phase and weakly stable stratification toward the end of the cooling phase. During the warming phase, highly variable stratification is observed extending into the water column, but only under conditions of calm weather and turbid waters. Under trade winds and clear waters, the lowest sensor or sensors show consistently higher temperature variability than higher sensors with spectral slopes indicative of shear and/or convective turbulence. During the cooling phase, the lower sensor shows consistently very low variance (nonturbulent), while other sensors show a spectral slope around the buoyancy frequency, evidencing weakly stratified waters supporting internal waves. These observations contrast with open-ocean near-surface observations of stable stratification during the warming phase and turbulent free convection during the cooling phase. Thus, lagoons seem to resemble the atmosphere more than the ocean in daytime thermodynamics and possibly act as a natural solar pond with bottom conductive heating (when salinity compensates for unstable temperature variations). [ABSTRACT FROM AUTHOR]

This paper deals with the modelling of solar ponds for different sizes to calculate saturation time and temperature by using discrete ordinates method. The modeled solar pond is a subsoil type and aimed to minimize the heat losses by isolating side wall and ground with foam with the thickness of 10 cm in all cases. In the model, upper convective zone is 10 cm deep and non-convective zone consists of five layer and each layer is 10 cm deep and storage zone depth ranges from 40-400 cm. Therefore, the solar pond totally consists of seven layers. The saturation temperature was found to be about 322 K for 12 different solar pond. For a depth of 40 cm, the equilibrium temperature was reached in 1000 hours, 1300 hours for 60 cm, 1400 hours for 80 cm, 1500 hours for 100 cm, 1600 hours for 120 cm, 1750 hours for 1140 cm, 1800 hours for 180 cm, 2700 hours for 200 cm, 1800 hours for 250 cm, 3400 hours for 300 cm, and 6000 hours have passed for 400 cm. As the depth increases, time to reach to the equilibrium temperature increases but increment amount of water and time to reach equilibrium temperature shows a proportional increase. At the same time we calculated that, when we increase the width of the pond by keeping the depth constant, the saturation temperature and the time did not changed for the seven different cases. [ABSTRACT FROM AUTHOR]

In this paper, we have numerically studied the phenomenon of unidimensional convectionconduction equation in a channel, cylinder and sphere immersed in a solar pond. Then we have studied bidimensional case in a heat exchanger, which undergoes an external heat flow provided by solar pond. We carried out the discretization of the mathematical model by finite differences method (explicit scheme). Calculation codes in Fortran language have been created for the temperature distribution in all these geometries. We presented the numerical results in terms of temperature profile functions, one- and two-dimensional, in laminar flow regime, for various parameters. We also present a study by COMSOL of the same phenomenon on these geometries. This study can be presented by two methods, the first using the physical model and the second using the mathematical part of COMSOL. [ABSTRACT FROM AUTHOR]

To cope with the large energy consumption in the most commercial desalination processes, along with the growing concern about climatic change resulting in CO2 emission, much effort has been made since almost four decades to use renewable energies to run desalination units. Among the numerous desalination processes driven by renewable energies, the seawater greenhouse received much attention for decentralized production of fresh water. The paper deals with an innovative hybrid approach of seawater desalination that has been explored. It combines a seawater greenhouse (SWGH) with a solar pond to produce more fresh water. Furthermore, it enables a better management of brine, which represents a major issue for all desalination processes. Indeed, the rejected brine of the SWGH will be recycled, by using it in a solar pond as a heat storage plant and a heat source to warm the air to more or less than 70°C at the inlet of the second evaporator of the SWGH. The process scheme and the mathematical and software models of both the classical SWGH and of its hybridization with a solar pond are presented. The calculations show that the fresh water production rate of the new SWGH concept is more than five times higher than of the classical SWGH one. Simulations on different Moroccan sites were realized as a case study, to estimate the added value of the new SWGH model and, at the same time, to compare its profitability in these implantation locations. [ABSTRACT FROM AUTHOR]

Water and energy are thoroughly linked: water is required to generate, transfer, and use the lot characteristics of energy; and energy is demanded to extract, treat, and distribute water. Shortage in clean water deems as the main challenge facing the world as a result of the escalating in the energy consumption required for desalinating the sea/brackish water which increases costs and provokes on the marine life and environment due to the high concentrate solute produced from desalination plants. Solar pond is a reservoir of water with different salt concentration implements to gather and store the incident solar energy which it can be employed later on in different thermal energy applications, such as industrialized heating process, electricity power generation, farming crop drying and cooling of houses. In this paper a short but concentrated review of the literatures that dealt with the implemented of the solar pond to illustrate succinctly the historical background for the solar ponds as well as the most word-wide established solar ponds. In addition to the theoretical background of heat and mass transfer which governed the solar pond operation is presented and discussed. [ABSTRACT FROM AUTHOR]

In this work, the thermal performance enhancement of a shallow solar pond (SSP) was verified theoretically. The SSP operates under the open cycle to extract heat in order to increase own efficiency. SSP was provided with two transparent glass covers to reduce heat loss and increase global warming. It was also coated with a heat insulation material; the bottom of the SSP is painted in black to improve the absorption of solar radiation. In order to enhance heat extraction, five types of nanofluids with different physical properties were passed through a heat exchanger in the form of a serpentine welded to the bottom of the SSP. Five types of metal nanoparticles such as Al2O3, CuO, TiO2, SiO2, and Cu were mixed with pure water under various concentrations ranging from 0 to 5 % to obtain the nanofluids. A numerical model was developed based on the solution of thermal balance equations after discretization by using real meteorological conditions of the Medea city located in Algeria. The simulation was conducted on June 8 from 5 am to 6 am hours for the next day. The obtained results, including thermophysical properties, temperature of the pond and exergy performance, were presented and discussed. [ABSTRACT FROM AUTHOR]

The salt gradient solar pond (SGSP) is a low-cost and large-scale solar energy capture and storage device. The stability of the non-convective zone (NCZ) is critical for the well-functioning and efficiency of SGSP. To understand when and how SGSP lost its effectiveness, the turbulent double-diffusive convection in solar ponds was first solved numerically with a Large Eddy Simulations (LES) model. The simulations show that attaching a porous layer or increasing the initial salt concentration effectively delays the destruction of NCZ. By increasing the initial salt concentration from 5.2% to 20.8%, the destruction time increases from 7 to 22 h. By attaching a porous layer, the overturn time can increase by about 8 h, resulting in a temperature rise from 46 °C to 73 °C in the storage layer. The flow field analysis shows that both interface erosion and turbulent mixing in NCZ cause the destruction of NCZ. The stability analysis shows that the turbulent mixing decreases the salinity gradient in NCZ, making it more susceptible to erosion. By inhibiting the turbulent mixing, the porous layer at the bottom can effectively delay the arrival of NCZ destruction. Thus, the heat storage capacity and stability of solar ponds are enhanced. • The turbulent double-diffusive convection in SGSP was analyzed by both LES modelling and stability analysis. • The turbulent double diffusions before and after the destruction of SGSP were analyzed. • Turbulent mixing decreases the salinity gradient and destabilizes the SGSP. • Attaching a porous layer to the bottom inhibits the turbulent mixing. • A porous layer enhances the heat storage capacity and stability of SGSP. [ABSTRACT FROM AUTHOR]

In this paper, thermal performance of solar pond for different condition was numerically investigated by using discrete ordinates method to facilitate a greater understanding of the effects of relative various condition on thermal performance improvement of solar pond. For this, a 3-D prototypes of solar ponds with square cross-sections were simulated for the oversoil and subsoil, insulated and uninsulated, open on and off conditions. The direction of sunlight (zenith angle and the solar elevation) was automatically computed from the latitude, longitude, time zone, date, and time. The estimated solar position is accurate for a date between year 2000 and 2199, due to an approximation used in the Julian Day calendar calculation. Seasonal temperature variation of solar pond was calculated for the full period of one year starting from March and calculated data were compared with experiment to validate simulation accuracy of heat transfer model. Result indicates that temperatures in the summer time were calculated at around 55 °C, while temperatures in the winter were in the range of 20 to 30 °C and temperature changes between 30 °C and 40 °C in spring and autumn. [ABSTRACT FROM AUTHOR]

Sainz-López, N.; Boski, T., and Sampath, D.M.R., 2019. Fleur de sel composition and production: Analysis and numerical simulation in an artisanal saltern. Journal of Coastal Research, 35(6), 1200–1214. Coconut Creek (Florida), ISSN 0749-0208. This study is a first approach to modelling of fleur de sel production, aimed at increasing its efficiency and contributing to the scarce literature on the topic. Quantitative forecasting of daily production of fleur de sel was applied to an artisanal solar pond unit in the environmentally protected area of Castro Marim, SE Portugal. The numerical model was based on simulations of the evaporation process, taking into account the effect of reduced vapour pressure of the brine solution. The controlling variables chosen as input parameters to the forecast model were brine temperature, brine concentration, harvesting efficiency, albedo, incoming solar radiation, precipitation, air relative humidity, air temperature, atmospheric pressure, day of the year, wind direction, and wind speed. Production predicted by the model was tested against actual production in two crystallisers in the years 2015 and 2017. The statistically evaluated match between the estimated and actual production was highly significant with a mean R2 of 0.8 and overall error of estimation was 14.5%. The chemical composition of nine samples of fleur de sel was analysed, showing the temporal evolution of several components during the harvesting period. A decrease of NaCl content from 96% to 87% and an increase by one order of magnitude of Mg, S, K, Br, and As were observed. The range of Ca, Si, Al, and Sr contents was 0.12–0.65%, 0.1–0.85%, 0.08–0.3%, and 0.009–0.013%, respectively. Ba, Fe, Mn, Mo, Pb, and Sn contents had the following ranges: 0.051–0.145, 1.2–5.5, 0.44–1.66, 0.03–0.05, <0.05–0.55, and <0.05–0.1 mg/kg, respectively. The following elements were below the detection limit and below the limits of the Codex Alimentarius: Cd, Th, U, Cu, Cr, Co, Ni, V, Bi, Zn, Rb, and Hg. [ABSTRACT FROM AUTHOR]

An average of concentrations of Na+, Mg2+, Ca2+, K+, and Cl– in fluid inclusions, from the Khorat Plateau evaporite primary halite, was employed. The evaporation–crystallization sequence and paths were obtained under various temperature conditions for the quinary system, Na+, K+, Mg2+, Ca2+//Cl–-H2O. The results showed (1) a halite, sylvite, and carnallite stage at 25°C; (2) a halite, sylvite, carnallite, and bischofite stage at 35°C; and (3) a halite, sylvite, carnallite, bischofite, and tachyhydrite stage at 50°C. These results indicated that (1) a hot state is favorable for tachyhydrite formation, (2) tachyhydrite occurs in the late evaporation stage, and (3) the stability field of tachyhydrite increases with increasing temperature. The crystallization paths were plotted by the application of Jänecke phase diagram at 25°C, 35°C, and 50°C involving the system Na+, K+, Mg2+, Ca2+//Cl–-H2O. The crystallization sequence predicted on the Jänecke phase diagram showed a good agreement with the experimental crystallization sequences and paths. Tachyhydrite precipitate more easily from a high Ca concentration solution during the late evaporation stage with increasing temperature under the same relative humidity condition. The evaporite mineral succession in the Khorat Plateau, Sergipe, and Congo basins agrees well with the mineral precipitation sequences predicted from their own fluid inclusions in halite. This is confirmed by the simulation of the Jänecke phase diagram at 50°C involving the system Na+, K+, Mg2+, Ca2+//Cl–-H2O. The precipitation of tachyhydrite was sensitive to the temperature, and that the thermal resource may originate from a temperature profile in the solar pond. This study presented a simulated approach that can help in understanding similar cases that studies the sensitivity of temperature to salt formation. [ABSTRACT FROM AUTHOR]

Within the last two decades, a large number of articles were published that report, as the authors claim, 'metastable phase equilibria', or 'metastable solubilities'. The main objective of these studies was to carry out experiments under conditions closely meeting those in solar evaporation ponds or industrial evaporation–crystallization processes. Occasionally, such studies were subject to controversial discussion and criticism and the question was raised whether metastable equilibrium data are worth being published at all. This paper provides a critical discussion of such evaporation experiments. The thermodynamic background of stable and metastable solubility and typical experimental difficulties in solubility determinations are discussed in detail. We also demonstrate that the knowledge of metastable equilibria is very useful in different research areas such as geochemistry or industrial application of solubility equilibria. Finally, it is shown that so-called 'isothermal evaporation method' used in the above-mentioned studies does not yield stable or metastable solubilities. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Photo-Fenton with Fe3+-EDDS removes CECs regardless water composition. • 80% CEC removal after 15 min in 5 real WWTP effluents. • Nature and not the load of organic matter has impact on CEC removal. • Short reaction time to remove CECs encourages continuous flow operation. • Mechanism developed with synthetic effluent explains reactions in real wastewater. Abstract This paper presents for the first time the treatment of contaminants of emerging concern (CECs) in a systematic study in different municipal wastewater treatment plants (MWWTPs) of the Mediterranean area, more than 1000 km away. Solar photo-Fenton process at neutral pH with Fe3+-EDDS has been demonstrated to be very efficient under controlled conditions and must be validated in realistic and variable conditions such as real MWWTP effluents of different composition. To this end, CEC removal was studied in effluents from 5 treatment plants in the Mediterranean area of Spain, the inorganic and organic composition varying in the range 161–641 mg L−1 (sulfate), 133–538 mg L−1 (chloride) and 10–20 mg L−1 (dissolved organic carbon). More than 45 CECs were quantified in MWW and results showed that the effect on CEC elimination of the concentration of anions and organic matter was interfered by the nature of the organic matter. However, origin and composition of MWW was not critic for attaining >80% degradation of CECs after 15 min of reaction. Moreover, conventional anions (sulfate, chloride) had a positive effect on CEC degradation rate. This paper demonstrates the consistency and predictability of the solar photo-Fenton process at circumneutral pH for treating CECs in simple and cheap photoreactors. [ABSTRACT FROM AUTHOR]

Abstract In the present work, an improved expression of the radiative intensity decay in solar ponds is proposed through an equivalent absorption coefficient calculated using Beer-Lambert's law. Based on the improved expression, a transient thermal model involving side and bottom heat losses is developed for a solar collector-type pond consisting moving storage zone. Thereafter, the effects of various thermophysical parameters on instantaneous and steady state efficiencies are studied. Finally to maximize the efficiency, simultaneous optimization of lower and middle zones of the pond is proposed. It is highlighted from the present study that the proposed expression of computing radiative intensity overcomes practical drawbacks of earlier models. The optimization also reveals that without its aid, practically unrealizable performance resulting in a net heat loss can occur for many parameters currently available in the literature. From the transient and sensitivity studies, it is observed that the appropriate selection of collector-type pond's parameters is synchronized by a mutual trade-off between the allowable time and the pond's efficiency. Highlights • Improved radiative intensity decay model is proposed for solar ponds. • Present model highlights the practical discrepancies of earlier models. • Simultaneous optimization of lower and non convective zones is done. • Transient analysis for solar collector type-pond with mobile storage zone is done. [ABSTRACT FROM AUTHOR]

The solar pond is one of the usual tools used for solar energy harvesting in the world, although its low efficiency is still a big challenge. In this study, to enhance the thermal efficiency of the laboratory-scale salinity gradient solar pond, three different nanoparticles, i.e., SiO2, Fe3O4, and ZnO, were dispersed into a salt-water solution as the based liquid. Nanoparticles' mass concentrations used in the based liquid were 0.012%, 0.036%, and 0.06%. The simulated sunlight thermal energy was supplied by a 500 W halogen lamp. The prepared nanofluids were used as lower layer of the pond. Approximately 3 days after filling the pond, the stable salinity gradient was formed and after almost 2 days of exposure to the simulated sunlight, the temperature of the pond layers reached thermal equilibrium. The results showed that lower layer temperature increased continuously with nanoparticles' concentration, for all nanofluids. Based on the measured temperature, the pond thermal performance was calculated, showing that all mentioned nanoparticles could enhance the thermal efficiency of the SGSP. The maximum lower layer temperature (~ 47 °C) and thermal efficiency enhancement ratio (35.13%) were obtained for the 0.06% ZnO nanofluid. This nanofluid showed the minimum light scattering (particle size parameter = 0.248) and transmittance (near zero) over the UV-Vis wavelength, leading to the increased thermal efficiency of the pond, as compared to the SiO2 and Fe3O4 nanofluids. In addition, using nanoparticles, the time required to reach equilibrium conditions in the pond was decreased, with the maximum of about 9 h. [ABSTRACT FROM AUTHOR]

In this work, 3-D and two-phase nanofluid flow and heat transfer is modeled over a stretching infinite solar plate. The governing equations are presented based on previous studies. The infinite boundary condition and shortcoming of traditional analytical collocation method have been overcome in our study by changing the problem into a finite boundary problem with a new analytical method called optimal collocation method. The accuracy of results is examined by fourth order Runge- Kutta numerical method. Effect of some parameters, Prandtl number, Schmidt number, Brownian motion parameter, thermophoresis parameter, λ=b/a (ratio of the stretching rate along y- to x-directions), and power-law index on the velocities, temperature, and nanoparticles concentration functions are discussed. As an important outcome of our 3-D model analysis, it is found that increase in thermophoretic forces can enhance the thickness of both thermal and nanoparticle volume fraction boundary-layers. [ABSTRACT FROM AUTHOR]

This paper deals with the modeling of two different solar ponds which has some different structural parameters such as aboveground and underground, and its performance evaluation. The solar pond system generally consists of three zones, and the densities of these zones decrease from the bottom of the pond to the surface. The most significant decrease in the density distribution of the salt between bottom and up of the pond is the gradient zone. The convective heat loss in the solar pond is prevented with this zone. In this study, aboveground and underground solar ponds were modeled at the same dimensions, but different structural parameters in the same conditions. In this model, the temperature distributions of the solar pond were obtained during a year. The thermal performances of the solar pond were calculated and the results were compared with an experiment. This study shows that the efficiency of the aboveground solar pond is observed to be a maximum of 25.93% in July, a minimum of 4.53% in January. Furthermore, the efficiency of the underground solar pond is observed to be a maximum of 21.49% in July, a minimum of 6.55% in January. This study indicates that the underground construction of solar ponds, designed to be insulated using appropriate insulation materials, is found to be more efficient with respect to the aboveground pond. [ABSTRACT FROM AUTHOR]

In the past three decades, Fenton and photo-Fenton processes have been the subject of a large number of research studies aimed at developing a low-cost and robust alternative to treat complex wastewater. Aspects such as installation and operating costs and technical complexity of reactors have limited the commercial applications of Fenton processes. In this study, we evaluated the potential of solar pond reactors to carry out degradation of the dye reactive orange 16 (RO16). Decolorization (D = 99 ± 0.6%), chemical oxygen demand reduction (COD = 55 ± 2%), total organic carbon removal (TOC = 28 ± 0.5%), and biocompatibilization can be accomplished using 15% peroxide (0.6 mg H 2 O 2 /mg RO16), which is theoretically required to mineralize the dye. Under dark conditions, decolorization and aromatic removal were scarcely affected (2%), whereas COD and TOC removal were reduced to 37% and 16%, respectively. The application of multivariable analysis and the use of low-cost reactors may lead to a reduction in annual treatment costs of colored effluents to 0.76 (US/m 3 ). Furthermore, the treatment capacity can be increased from 0.6 m 3 wastewater/m 2 reactor surface to 1.7 m 3 wastewater/m 2 reactor surface without compromising process efficiency or the biodegradability (BOD 5 /COD ratio) of the effluent. Dyeing auxiliaries, mainly NaCl, appreciably reduced the decolorization performance in Fenton (13 ± 0.4%) and photo-Fenton (83 ± 0.5%) processes due to the formation of iron-chloride complexes and less powerful oxidants. To reduce the impact of auxiliary agents on process performance and treatment capacity, the Fe 2+ concentration should be increased from 5 mg/L to 15 mg/L. The results seem promising; however, additional studies at pilot and semi-industrial scales should be conducted to demonstrate the potential of low-cost reactors to carry out colored wastewater treatment. [ABSTRACT FROM AUTHOR]