Operational Decision-Making on Desalination Plants

Desalination of brackish water by nanofiltration and reverse osmosis

Purpose: To study a case of modeling an industrial distillation system, using the Aspen Plus simulator as the mathematical model and subsequently generating surrogate models using Machine Learning techniques in Matlab. Theoretical Framework: Metamodels are reduced models obtained from data generated by rigorous models, replacing them entirely or partially when the computational codes originating from them require excessively large computational effort to be used feasibly. Method/Design/Approach: The simulation of the process was performed in Aspen Plus. Subsequently, the most important variables were selected, and an experimental design was created using Latin Hypercube Sampling in Matlab, generating points to be used in sensitivity analysis in Aspen Plus. The next step was the construction of metamodels using the Statistics and Machine Learning toolbox in Matlab, employing linear regression and Gaussian process regression models. Finally, a statistical analysis was conducted. Results and Conclusion: The distillation system simulation converged, and the obtained metamodels had good regression indicators, especially the Gaussian process regression models, making them the most suitable for representing the rigorous Aspen Plus model. Research Implications: Understanding the multicomponent distillation process integrated with computational tools and data regression models, leading to a reduction in computational effort. Originality/Value: Development of a tool that enables the simulation and evaluation of a distillation process without the need to acquire software with rigorous equation databases.

This study aims at analyzing fluoride levels in water sources and drinking water in Saveh City, with a focus on health risks assessment. Excessive fluoride concentrations (above 2 to 4 mg/L) can lead to skeletal issues, dental fluorosis, and brain damage, while low concentrations (below 0.7-1.5 mg/L depending on temperature) can harm tooth health and strength. For drinking water consumptions, centralized and decentralized desalination units were utilized from, Saveh's brackish water. In this research study a total of 63 samples were collected randomly from underground and surface water sources, distribution networks, and desalination units during both Winter and Summer seasons. Fluoride analysis was conducted using the spectrophotometric method with the DR6000 device and SPADNS reagent. The results indicated that during winter, average fluoride concentrations in underground water, water treatment plant output, distribution network, centralized desalination unit output, and decentralized desalination unit output were 0.67, 0.64, 0.62, 0.064, and 0.07 mg/L, respectively. In summer, the average concentrations were 0.79, 0.75, 0.71, 0.04, and 0.07 mg/L, respectively. For desalinated water produced by centralized desalination units during the summer season, the Estimated Daily Intake (EDI) values for fluoride in different age groups, including infants, children, teenagers, and adults, were found to be 0.0003, 0.0023, 0.0016, and 0.0013 mg/kg, respectively. Health risk assessment data indicated Hazard Quotient (HQ) values for fluoride in these age groups were 0.005, 0.037, 0.026, and 0.02, respectively. Similar values were observed in the winter data. However, it is important to note that the fluoride concentration in Saveh's drinking water is nearly zero, and the absence of fluoride in desalinated drinking water can have a negative impact on dental health. Therefore, it is crucial to address the lack of fluoride in the drinking water of this city.

Southwest coastal Bangladesh has an acute scarcity of safe drinking water. Both the government and non-government organizations are now promoting reverse osmosis based small scale desalination plants (SSDPs) to ensure safe drinking water. The aim of this study was to assess the physico-chemical and bacteriological quality of the desalination plants (DPs) installed in southwest coastal Bangladesh. Water samples were collected from the inlet and outlet of 10 DPs. The product water mostly complied with water quality standards. High levels of total dissolved solids (TDS) and electrical conductivity (EC) in feed water were reduced significantly after the treatment, although 10% and 20% of the product water samples respectively did not comply with the WHO drinking water standards for those parameters. Compliance of product water with the WHO and Bangladesh drinking water standards for chloride, bicarbonate and sodium were found in respectively 80%, 90% and 70% of the samples, although their concentrations in all the feed water samples were higher than both of the standards. About one-third of the DPs did not meet the drinking water standard for sodium, which may be an important health concern for the people consuming this water. Apart from one of the DPs, all of them complied with the standard for faecal coliform and Escherichia coli. Results suggest that proper maintenance of the SSDPs is necessary to ensure safe drinking water for the coastal population of southwest Bangladesh.

A novel multi-salt crystallization process is presented to separate the salts from the desalination brine and is optimized using the gradual optimization integration strategy based on T-H diagram. Firstly, the process is simulated by Aspen Plus software to obtain the cold and hot load curve and the bottlenecks and unreasonable heat transfer processes are analysed. Secondly, considering the energy utilization and conversion procedure, the turbine and/or heat pump are introduced to improve the process. Then the parameters of production process and utility system are adjusted. Thirdly, the new stream information is obtained by process simulation and the new composite curves are drawn, which will guide the further adjustment of the system. If the new composite curves do not satisfy the process demand, then the above steps are repeated. Through several improvements, two approximate parallel hot and cold stream curves are constructed. The hot streams and cold streams are maximum possible matched, and the amount of utility and power consumption is significantly reduced. In a case study, two optimization schemes are adopted: the feed brine is preheated by the flash steam and the heat pump crystallization technology is introduced. The results show that the energy consumption of two optimized processes is 94.8 kW and 90.1 kW, and the total energy loss decreased 86.7 % and 87.3 %.

Life cycle assessment (LCA) of a novel geothermal-based multigeneration system using LNG cold energy- integration of Kalina cycle, stirling engine, desalination unit and magnetic refrigeration system

Operational digital twins bring together digitalization technologies, including machine learning, IIoT, data analytics, process simulation and optimization. A digital twin model reconciled with real-time process data provides the foundation for a range of layered applications that are key to transforming the way that process plants and value chains are operated and managed. After outlining the basic numerical methods, this paper will describe three industrial applications of dynamically reconciled digital twin models in gas processing, refining and olefins production. The focus is on application robustness and high availability, delivering increased operating margins and plant flexibility. An operational digital twin model can provide a versatile tool for real-time process optimization, and what-if analysis, as well as operations planning and scheduling. To be effective, the digital twin model needs to be reconciled with real-time process data frequently. In a dynamic operating environment where feed composition, process conditions and product demand may change continuously, this challenging data reconciliation task is solved using a combination of numerical methods: Equation-oriented model structures and solvers provide the flexibility required to solve simulation, parameter estimation and optimization cases. Extended Kalman filter and moving horizon estimation enable reconciliation using real-time dynamic data without the need for steady-state operation. Process models are developed using both first principles and data-driven surrogate modelling methods. A dynamically reconciled digital twin model provides the basis for an equation-oriented multi-period optimizer that can be solved for facility-wide steady state optimization, short-range dynamic optimization and long-range planning and scheduling problems within a single unified modelling and optimization framework. The use of hybrid models that include both data-driven and first principles components can significantly reduce the deployment and maintenance effort, the resulting low-order models facilitate model reuse across the different optimization horizons and objectives and enable large-scale optimization problems to be solved across an entire process plant or value chain. Three industrial applications of these methods will be outlined. The first is a gas plant optimizer that provides real-time process optimization and what-if analysis. The reconciled gas plant model tracks the process under significant feed and ambient variations. The second application is a refinery-wide optimizer that encompasses multiple crude distillation, vacuum and reaction units. The third application is an olefins process scheduling application that optimizes feed distribution, cracking furnace operating conditions and decoke cycle over an extended future time horizon.

Purpose. The paper analyzes the state of water management in Ukraine and worldwide, as well as the best practices in this area. Methodology. The study was carried out based on the analysis of literature sources and reporting data on the state of water management in Ukraine, European countries, the USA (2010-2016). Findings. The water state analysis in the regions of Ukraine showed that the quality in most cases is close to or meets the requirements for drinking water. Drinking tap water requires post-treatment in all regions of the country. The main issue for today is the production of the necessary equipment for treatment plants. Unfortunately, not all equipment is produced in Ukraine. The condition of rural water pipelines is of particular concern. Among the tested pipelines 7.3% do not comply with the rules and regulations. At the same time, only 25% of villages in Ukraine are provided with centralized water supply. Originality. The authors presented the results of a comprehensive review of the world's issues on disinfection of drinking and waste water, where various methods are used, partly in combination with each other in Ukraine and the worldwide. The main unresolved issue today is the issue of the residual quantity of drugs in the drinking water. The main environmental threat of the world scale is the presence of medicines in drinking water. The treatment facilities are not suitable for the decomposition or trapping of medicinal products. Nowhere in the world there is protection from these substances. One of the key issues in the solution of drinking water production is seawater desalination. To reduce the cost of desalination of sea water the SWRO-membrane technology is used. Practical value. Water problems are number one problems all over the world and in Ukraine as well. It is necessary to provide for additional financing to solve problems in the preparation and purification of waters, not with whatever funds remain, taking into account the fact that water is the basis of life on earth as a whole, the health and life of the nation depends on the quality of the water supply source.

Objective To research the proper bicarbonate concentration for shipboard seawater reverse osmosis (RO) remineralization. Methods Comprehensive analyses were made on the effects of HCO3- l on the desalination corrosion index, the methods of shipboard seawater reverse osmosis remineralization and related remineralization criteria. Then, the range of proper bicarbonate concentration of soft water remineralization was recommended for shipboard seawater reverse osmosis remineralization from different angles, which was verified by municipal drinking water quality survey results. Results HCO3- concentration greater than 90 mg/L could significantly reduce corrosiveness of desalinated water. Nevertheless, the contribution ration for Langelier index (LSI) was debased when HCO3- was greater than 90 mg/L. At present, the minimum quality criteria for HCO3- concentration was equal or greater than 30mg/L proposed by most countries. Shipboard desalination remineralization was more preferable with direct addition of agent, but the dissolution of bicarbonate was quite low in water. Conclusion In consideration of the shipboard environment and support capability, the applicable bicarbonate concentration of shipboard RO desalination remineralization was 30-90 mg/L, which was within the range of drinking water bicarbonate concentration for 50% of the cities in our country. Key words: Ship; Seawater reverse osmosis; Bicarbonate; Remineralization; Proper concentration

Low energy desalination and wind energy — sustainable solutions for drinking water production

Seawater desalination plants influents and effluents analysis in Libya

In several areas around the world, clean water is a precious asset that at anytime, and mainly due to circumstances of weather and climate, can become scarce. Mainly in the dry and remote places, people suffer with lack of water. A solution for this suffering can be a water desalination system, which makes water potable and usable for industry. That solution inherently, brings the problem of power requirement, which is sometimes arduous to accomplish in such remote areas of difficult access and long distances to overcome to build the infrastructure required to operate an electric power plant. Texas and the USA also face this scenario for many regions, for which the government has been creating some programs and driving forward incentives, looking for solutions to support water desalination. Water desalination has future applications for municipalities water-consuming or for arid and remote regions, as well as for industries that rely on heavy water usage, such as natural gas drilling operations, for which millions of gallons are trucked overland to the site and also hauled away afterwards, when the waste water produced must be treated. This thesis created the concept of autonomy for water desalination plants replacing the actual power supply from fossil fuel to a renewable source from wind or sun, giving capacity to them to produce its own electricity to operate as an autonomous unit, as demonstrated in the business case done for the Brownsville water desalination facility.

The relevance of the study is due to the fact that the presented object, namely mineral waters in the modern world have a huge potential and play an important role in farming, the coal industry, and in many other fields of life. Mineral water desalination technologies also affect the environment, so there are requirements for improving the methods of recycling brines and regenerative solutions in the desalination of water, due to which it is possible to make a substantial contribution to meeting the requirements of a number of consumers. The purpose of the study is to conduct an experiment, as a result of which recommendations will be made to eliminate errors and improve the quality of various methods of desalination of mineral waters and prevent the problem of disposal of brine, which, when discharged into reservoirs or evaporative sites, substantially worsen the ecological situation. Among the methods used are analytical, experimental, functional, statistical, classification, synthesis. In the course of the study, the features of mineral waters were noted, errors that were made during treatment, and the causes of their occurrence were analysed, and difficulties in the field of coal industry enterprises were analysed: the formation of water, its composition, properties, and degree of impact on the environment. It is important to understand the possibilities of various methods that allow choosing the best technological modes of operation of water treatment processes and successfully solving environmental problems with minimal consumption of reagents, water, and its discharge to the external environment. The practical value lies in the fact that the results obtained can be useful for the industry where mineral resources are extracted and processed, for researchers engaged in the development of new desalination methods, and can substantially reduce production costs and ensure the ecology of the process.

Wildfires are an increasing threat in Mediterranean regions, where extreme fire weather and long-term fuel accumulation are driving more frequent and severe events. In this context, fast and reliable fire spread simulations are essential to support both risk mitigation planning and real-time emergency management. PROPAGATOR is a stochastic Cellular Automata (CA) wildfire spread simulator designed to generate ensemble-based fire spread forecasts. The model, currently available as both an online application and open-source software, operates within a raster-based framework in which each cell is described by static attributes (e.g. fuel type, topography) and dynamic drivers (e.g. wind, fuel moisture). Fire propagation is modelled through a stochastic contamination process between burning and unburned cells, allowing the production of probabilistic maps of fire spread, as well as statistics on rate of spread and fireline intensity. PROPAGATOR also includes the capability to simulate the spotting phenomenon and suppression actions such as water drops or firebreak construction, making it suitable for both operational decision support during active fires and pre-event risk mitigation analyses. A current limitation of operational applications of PROPAGATOR is its focus on surface fire propagation, with no explicit representation of vertical fuel structure or transitions to crown fire. Crown fires, however, are characterized by higher spread rates, greater energy release, and increased unpredictability, with major implications for suppression effectiveness and ecological impacts. To address this limitation, an enhanced version of PROPAGATOR has been developed by extending the model to a quasi-three-dimensional (2.5D) representation of fuels, enabling the simulation of crown fire processes within the stochastic CA framework. The proposed Crown Fire Module relies on established empirical and semi-empirical formulations for crown fire initiation and spread that are compatible with a cellular automata approach. Crown fire initiation is governed by surface fireline intensity and crown base height, while crown fire rate of spread depends primarily on canopy bulk density and fire behaviour. These mechanisms have been integrated into the propagation rules of PROPAGATOR, allowing dynamic transitions between surface and crown fire behaviour within a probabilistic modelling framework. The implementation of these processes requires detailed information on both surface and canopy fuel structure and characteristics, which remains challenging at operational scales. To address this issue, we investigated the use of UAV-based LiDAR remote sensing to derive key fuel structure parameters using semi-automatic algorithms available in the literature. This approach offers a balance between spatial detail and areal coverage that is suitable for operational wildfire applications. A pilot study conducted in the Venafro area (Molise, Italy), based on a past wildfire event with a comprehensive dataset describing fire evolution, provided high-resolution inputs to test the enhanced model. By explicitly simulating surface-to-crown fire transitions, the upgraded version of PROPAGATOR aims to improve decision support for wildfire risk management, supporting applications ranging from fuel treatment planning to operational response under extreme fire weather conditions.

The Kingdom of Saudi Arabia obtains the most desalination water from the Red Sea. In Saudi Arabia, 14 desalination plants receive water from the Red Sea, and three are located in the country’s east and rely on the Arabian Gulf. The study has observed 16 desalination plants out of 17 desalination plants in the kingdom. Most of the desalination plants in Saudi Arabia currently use the advanced technologies to produce potable water with less impact on the surrounding environment. The current study examined the variation of hydrographic parameters along all available desalination plants in Saudi Arabia. This is the first inter-annual database of hydrographic parameters in the last 4 years. The peak salinity was measured at the Duba desalination plant in 2020, and it was 67.2 ppt. During 2018, the Azizia desalination plant reported the lowest value of 36.8 ppt. The maximum temperature recorded at the Qunfudah desalination plant in 2019 was 34.6°C. In 2017, the minimum temperature was 19.1°C at the Jubail desalination plant. The level of dissolved oxygen and pH were likewise not significantly changed along the brine outflow and in the outfall, in contrast to temperature and salinity. On the basis of 4 years’ of data from observed desalination facilities, the current study sheds light on the less environmental impact with regard to hydrographic factors.