ENERGY REQUIREMENT OF ALTERNATIVE TECHNOLOGIES FOR DESALINATING GROUNDWATER FOR IRRIGATION

Increased global water demand coupled with limited water resources has led to acute water shortage in many regions, significantly affecting a griculture, which is the world’s largest consumer of water. Groundwater resources are thus increasingly being used to meet irrigation requirements. However, groundwater resources around the world tend to be saline ( 0.5 ≤ S ≤ 5 g/kg ) rquiring desalination before use. Furthermore, with decreasing water availability, demands for producing permeate from the feed at higher recoveries (>85%) is also increasing. In this work, a thermodynamic least work analysis for desalination and pumping ground water is developed first. Then, the actual energy required by high recovery desalination technologies such as brackish water reverse osmosis (RO), closed circuit reverse osmosis (CCRO) and electrodialysis reversal (EDR) are compared with the thermodynamic least work of desalination from 50-95% recovery. CCRO consumed the least energy until a recovery of 92% after which EDR consumed the least energy. While the energy required for RO and CCRO changed with recovery, EDR energy consumption remained approximately constant at 0.85 kWh/m³. Water table depth was also found to significantly contribute to the total energy consumed, with the power required to pump groundwater being comparable to the desalination power requirements at water table depths greater than 50 m. Thus, the choice of selection of desalination technologies is particularly crucial for water table depths less than 50 m

Feasibility Study of an Electrodialysis System for In-Home Water Desalination and Purification in Urban India

Desalination of high salinity water is an effective way of improving the aesthetic quality of drinking water and has been demonstrated to be a characteristic valued by consumers. Across India, 60% of the groundwater, the primary water source for millions, is brackish or contains a high salt content with total dissolved solids (TDS) ranging from 500 parts per million (ppm) to 3,000ppm. The government does not provide sufficient desalination treatment before the water reaches the tap of a consumer. Therefore consumers have turned to in-home desalination. However, current products are either expensive or have low recovery, product water output per untreated feed water, (∼30%) wasting water resources. Electrodialysis (ED) is a promising technology that desalinates water while maintaining higher recovery (up to 95%) compared to existing consumer reverse osmosis (RO) products. This paper first explores the in-home desalination market to determine critical design requirements for an in-home ED system. A model was then used to evaluate and optimize the performance of an ED stack at this scale and designated salinity range. Additionally, testing was conducted in order to validate the model and demonstrate feasibility. Finally, cost estimates of the proposed in-home ED system and product design concept are presented. The results of this work identified a system design that provides consumers with up to 80% recovery of feed water with cost and size competitive to currently available in-home RO products

Brackish water desalination for greenhouse agriculture: Comparing the costs of RO, CCRO, EDR, and monovalent-selective EDR

Greenhouses are a rapidly growing agricultural sector that uses desalination systems. However, the desalination requirements of the greenhouse industry and an economic evaluation of desalination technologies for greenhouses have not been reported previously. Several greenhouse operators in North America using desalination systems were interviewed to identify key design specifications. A detailed cost comparison was conducted for key technologies: reverse osmosis (RO), closed circuit RO (CCRO), electrodialysis reversal (EDR) and monovalent selective EDR (MS-EDR). Capital, energy and membrane replacement costs, savings in feedwater costs from operating at higher recovery, and potential savings in fertilizer from using MS-EDR, were calculated. For 10-hectare greenhouses, alternatives can be considered. MS-EDR is economically competitive if it can retain at least 20% of the calcium and magnesium needed for growing and if membranes last 7 years. CCRO is competitive if the sum of feedwater and brine disposal costs are >$0.24/m³. If this cost was$0.32/m³, additional investment over RO for CCRO, EDR and MS-EDR, could pay itself back in 2.4, 3.4 and 2.1 years. In Ventura county where municipal water costs $1.05/m³, RO, CCRO, EDR and MS-EDR had payback periods of 7.1, 8.4, 7.8 and 8.2 months. Keywords: SBOL Visual; Standards; DiagramsUnited States. Bureau of Reclamation (Contract R17AC00135

Optimal design and operation of electrodialysis for brackish-water desalination and for high-salinity brine concentration

Electrodialysis (ED) is a desalination technology that has been deployed commercially for decades. However, few studies in the literature have looked at the optimal design and operation of these systems, especially for the concentration of high-salinity brines. In this paper, a set of constraints is defined to allow a fair comparison between different system sizes, designs, and operating conditions. The design and operation of ED are studied for the applications of brackish-water desalination and of high-salinity brine concentration for a fixed system size. The set of variables that determine the power consumption of a fixed-size system is reduced to include only the channel height and the velocity, with all the other design and operation variables depending on these two variables. After studying the minimization of power consumption for a fixed system size, the minimum costs associated with the different system sizes are studied, and the differing trends in brackish-water and high-salinity applications are compared. Finally this paper presents the effect of the cost modeling parameters on the trends of the optimal system size, current density, length, channel height, and velocity for the two applications studied

Feasibility study of an electrodialysis system for in-home water desalination in urban India

Poor quality of drinking water delivered to homes by state utilities, and a large reliance on brackish ground water resources in parts of urban India, has resulted in the adoption of in-home water treatment solutions. The only existing in-home water treatment solution capable of desalination is reverse osmosis (RO). However, existing RO products can recover only 25â50% of the feed water supplied as usable product water. In this study, an alternative solution that relies on electrodialysis (ED) was designed and experimentally shown to achieve a recovery of 80%, producing 12 L/h of water at the desired salinity of 350 ppm from a feed salinity of 3000 ppm. The cost and size of the proposed system were also found to be comparable to existing in-home RO systems. In-home ED water treatment systems could compete with existing RO products while providing the advantage of improved water-conservation in water-stressed India. Keywords: Electrodialysis, Desalination, Reverse osmosis, Brackish wate

Proceedings of International Web Conference in Civil Engineering for a Sustainable Planet

This proceeding contains articles of the various research ideas of the academic community and practitioners accepted at the "International Web Conference in Civil Engineering for a Sustainable Planet (ICCESP 2021)". ICCESP 2021 is being Organized by the Habilete Learning Solutions, Kollam in Collaboration with American Society of Civil Engineers (ASCE), TKM College of Engineering, Kollam, and Baselios Mathews II College of Engineering, Kollam, Kerala, India. Conference Title: International Web Conference in Civil Engineering for a Sustainable PlanetConference Acronym: ICCESP 2021Conference Date: 05–06 March 2021Conference Location: Online (Virtual Mode)Conference Organizer: Habilete Learning Solutions, Kollam, Kerala, IndiaCollaborators: American Society of Civil Engineers (ASCE), TKM College of Engineering, Kollam, and Baselios Mathews II College of Engineering, Kollam, Kerala, India