An economic comparison of 2 × 1000 m 3/day desalination plants

Copenhagen and the surrounding municipalities face serious water supply challenges due to the combined effects of population growth, urbanization, pollution, and political pressure from the EU Water Framework Directive. The Blue Lagoon has been identified as a possible solution to these challenges that would improve both the self-sufficiency and long term sustainability of the city’s water supply through the utilization of an internal resource that is currently considered as a waste product. In addition, the lagoon would provide an environmental benefit through reduction of the nutrient load that is currently released from wastewater treatment plants during normal flow and overflow events. The Lagoon could also be a valuable component of an improved storm water management system. Presently, water is abstracted from groundwater resources, used, treated, and then pumped to either the Oresund or Koge Bugt. The Blue Lagoon would reuse the waste stream that is currently discharged and recycle the resource back into the urban water cycle [Figure 1]. An artificial lagoon would be used to mix effluent from wastewater treatment plants with seawater, and then used as a source for a Reverse Osmosis (RO) water treatment plant. In addition to improving self-sufficiency and sustainability, this configuration would reduce the salinity (TDS) of the source water for the RO plant and reduce the economic and energy burden when compared to conventional desalination of seawater. Data regarding possible flow sources to the lagoon was compiled and combined with other information in a model to evaluate possible lagoon configurations, resulting water quality and whether or not the lagoon would meet requirements that had been established. In addition, an economic analysis was conducted to further assess lagoon configurations and the economic viability of the lagoon compared to direct desalination of water from Koge Bugt. Results indicate that connection to one or two treatment plants would provide a constant supply and excess lagoon volume for dilution with seawater while still achieving a 35-80% reduction in TDS in the feed stream to a RO plant. No configurations met the water quality standards that had been set for the lagoon. Additional treatment processes are necessary to reduce the average total phosphorus concentration in treatment plant effluent streams from approximately 0.5 mg/l to 0.04 mg/l. Economic evaluation revealed that the operational cost of producing water via the lagoon would be 0.003 to 0.018 DKK/m3 cheaper than direct seawater desalination. Through efficient lagoon configuration, dilution of wastewater effluent is achieved, while still reducing TDS in the feed stream to the RO plant. More investigation is necessary to fully evaluate The Blue Lagoon; however none of the results of this project indicate that this concept is a “pie in the sky”. On the contrary, there is ample evidence to indicate that this is a viable solution that would provide a reliable, high quality, sustainable, and self-sufficient water supply for the city of Copenhagen and the surrounding municipalities.

A comparative study of RO and MSF desalination plants

A comparative study of RO and MSF desalination plants

Design of a 1.4 mgd desalination plant based on MSF and RO processes for an arid area in India

Design of a 1.4 mgd desalination plant based on MSF and RO processes for an arid area in India

scarcity. Underground water is mostly saline and other sources are small seasonal rivers and dams that collect rain water for sprawling population. Desalination plants can alleviate this problem to an extent. This paper examines various desalination plants, provides detailed technical discussion of Passive Vacuum Flash Type Solar Thermal technology and compares it with Concentrating Solar Desalination technology. Comprehensive levelised cost of water calculations are laid out for conventional Reverse Osmosis (RO) plant, Photovoltaic (PV) RO plant, conventional thermal Multi Effect Desalination (MED) plant and solar thermal MED plant. PVRO with cost of PKR 0.39 per gallon is the most suitable option.

Recently, the use of filters has come into light for sanitizing water plants. This study investigated the role of heat-tolerant ultrafilters (UFs) for the remediation of reverse osmosis (RO) plants using periodic thermal disinfection. Two completely identical RO plants (RO plants A and B) were installed in 2006 for surgical hand antisepsis in the operating theater. RO water was stored in the 300 L storage tank and recirculated in the 190 meter-long loop delivering water to 12 faucets in each RO plant. Periodic thermal disinfection came into practice periodically when a UF module was retrofitted to the recirculation loop of each RO plant in 2010. Endotoxin was monitored closely before and after thermal disinfection. Before UF modules were retrofitted, endotoxin increased to a maximum of 0.301 EU/mL in RO plant A and 1.446 EU/mL in RO plant B after thermal disinfection, respectively. Since a UF module was retrofitted to each RO plant in 2010, endotoxin has been continuously below 0.025 EU/mL in RO plant A and exceeded this level five times in RO plant B. On one occasion, endotoxin increased in all samples collected simultaneously after solenoid valves were replaced in the recirculation loop near the air conditioner outlet. At this time, the inside of the pipework was exposed to the ventilation airflow. After the valves were replaced again, this time with the workplace isolated using a curing sheet, endotoxin decreased. On the other occasions, endotoxin increased only in one sample and decreased after thermal disinfection. Annually replaced UF modules were examined twice for estimating the amounts of immobilized endotoxin. The estimated amounts decreased in 2013 by the order of 10-3 in comparison with those in 2011 in both RO plants. The present study suggested that UFs acted synergistically with periodic thermal disinfection for the remediation of RO plants.

Coupling of a nuclear reactor to hybrid RO-MSF desalination plants

Hybrid desalting systems

Chemical impacts from seawater desalination plants — a case study of the northern Red Sea

In the past few years, the commercialization of small scale reverse osmosis (RO) plant for low total dissolved solids (TDS) brackish and contaminated groundwater water desalination offered an alternative solution to obtain drinking water with TDS lower than 500 mg/L. Due to rapid development in membrane technology the technical and economical usefulness of RO process has been improved. In the current research work, a prototype Reverse Osmosis (RO) wastewater treatmentplant has been developed and its performance was evaluated to produce the safe and drinkable water at local small community.Salt rejection and ermeatewater flowrate are the key performance parameters. These performance parameters are influenced by other variable parameters such as applied feed pressure, temperature, recovery and feed water salinity.The RO plant performance has been evaluated through testing different water quality parameters; including physical, chemical and biological analysis of the treated sample. The plant was operated by varying feed water pressures and feed water salinity which indicated that the product water has the highest quality and maximum permeateflow rate at 25 bar of applied feed water pressure for feed water salinity upto 4000 mg/L. The water quality results indicate that permeate obtained after treatment has excellent quality free physical and microbial contaminants.

Chronic Interstitial Nephritis in Agricultural Communities (CINAC) causes major morbidity and mortality for farmers in North-Central province (NCP) of Sri Lanka. To prevent the CINAC, reverse osmosis (RO) plants are established to purify the water and reduce the exposure to possible nephrotoxins through drinking water. We assessed RO plant maintenance and efficacy in NCP. We have interviewed 10 RO plant operators on plant establishment, maintenance, usage and funding. We also measured total dissolved solids (TDS in ppm) to assess the efficacy of the RO process. Most RO plants were operated by community-based organizations. They provide clean and sustainable water source for many in the NCP for a nominal fee, which tends to be variable. The RO plant operators carry out RO plant maintenance. However, maintenance procedures and quality management practices tend to vary from an operator to another. RO process itself has the ability to lower the TDS of the water. On average, RO process reduces the TDS to 29ppm. The RO process reduces the impurities in water available to many individuals within CINAC endemic regions. However, there variation in maintenance, quality management, and day-to-day care between operators can be a cause for concern. This variability can affect the quality of water produced by RO plant, its maintenance cost and lifespan. Thus, uniform regulation and training is needed to reduce cost of maintenance and increase the efficacy of RO plants.

This paper studies energy consumption management of seawater Reverse Osmosis (RO) desalination plants to maintain and enhance the Voltage Stability (VS) of Power Systems (PS) with Photovoltaic (PV) plant integration. We proposed a voltage-based management algorithm to determine the maximum power consumption for RO plants. The algorithm uses power flow study to determine the RO plant power consumption allowed within the voltage-permissible limits, considering the RO process constraints in order to maintain the desired fresh water supply. Three cases were studied for the proposed RO plant: typical operation with constant power consumption, controlled operation using ON/OFF scheduling of the High-Pressure Pumps (HPPs) and controlled operation using Variable Frequency Drive (VFD) control. A modified IEEE 30-bus system with a variable load was used as a case study with integration of three PV plants of 75 MWp total power capacity. The adopted 33.33 MW RO plant has a maximum capacity of 200,000 m3/day of fresh water production. The results reveal that while typical operation of RO plants can lead to voltage violation, applying the proposed load management algorithm can maintain the vs. of the PS. The total transmission power loss and power lines loading were also reduced. However, the study shows that applying VFD control is better than using ON/OFF control because the latter involves frequent starting up/shutting down the RO trains, which consequently requires flushing and cleaning procedures. Moreover, the specific energy consumption (SEC) and RO plant recover ratio decreases proportionally to the VFD output. Furthermore, the power consumption of the RO plant was optimized using the PSO technique to avoid unnecessary restriction of RO plant operation and water shortage likelihood.

Integrated approach in eco-design strategy for small RO desalination plants powered by photovoltaic energy

Potential Applications for Desalination in the Area