Beach Wells Research Articles

Performance study on the seepage and heat transfer in a bench-scale multi-well infiltration intake system for seawater source heat pump

The Beach Well Infiltration Intake (BWII) system is one of the various methods for pumping seawater for Seawater Source Heat Pump (SWHP) systems that improve the stability, reliability, and energy efficiency of the SWHP systems in cold climate areas. Because of the limitations of the site conditions, it is difficult to perform experimental studies on the BWII system under different experimental conditions, especially for multi-well systems. Therefore, a BWII experimental system that incorporated nine beach wells was established in a laboratory in this paper. The goal was to study the seepage and heat transfer performance of the multi-well infiltration intake system and calculate the influencing range for pumping groundwater on sands in a sandbox. Then, an established seepage and heat transfer model of the BWII system was validated by the experiment. Based on the validated model, the method for designing an experimental sandbox was studied. The research results showed that the effective width increased with an increase in the distance between the pumping well and the long water tank. However, the effective width in the back part of the pumping well decreased with an increase in this distance. The result that the effective length decreased with an increase in this distance was contrary to our subjective expectations. When the distance between the pumping well and the long water tank was 0.5 m, the effective length and effective width were 1.5 ∼ 2.1 m and 0.9 m respectively. The formulas of the effective width and the effective length were derived. The experimental study provided a method to study the seepage and heat transfer performance of the BWII system and was complementary to the theoretical research and the practical engineering field research. The research results provided in this study will contribute to the establishment of a set of seepage heat transfer similarity test methods.

Redox condition of saline groundwater from coastal aquifers influences reverse osmosis desalination process

Reverse osmosis (RO) seawater desalination is a widely applied technological process to supply potable water worldwide. Recently, saline groundwater (SGW) pumped from beach wells in coastal aquifers that penetrate beneath the freshwater-seawater interface is considered as a better alternative water source to RO seawater desalination as it is naturally filtered within the sediments which reduces membrane fouling and pre-treatment costs. The SGW of many coastal aquifers is anoxic – and thus, in a low redox stage – has elevated concentrations of dissolved manganese, iron and sulfides. We studied the influence of the SGW redox stage and chemistry on the performance - permeate flux and fouling properties - of RO desalination process. SGWs from three different coastal aquifers were sampled and characterized chemically, and RO desalination experiments were performed under inert and oxidized conditions. Our results show that all three aquifers have anoxic saline groundwater and two of them have intensive anaerobic oxidation of organic matter. Two aquifers were found to be in the denitrification stage or slightly lower and the third one in the sulfate reduction stage. Our results indicate that the natural redox stage of SGWs from coastal aquifers affects the performance of RO desalination. All SGW types showed better RO performance over seawater desalination. Furthermore, air oxidation of the SGW was accompanied with pH elevation, which increased the membrane fouling. Hence, keeping the feed water unexposed to atmospheric conditions for maintaining the natural reducing stage of the SGW is crucial for low fouling potential. The observed benefits of using naturally reduced SGW in RO desalination have significant implications for reduction in overall process costs.

Numerical Modeling of Beach Well Intake as Pre-Treatment for a Desalination Plant

Pre-treatment of seawater plays a critical role in removing colloidal particles, algae, sediment, and microbes, which could adversely affect the desalination process. This study focused on the utilization of the natural process of infiltration by beach wells to pre-treat the intake water for the desalination process. The scope of the study was achieved by drilling two beach wells at Al-Khobar and Jubail sites at the Arabian Gulf of Saudi Arabia at 50 m depth each. In addition to that, a total of eight monitoring wells were drilled for pump testing. Numerical modeling was conducted using SEEP/W to investigate the properties of well water flux at the beach wells. The comprehensive physio-chemical parameters such as cation, silt density index (SDI), total dissolved solids (TDS), total suspended solids (TSS), chemical oxygen demand (COD), total organic carbon (TOC), salinity, and alkalinity were analyzed for a quality assessment concerning the actual seawater. Preliminary experimental results show a reduction of the targeted parameters and indicate that beach well sand filtration in the Eastern Province would be a valuable pre-filtration step in reverse osmosis (RO)-based drinking water production systems. The water flux values for both sites were 0.0197 and 0.0208 m3/s/m2, respectively, which corresponds to 72 m3/h/m2 and 1356.48 m3/h/m2. In terms of the rate of pumping flow, the model suggests production can be increased by 20 and 53 times the measured production of the Jubail and Al-Khobar sites, respectively. The experimental results of water parameters, such as cation, SDI, TDS, TSS, etc., indicate that beach well sand filtration in the Eastern Province would be a valuable pre-filtration step in reverse osmosis drinking water production systems.

The effects of long-term saline groundwater pumping for desalination on the fresh–saline water interface: Field observations and numerical modeling

This study tests for the first time the long-term effects of pumping saline groundwater (SGW) as feed for a desalination plant on a coastal aquifer. Field measurements combined with 3D modeling of the hydrological conditions were conducted to examine the effects of SGW pumping on the aquifer system. The plant is next to the city of Almeria (South East Spain) and has been operating since 2006. It uses multiple beach wells along the shore to draw SGW from beneath the fresh–saline water interface (FSI) of the Andarax coastal aquifer. The long-term impact of the intensive pumping on the aquifer was assessed by electrical conductivity profiles in three observation wells during 12 years of pumping. The FSI deepened with continuous pumping, reaching a decrease of ~50 m in the observation well closest to the pumping wells. A calibrated three-dimensional numerical model of the Andarax aquifer replicates the freshening of the aquifer due to the continuous pumping, resulting in a salinity decrease of ~16% in the vicinity of the wells. The salinity decrease stabilizes at 17%, and the model predicts no further significant decrease in salinity for additional 20 years. Submarine groundwater discharge is lowered due to the SGW pumping and ~19,000,000 m3 of freshwater has not lost to the sea during the 12 years of pumping with a rate of ~1,100,000 m3 yr−1 after 6 years of pumping. After pumping cessation, hydrostatic equilibrium would take about 20 years to recover. This work presents the complex dynamics of the FSI due to the SGW pumping for desalination in the first real long-term scenario. It shows by combining field work and numerical modeling, a significant freshening of the aquifer by pumping SGW, emphasizing an additional advantage and the effectiveness of this use as a negative hydraulic barrier against seawater intrusion.

Use the beach

Marine Pollution Coastal power stations regularly draw water from the ocean as a cooling source, and this water is later returned to the marine environment. The water and any marine organisms that happen to be drawn in with it are exposed to high temperatures and other mechanical processes that generally reduce survival and affect populations near outflows. Jebakumar et al. looked at the impacts of this process on an Indian creek system influenced by power station cooling draws. They found reductions in abundance, decreases in survival, and changes in community structure across marine taxa influenced by the draws. Further, regulations to reduce the temperature of the water before it is returned, though necessary, increased the impact owing to the need to draw larger amounts of water into the plant for cooler outflows. The authors suggest that a relatively simple solution would be to widely institute subsurface intake systems, or “beach wells,” which naturally filter out marine organisms before intake and improve water quality, across tropical regions. Mar. Pol. Bull. 10.1016/j.marpolbul.2018.05.053 (2018).

Multifactor analysis on beach well infiltration intake system for seawater source heat pump

The seawater source heat pump (SWHP) is a renewable energy utilization system. The beach well infiltration intake system (BWIS) effectively improves the stability, reliability, and energy efficiency of SWHP systems in cold climate areas. BWIS research requires a multidisciplinary approach that involves both hydrogeology and heat transfer theory. There are many factors influencing the energy consumption and life-cycle costs of the systems, with each factor having many possible values. This paper aims to determine the degree of influence of ten representative factors of BWIS: specific heat capacity of rock-soil, rock-soil density, thermal conductivity of rock-soil, void fraction of rock-soil, rock-soil permeability, beach well radius, site length, site width, row number of beach wells, and column number of beach wells. In this paper, a BWIS seepage and heat transfer model is established. Based on the model, an orthogonal design optimization method is presented and analyses are conducted for heat pump unit energy consumption, seawater pump energy consumption, and economic cost for various conditions using MATLAB code. The results indicate that a greater number of beach wells is not always better and the number and placement of beach wells should be scientifically and objectively optimized by the orthogonal design method. The optimization method can scientifically guide engineering design for BWIS and offset the design deficiency that results from the current practice of only using a hydrogeological report of randomly selected test wells.

The potential of using beach wells for reverse osmosis desalination in Qatar

Qatar is an arid country, with limited water resources. The country relies on desalination of seawater to meet the increasing water demand for municipal and industrial needs, while the agricultural sector uses the precious fresh groundwater. Groundwater underneath Qatar is mostly saline or brackish with small lenses of fresh water in the northern part of the country. Brackish groundwater in Qatar has a Total Dissolved Solids of less than 10,000 mg/l, compared to seawater, which is 35,000 mg/l. Using brackish and saline groundwater for desalination via beach wells is less costly and more environmental friendly than direct sea water intake, which is being used in Qatar. The main challenge facing beach wells usage is their questionable capacity to provide enough quantities for desalination plants. This study investigates the optimal location and the maximum yield of beach wells in Qatar, using Sea Water Intrusion model (SWI2), coupled with MODFLOW. Model results show the maximum yield of wells at a depth of 100 m is 16,000 m3 per km2. This quantity is good enough for a medium size reverse osmosis plant. Based on hydrogeological settings, the proposed location for the beach wells is near Al-Khor town and to the north of it.

Saline Groundwater from Coastal Aquifers As a Source for Desalination.

Reverse osmosis (RO) seawater desalination is currently a widespread means of closing the gap between supply and demand for potable water in arid regions. Currently, one of the main setbacks of RO operation is fouling, which hinders membrane performance and induces pressure loss, thereby reducing system efficiency. An alternative water source is saline groundwater with salinity close to seawater, pumped from beach wells in coastal aquifers which penetrate beneath the freshwater-seawater interface. In this research, we studied the potential use of saline groundwater of the coastal aquifer as feedwater for desalination in comparison to seawater using fieldwork and laboratory approaches. The chemistry, microbiology and physical properties of saline groundwater were characterized and compared with seawater. Additionally, reverse osmosis desalination experiments in a cross-flow system were performed, evaluating the permeate flux, salt rejection and fouling propensities of the different water types. Our results indicated that saline groundwater was significantly favored over seawater as a feed source in terms of chemical composition, microorganism content, silt density, and fouling potential, and exhibited better desalination performance with less flux decline. Saline groundwater may be a better water source for desalination by RO due to lower fouling potential, and reduced pretreatment costs.

Assessing the Seawater Intrusion Due to Beach Wells in the Desalination Plant

Short-Term Low Volume (STLV) Sea Water Desalination Plant of 6000 m3/d is under construction in the middle area of Gaza Strip. The plant will provide desalinated water for 75,000 inhabitants in regions in Khanyounis and Rafah. The intake of desalination plant will be indirectly from four beach wells. This article aims at providing the environmental impacts of these wells on the aquifer and the mitigation measures in case of negative impacts. In order to study the impacts of beach wells on the aquifer, a prediction groundwater three-dimensional model for the beach wells area, starting from the year 2000 until year 2030, was used. MODFLOW software was used for modeling the groundwater flow and SEAWAT software was used to model the seawater intrusion effect. The aquifer parameters were set as if they were in the transient model. The long term seasonal recharge rate for the summer and winter is considered to represent the seasonal differences in recharge through each year. The study showed that the steady four-meter drawdown in the beach wells will force the flow from the eastern direction to the sea. This will have positive impacts on the aquifer since it will decrease the seawater intrusion to the aquifer. The beach wells will pump water with Cl concentration equal to 18,000 mg/l. This means that the beach wells will accelerate the flow from the aquifer to the sea direction but still the pumped water is considered as seawater. This indicates the positive impacts on the groundwater aquifer since it will decrease the seawater intrusion in the beach wells area (Gaza Strip Middle area). In conclusion, these beach wells in this desalination plant (small capacity) are safe for the groundwater aquifer and it will decrease the effect of seawater intrusion on the aquifer.

CCD Series No-15: simple design batch SWRO-CCD units of high recovery and low energy without ERD for wide range flux operation of high cost-effectiveness

Closed-circuit desalination (CCD) is a batch process of low energy without need for an energy recovery device (ERD), high recovery irrespective of the number of elements per module, and wide range flux independent of cross-flow and/or recovery, which can be made continuous by the engagement of a side conduit for brine replacement with fresh feed. Batch units for seawater desalination (SWRO-CCD) of the general NMEn (n = 1–3) design, where N stands for the number of modules and n for the number of elements per module, are low-cost systems since avoid the need for ERD and the valves means for the making such a process continuous. Such SWRO-CCD batch units, which pose for recharge between desalination steps, can supply 10 → 1,200 m3/d low-cost seawater permeates sufficient for communities of 100 → 12,000 resident on the basis of 100 L/d/person and for much larger communities if supplied permeates used primarily for drinking and cooking applications. Batch SWRO-CCD units are ideal for small seashore communities with access to shallow beach wells in light of their low-energy consumption and great operational flexibility such as of low flux energy saving mode during night time of low demand with increased production as function of demand at higher flux and greater energy expense during daytime. The wide range flux performance capability of the referred batch units make them ideal for integration with renewable energy sources through solar panels and/or small wind turbines. The energy consumption and permeates quality (parenthesis) as function of flux for the referred units with ME3 (E = SWC6-MAX) modules’ designs for ocean seawater (35,000 ppm) operation of 50% recovery using pressurizing means of 85% efficiency are as follows: 1.79 kWh/m3 (595 ppm) at 13 Lmh; 1.97 kWh/m3 (388 ppm) at 20 Lmh; 2.12 kWh/m3 (309 ppm) at 25 Lmh; and 2.25 kWh/m3 (259 ppm) at 30 Lmh. The experimentally confirmed cited energy figures, even at high flux, manifest high-energy conversion efficiency unattainable by conventional SWRO techniques.

Origin and evolution of groundwater collected by a desalination plant (Tordera, Spain): A multi-isotopic approach

Summary The Tordera Desalination Plant located in Blanes (NE Spain) has seawater intake through 10 beach wells located a few meters inland on the shoreline at the Tordera River Delta. Between October 2002 and October 2003, the extracted groundwater showed a decrease in conductivity, especially in the wells located in the northern area, prompting the present study. A multi-isotopic approach (δD, δ18 O H 2 O , 3H, δ34 S SO 4 , 87Sr/86Sr and 228Ra/226Ra) coupled with chemical data was applied in order to assess the origin of the water collected for the desalination plant and to quantify the extent of freshwater collection from the Tordera aquifer, when applicable. Three multi-piezometers located in the Tordera aquifer were also sampled in order to characterize the freshwater end-member. A seasonal survey was performed in order to assess the evolution of mixed freshwater–seawater intake. Tritium isotopes showed values ranging from 0.6 to 2.5 TU indicating recent origin of the collected waters. This was further confirmed using radium isotopes (226Ra and 228Ra), as the 228Ra/226Ra activity ratio (AR) indicated a continuous input of seawater on a yearly time scale. The water extracted from the beach wells was at least 95% seawater, except for wells 8–10. The latter two were extracting up to 15% of freshwater from the Tordera aquifer system. From a methodological point of view, while δ34S of dissolved sulphate and the ratio 87Sr/86Sr are good tracers of seawater mixing with freshwaters, the isotopic composition of water (δD and δ18 O H 2 O ) and the Cl−/Br− ratio are conservative tracers that allow for quantifying the contribution of freshwater to the extracted water. Although slight variations linked to seasonality were observed in all wells during the 3-year study period (November 2003 to December 2006), wells 1 and 7 showed an increase in freshwater contribution from 4% to 11% and well 10 a decrease from 15% to 10% over this period.

Reducing the impact of a desalination plant using stochastic modeling and optimization techniques

Summary Water is critical for economic growth in coastal areas. In this context, desalination has become an increasingly important technology over the last five decades. It often has environmental side effects, especially when the input water is pumped directly from the sea via intake pipelines. However, it is generally more efficient and cheaper to desalt brackish groundwater from beach wells rather than desalting seawater. Natural attenuation is also gained and hazards due to anthropogenic pollution of seawater are reduced. In order to minimize allocation and operational costs and impacts on groundwater resources, an optimum pumping network is required. Optimization techniques are often applied to this end. Because of aquifer heterogeneity, designing the optimum pumping network demands reliable characterizations of aquifer parameters. An optimum pumping network in a coastal aquifer in Oman, where a desalination plant currently pumps brackish groundwater at a rate of 1200 m 3 /h for a freshwater production of 504 m 3 /h (insufficient to satisfy the growing demand in the area) was designed using stochastic inverse modeling together with optimization techniques. The Monte Carlo analysis of 200 simulations of transmissivity and storage coefficient fields conditioned to the response to stresses of tidal fluctuation and three long term pumping tests was performed. These simulations are physically plausible and fit the available data well. Simulated transmissivity fields are used to design the optimum pumping configuration required to increase the current pumping rate to 9000 m 3 /h, for a freshwater production of 3346 m 3 /h (more than six times larger than the existing one). For this task, new pumping wells need to be sited and their pumping rates defined. These unknowns are determined by a genetic algorithm that minimizes a function accounting for: (1) drilling, operational and maintenance costs, (2) target discharge and minimum drawdown (i.e., minimum aquifer vulnerability) and (3) technical feasibility of the solution. The performance of the optimum pumping network is compared to that of a synthetic, tradition-based hand-delineated design, where optimization is not performed. Results show that the combined use of stochastic inverse modeling and optimization techniques leads to minimum side effects (e.g., drawdowns in the area are reduced substantially) and to a significant reduction of allocation and operational costs.

Innovative seawater intake for reverse osmosis desalination plants

Seawater desalination plants typically consist of four major unit operations: seawater intake, pretreatment, Reverse Osmosis (RO) stage, and posttreatment and brine discharge. The best way is to go through vertical beach wells, but the increase of the production capacity of the plants built in recent years makes open intake the only solution. These open ocean intakes draw seawater through the meshed intake screen and then convey the seawater to the desalination plant. The raw seawater then undergoes pretreatment, typically using either conventional or membrane pretreatment processes to prevent particle/colloidal fouling of Reverse Osmosis/Nanofiltration (RO/NF) membranes. Use of these pretreatment processes increases the capital cost of the facility and also escalates the operational costs, as these facilities require additional chemicals and energy. For these reasons, an alternative has arisen in recent years, namely horizontal boreholes. The present paper analyses this option and compares its performance in a real case study.

The advantages of a flexible rising main in beach wells

Angus Flexible Pipelines is the industrial hose division of Kidde plc — a major FTSE200 British company — manufacturing a range of long-length layflat hoses for use in potable water and general bulk liquid transfer applications. These include Wellmaster Flexible Rising Main, which is designed to replace steel pipes with submersible pumps in boreholes. The selection of appropriate materials throughout the desalination process is critical for cost-effective, longterm operation of plants. In addition to the economic considerations of a long efficient service life, as the provider of a life-sustaining service, it is essential that interruptions to operations be kept to an absolute minimum. The concept of Flexible Rising Mains was developed over 20 years ago and they are in use throughout the world in applications where water is abstracted from boreholes. Their all-synthetic construction makes them particularly attractive to operators of reverse osmosis plants where the water intake is from beach wells using submersible pumps. Features of Flexible Rising Mains include: • Totally unaffected by high salinity. No corrosion. • No scaling • No flanges or joints except at the pump and wellhead. • Hydraulically more efficient than steel or GRP pipe. • Light and compact. Benefits to the user as a result include: • Long service life. • No deterioration in hydraulic performance over time. No scaling which can detach and damage the membrane. • Rapid installation and retrieval of the submersible pump. Minimum downtime for maintenance or repair, with minimum interruption of supply. • This benefit can be taken as power savings, smaller pump for the same flow or smaller diameter riser. • Easy to store and transport — particularly relevant in remote areas. They require less heavy-duty plant (trailers and cranes) and smaller work crews. A technology that has been used extensively in other areas of the water market for many years has been growing strongly in the desalination sector for the past 7 years. The paper will seek to fully detail the concept and to expand on the features and benefits relevant for operators of reverse osmosis desalination plants.

Seawater intakes for desalination plants

The seawater intake has to ensure sufficient seawater in terms of quantity and quality independently from the type of desalination plant (RO, MED, MSF) installed downstream. The best seawater quality can be reached by beach wells, but in these cases the amount of water which can be extracted from each well is limited by the earth formation, and therefore the amount of water available by beach wells is very often far below the demand of the desalination plant. In these cases the developer has the choice between (1) an intake from deep seawater with the advantage to have less polluted seawater and the disadvantage of high investment cost which normally limits this type of seawater intake to 20,000 m 3/h; (2) open seawater intakes with the advantage of low investment cost but the disadvantage of biologically more active water which requires more efforts to treat the seawater. Offshore seawater intakes require a submerged pre-screening device minimizing the amount of sand sucked into the pipeline and ensuring that no particles able to damage or block the pump can enter. A description with pros and cons of the different available pre-screening devices will be given in the presentation, with special consideration of how the different types influence the total project cost. Open seawater intakes have to handle much higher amounts of coarse debris as well as micro organisms. The different kinds of available open seawater intakes will be presented in the presentation as well, demonstrating how efficiently and economically the different intake types fulfil this requirement.

Low cost incremental seawater plant capacity increase by coupling advanced pumping and RO technologies

Many localities throughout the world, particularly those bordering of the Caribbean and Mediterranean Seas, have installed reverse osmosis plants to provide potable water to their populations. A large number of these facilities operate at pressures 900 to 1000 psig with feedwater temperatures ranging 18° to 32°C (64° to 90°F) Water sources are from beach wells for most small units to open sea intakes for the larger capacity ones. A number are built with energy recovery modules designed to reuse 25 to 35% of the electrical power. Installation costs range from US$ 4 to 8 per gpd (US$ 1000 to 2000 m 3/d) with operational costs of US$ 6 to 15 per 1000 gals (US$ 1.50 to 4.00/m 3). The RO plants have provided an excellent, reliable supply of drinking water. Today a number of these localities are faced with the need to expand their potable water supplies to meet growing population and tourists demands. The world's economies, however, have placed severe restrictions on the availability of money to finance the resolution of these needs. This paper discusses a technical and commercial approach to an inexpensive capacity increase for existing RO plants. The technology involves the marriage of two systems which have had, individually, years of market place demonstration. Technically the brine effluent from an existing RO plant is pressure upgraded to 1200 psig in a Pump Engineering Hydraulic TurboCharger TM TURBO TM and then fed to DuPont B-10 TWIN TM permeators. Additional permeate is extracted in this high pressure membrane array resulting in overall plant recoveries that approach 60%. The brine from the high pressure stage solely energizes the TURBO TM, thus electrical consumption is zero excepting for instrumentation. No added pretreatment or raw water supply is usually required. Energy consumption on a unit permeate basis can be significantly reduced. Production of WHO quality water is possible. Capital and operating costs are much less than new plant capacity. Studies and case histories are presented.

Seawater desalination by reverse osmosis : Plant design, performance data, operation and maintenance (Tanajib, Arabian Gulf Coast)

A systematic interpretation of critical combinations of feed water, pretreatment and membranes and adequate conclusions can avoid setbacks of reverse osmosis processes. Reputed systems manufacturers will find the right approach if their tasks will be changed from a limited responsibility — for design, construction, installation and commissioning only — to an overall responsibility which includes operation and maintenance. In 1982/83 Preussag received from Aramco in Saudi Arabia the order for the first temporary reverse osmosis seawater desalination plant at Tanajib, Arabian Gulf Coast, with a total net capacity of 600,000 gpd. The orders were placed on a turnkey basis including operation and maintenance. The highlights of the RO seawater desalination plant are: shallow beach wells, ultrafiltration, vacuum deaeration, high-pressure multi-stage centrifugal pumps with energy recovery turbine, single stage reverse osmosis and free programmable logic and process controller. During the first more than one and a half years of operation, product quantity and quality has always met the requirements of Aramco's specification. The excellent experiences until today with the first temporary Tanajib reverse osmosis seawater desalination plant permit the conclusion that RO technology can avoid major setbacks and may face the competition with the distillation processes with confidence.