Our water treatment solutions produce 20.1 billion gallons of drinking water per year
Seven Seas Water Group delivers abundant, safe, and reliable high-purity drinking water to communities and to some of the most demanding industries around the world. We are committed to solving water challenges through our portfolio of advanced technical solutions.
The Seven Seas lineage stretches back to the origins of reverse osmosis desalination more than 60 years ago. As the company evolved, a majority of its senior management and engineers arrived with the acquisition of Ionics, a company that has designed and built more than 1,000 seawater reverse osmosis (SWRO) desalination plants, including the largest in the Western Hemisphere.
Seven Seas owns and operates the plants it builds and updates, and is responsible for long-term contracts. That means a business model founded on quality design, construction, and equipment, one that delivers reliable water services with an appreciation for continuing relationships.
Delivering Reliable Service Using Proven, Sustainable Water Treatment Technologies
Seven Seas owns and operates more than 100 plants worldwide with a consistent average of 97% plant availability, which is made possible by the most reliable technologies in the business:
Reverse Osmosis
Reverse Osmosis Water Purification: Reverse osmosis (RO) is the most popular desalination technology in the world due to its higher cost-efficiency. In the process, pressurized seawater is forced through a membrane with very small pores (0.001-0.0001 microns) that reject dissolved substances, including salts and minerals. It can purify water destined for domestic taps or industrial applications.
Drinking water purification plants are frequently built around reverse osmosis because the utmost care must be taken with water for human consumption. RO water purification is usually preceded by stages such as coagulation, flocculation, and sedimentation, and can be followed by disinfection. Reverse osmosis is also important to many industries for demineralizing water and meeting the exacting ultrapure water standards of the chip manufacturing industry. RO remains energy-intensive, so lower-pressure membrane processes are a better fit when the higher reverse osmosis standard is not required.
Seawater Reverse Osmosis Desalination: Seawater reverse osmosis (SWRO) is widely used to transform seawater into drinking water or process water. While it is the most energy-efficient desalination process, it remains energy-intensive. Membranes must be cleaned to control fouling, and the concentrated brine left over by the process must be thoughtfully managed to avoid environmental impacts.
Brackish Water Reverse Osmosis Desalination: In brackish water reverse osmosis (BWRO), the lower salt content of brackish water simplifies the process and makes it more efficient. While SWRO plants generally must have coastal access, BWRO can source water from brackish aquifers even far inland. It has been estimated that in the United States, there is more than 800 times more brackish groundwater in aquifers than there is fresh groundwater pumped from aquifers. When BWRO is conducted far inland, however, piping brine to the ocean is not an option, so an alternate disposal protocol must be established.
Other Membrane Processes
Microfiltration: Microfiltration (MF) uses low-pressure membranes with a pore size range of 0.03 to 10 microns to remove suspended solids, frequently as a pretreatment stage before RO or nanofiltration (NF) to control membrane fouling. The process is generally configured either in aeration tanks with vacuum systems or in external pressure-driven membrane units that can take the place of secondary clarifiers and tertiary filtration. The process can remove sand, silt, and clay; giardia lamblia and cryptosporidium cysts; algae; and some bacteria. MF is, however, insufficient on its own for more exacting applications.
Ultrafiltration: Ultrafiltration (UF) uses membranes with pore sizes of 0.002 to 0.1 microns to remove particles, viruses, and microorganisms. It is more effective than MF at removing smaller particles at submicron and colloidal sizes, and can remove dissolved proteins and polysaccharides. UF has a number of advantages over conventional clarification and disinfection processes. It requires a very small physical plant footprint and automation is simple. Chemicals (coagulants, flocculants, disinfectants, and pH adjusters) are not needed to produce a consistent level of particle and microbial removal.
Nanofiltration: Nanofiltration (NF) membranes have a pore size of approximately 0.001 microns to separate dissolved substances including ions and small molecules. It is often used to soften water, and remove color and organic carbon.
Electrodeionization
Electrodeionization: Electrodeionization (EDI) is a water treatment technology that uses DC power, ion exchange membranes, and ion exchange resin to deionize water to a high degree of purity suitable for chip and pharmaceutical manufacturing. EDI is generally used as a polishing stage after RO, operating continuously without chemical regeneration. Instead, the DC current continually regenerates the ion exchange resin. EDI requires pretreatment to control water hardness, silica, carbon dioxide, total organic carbon, chlorine, ozone, and other oxidizers.
Filtration
Multimedia Filtration: Multimedia filters use three or four stages of media to deliver a higher filtering capacity and flow rate than single-media filters of the same size. Generally, multimedia filters require less frequent maintenance than single-media, which tends to lower operating expenses. Multimedia filtration removes particles that cause turbidity, but dissolved iron, manganese, and hydrogen sulfide must be oxidized into solid particles via chlorination or ozonation before they can be removed by a multimedia filter. Multimedia filters must be carefully backwashed on a schedule.
Gravity Filtration: Gravity filtration is a fundamental and widely used water treatment technology that relies on the force of gravity to separate impurities from water. This time-tested method operates simply by allowing water to flow through a porous medium, typically a bed of sand, gravel, or other filtration media. As the water passes through, suspended particles, sediment, and impurities are captured by the medium, leaving behind cleaner, clearer water. Gravity filtration is highly effective in removing larger particles and is often employed as a preliminary step in the water treatment process. It’s appreciated for its reliability, ease of maintenance, and energy efficiency, making it a valuable component in ensuring safe and clean drinking water for communities around the world.
Disinfection
Chloramine Disinfection: Chloramine is a combination of chlorine and ammonia. It is used as an alternative to chlorine and provides longer-lasting residual disinfection, which can help control the growth of pathogens in distribution systems.
Ultraviolet (UV) Disinfection: UV disinfection uses ultraviolet light to disrupt the DNA of microorganisms, rendering them unable to reproduce or cause infections. UV treatment is a chemical-free process and is effective against a wide range of pathogens.
Chlorine Dioxide: Chlorine dioxide (ClO2) is another disinfectant used in water treatment. It is effective against a broad spectrum of microorganisms and has the advantage of not forming halogenated disinfection byproducts (DBPs).
Resilient Water Treatment Plants
Seven Seas understands that as climate change moves forward, the importance of resilience to climate shocks and water risk will continue to grow. We also understand that some of the most serious impacts of disasters are secondary impacts that come from the loss of critical services such as providing water. We know water utilities are on the front lines, so we are innovating to safeguard this vital resource in emergencies.
Our plants maintain the lowest downtime in the industry at 3% compared to the industry average of 15-20%, thanks to our computerized maintenance management system (CMMS) that keeps operations and maintenance on track and alerts operators to issues that could develop into failures.
Deep roots in the hurricane-prone Caribbean have also driven Seven Seas to innovate for resilience, and in 2022 our desalination plant on St. Thomas in the U.S. Virgin Islands received the first ever Gold Wind Rating from the U.S. Resiliency Council for its structural features that stand up to wind and storm surges. The plant was also awarded a USRC Silver Earthquake Rating.
Sustainable Approaches to Water Treatment
Seven Seas’ innovative Water-as-a-Service® (WaaS®) model stands in stark contrast to traditional infrastructure delivery methods. With WaaS®, financing is provided in-house, alleviating the burden on customers to secure capital independently. Seven Seas takes on the responsibility for plant construction and assumes operational and maintenance risks, offering build-own-operate and build-own-operate-transfer agreements that ensure long-term expertise. Customers simply pay for the water they use at a guaranteed price and quality, eliminating the need for capital procurement, organizational development, and operational complexities. Moreover, the Lease Plant Program provides additional flexibility, allowing for temporary, modular, and customizable options that cater to specific requirements, ultimately promoting cost-effective and sustainable water solutions.
Featured Water Treatment Case Studies
Alice, Texas
Seven Seas’ Water-as-a-Service® (WaaS®) will save millions for Alice, Texas, which long relied on a 20-mile pipeline for raw water to feed its water treatment plant, at cost of $3.05-$4.05/1,000 gallons. For savings, resilience, and independence, Seven Seas proposed an expandable 3 million GPD brackish water desalination solution to tap Alice’s brackish aquifer. The project’s WaaS® BOOT contract required no upfront investment, saving taxpayers $12 million that the competing solution would have cost. It also cut long-term water prices to between $2.24-$3.65/1,000 gallons. That means Alice will receive the plant virtually free, pay less for water, and offload risk, operations, and maintenance to Seven Seas with no discernable downside.
Point Fortin, Trinidad
Seven Seas’ overcame obstacles to fast-track a 6.7 million GPD (25,379 m3/d) desalination plant on a 1.2-acre site, delivering in just 14 months after receiving permits. The plant transforms high TDS/TSS feedwater into a reliable municipal supply of fresh water while protecting a sensitive marine ecosystem. The BOO financing model allowed project delivery with no upfront capital investment.
Limetree Bay Terminal, USVI
In the U.S. Virgin Islands, one of the world’s largest petroleum refineries needed 650,000 GPD (2,460 m3/d) of industrial-quality water on an emergency basis. Seven Seas constructed a two-pass solution consisting of three mobile seawater reverse osmosis units and one land-based brackish water reverse osmosis unit to deliver the requested capacity ahead of schedule — only 67 days — with no capital investment. The plant exceeds the required quality specifications and has been operating continuously since startup. As the client’s needs changed, the plant capacity was reduced to 200,000 GPD (757 m3/d).
Water-as-a-Service®
With Water-as-a-Service®, Seven Seas Water Group takes on all the business of water and wastewater treatment with no upfront investment, charging clients only for water delivered. We offer variable-year arrangements and can buy existing infrastructure. And, equipment can be scaled up or down to meet changing demand.
Learn more about our turnkey water and wastewater solutions.
Lease Plant Program
Looking for smaller treatment capacities or a lease arrangement? We also offer the option to lease water and wastewater treatment plants or use design-build or design-build-finance models.