Our wastewater solutions treat billions of gallons per year in plants around the globe
In addition to the desalination and water treatment it’s known for, Seven Seas Water Group also offers a range of wastewater treatment solutions and technologies.
Seven Seas owns and operates the plants it builds under long-term, performance-based contracts. Our business model depends on quality design, construction, and equipment to deliver reliable services with a focus on continuing relationships, not the end of a warranty period. We’re always searching for the most robust technologies in the industry, and those technologies now help maintain a consistent record of 97% availability at our plants across sectors and around the world.
Our Water-as-a-Service® (WaaS®) infrastructure delivery model helps to make this reliability a reality. WaaS® can serve public entities with public-private partnerships, as well as private customer.
WaaS® uses contracts including build-own-operate (BOO) and build-own-operate-transfer (BOOT) that deliver wastewater treatment service at no upfront cost. And because we’re responsible for operations and maintenance (O&M) over the long term, it’s in our interest to build headache-free plants.
Whether a customer is not prepared for a full-scale plant acquisition, prefers aligning project growth with phased installations, or requires a temporary shutdown of an existing plant for any reason, we also have a Lease Plant Program, offering both short-term and long-term leases, with the added flexibility of an eventual purchase.
Providing Dependable Service With Sustainable Wastewater Treatment Technologies
Seven Seas owns more than 160 plants around the world, maintaining an impressive 97% average plant availability. This exceptional performance is all thanks to our industry-leading technologies:
Conventional Activated Sludge
Conventional activated sludge (CAS) wastewater treatment is a robust and efficient workhorse process used widely in the water sector to treat municipal and industrial wastewater. Activated sludge plants mix wastewater with microorganisms in an aeration tank, where they naturally break down and convert organic contaminants into benign byproducts. The activated sludge is then separated from the treated water in a settling tank, and some of it returns to the aeration tank to continuously support highly effective levels of active microorganisms.
Fixed Film
Fixed film (FF) wastewater treatment also relies on microorganisms to do the heavy lifting, but they are allowed to colonize a solid support medium. Once attached, they form a robust colony called a biofilm that can stand up to temperature and chemical shocks better than detached microorganisms on their own. When wastewater comes into contact with the biofilm, the biofilm metabolizes and removes the contaminants. Biofilm offers the distinct advantages of high efficiency, shock resistance, and a smaller physical footprint.
Membrane Bioreactors
Biological Nutrient Removal
Biological nutrient removal (BNR) targets nitrogen and phosphorus compounds, which are growing health and environmental concerns due to the toxic algal blooms and dead zones they create in water bodies. BNR systems use specific microorganisms that convert nitrogenous compounds like ammonia into harmless nitrogen gas, and microbes that metabolize phosphate. BNR can be integrated into other wastewater treatment configurations, including activated sludge systems and other advanced treatment systems.
Dissolved Air Flotation
Dissolved air flotation (DAF) is a popular process for separating suspended solids and oils from water, clarifying, reducing solids, and generally improving effluent quality. DAF systems use high pressure to saturate wastewater with air. The pressurized wastewater is then routed to a flotation tank or basin. When the pressure is released, tiny air bubbles form and adhere to the suspended solids, creating buoyant “flocs” that rise to the surface and form a sludge layer that is then skimmed. DAF effectively removes colloidal and small particles that may be a challenge for sedimentation systems in food processing, paper and pulp processing, and wastewater treatment.
Clarification
After primary treatment processes, clarification separates suspended solids and impurities from water by allowing particles to gradually settle in a sedimentation basin. A sludge layer forms on the bottom and is removed periodically. The clarified water moves upward and is collected from the top of the basin. Additional processes such as flocculation may precede clarification, and it is often followed by secondary processes.
Microfiltration and Ultrafiltration
Microfiltration (MF) and ultrafiltration (UF) are membrane filtration processes that can remove suspended solids, bacteria, and other contaminants from water. While reverse osmosis (RO) offers finer filtration, MF and UF balance energy efficiency and water quality when the highest level of filtration is not required.
MF membranes have larger pore sizes (0.1 to 10 microns) that efficiently remove suspended particles, some bacteria, and larger colloidal matter. It is commonly used as a pretreatment stage before other membrane processes or by itself when the highest water quality is not critical.
Ultrafiltration uses membranes with smaller pore sizes (0.005 to 0.1 microns) for finer filtration of suspended solids, bacteria, viruses, and macromolecules. It can be used as a standalone treatment or in a multi-barrier advanced wastewater treatment system, offering high pathogen removal and producing effluent suitable for many reuse applications.
Disinfection
In cases where effluent must meet purity standards for discharge or reuse, disinfection is the important final stage that eliminates pathogenic microorganisms and bacteria. Common disinfection methods include chemical agents, ultraviolet (UV) irradiation, and ozonation. The choice of disinfection method generally depends on factors such as targeted pathogens, quality standards, and environmental considerations. Common methods include:
Chlorination: Chlorine can be added in various forms — including chlorine gas, sodium hypochlorite, and calcium hypochlorite — to kill bacteria, viruses, algae, mold, and other microorganisms.
Chloramine disinfection: Chloramine is a mixture of chlorine and ammonia that yields longer-lasting disinfection to control pathogens in distribution systems.
Ultraviolet (UV) disinfection: UV disinfection employs ultraviolet light to destroy pathogens without using chemicals.
Chlorine dioxide: Chlorine dioxide is effective against a wide range of microorganisms and has the advantage of not contributing to the formation of halogenated disinfection byproducts (DBPs).
Wastewater Treatment Plants Built for Resilience
Seven Seas plants routinely post the lowest downtime, and our industry-topping 97% plant availability can be explained by our preventative maintenance systems, durable plant and equipment design, and wind and earthquake-resistant construction.
We own and operate more than 100 plants, so it benefits us to build to the highest standards and use the most durable materials and equipment. We also use a limited number of tried-and-true standardized designs, which allows us to keep a comprehensive parts inventory on hand for quick response to failures.
Our focus on decentralization also addresses resilience. In a region with a single centralized plant, a direct hit from a hurricane can cripple the entire region. In an area served by an array of smaller plants, however, damage to one plant causes a much more localized problem, and repairs are typically accomplished more quickly and cost-effectively.
Sustainable Wastewater Treatment Solutions
In 2024, Seven Seas Water Group attained GRESB’s top five-star ESG performance rating with a score of 100/100, ranking first among peers and earning recognition as a GRESB Sector Leader in Infrastructure. We think our WaaS® model is a viable tool to stop the build-neglect-rebuild cycle that ends the service lives of so many plants prematurely. It makes plants financially sustainable when traditional arrangements just can’t.
We’re constantly looking for ways to support communities and industries in ways that are also a win for the environment.
Our water reuse activities are purifying wastewater to release into the environment to support healthy ecosystems or to reuse for nonpotable applications. Reuse increases the supply of available water, which lessens the need to pump water from depleted aquifers or surface water bodies. And, we have begun installing solar arrays to power ancillary functions at our plants.
Featured Wastewater Treatment Case Studies
Leeward Estate, Turks and Caicos Islands
On the Turks and Caicos Islands in the Caribbean, a developer had difficulty finding a company with flexible solutions that could be installed in phases to match the expansion of a new resort featuring residences and a marina. Seven Seas Water Group was able to provide the modular technologies that allowed phased installation of a desalination plant, along with a 0.05 MGD (189 m3/d) membrane bioreactor wastewater treatment plant. The high-quality effluent produced from the complex’s wastewater now provides safe, low-cost irrigation water for the development.
Community Development in Harris County, Texas
In Harris County, Texas, a commercial real estate developer needed a 0.6 MGD (2,271 m³/d) wastewater treatment plant for a new planned community, but the lowest bid for the secondary activated sludge project came in at $8 million. Seven Seas Water Group was able to offer a 5-year lease agreement that would not only lower the total cost to $2 million, but would break up capital investment into more manageable sums. Installation was phased in four stages to add capacity as new sections of the development were completed, allowing the developer to redirect money saved toward continuing overall development of the community.
Hunt County, Texas
A new community development in Hunt County, Texas, was growing quickly and needed to add wastewater treatment capacity to its existing operation until a larger, permanent plant could be built. Seven Seas Water Group was able to provide a 155,000 GPD (587 m3/d) temporary bypass plant during the construction of the new plant. Our assets were quickly mobilized to prevent service disruption, and the bypass plant was fully operational within only three months of the contract’s execution.
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 customers 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 the design-build or design-build-finance models.