Technical Solutions

With water plants that produce millions of gallons of potable and high-purity water and other plants that treat up to 1,500,000 gallons of wastewater per day, Seven Seas Water has an impressive track record. We deliver abundant, safe and reliable fresh and high-purity water and wastewater treatment to communities in water scarce regions and to some of the most demanding industries around the world. We are committed to solving water challenges through our repertoire of advanced technical solutions.

REVERSE OSMOSIS

Seawater Reverse Osmosis (SWRO) and Brackish Water Reverse Osmosis (BWRO) are pressure-driven membrane processes. Hydraulic pressure is used to overcome the feed solution’s osmotic pressure and induces diffusion of pure water referred to as permeate, through a semi-permeable membrane. The solutes in the feed stream are concentrated during the process and leave the system as concentrated brine, also known as reject. These systems effectively remove all organic and inorganic constituents, including monovalent species. Seawater systems compared to brackish water systems are capable of more selective separation of water from other constituents in the feed stream due to higher pressures and smaller membrane pore sizes. Operating pressures for SWRO range from 750-1000 psi while BWRO ranges from 200-400 psi.

ULTRA-FILTRATION / MICRO-FILTRATION

Micro-filtration is a size-exclusion, pressure-driven membrane process. This technology uses microporous membranes, which can remove contaminants ranging from 0.1 to 10 μm. Microfiltration provides an effective barrier for particles, bacteria and protozoan cysts. Operating pressures range from 5 to 30 psi. Ultra-filtration (UF) is also a size-exclusion, pressure-driven membrane process. Compared to micro-filtration, UF retains much smaller particles. Molecules greater than the nominal pore size or nominal molecular weight cutoff (MWCO) are retained. Most UF systems range from 80k to 100k MWCO. This type of water treatment typically targets particulates, bacteria, protozoa, viruses and organic molecules. Operating pressures range from 10 to 50 psi.

DISSOLVED AIR FLOTATION

Dissolved Air Flotation (DAF) is a water treatment process which removes suspended matter such as oil or solids. The removal is achieved by dissolving air in the water or wastewater under pressure and then releasing the air at atmospheric pressure in a flotation tank or basin. The released air forms tiny bubbles which adhere to the suspended matter causing the suspended matter to float feedwater to SWRO and BWRO plants as well as to the surface of the water. There it may be removed by a skimming device. Dissolved air flotation is very widely used in treating the industrial wastewater effluents from oil refineries, petrochemical and similar industrial facilities.

ELECTRODEIONIZATION

Electrodeionization (EDI) is a water treatment technology used to produce ultra-pure water. It utilizes ion-exchange resins and ion-selective membranes, which are continuously regenerated by an electric current. The ion-exchange process removes ionized species from water by exchanging them for H+ and OH- ions. This type of water treatment requires no chemicals to regenerate the resin beds unlike older technologies for ultra-pure water production. The product water from an EDI system can reach very high purity (5-18 MΩ/cm) and is used for industrial processes such as steam generation/boiler feed, pharmaceutical industry, biotechnology, chemical production, laboratories and electronics.

MULTIMEDIA FILTRATION

Multimedia filtration is a pressurized filtration process where water is filtered through three or more different media. The types of media used can include sand, anthracite, and garnet. This type of filtration can remove particles from 10-25 micron in size. They are typically operated at loading rates of 3-8 feet per second. The media periodically must be backwashed to remove the trapped contaminants.

GRAVITY FILTERS

Gravity filtration is used to remove suspended material from water by trapping the material between the grains of filter media. The force of gravity is utilized to move the water through the filter. The filter tanks are typically rectangular and contain the filter media and an under-drain system. Filter media consists of different grades of sand with different grain sizes, anthracite, which is lighter than sand (so remains above the sand) and garnet which is used as the bottom media because of its greater density. The under-drain system allows for uniform collection of filtered water and an even distribution of backwash water. Rapid sand filters have a desired filtration rate of 2 feet per second and high-rate filters have a filtration rate of 4-6 feet per second.

CLARIFICATION

Also known as sedimentation, clarification is the removal of settleable solids by gravity. Sand, grit, precipitates, pollutants, flocs, and other solids are kept in suspension in water as long as the water is flowing with sufficient velocity and turbulence. Sedimentation removes these solids by reducing the velocity and turbulence. The process takes place in large tanks called sedimentation basins. Basins designed for efficient sedimentation allow the water to flow very slowly with minimum turbulence at entry and exit points. The solids accumulate at the bottom of the basin as a sludge. The sludge must be pumped out and disposed of.

MEMBRANE BIO REACTOR

Membrane Bio Reactor (MBR) is a wastewater treatment technology. Membrane bio reactors function similarly to traditional waste activated sludge water treatment processes except that separation of liquids and solids is accomplished by membrane filtration rather than sedimentation in clarifiers. The key components in an MBR system are micro-filtration or ultra-filtration membranes. These allow for the removal of particulate materials. The MBR process also has the advantage of being able to process wastewater with a higher suspended solid content compared to a conventional wastewater treatment plant. Generally, the footprint of an MBR system is smaller than traditional wastewater treatment technologies because it eliminates the need for a clarifier and tertiary treatment. Other wastewater treatment technologies available include Activated Sludge Process (Extended Aeration, Single State Nitrification, Contact Stabilization, Complete Mix), Fixed Film/Attached Growth (MBBR and IFAS), Sequencing Batch Reactors (SBR), Biological Nutrient Removal, Chemical Phosphorous Removal, and Tertiary Treatment.