For over 30 years WSI has been building and designing wastewater treatment systems and equipment
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    At WSI we only use the highest sourced stainless steel and products. We do not compromise when it comes to quality.
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    We have the best trained wastewater support staff in the world
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Wastewater Treatment Plant Designs

Design-Build WWTP

WSI has the capability to build large scale wastewater treatment plants for major community centers and industrial operations. Our plants have phased designs to accommodate early budgets and meet future demand and local regulations.

Our plants can be custom designed to meet local and regional discharge standards, custom footprints and integrated controls with existing systems. The control systems are easy to operate, can be remotely accessed and can collect long-term data to send anywhere in the world.

Our primary technology is based around MBBR's (Moving Bed Biofilm Reactor).  This technology is easy to maintain and requires little operator oversite. MBBRs are have been proven reliable and are easy to permit.
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Modular Wastewater Treatment Plants

Our pre-designed and pre-fabricated packaged plants are perfect when it's not feasible to tie into a traditional centralized wastewater treatment plant. These plants are best used in land development, housing, subdivisions, and small to medium-sized communities.

The plants are custom design using MBBR technology, Anoxic and Anaerobic Processes, DAF (Dissolved Air Flotation), Coagulants, and specialized controls and systems.

Standard designs have been approved by many state and local counties to expedite the permitting process. 
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Containerized Wastewater Treatment Plants

WSI containerized plants are perfect for temporary operations, remote locations and man camps. Our plants use the latest in wastewater technology and controls so a single part-time operator can operate the plant 24/7. These plants can be interconnected to increase capacity.

Containers are easy to ship by truck, helicopter, and ships. Each container can be crushed tested and rated by the American Bureau of Shipping if required.

Every container is designed around our MBBR technology, Micro-DAFs, and custom control systems.
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Custom Equipment

We build dissolved air flotation,
belt presses and coagulation systems
all over the world.

At WSI there is not much we can't design. We've built custom wastewater equipment for every industry:

Oil and Gas, Food and Beverage, Municipal, Mining, Industrial


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Dissolved Air Flotation Systems (DAF)

WSI has a standard line of DAF systems that are pre-designed and ready for fabrication.

Belt Presses

Our belt presses are the best in the industry due to their heavy-duty tubular design.

Meet Our Knowledge Base

At WSI we believe that all knowledge should be easily accessible by everyone. 

We are publicly posting all of our engineering notes, troubleshooting guides, maintenance manuals, and equipment cut-sheets.  If there is a guide you would like to see, let our engineers know through a support ticket and we will post one within 24 hours.

Our knowledge base contains everything from; pumps, drawings, curves, cut-sheets, control system components, blowers, valves, seals, and much much more!
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​About Us

WSI International has been designing industrial and municipal wastewater treatment plants and wastewater equipment for over 30 years. We are currently maintaining over 80 plants around the world.

Our staff has the expertise to tackle any wastewater project in Oil &Gas, Food & Beverage, Industrial Pre-Treatment, and Municipal.

Call us to design your next plant

(303) 985-0885

Core Technologies

Biological Treatment Process

Biological Treatment Process

The biological wastewater treatment process is the most proven technology for organic matter removal and nutrient removal. Based upon the growth type of the microorganisms, the biological wastewater treatment can be divided into two major groups, suspended growth process (e.g., activated sludge) and attached growth process (e.g., trickling filter). 

In a suspended growth process (e.g., activated sludge), the microorganisms are suspended in mixed liquor and have more opportunities to capture food sources (organic matter and nutrients) and dissolved oxygen. The advantages of a suspended growth process include higher quality effluent (90-95% BOD5 removal), nitrogen and phosphorus removal, and the flexibility to adapt to minor pH, organic and temperature changes. However, the major disadvantages of a suspended growth process include sludge bulking, highly skilled labor requirements, and sensitivity to shock loads, metallic and other toxic compounds. 

An attached growth process (e.g., trickling filter) consists of a bed of permeable medium of either rock or plastic media used to host the microorganisms. The organic matter (BOD5) and nutrients in the wastewater diffuse into a film, where it is then metabolized. To acquire a good quality effluent (80-90% BOD5 removal), multiple stages of the attached growth system may be required. 

WSI’s BCR (Bio-Chip Reactor) system is an enhanced activated sludge process with the biomass attached to a small bio-media that is suspended in the mixed liquor. The BCR system combines the advantages of a suspended growth process and an attached growth process. Compared to conventional activated sludge and extended aeration system, the BCR system has the advantages of providing greater biomass concentration, therefore increasing treatment capacity, eliminating sludge bulking concerns, stabilizing process operations, reducing sludge production, enhancing sludge settleability, and lowering costs for operations and maintenance. Compared to other attached growth processes, the BCR system has the advantages of providing a higher quality effluent, is easily adapted for nitrogen and phosphorus removal, provides more opportunities for contact with organic matter nutrients and eliminates odor and insect problems. 

The BCR system is mostly self-regulating and does not require daily measurements of mixed liquor suspended solids (MLSS), sludge volume index, sludge settleability, Return Activated Sludge (RAS) and Waste Activated Sludge (WAS) rate calculations for proper operation. This reduces the skill level required for successful operation and daily time requirements to maintain the system. This is critical for small community wastewater treatment facilities that do not have the resources for full-time management. 

Dissolved Air Flotation (DAF)

Dissolved Air Flotation (DAF)

The DAF unit acts to remove the suspended solids (Biomass) from the BCR reactor effluent. The BCR reactors convert soluble nutrients into cell mass and the DAF removes the cell mass and inorganic suspended solids from the reactor effluent through dissolved air floatation. The DAF pump recirculates DAF effluent and flash mixes it with ambient air (aspirated on the suction side of the DAF pump). The air dissolves into the effluent under the pressure of the pump.

The air-water solution is then passed through a saturation tank to allow additional time for the air to dissolve and to remove any coalesced air bubbles. The solution is then expanded across diaphragm control valves leading into WSI’s proprietary diffusers inside the body of the DAF. By reducing the pressure of the solution rapidly (expanding), the dissolved air is forced out of solution in the form of micro-bubbles (90% of the bubbles formed are less than 10 µm in diameter).

The small bubbles collect under the biomass floc and float it to the surface, forming a thickened sludge blanket on the surface of the DAF that is raked directly into the aerobic digester. The DAF provides greater thickening of the sludge as well as a reduced footprint from a conventional clarifier. Settled sludge is periodically pumped to the aerobic digester via a Seepex progressive cavity pump. 

Why choose WSI International?

  • Safety & Compliance Ensured
  • Start-to-Finish Solutions
  • Superior Service
  • Sustainable
  • Trained Professionals
  • On-Time Delivery
  • All Stainless Steel Designs
  • Reliable Technology

Operational Experience 

WSI is well diversified in several markets, including Oil and Gas, Food and Beverage, Municipal and Mining.



  • Application Only up to $500,000
  • Up to $10,000,000 with Financial Package
  • Terms 12-84 Months
  • Technology & Equipment Upgrades
  • 100% Financing
  • All Soft Costs Included (Maintenance, Install, etc.)
  • New & Used Equipment


Engineering Office 
1709 W Baltic PL

Englewood CO 80110

Phone: (303) 985-0885

Corporate Office

77 West St, Suite 305

Annapolis MD 21401

Phone: (443) 320-0211