Most engineers know Coanda screens as water intake technology: passive, gravity-fed devices that filter debris from rivers, reservoirs, and canals before the water reaches a turbine, pump, or treatment plant. That is where the technology was developed, and it is where ADENCO has built its reputation over more than a decade of manufacturing.
But the physics that make a Coanda screen effective for clean water intake (gravity-powered flow, tilted wedge wire separation, continuous debris removal, operation without electricity) are exactly the same physics required for the first stage of wastewater treatment: removing solids from a liquid without mechanical components, without electricity, and without chemicals.
This is not just theory. Static screens and sieve bends built on Coanda-effect principles have been used in wastewater pre-treatment for decades: in food processing plants, municipal stormwater systems, mining operations, and industrial effluent treatment. What has been missing is a systematic engineering guide that connects the Coanda screen expertise developed in the water intake sector with the specific demands of wastewater solid-liquid separation.
This guide fills that gap.
Table of Contents
- The Wastewater Pre-Treatment Problem
- How Coanda Screens Perform Solid-Liquid Separation
- The Static Screen Family: Coanda, Sidehill, Sieve Bend, and Hydrosieve
- Wastewater Performance Data
- Static vs. Mechanical Screening: A Wastewater Comparison
- Wastewater Applications for Coanda Screens
- Material Selection for Wastewater Environments
- Design Considerations for Wastewater Applications
- ADENCO and ADEN Wedge Wire: Complete Filtration Systems
- Frequently Asked Questions
- References
The Wastewater Pre-Treatment Problem
Wastewater (whether from a municipality, food processing plant, brewery, slaughterhouse, textile facility, or urban stormwater system) contains suspended solids that must be removed before biological or chemical treatment can proceed effectively. These solids include organic material (food waste, fibres, biological matter), inorganic particles (sand, grit, plastic fragments), and fats, oils, and grease (FOG).
The wastewater screening equipment market reached approximately $2.5 billion in 2025, growing at 6.3% annually [1]. This growth is the result of tightening discharge regulations, increasing industrial wastewater volumes, and the recognition that effective pre-screening dramatically reduces the cost and complexity of downstream treatment.
The challenge: most wastewater screening systems rely on mechanical equipment. Rotary drum screens, step screens, auger screens, chain-and-rake bar screens: all require motors, drive mechanisms, and regular mechanical maintenance. In a wastewater environment, where corrosive chemistry, abrasive solids, and grease exposure are normal operating conditions, mechanical components degrade faster than in clean water applications. Maintenance costs are higher. Failure rates are higher. And every hour of screen downtime is an hour of untreated solids entering the downstream process.
Static screens (including Coanda-effect designs) eliminate these mechanical failure modes entirely.
How Coanda Screens Perform Solid-Liquid Separation
The operating principle is identical to a clean water intake screen, adapted for wastewater loading [2][3]:
-
Feed distribution. Wastewater is delivered to the top of the screen via a headbox or weir that distributes flow evenly across the screen width.
-
Acceleration. The liquid flows down a solid acceleration plate, forming a thin, high-velocity sheet of liquid as gravity pulls it down.
-
Separation. The sheet of liquid passes over the slots between the tilted wedge wires (V-profile wires). The Coanda effect causes the thin liquid layer closest to the wire surface to adhere and bend into the slot, passing through as filtrate. Solids larger than the slot opening (and many smaller solids held at the liquid surface by surface tension) are carried across the wire tips by their momentum.
-
Solids discharge. Retained solids slide down the curved screen face under their own weight and are collected at the screen's lower edge (the discharge edge) for disposal or further processing.
-
Filtrate collection. Clean filtrate collects in a trough or sump below the screen and flows to the next treatment stage.
The entire process is powered by gravity. There is no pump, no motor, no backwash system, and no chemical addition. The screen operates whenever wastewater flows over it and stops when flow stops.
The Static Screen Family: Coanda, Sidehill, Sieve Bend, and Hydrosieve
The Coanda screen is part of a broader family of static wedge wire screening devices used in wastewater. Understanding the family helps engineers select the right configuration:
Sidehill Screens
Positioned at 45°–60° from horizontal, sidehill screens use gravity and a thin-film flow effect to separate solids. Wastewater flows down the curved wedge wire surface; liquid passes through the slots while solids slide to the discharge point [4]. Slot widths typically range from 0.25–1.0 mm for wastewater applications.
Sieve Bends (DSM Screens)
Originally developed for mineral processing (DSM = Dutch State Mines), sieve bends are concave curved wedge wire panels oriented perpendicular to the flow. The parabolic curvature enhances the Coanda effect, producing more effective dewatering than flat screens [5]. Sieve bends are widely used in coal preparation, starch processing, and wastewater dewatering.
Hydrosieve Screens
Hydrosieve is a trade name that has become generic. Hydrosieve screens are gravity-fed static wedge wire filters with a parabolic curvature. Wastewater is distributed across the top of the curved screen; liquid passes through while solids are retained and discharged at the bottom [6]. Common in food processing, dairy, and brewery applications.
Coanda Intake Screens (ADENCO)
ADENCO's Coanda screens incorporate the same wedge wire separation principle with the addition of a precision-fabricated acceleration plate and an optimised wire tilt angle that maximise both throughput and solids rejection. The design experience gained in water intake applications, where screens must work reliably in remote, unattended locations, applies directly to wastewater applications, where minimal maintenance is the priority.
What connects all four configurations: tilted wedge wire, gravity-powered flow, fully static construction, zero electrical demand, and the Coanda effect at the wire surface. The differences are in the feed arrangement, screen curvature, and angle of installation: all of which ADENCO optimises for the specific application.
Wastewater Performance Data
Suspended Solids Removal
Wedge wire sidehill screens in wastewater applications achieve 30–60% removal of suspended solids (TSS) before biological or chemical processing [4]. The removal rate depends on:
- Slot opening (narrower slots = higher removal)
- Solids particle size distribution (wastewater with mostly coarse solids yields higher removal)
- Hydraulic loading rate (lower rates allow better separation)
- Solids characteristics (fibrous material is retained more effectively than fine colloidal particles)
Stormwater Treatment
A USGS/ASCE peer-reviewed study evaluated an underground stormwater treatment chamber fitted with a Coanda screen in Madison, Wisconsin [7]. Results from 33 storm events over 2016–2017:
- Suspended solids (SSC): 45% reduction
- Total suspended solids (TSS): 23% reduction
- Total phosphorus (TP): 16% reduction: primarily through removal of particulate-bound phosphorus
The study found that the Coanda screen was most effective during intense storms: precisely when conventional stormwater inlets (catch basins) are least effective.
Downstream Energy Savings
By removing 30–60% of suspended solids before biological treatment, static screens reduce the organic load entering aeration basins. Published research shows that this early solids removal can reduce aeration energy consumption by up to 20% [4]: a significant operational saving given that aeration typically accounts for 40–60% of a treatment plant's total energy use [8].
Static vs. Mechanical Screening: A Wastewater Comparison
| Parameter | Coanda / Static Screen | Rotary Drum Screen | Step Screen | Chain-and-Rake Bar Screen |
|---|---|---|---|---|
| Slot opening range | 0.25–2.0 mm | 0.25–6 mm | 3–6 mm | 6–40 mm |
| TSS removal | 30–60% | 40–70% | 20–40% | 10–25% |
| Electricity required | None | 0.5–5 kW | 1–3 kW | 0.5–3 kW |
| Moving parts | None | Drum, spray system, motor | Step plates, hydraulics | Chain, rake, sprockets, motor |
| Self-cleaning | Passive (gravity) | Active (spray wash) | Active (step motion) | Active (rake) |
| Maintenance frequency | Annual inspection; periodic pressure wash | Monthly mechanical maintenance | Monthly mechanical maintenance | Weekly–monthly mechanical maintenance |
| FOG tolerance | Moderate: may require periodic hot-water wash | Good with spray system | Good | Moderate |
| Abrasion resistance | Excellent (static stainless steel) | Moderate (drum mesh wears) | Good | Moderate (chain wear) |
| Design life | up to 25 years | 10–15 years | 15–20 years | 10–15 years |
| Capital cost | Low–moderate | Moderate–high | High | Moderate |
Where static Coanda screens outperform mechanical alternatives:
- Applications where operation without electricity is required or valued
- Remote or distributed sites without a reliable electricity supply
- Sites where eliminating mechanical maintenance is a priority
- Environments with high abrasive content (sand, grit) that accelerates mechanical wear
- Pre-treatment stages where 30–60% TSS removal is sufficient before downstream processes
Where mechanical screens are more appropriate:
- Applications requiring >60% TSS removal at the screening stage
- Heavy grease and oil loading that requires active spray washing
- Very large municipal treatment plant inlet works where mechanical reliability has been proven
For a detailed technology comparison in the water intake context, see: Coanda Screen vs. Bar Screen vs. Drum Screen.
Wastewater Applications for Coanda Screens
Food and Beverage Processing
Dairy plants, breweries, canneries, meat processing facilities, and fruit/vegetable operations generate wastewater with high organic content: BOD (biochemical oxygen demand) levels 10–20 times higher than domestic sewage [9]. Static screens at the process discharge remove food waste (peels, seeds, stems, bone fragments, fibres) before the effluent enters biological treatment. This reduces BOD and TSS loading on the biological process, decreasing chemical and aeration costs.
Common food processing applications:
- Recovering product from washing, chilling, and rinsing flume water
- Separating stems, peels, seeds, and leaves from process wastewater
- Pre-screening dairy effluent before dissolved air flotation (DAF)
- Brewery spent grain and trub separation
Municipal Stormwater
The USGS Madison study [7] demonstrated that Coanda screens can be integrated into modified stormwater inlets to remove sediment and particulate phosphorus from urban stormwater runoff: a growing regulatory priority as municipal separate storm sewer systems (MS4) face tightening nutrient discharge limits.
Industrial Effluent
Textile mills, pulp and paper facilities, chemical plants, and mining operations use static wedge wire screens to remove fibrous material, mineral particles, and process solids from effluent. The static screen's abrasion resistance (no mechanical components subject to wear) is particularly advantageous in mining and mineral processing applications.
Aquaculture
Fish farms generate wastewater containing feed particles, faeces, and organic debris. Static screens provide effective pre-treatment before discharge or recirculation, with the added benefit that fully static construction eliminates the risk of mechanical failure in wet, corrosive aquaculture environments.
Material Selection for Wastewater Environments
Wastewater is more corrosive than most natural waters. Lower pH, higher chloride, elevated temperature, biological activity, and exposure to cleaning chemicals all accelerate corrosion. Material selection for wastewater Coanda screens must account for these conditions:
| Wastewater Type | Typical Chemistry | Recommended Grade |
|---|---|---|
| Municipal stormwater | Low chloride, variable pH | 304L |
| Food processing (freshwater-based) | Moderate organics, neutral pH, cleaning chemicals | 316L |
| Dairy / brewery | Acidic pH (4–6), organic acids, hot wash cycles | 316L minimum; duplex for hot acidic conditions |
| Slaughterhouse | High organics, FOG, chlorinated wash water | 316L |
| Textile | Variable pH, dye chemicals, high temperature | 316L or duplex |
| Pulp and paper | Sulphur compounds, acidic pH, high temperature | Duplex 2205 |
| Mining / mineral processing | Low pH, high chloride, abrasive slurry | Duplex 2205 or super-duplex |
The universal rule for wastewater: choose at least one grade higher than you would for the equivalent freshwater application. The combination of chemical exposure, elevated temperature, and crevice conditions at the wire-to-support-rod junctions creates a more corrosive environment than the chloride concentration alone would suggest.
For detailed material selection methodology, see: 304 vs. 316 Stainless Steel for Water Intake Screens.
Design Considerations for Wastewater Applications
Designing a Coanda screen for wastewater differs from water intake design in several important ways:
Higher Solids Loading
Wastewater carries many times more suspended solids than natural waters. The screen must be sized for both the hydraulic flow rate and the solids loading rate. Higher solids loading requires wider screens (lower hydraulic loading per metre of width) to ensure the debris removal mechanism can cope with the volume of rejected material.
Grease and Oil
FOG in wastewater can coat the wire surface, reducing the Coanda effect and increasing the frequency of manual cleaning. For applications with significant FOG content, ADENCO recommends:
- Wider slot openings (1.0–2.0 mm) to reduce the risk of bridging
- Periodic hot-water washing (60–80°C) to dissolve grease deposits
- 316L minimum material grade to withstand hot wash chemistry
Feed Distribution
Uniform feed distribution across the screen width is critical. In wastewater applications, a properly designed headbox or overflow weir ensures that the full screen width is utilised and no localised overloading occurs. ADENCO designs headbox configurations specific to each wastewater application.
Solids Handling
The rejected solids must be collected and disposed of. Unlike water intake applications where debris returns to the natural watercourse, wastewater solids require collection, transport, and disposal. ADENCO designs screen systems with integrated solids collection troughs, screw conveyors, or waste containers depending on solids volume and site logistics.
Cleaning Access
Wastewater screens require more frequent cleaning than water intake screens: periodic pressure washing (monthly to quarterly) and hot-water degreasing for FOG-laden applications. The site layout must provide safe, convenient maintenance access to the screen face.
ADENCO and ADEN Wedge Wire: Complete Filtration Systems
ADENCO's Coanda intake screen expertise is part of a wider group of filtration companies. ADEN Wedge Wire (ADENCO's sister company) manufactures the full range of wedge wire products for industrial applications:
- Sidehill screens for wastewater dewatering and pre-treatment
- Sieve bend / DSM screens for mineral processing and industrial separation
- Flat panel screens for under-drain and media retention
- Cylindrical screens for well and borehole applications
- Custom wedge wire profiles for specialised filtration requirements
This means that when a wastewater application requires a Coanda screen for pre-treatment, ADENCO designs and manufactures it with the same wedge wire expertise, material quality, and engineering precision that ADEN Wedge Wire applies across its full product range. The wire is manufactured to the same tolerances. The welds meet the same standards. The material traceability is identical.
For wastewater projects that require multiple screen types (a Coanda screen for primary pre-treatment plus sidehill screens for secondary dewatering, for example) ADENCO and ADEN Wedge Wire deliver the complete system from a single engineering team.
Frequently Asked Questions
Can Coanda screens be used for wastewater treatment?
Yes. Coanda screens and their related configurations (sidehill screens, sieve bends, Hydrosieve screens) have been used in wastewater pre-treatment for decades. They provide gravity-powered, passive solid-liquid separation through fully static construction: removing 30–60% of suspended solids before biological or chemical treatment. Applications include food processing, dairy, brewery, slaughterhouse, municipal stormwater, textile, pulp and paper, mining, and aquaculture wastewater.
How much suspended solids do static screens remove from wastewater?
Static wedge wire screens typically remove 30–60% of total suspended solids (TSS) from wastewater, depending on slot opening, solids particle size, and hydraulic loading rate. A peer-reviewed USGS study documented 45% suspended solids reduction from urban stormwater using a Coanda screen with 1.0 mm slots. This pre-treatment reduces the organic load on downstream biological processes, with documented aeration energy savings of up to 20%.
What is the difference between a Coanda screen and a Hydrosieve?
Both are static, gravity-fed wedge wire screens that separate solids from liquids without moving parts. The Coanda screen incorporates a precision-fabricated acceleration plate and optimised wire tilt angle that maximise throughput and solids rejection: design features originally developed for water intake applications where reliability and self-cleaning performance are critical. A Hydrosieve is a general-purpose static screen with a parabolic curvature. ADENCO manufactures Coanda screens that bring water intake engineering precision to wastewater applications.
What material grade is needed for wastewater Coanda screens?
Wastewater is more corrosive than natural water. As a general rule, choose at least one stainless steel grade higher than for the equivalent freshwater application. Municipal stormwater: 304L. Food processing and brewery: 316L minimum. Acidic industrial effluent (pulp and paper, mining): duplex 2205. ADENCO selects the grade based on a complete effluent chemistry analysis. For the underlying freshwater material selection methodology including PREN values and chloride thresholds, see: 304 vs 316 Stainless Steel for Water Intake Screens.
Do Coanda screens cope with grease in wastewater?
Coanda screens cope with moderate grease levels effectively, but heavy FOG (fats, oils, and grease) loading (typical of slaughterhouse and dairy wastewater) can coat the wire surface and reduce debris removal performance. For FOG-laden applications, ADENCO recommends wider slot openings (1.0–2.0 mm), periodic hot-water washing (60–80°C), and 316L minimum material grade. For very high FOG concentrations, a DAF (dissolved air flotation) unit upstream of the screen may be necessary.
How does a static Coanda screen compare to a rotary drum screen for wastewater?
A rotary drum screen typically achieves slightly higher TSS removal (40–70% vs. 30–60%) due to active spray washing, but it requires a motor, drive mechanism, spray pump, and regular mechanical maintenance. A Coanda screen operates without electricity, with fully static construction and requires only periodic pressure washing. For applications where 30–60% TSS removal is sufficient, the Coanda screen offers dramatically lower operating cost, longer design life (up to 25 years vs. 10–15 years), and higher reliability. For applications requiring maximum TSS removal, a drum screen may be more appropriate.
Can ADENCO supply both Coanda screens and other wedge wire products?
Yes. ADENCO manufactures Coanda screens for water intake and wastewater pre-treatment. ADEN Wedge Wire (ADENCO's sister company) manufactures the full range of wedge wire products including sidehill screens, sieve bends, flat panels, and cylindrical screens. For wastewater projects requiring multiple screen types, the combined ADENCO and ADEN Wedge Wire engineering team delivers complete filtration systems from a single supplier.
References
-
"Wastewater Screening Equipment Market Report: Trends, Forecast and Competitive Analysis to 2031." Lucintel / Research and Markets. Retrieved April 2026, from https://www.researchandmarkets.com/reports/6175474/wastewater-screening-equipment-market-report
-
Wahl, T.L. (2003). Design Guidance for Coanda-Effect Screens. U.S. Bureau of Reclamation, Research Report R-2003-03. Denver, CO.
-
Wahl, T.L. (2001). "Hydraulic Performance of Coanda-Effect Screens." Journal of Hydraulic Engineering, Vol 127, No 6. ASCE.
-
"Wastewater Treatment Optimization Using Wedge Wire Sidehill Screens." UBO Screen. Retrieved April 2026, from https://www.uboscreen.com/news/wedge-wire-sidehill-screens-wastewater-treatment.html
-
"Sieve Bend / DSM Static Screen Wastewater." Wedge Wire Filter. Retrieved April 2026, from https://www.wedgewire-filter.com/news-sieve-bend-dsm-static-screen-wastewater.html
-
"Hydrosieve Screen for Wastewater Treatment System." Johnson Wedge Wire. Retrieved April 2026, from https://www.johnsonwedgewire.com/news/hydrosieve-screen-for-wastewater-treatment-system.html
-
Buer, N. and Selbig, W. (2020). "Evaluation of Stormwater Treatment Vault with Coanda-Effect Screen for Removal of Solids and Phosphorus in Urban Runoff." Journal of Sustainable Water in the Built Environment, Vol 6, No 1. ASCE / USGS. Retrieved April 2026, from https://ascelibrary.org/doi/10.1061/JSWBAY.0000892
-
"Energy Consumption in Water/Wastewater Treatment Industry: Optimisation Potentials." MDPI Energies, Vol 16, No 5, 2023.
-
"Food and Beverage Processing: Wastewater Treatment." JWCE. Retrieved April 2026, from https://www.jwce.com/application/food-and-beverage-processing-wastewater-treatment/
-
"Static Screens in Wastewater Treatment: Applications and Advantages." Lakeside Equipment Corporation. Retrieved April 2026, from https://www.lakeside-equipment.com/static-screens-in-wastewater-treatment-applications-and-advantages/
-
"Guide to Wastewater Screening Equipment." JWCE, January 2024. Retrieved April 2026, from https://www.jwce.com/2024/01/25/guide-to-wastewater-screening-equipment/
-
ADEN Wedge Wire. "Coanda Intake Screen." Retrieved April 2026, from https://adenwedgewire.com/products/special-screen/coanda-intake-screen/
Published by ADENCO: Advanced Engineering Coanda Intake Screens, in partnership with ADEN Wedge Wire. From water intake to wastewater pre-treatment, ADENCO and ADEN Wedge Wire deliver complete wedge wire filtration systems, designed for your application and manufactured to the same precision standards. Contact us about your wastewater screening project →