Stjernholm

What Stjernholm does

Stjernholm A/S is a Danish environmental technology company founded in 1997 by Kaj Stjernholm Sørensen, headquartered in Randers, Denmark. The company specializes in water treatment and separation solutions for municipal wastewater treatment plants, dairy farms using sand bedding, biogas plants, and the chemical/technical industry. Its portfolio covers five categories: pre-treatment (sand/grit washers, screens, drum filters), process (OXxOFF aeration monitoring, Supratec aerators, Spaans screw pumps), sludge treatment (screw presses, Alfa Laval decanters, drum screens), outside-the-fence infrastructure (patented purge systems, cleaning pigs, pumping stations), and dairy farm systems (sand-slurry separators with rotary screens, pumps, mixers, macerators, and PLC controls). The proprietary Stjernholm Sand Washer, with 100+ installations since 1997 and documented 15-20 year equipment lifetimes, is the company's flagship product, complemented by the patented OXxOFF floating aeration measurement system that delivers up to 25% energy reduction in activated sludge processes.

Stjernholm combines in-house engineering and stainless steel fabrication with strategic distribution partnerships for complementary equipment (Alfa Laval, Spaans Babcock, Supratec, Kaeser, FSM, Landia, GEA, Vogelsang), enabling turn-key project delivery. The company operates an enterprise field sales model branded as "Cooperation with Value," emphasizing pre-sale consultation, Total Cost of Ownership analysis, and typical 2-5 year customer payback periods. Revenue is generated through one-time equipment sales, recurring service and maintenance contracts, custom fabrication/installation, and turn-key engineering services. Pricing is quote-based and not publicly disclosed.

The company serves primarily Danish municipal utilities with a customer base including Århus Vand, Novafos, EnergiViborg, Ringkøbing-Skjern Forsyning, Langeland Forsyning, Vesthimmerlands Forsyning, Din Forsyning, and Nyborg, plus international installations at Silicon Valley Clean Water (USA) and Trillium Hill Farm (USA). In 2021, Stjernholm consolidated operations at a single Randers headquarters; it subsequently established Stjernholm US Inc. in Chicago and signed an exclusive China distribution partnership with Suzhou Howye Environment Technologies in 2023. The company received the 2020 European Business Award for the Environment for its sand-slurry separator system, recognized as a circular economy example.

Name

Stjernholm

Legal name

Stjernholm A/S

Website

https://stjernholm.dk

Company type

Private

Founded year

1997

Operating status

Operating

Headcount range

11–50 employees

Short description

Stjernholm A/S is a Danish environmental technology company founded in 1997 that designs, manufactures, and services proprietary water treatment and separation equipment—including sand washers, the OXxOFF aeration system, and dairy-farm sand-slurry separators—for municipal wastewater plants, dairy farms, and biogas facilities in Denmark, the US, and China.

Ownership category

akta.pro rank

Product category

Water Treatment Equipment

NAICS

Measuring, Dispensing, and Other Pumping Equipment Manufacturing (333914), Totalizing Fluid Meter and Counting Device Manufacturing (334514), Farm Machinery and Equipment Manufacturing (333111)

SIC

Special Industry Machinery (No Metalworking Machinery) (3550), Industrial Instruments For Measurement, Display, And Control (3823), Industrial & Commercial Fans & Blowers & Air Purifing Equip (3564)

akta.pro primary industry

Water & Wastewater Treatment Plant Equipment (Clarifiers, Aeration, Membrane Systems) (IMAHAEAJ)

akta.pro secondary industries

Separation & Filtration Equipment (Filters, Centrifuges, Membranes) (IMAHAEAB), Manure Handling & Waste Management (Scrapers, Separators, Digesters Interfaces) (AFAAAIAI), Industrial Water Reuse Utilities (ZLD/MLD & Process Water Recycling) (EUANAGAG), Pipework, Calorifier & Heat Exchanger Descaling/Decontamination (BPABAJAI)

Keywords

• Wastewater treatment equipment
• Grit and sand washing
• Aeration monitoring systems
• Dairy farm sand separation
• Sludge dewatering solutions

Headquarters

HQ city

Randers

HQ country

Denmark

HQ region

Europe

Offices2 records

Markets served

GTM type

B2B

Offering type

Hardware or Manufacturing

Cost components

Personnel, Operations, Supply Chain, Technology or R&D, Marketing or Sales, Infrastructure

Revenue model

1. Water Treatment Equipment Sales: Direct sales of proprietary and distributed water treatment equipment including sand washers, aeration systems, screens, pumps, and sludge treatment equipment. Revenue is generated through project-based equipment sales to municipal utilities, private wastewater treatment plants, and industrial facilities.
2. Service and Maintenance: Comprehensive service offering including contracted maintenance, ad hoc repairs, and full service programs for all types of utility machinery regardless of original supplier. Service technicians equipped with customized service vehicles provide on-site support throughout Denmark.
3. Custom Fabrication and Installation: Construction, production, and installation of stainless steel and galvanized equipment including black-smith work, piping, stairs, landings, platforms, and railings for purification plants, pumping stations, and waterworks.
4. Turn-key Solutions and Consulting: Engineering and consulting services including surveyor reports, process optimization studies, and complete turn-key project delivery including containerized solutions for wastewater treatment plants.

Pricing tiers

Go-to-market motion1 record

Distribution channels4 records

Marketing channels5 records

Core offering

Stjernholm A/S designs, manufactures, and installs specialized water treatment and separation equipment — including proprietary sand/grit washers, the OXxOFF aeration monitoring system, and sand-slurry separation systems for dairy farms — and delivers these along with custom stainless steel fabrication, turn-key project execution, and ongoing service to municipal wastewater treatment plants, agricultural operations, biogas facilities, and chemical/technical industrial customers.

Product overview

Stjernholm A/S offers a comprehensive portfolio of environmental technology solutions for water treatment, primarily serving sewage treatment plants, agricultural operations, biogas facilities, and the chemical/technical industry. The product range covers five main categories: Pre-treatment (Mechanical Fine Screens, FSM Filterband Screens, Screens for Overflow Structures, Screening Washing Press, Drum Thickener/Filter, Compact Bar Grate Stokers, and Sand/Grit Washers), Process (Supratec Aerators, Spaans Screw Pumps, and the proprietary OXxOFF Aeration Monitoring System), Sludge Treatment (Alfa Laval Aldec Decanter Centrifuges, Stjernholm Screw Presses, Drum Screens, and Transport/Conveyor Systems), Outside-the-Fence Solutions (Purge Systems, Cleaning Pigs Systems, and Pumping Stations), and Dairy Farm Systems (Sand-Slurry Separator Systems with Rotary Screens, Sand Washers, GEA/Landia Pumps, Landia Mixers, Vogelsang Macerators, Conveyers, and Opicon Control Systems). The core technologies are the Sand Washer/Grit Washer (with over 100 installations worldwide), the OXxOFF aeration monitoring system, and the Sand-Slurry Separator for dairy farms. Products are distributed in Denmark through the company and internationally through subsidiaries in the USA and distribution partners in China.

Differentiator

Problem solved

Functional benefit

Products and services

• Stjernholm Sand Washer / Grit Washer Mechanically washes organic material from sand/grit in municipal wastewater treatment, receiving stations for vacuum trucks, and lift stations. Achieves up to 95% dry matter and less than 3% ignition loss, retaining over 90% of grit particles above 125 microns. Available in four sizes with treating capacity up to 3,000 l/min and grit output up to 3 tons per hour.
• Sand-Slurry Separator System Complete turn-key system for dairy farms that separates sand from dairy manure slurry, cleans sand for reuse in cow cubicles, and produces sand-free slurry suitable for biogas production. Achieves up to 99.6% grit retention (about 1g grit per litre of separated slurry) and dry matter content above 9% in washed slurry.
• OXxOFF Aeration Monitoring System Floating online measurement and control system for aeration efficiency in wastewater treatment process tanks. Continuously monitors oxygen transfer efficiency (OTE), SOTE, air flow, and oxygen transfer rates via wireless or cable connection, and reduces energy consumption by 25% through automated 24/7 optimization of compressors, valves, and biological processes.
• Mechanical Fine Screen Efficient separation of screen materials in outlet boxes with stable operation and high percentage of solid particle separation. Activated by level regulation with parallel screen bars alternately fixated and moveable, powered by worm gear.
• FSM Filterband Screen FSM filterband screen that captures up to 85% of screenings. Perforated, moveable steel panels automatically create a mat of screen material removed by brushes at the top. Available in widths from 300 to 3,000 mm and ejection height up to 11,000 mm.
• Screens for Overflow Structures (VR and RO types) Self-cleaning screens for overflow structures. The patented VR type uses hydraulically powered vertical screen bars with 90% collection efficiency; the RO type uses an engine-powered auger with brushes, with capacity up to 1,200 litres per second.
• Screening Washing Press Efficient transport and washing of screening for organic material, achieving up to 45% dry matter and screen material production up to 60%, with up to 25% disposal savings and 80% screen material reduction. Service life 15-20 years and payback 4-6 years.
• Drum Thickener / Drum Filter Drum screen for filtering and separating particles as early as in the purification plant inlet, from the sand washer section, or for concentration of sludge from process and purification tanks. Constructed as closed casing with perforated plate drum in stainless steel or polyester woven filter.
• Compact Bar Grate Stoker with Perforated Plates FSM inlet grates in compact packaging. Available for concrete piping with holes from 1 to 10 mm. Used as inlet grate at purification plants, for treatment of suction vehicle mediums, and for separation of mediums from industries.
• Supratec Aerators Aeration systems for optimal oxidation in purification plants. Based on rubber membranes (EPDM rubber and silicone) producing fine air bubbles. Available as plate diffusers, disc diffusers, and fine bubble diffusers. Up to 40% electricity savings compared to pipe aerators.
• Spaans Screw Pumps Screw pumps from Spaans Babcock characterized by high capacity, durability, minimal maintenance, and long service lives (30-40 years). Capacity from 15 litres/sec. to 11 m3/sec. Well-suited for transporting sludge with coarse particles while being gentle towards biological structures.
• Alfa Laval Aldec Decanter Centrifuge Alfa Laval Aldec, Aldec G2, and Aldec G3 decanters for sludge dewatering. Typical energy savings of 20%, deposit savings of 5% compared to competing products, payback time of 5-7 years, and high dry matter levels up to 35%.
• Stjernholm Screw Press Sludge treatment press with maximum 1.5 revolutions per minute and a low-energy 1.5 kW gear motor. Achieves dewatering of 18-25% TS with minimal polymer utilization. Made of durable stainless Aisi 304 with service life of 10-15 years.
• Stjernholm Drum Screen Sludge concentrator that lifts separated sludge from 0.5% dry matter to more than 12% dry matter. Closed casing with stainless steel perforation drum rotating on 4 wheels, designed for continuous operation with large hinged lids for easy inspection and service.
• Transport Systems (Conveyors) Efficient, hygienic and reliable transport of sludge and other waste. Available with or without shaft; shaft-less screw conveyors handle sticky, greasy products or products with long fibres. Service life of 15-20 years with very low operation and maintenance costs.
• Purge System Patented vacuum valve system for cleaning basins, round and rectangular static tanks, and larger piping systems. Features adjustable opening/closing period of 0.6-0.5 seconds with configurable valve opening patterns for optimal operation at any facility.
• Cleaning Pigs System Pipeline cleaning system using cylindrical pigs of synthetic foam rubber with open cells, pushed through piping by liquid or air to remove internal deposits from sewer pipes and other pipes. Maximizes pipe capacity during cleaning without interrupting operations.
• Pumping Stations Turnkey pumping stations with neutral architecture, preassembled according to customer needs. Includes digging and moulding through to housing for pumps, electrical installations, and control units. Covered with almost maintenance-free exterior materials.
• Opicon Control System (Dairy Farms) Control system for sand/slurry separation and sand retention/cleaning for reuse on dairy farms. Built for fully automatic continuous operation with measuring devices for flow and dry matter content registered in a PLC. All data logged for continuous performance history with adjustment via touch screen or remote control from PC or smartphone.
• Service and Maintenance Program Comprehensive contracted maintenance, ad hoc repairs, and full service programs for all types of utility machinery regardless of original supplier. Service technicians equipped with customized service vehicles provide on-site support throughout Denmark.
• Custom Stainless Steel Fabrication and Installation Construction, production, and installation of stainless steel and galvanized equipment including black-smith work, piping, stairs, landings, platforms, and railings for purification plants, pumping stations, and waterworks.
• Turn-Key Solutions and Engineering Consulting Engineering and consulting services including surveyor reports, process optimization studies, and complete turn-key project delivery including containerized solutions for wastewater treatment plants.

Quantifiable outcome

• 90%+ grit retention with >95% dry matter and <3% organic content in washed sand
• +4 more outcomes

Named customers10 records

Segments4 records

Ideal customer profiles3 records

Technology focussed Yes

API detail

Has API

No

API docs

API detail

Core technology

AI maturity

App detail

Integration12 records

AI capability3 records

Feature5 records

Partnerships

One partnership is on record.

• Suzhou Howye Environment Technologies Co., Ltd.coreChannel Partner/ Reseller/ Distributor · 1 January 2023First distribution agreement on the Chinese market for OXxOFF products. Suzhou Howye Environment Technologies Co., Ltd. in Jiangsu province (east coast, north of Shanghai) will market and distribute the OXxOFF floating aeration monitoring system throughout China, targeting the large market for energy-saving equipment at wastewater treatment plants.

Scale indicators7 records

Recent moves7 records

Expansion highlights6 records

Broad incumbents

• Huber SE: Huber SE is a German manufacturer of water and wastewater treatment equipment, including screens, grit removal systems, and sludge dewatering. It is directly comparable to Stjernholm in municipal WWTP pre-treatment equipment, but operates at significantly larger scale with a broader global footprint.
• Alfa Laval: Alfa Laval supplies decanter centrifuges (Aldec series) that Stjernholm distributes in Denmark, and competes in the broader sludge dewatering and separation equipment space. It is both a partner and adjacent competitor for industrial separation technology.
• Andritz AG: Andritz is a global supplier of separation and dewatering equipment for municipal and industrial water/wastewater applications, including screens, centrifuges, and pumps. It is a broad incumbent competing with Stjernholm in WWTP pre-treatment and sludge handling.
• GEA Group: GEA is a global supplier of dairy farming equipment, separators, and process technology. GEA Electromix is distributed by Stjernholm, but GEA also competes broadly in dairy farm and food wastewater separation systems.
• Sulzer Ltd: Sulzer supplies pumps, mixers, and aeration equipment for municipal and industrial water treatment. It competes with Stjernholm in the WWTP process and sludge treatment equipment market as a broad incumbent.

Direct peers

• WAMGROUP: WAMGROUP manufactures screw conveyors, pumps, and waste water treatment equipment. It is a direct peer in screening, conveying, and sludge handling equipment for municipal WWTPs, serving similar European utility customers.
• Vogelsang GmbH & Co. KG: Vogelsang is a German manufacturer of pumps, macerators (RotaCut), and spreading technology with significant applications in agricultural biogas and wastewater. It is both a partner (RotaCut) and direct competitor to Stjernholm's dairy farm system.
• Landia A/S: Landia is a Danish manufacturer of submersible mixers and chopper pumps used in wastewater and biogas applications. Its mixers and pumps are distributed by Stjernholm in dairy farm systems, making it both a partner and a niche Danish peer.
• JWC Environmental (Sulzer brand): JWC Environmental specializes in screening, grinding, and solids reduction equipment for municipal wastewater treatment. It is a direct peer to Stjernholm in pre-treatment screens and grit handling for WWTPs.
• Opicon Srl: Opicon is an Italian supplier of process controls and integrated sand/manure separation systems for dairy farms. Its control system is integrated into Stjernholm's dairy farm offering, making it both a partner and the closest direct peer in dairy slurry separation.

Market position

Strengths5 records

Weaknesses5 records

Competitive moat5 records

Key risks6 records

Key highlights7 records

Customer concentration

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Compliance3 records

Revenue estimate

Valuation estimate

Number of profiles

Profiles6 records

Subsidiaries1 record

Funding overview

Funding rounds

Investors

Funding detail is available on the Subscription and Enterprise plan.Contact sales →

M&A

Investments

M&A and investment is available on the Subscription and Enterprise plan.Contact sales →

Frequently asked questions about Stjernholm