Accel-o-Fac®The Zero-to-Low Energy Wastewater Treatment System

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Accel-o-Fac®  Wastewater Treatment System


accel logoZero-to-Low Energy 100% Total On-Site Treatment

page ww accel intro picThe Accel-o-Fac® wastewater treatment system is a proven, green, highly sustainable, nature based system for retrofit or new build applications. Based on the proven facultative biological process, the highly advanced Accel-o-Fac® reliably treats wastewater of all types providing extremely robust, odour-free wastewater treatment with little operator attention or maintenance for truly sustainable, green, low carbon footprint, 100% on-site total treatment producing effluent quality for discharge, reuse and/or irrigation.

A Greener, No-Sludge Wastewater Treatment System

Accel-o-Fac® offers a self-digesting sludge process that requires no pre-screening, sedimentation tanks, clarifiers, sludge removal, dewatering, chemicals or conditioning, and best of all, Accel-o-Fac® requires no routine sludge disposal or the associated lorry tanker traffic in and out of the treatment plant. The secret to unlocking the maximum potential of the facultative biological process is the maintenance and optimisation of the critical layering or zoning of the three biological areas — aerobic, facultative and anaerobic (see diagram below). The Accel-o-Fac® system uses the unique SERIES 3 wind powered/renewable energy aerator/mixers to establish, optimise and maintain this necessary layering for superior optimised treatment performance. This also ensures that all solids fall out undisturbed into a “capped” anaerobic zone for complete digestion at the bottom of the primary treatment cell.

Extremely Low Capex, Opex And Carbon Footprint

Another advantage of Accel-o-Fac® is the extremely low operating cost and truly low carbon footprint. Gurney Environmental is unique in its use of a fully biological process along with zero-to-low energy wind powered aerator/mixers. Overall the system can operate at anywhere from 80-95% less than typical activated sludge systems — a significantly greener approach.

The wind powered SERIES 3 units have been extensively proven in both municipal and industrial wastewater treatment and other applications. For decades these units have been used to resolve extremely problematic lagoon-based (WSPs) WwTPs by improving effluent, eliminating odour, disinfecting and cutting energy and other costs.

These many benefits are accomplished with almost zero operating cost by employing renewable energy wind power as the primary energy source and through the use of highly specialised equipment combined with a number of unique design, construction and operation techniques. The net result is a total “optimisation” of a purely biological process resulting in an overall acceleration of the processing rate. This “optimisation” enables Accel-o-Fac® wastewater treatment plants to be smaller than old-fashioned WSP designs — all at zero-to-low operating cost and without the use of expensive and complex conventional mechanical aeration, chemicals or significant manpower.

Enhancing the Facultative Biological Process

Accel-o-Fac® not only boosts natural oxygen transfer, but also provides an ideal quiescent zone for solids settling and self-digestion of the sludge — a fundamental and essential part of the “All-in-One” facultative biological 100% total treatment process.

The Accel-o-Fac® system also eliminates the problems of short circuiting by radially dispersing and distributing the incoming organic load throughout the entire treatment volume. With Accel-o-Fac®, the entire cell volume and surface area are put to work with no dead spots and no “hot” or overloaded spots (such as near the influent area). This alone dramatically increases the processing capacity of the cells enabling it to automatically deal with shock loads.

Accel-o-Fac® can accommodate huge variations in flows without any operating problems. Storm water flows, peak flows, seasonal increases are all effortlessly handled.

Self Digesting Sludge

Long term studies prove these systems anaerobically self-digest all organics within the system with the inert materials accommodated for the life of the plant. That can be an important consideration with regulations and concerns regarding sludge disposal and handling. Accel-o-Fac® acheives this important benefit by ensuring correct loadings and detention times as part of the overall design process along with optimised conditions within the system.



Combined sewer systems collect rainwater runoff, domestic sewage and industrial wastewater in the same pipe. Most of the time, combined sewer systems transport wastewater to a sewage treatment plant where it is treated and then safely discharged to a water body — if flows stay within the daily capacity of the WwTP! However, during periods of heavy rainfall or snowmelt, the wastewater volume in a combined sewer system can exceed the capacity of the treatment plant. For this reason, combined sewer systems are designed to occasionally overflow and discharge excess wastewater directly to nearby streams, rivers, or other water bodies. These overflows, called combined sewer overflows (CSOs), contain not only storm water but also untreated human and industrial waste, toxic materials, and debris.

page accel cso pic1Accel-o-Fac® is uniquely designed to handle peak flow and loads automatically without operator intervention, and do so utilising green renewable energy (wind power) for optimisation and aeration. Whether peaks are from tourism, storm events, industrial flow variations or population growth, Accel-o-Fac® uniquely automatically handles the changes without excess costs or intervention.

By design both the primary and secondary treatment cells in an Accel-o-Fac® system are designed for 30-50 days of retention, thereby buffering any typical 3 or 6x storm surge or other peak flow/load event. The windpowered aeration units provide the necessary aeration and optimised biological conditions for full treatment, but do so without any significant ongoing cost, maintenance or increased carbon footprint.

page accel cso pic2The “secret” to Accel-o-Fac’s® capability to handle dramatic flow/load variations is the essential design. Uniquely, Accel-o-Fac® can operate with virtually no load for extended periods whilst also having the ability to suddenly/instantly handle much larger flow/loads. Accel-o-Fac® cells are designed to handle the maximum average flow/load over a 30-50 day period, but can automatically without operator intervention revert to low-to-zero flow/loads without any loss of performance.

The Accel-o-Fac® facultative biological process has decades of well-proven performance and is considerably more stable and robust under varying flow/load conditions, thereby affording more flexible and stable performance over the years. A truly sustainable, lower carbon footprint option!

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For over 4 decades, Accel-o-Fac® has been used to resolve extreme problems plaguing countless municipal and industrial WSPs/lagoons. The system is a cost-effective, green method to assure high levels of treatment with the least operator attention and ongoing operating costs. Overall, Accel-o-Fac® offers an extremely low total life cost and true long-term sustainability as compared to other options and systems.

Suitable for Large, Medium and Small Populations

ww tech lagoon profile Accel-o-Fac® is modular and can be scaled to handle any size flow and population. The modular design allows phased construction or multi-location options.

Mechanically & Biochemically Simplified For Reliability, Low OPEX & Capital Equipment Longevity

Accel-o-Fac® is a high-process-rate wastewater treatment system that has been well proven for decades with a variety of municipal and industrial wastewater applications in all types of climates. Accel-o-Fac® employs an advanced and optimised form of a completely biological "accelerated"™ facultative treatment process that adjusts to handle large variations in flows and loadings. Accel-o-Fac® incorporates fast and easy construction techniques, uses little energy, requires exceptionally simplified operator skills, almost no maintenance, and yet turns out effluent quality that can be superior for reuse and irrigation.

New Construction or Retrofit

Accel-o-Fac® can be designed as a new wwtp such as was done for the Holkham Estate and Village. On the other hand, the Accel-o-Fac® system can be retrofit to existing lagoons where it can solve serious issues, boost performance and in many cases, replace existing expensive aeration.




The TYTAN® Titanium Algae Management System is a broadband frequency device designed to transmit ultrasound directly through the water, with an exposed titanium face that cleans itself during operation. This design means that maintenance is minimal, which is important in situations where contact with water is hazardous such as sewage treatment cells. The TYTAN® system covers all frequencies to address a range of algal species and does so without requiring repro­gramm­ing for different algal species as some other systems do.

The TYTAN® has a wide range of applications from open waters, irrigation lakes, canals, reservoirs, drinking water systems, sewage treatment lagoons, wetland polishing systems, natural swimming pools, biofilm control and antifouling of boat hulls in marinas.

Industrial Quality

The system is truly designed and manufactured to “industrial quality” standards for tough industrial applications, and is manufactured of titanium and stainless steel. Each unit covers a maximum line-of-sight area of about 21 hectares.



Example – Australian Retrofits

As an example, South Gippsland Water in Australia partially upgraded their Inverloch wwtp with the Accel-o-Fac system in April of 2014. Through routine monitoring of the conditions of the cell since installation, the utility company reported that not only had they benefited from a 16% increase in average DO, but they have also been able to significantly reduce the operation of the existing electric powered aeration system at the plant. This has provided South Gippsland Water with a 22% reduction in overall energy costs, which will pay for the upgrade within a few years of operation.


South Gippsland Water upgraded the Toora wwtp with the Accel-o-Fac system in April of 2015. Through routine monitoring of the conditions of the cell since installation, the utility company reported that not only have they benefited from a dramatic increase in average DO, but they have also been able to significantly reduce the operation of the existing electric powered aeration system at the plant. This has provided South Gippsland Water with a 72% reduction in overall energy costs, which will pay for the upgrade within a few years of operation.

The Importance of Positive DO Conditions

Accomplishing maximum BOD removal processing rates in a facultative biological treatment system is dependent on maintaining positive DO at all times. With positive DO conditions, the aerobic bacteria will perform at their maximum for a given water temperature. Additionally, odours can be 100% buffered/stripped by an oxygen-rich water column.


Gurney Environmental completed the installation of the primarily wind-powered Accel-o-Fac® wastewater treatment system upgrade for South Gippsland Water in mid 2015. After a year of operation, managers of the wwtp have provided the results of typical DO profiles now being accomplished with dramatically reduced energy, and the results are impressive. The high residual DO levels being maintained by the Accel-o-Fac system now allow the original electric aeration to be shut off for much of the time through the use of a DO controller.

Example – New Construction Project With Negligible Operating Costs for Over 16 Years

Selecting The Best “Total Life” Options

The Accel-o-Fac® wastewater treatment plant for Holkham Hall Estate also serves the Victoria Inn and village at Holkham in Norfolk and has been treating sewage since the spring of 2006 with almost no significant ongoing operating costs.

The Holkham Estate, owned by the Earl of Leicester, includes the Victoria Inn, which is very popular with tourists visiting this part of the country. Previously, the village had been served by septic tanks requiring regular emptying. The Estate had a choice of either sending the sewage to the nearby water company's treatment works via pipeline, remain on septic tanks or treat their own wastewater. The appeal of the unique Gurney Environmental Accel-o-Fac® solution was low energy, no sludge or odour, and effluent water of a quality appropriate for either discharge or potential irrigation reuse on the Estate.

Simple, Low Maintenance Operation

After careful consideration of options, the Estate elected to use the Accel-o-Fac® windpowered system from Gurney Environmental to keep ongoing operating and total lifetime expenses (TOTEX) at a minimum. The plant also includes a simple Septic Reception Station to accommodate septic tanks from the Estate. All septage and solids are transferred to the new Accel-o-Fac® primary cell for treatment and digestion of the sludge. The system is simple, odour free and inexpensive to operate.

One of the key benefits of the system for Holkham was the need for very little operator attention. There has been almost nothing for an operator to do at the plant this last decade short of mowing the grass in the summer. Equipment maintenance includes inspections every 3-4 months. Not much else is required, making the operator's job truly part time!



View or Download a PDF of this Case Study

17+ Years of Incredibly Low OPEX. No Odour. No Sludge. No Storm Overflows. Holkham Village, Estate and local Inn have enjoyed an amazingly simplified WwTP. The Accel-o-Fac® wastewater treatment plant serves Holkham Estate, the Victoria Inn and the village at Holkham in Norfolk and has been treating sewage since the spring of 2006 with almost no significant ongoing operating costs!






Example – Australian Water Company Addresses Overloaded WWTP With Wind-Powered Accel-o-Fac®

Australian Water utility, GWM Water, completed the installation of an Accel-o-Fac® upgrade to their WWTP at Donald, Victoria using Gurney Environmental’s wind-powered SERIES 3 mixer/aerators on 29 October 2018.

Previously Anoxic/Septic, Overloaded Primary Treatment Cell

Prior to installation of the Accel-o-Fac® retrofit, the WSP primary cell at Donald, Australia was loaded well above what natural reaeration could keep up with (see data block). The pink colour indicated the presence of pink sulphur-producing bacteria indicating anoxic/septic conditions. When the BOD loading exceeds the ability to maintain aerobic conditions within a treatment cell, the powerful aerobic and facultative bacteria become dormant and no longer perform healthy rates of BOD/TSS removal, odour control, sludge digestion and disinfection.

Healthy, Well-Performing Primary Treatment Cell After Retrofit

The installation of the highly-sustainable Accel-o-Fac® retrofit utilising the wind-powered SERIES 3 Aerators/Mixers restored surplus dissolved oxygen (DO) in the upper portion of the primary cell, thereby activating strong aerobic and facultative BOD/TSS processing, odour control, ammonia-nitrogen removal, sludge control and disinfection. By restoring the upper two biological zones — the aerobic and the facultative — the bottom anaerobic zone can now begin proper digestion of all biosolids, thereby eliminating extra accumulated sludge.

For decades, Accel-o-Fac® has proven capable of turning around poorly performing lagoon-based WWTPs, both municipal and industrial, and doing so with zero-to-low energy and almost no manpower or ongoing maintenance requirements.

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Accel-o-Fac® Offers Clear Benefits

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Stainless Steel

Accel-o-Fac® system components are mostly all stainless steel and designed to last the life of the wwtp with virtually no ongoing, costly maintenance or capital equipment replacements.

page accel Benefits 2 Little Maintenance

Little Routine Maintenance

The only routine maintenance for the entire Accel-o-Fac® wwtp is checking the auto-lubrication cartridges every 3-6 months. The result is incredibly low ongoing operating costs over the 20-year life of the wwtp.

page accel Benefits 3 Operations

Site Operations

Accel-o-Fac® wwtp's require no routine operator intervention. Day-to-day facility operations are reduced to virtually lawn mowing and other general upkeep. The Accel-o-Fac® system will automatically resolve shock and peak flows, self-digests the sludge, doesn't require screening or other labour-intensive operations or costly equipment.

page aero 5 Benefits 4 Wind Powered

Energy-Free Aeration

Windpower provides up to 100% of the energy needed for wastewater processing with an Accel-o-Fac® wwtp. Unique wind powered SERIES 3 aerator/mixers have been proven in severe wastewater treatment applications for decades, providing aeration, process acceleration and biological optimisation. An optional electric backup Motor Kit is available activated by wind speed. Cost savings in electricity alone can often pay for entire installations within 2–3 years. Accel-o-Fac® systems process intense wastewater but do so at incredibly low cost.

page aero 5 Benefits 5 Effluent Quality

High Quality Effluent

Water from Accel-o-Fac® treatment systems not only meets rigid standards, it is also better in overall quality due to advanced stabilisation of all biochemistry. This makes it ideal for water reuse options.

Clear Advantages Offered By Aero-Fac® & Accel-o-Fac®

  • icon Sludge Digestion
  • icon Shock & Peak Loads
  • icon No Odour WWTP
  • icon Modular Design
  • icon Design Assistance

No-Sludge Wastewater Treatment System

page aero sludge 1Aero-Fac® and Accel-o-fac® offer a number of unique benefits, not the least of which is a self-digesting sludge process that requires no pre-screening, sedimentation tanks, clarifiers, sludge removal, dewatering, chemicals or conditioning. And best of all, Aero-Fac® and Accel-o-fac® require no routine sludge disposal or the associated tanker traffic in and out of the treatment plant. Sludge is continuously self-digested within the initial treatment stage eliminating costly equipment, labor and regulation.

Extraordinary Flow/Load Flexibility

page aero peak flowSeldom does a wastewater treatment plant see exactly the same flows or loadings throughout its lifetime or even during various parts of a week or year. Whether from tourism, storm water infiltration/flows, industry, growth or other issues, flows and loads vary at many facilities. This is where Aero-Fac® and Accel-o-fac® really shine. Aero-Fac® and Accel-o-fac® can be designed to automatically accommodate anywhere from zero flows up to almost unlimited flows — all unattended. Shock or spike loads have little effect under most any circumstances. This makes Aero-Fac® and Accel-o-fac® ideal for tourism areas, developments with planned growth, areas with large storm water fluctuations or industrial users.

No Odour

page aero odourVirtually no odour is generated from an Aero-Fac® and Accel-o-fac® WWTP. Water industry personnel are routinely amazed by the lack of odour at Aero-Fac® and Accel-o-fac® facilities. Many remark that it is hard to believe that they are actually at a sewage treatment plant! Our technology has been used for decades to solve serious odour issues at existing facilities including both municipal and difficult industrial applications such as food processing and meat packing plants.

Scalable, Modular Design For Any Size WWTP

page aero modular Aero-Fac® and Accel-o-fac® utilise multiple cells, both in parallel trains and in series. Each cell or stage reduces BOD by about 80-85% (water temperature dependent). Parallel trains provide for a modular approach to accommodate larger flows with complete and predictable scalability. 

Examples of Modular Scaling

Design Assistance Based on Global Experience

page aero design 2Our design assistance program allows you to tap into our experience, expertise and global networking capability. Our highly experienced process engineers can be your “back room” with specific expertise when it comes to examining wastewater treatment problems or developing possible solutions, alternatives and costs. Gurney Environmental has extensive experience in process, equipment, operations and maintenance.

Decades of Proven, Reliable Performance

  • "The installation of the Accel-o-Fac sewage treatment system at Holkham in 2006 enforced our ethos of becoming an environmentally sustainable Estate and Community. The system continues to provide a low cost and low maintenance solution to wastewater treatment for Holkham Village with additional capacity for any needed future increase. The fact that there is no associated sewage odours meant that the system could be located relatively near to the village, and, after 10 years of use, no sludge removal has been needed."
    Stephen Twyford, Holkham Estate Land & Property Department
  • "Adding the Accel-o-Fac® system to South Gippsland Water treatment cells where traditional surface aeration was previously used allowed the corporation to significantly reduce energy use. The savings in kWh are excellent with one application saving 72% in energy compared to the previous year."
    Brett Vurlow of South Gippsland Water
  • 1

100% Total On-Site Treatment

Surge & Shock Protection. No Sludge. No Odours. Zero-to-Low Energy. Negligible Operating Costs.
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Decades of Research

Starting in 1976, an intensive and ongoing research program began that was designed to resolve the common problems and limitations associated with traditional wastewater lagoons/ponds including odour, short-circuiting, uneven loading, sludge accumulation and poor processing rates. 40 years later, Gurney Environmental offers technology and designs based on this 4 decades of intensive study of hundreds of municipal and industrial lagoons from around the world.

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Mechanical vs. Biological

The more biological/biochemical removal of contaminants used in a treatment scheme, the lower the initial cost (CAPEX) and ongoing costs (OPEX) for a wwtp. 40 years of research have defined the extraordinary capabilities of advanced biological/biochemical wastewater treatment.


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Truly Advanced Lagoon Design

4 decades of research based on solving problems with hundreds of wwtp's worldwide has resulted in a design philosophy that provides high rate processing, no odours and complete sludge digestion.

New-build lagoon systems are designed with the correct length-to-width ratio, parallel trains of cells to avoid large, poorly performing cells, and correct/optimal depth of cells to maintain perfect aerobic conditions while allowing for a smaller footprint. Experience does make a difference.


Comparison of OPEX in Wastewater

All Gurney Environmental systems come with design assistance and follow-on operational support.

  • Activated Sludge
  • OPEX 100%
  • High CAPEX
  • High initial cost and complex, expensive ongoing energy & operations costs
  • Shock & Peak Loads Can Upset Process
  • Prescreening Equipment Generally Required
  • Aeration Required for Both Oxygen & Mix
  • Clarifier Required
  • Can Have Odour Issues
  • Sludge Handling & Regulation Required
  • High Consumables/Chemicals
  • High Level of Operator Attention/Expertise
  • Annual Maintenance*
  • ?????
  • * 4000 m3
  • Aero-Fac®
  • OPEX –85%
  • Low CAPEX
  • Low initial cost and dramatically lower ongoing energy & operations costs
  • Easily Accepts Shock & Peak Loads
  • No Prescreening Equipment Required
  • Aeration Required only for Oxygen Demand
  • No Clarifier Required
  • Odour-Free wwtp
  • No Sludge Handling & Regulation Required
  • Few Consumables/Chemicals
  • Very Low Operator Attention/Expertise
  • Annual Maintenance*
  • £882/yr est.
  • * 4000 m3
  • Accel-o-Fac®
  • OPEX –95%
  • Lower CAPEX
  • Low initial cost and dramatically lower ongoing energy & operations costs
  • Easily Accepts Shock & Peak Loads
  • No Prescreening Equipment Required
  • Aeration Required only for Oxygen Demand
  • No Clarifier Required
  • Odour-Free wwtp
  • No Sludge Handling & Regulation Required
  • Few Consumables/Chemicals
  • Very Low Operator Attention/Expertise
  • Annual Maintenance*
  • £532/yr est.
  • * 4000 m3
  • WS Ponds
  • OPEX –97%
  • Lowest CAPEX
  • Low initial cost and low ongoing energy & operations costs, but several common problems
  • Problems With Shock & Peak Loads
  • Prescreening Equipment Sometimes Required
  • No Aeration used for Oxygen Demand
  • No Clarifier Required
  • Can Have Odour Problems
  • Possible Future Sludge Removal Required
  • Few Consumables/Chemicals
  • Very Low Operator Attention/Expertise
  • Annual Maintenance*
  • £200/yr est.
  • * 4000 m3

Both Aero-Fac® and Accel-o-Fac® can be designed as modular units and can accept a wide range of flows and loading. Both Systems can be designed as "new build" or retrofit to existing wwtp's.

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