Category Archives: Wastewater Treatment Process Technologies

KEE MICROFLOAT DISPERSED AIR FLOTATION TECHNOLOGY REDUCES POLLUTION

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KEE continually introduce improvements to effluent treatment technology in a bid to minimise environmental pollution from wastewater.

Many industrial processes, particularly food processing, drinks/brewery and dairy, generate a large volume of effluent that is discharged into the sewer. The raw wastewater has high biological oxygen demand (BOD), high chemical oxygen demand (COD) and Fat, Oil and Grease (FOG).  To reduce environmental pollution, companies often pre-treat the wastewater before the wastewater is discharged into the sewer.

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Cut-away view of the KEE Microfloat Dispersed Air Flotation Technology.

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Process diagram of the KEE Microfloat technology.

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This food processing plant reduced surcharges with the KEE Microfloat.

Until now, a system known as Dissolved Air Flotation (DAF) has been used to do this.  The conventional DAF system uses a high-pressure pump, venturi system and pressure vessel to dissolve air into the wastewater. The solution of air and water is stabilised in a pressure vessel under high pressure. A stream from the pressure vessel is discharged into a separating vessel where the air comes out of solution and is released as a fine bubble spray. These bubbles greatly reduce the pollutants by floating them to the surface where they are removed by equipment designed to remove the floating layer.

The KEE Microfloat system achieves the same result without the need to use a high-pressure pump and venturi. Instead, it incorporates a patented system from Aeration Industries that uses a low-power motor. A specially designed propeller disc on the aerator’s shaft produces extremely fine bubbles and transfers these 10-50μm air bubbles into the water through special ejectors.

The whole system is mounted in the circular flotation tank or could be mounted in a rectangular tank be retro-fitted into an existing DAF system.

Some major advantages of the KEE Microfloat system are that it:

  • Removes in excess of 90% of fats, oils and grease (FOG).
  • Substantially reduces the BOD and COD of the effluent.
  • Eliminates the need for fine screens either before or after fat traps.

The KEE Group of Companies is committed to providing a customised approach to domestic, commercial and industrial wastewater treatment applications. With over 60 years’ experience in the development, design and manufacture of equipment, KEE has installed more than 350,000 solutions worldwide.

To see the capabilities of the KEE Group of companies please visit the KEE Group website

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KEE NuDisc ® and KEE NuDisc-R ® – THE VERSATILE PACKAGED TREATMENT SYSTEM

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The KEE NuDisc® Single Piece Packaged Plant and the NEW NuDisc-R®  – is an innovative and a truly versatile systems for the effective treatment of wastewater, including Nutrient removal. A new optional feature has been built into the NuDisc Single Packaged Plant to create the NEW KEE NuDisc-R® Packaged Plant System – physical-biological tertiary treatment with water recycling.

Flexible solutions have long been at the heart of our philosophy and we are now pleased to be able to offer one solution to meet every need. Despite being able to handle a variety of flow rates and numerous final effluent types, the KEE NuDisc® technology combines features that actually simplify its operation and maintenance without compromising the results.

From the moment the KEE NuDisc® is installed, low operating and powercost with long design life ensures low life time cost. The KEE NuDisc® provides the assurance that wastewater is being properly handled and the risk of pollution in the local environment is minimised. KEE can provide a fixed price maintenance package to cover for all mechanical and electrical items and the labour costs after the initial warranty periods.

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KEE NuDisc®

RBC Single Piece Packaged Wastewater Treatment System

KEE Process Ltd has always been a leader in innovative technology for wastewater treatment. The company offers the versatile NuDisc® Single Piece Packaged Plant for the treatment of wastewater. It can be applied to achieve any one or a combination of requirements, including BOD5 reduction, nitrification, total nitrogen reduction or phosphorous removal. Built on KEE’s own proven technology introduced over 60 years ago, the NuDisc® brings many advanced features specifically aimed at simplifying the operation and maintenance of the plant. Its design provides a structural GRP Tank and internal components designed for a life in excess of 30 years. The mechanical components are selected for 100,000 hours L10 life. The end result is a plant with extremely low lifetime costs.

The KEE NuDisc® uses the well-proven principle of attached growth rotating biological contactors (RBC), which support an active film (biomass) for biological treatment of the wastewater. The RBC stage is divided into two specific zones, the first acting as an anoxic reactor and the second as an aerobic reactor. The whole system, including the primary settlement tank, the RBC and the final settlement tank, are housed in a single GRP tank and arranged in such a way that flow attenuation becomes an integral part of every plant.

At the first stage of the treatment process, the wastewater enters the primary settlement tank. Here the solids are settled out and retained as sludge, which is drawn off periodically for disposal. The partially clarified liquor is then brought in contact with the anoxic stage of the RBC reactor where partial degradation of BOD and de-nitrification take place. The biomass in the anoxic stage also provides biological attenuation of organic pollutants, which are partially treated and degraded into much more readily treatable substrates for the aerobic RBC stage.

The downstream aerobic RBC stage is operated under plug flow conditions where BOD removal and nitrification take place. The KEE NuDisc® technology can be applied to different applications to achieve the desired final effluent quality. For instance, where phosphorous removal is required this is achieved by coagulating phosphorous out of the treated effluent at the end of the RBC stage.

The final clarifier is benched at the bottom to facilitate the consolidation of sludge which is then returned to the primary clarifier through the pump assisted hydrostatic sludge return system. In applications requiring de-nitrification, this is achieved by further treating the nitrified effluent in the anoxic zone of the treatment system.

KEE NuDisc® - R

Built-in Optional Tertiary Treatment

The treated effluent from the final clarifier can be discharged to a watercourse or, as an option, this can be further treated to a much higher quality in a physical-biological tertiary stage. This physical-biological filter includes media with extremely large surface area to volume ratio and is arranged in the unit to work as alternating aerobic and anoxic zones for the most effective breakdown of the residual organic constituents (hard BOD) of the treated wastewater from the first and second zone RBC process. The tertiary filter stage is fitted with natural wind turbine or electric fan assisted aeration zones for creating the alternating aerobic-anoxic stages in the filter. The tertiary stage media structure is such that the effluent undergoes breakdown of the remaining soluble organic material and the fine solids contained in the wastewater. The fine organic solids are captured and retained in the media for breakdown.

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Effluent Disinfection:

The treated effluent from the compact KEE NuDisc® or KEE NuDisc®-R can be disinfected using packaged UV light disinfection system before discharge. The disinfected effluent can be either discharged to a watercourse or recycled for irrigation or other applications such as toilet flushing or non-portable use.

The KEE NuDisc® is offered for flows from 1m³/day through to 70m³/day and the KEE NuDisc®-R is offered for flows from 1m³/day through to 40m³/day and is normally packaged into a single piece structure with low profile aesthetically acceptable sectional GRP covers. They incorporate hatches that allow easy desludging and access to mechanical components for regular maintenance. This same KEE NuDisc® and KEE NuDisc®-R technology are also available as Modular RBC Systems, where the individual unit process operations are separated to provide greater flexibility in design, whilst retaining the essential design features such as Managed Flow and flow/load attenuation.

For additional information on NuDisc technology please visit the KEE website

 

 

 

NEW SERVICING REGULATIONS have been introduced for small sewage treatment plants and septic tanks.

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KEE offer Maintenances Plans to that ensure that your sewage treatment plants and septic tanks are compliant.

The Environmental Agency in January 2015, introduced a new code of practice making you as a home or business owner fully responsible for the maintenance of your wastewater system. If you have a small sewage plant or a septic tank, by law you must ensure that your system is maintained properly and does not cause pollution.  It must comply with the ‘general binding rules’.  https://www.gov.uk/permits-you-need-for-septic-tanks.

Protect your local environment by following the rules.

Comply with the general binding rules, just follow our recommended steps below:

  • Get expert, specialist advice, call in a KEE Services engineer for an appraisal; your wastewater treatment systems should be serviced regularly and properly maintained. If it isn’t it can be a serious health hazard and pollute the local environment. Your sewage treatment system must be ‘fit-for-purpose’ and comply with industry standard EN 12566.
  • You are also at risk of prosecution if the regulations are not upheld.
  • You are limited to discharge a maximum of 2,000 litres of treated sewage per day into the ground or 5000 litres of treated sewage per day to flowing water.

If you discharge more you will need a permit.

Regularly maintaining your treatment system properly will help prevent pollution, avoid costly repair bills and minimise your energy consumption:

  • Get the sludge emptied regularly
    http://www.keeservices.com/kee-tankering.html.
  • Get it serviced using a KEE engineer and fix any problems immediately
    http://www.keeservices.com/planned-maintenance.html.
  • Regularly check your system for any signs of pollution such as sewage smells, pools of water, sludge, foam etc. If you notice any of these issues please contact KEE to arrange a service visit.  http://www.keeservices.com/book-a-service.html.
  • Don’t flush sanitary items, nappies, ‘flushable’ wipes or similar objects down the toilet as they can block the system.
  • Don’t push fats, oils or chemicals down the drain as they kill bacteria that break-down the waste. KEE offer a biological solution to solve this problem:
    http://www.keebioguard.com/index.html.
  • Use low or no phosphate detergents, which are kinder to the environment.
  • Keep maintenance records to know when to service and empty your system.

Call KEE today on 01296 634500 for advice on a maintenance plan that ensures your system is compliant or visit:  http://www.sewage-plant-maintenance.co.uk  and arrange a call-out.

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KEE UK Developed RBC Project goes to Europe

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Low lifetime cost RBC wastewater treatment plant for total nitrogen and phosphorous (nutrient) removal

KEE Process was commissioned to develop municipal wastewater treatment plants and include features to ensure that the plants are designed to operate during the high summer and low winter loads without losing performance, provide low lifetime cost, low capital cost, low energy cost, low day to day operational input and low sludge production rates.

Over the last few years, KEE has provided solutions for total nutrient removal for small, medium and large scale systems and these systems have been type tested by various authorities. There is a requirement for many locations in the sun-kissed Mediterranean that systems are capable of operating during the high summer usage and low winter usage, whilst maintaining the plant performance. In addition to this, the plant must be able to operate without the need for daily or weekly operational input. KEE was required to produce two such systems, one for Southern Spain and one for Northern Spain. Both sites required operation in fluctuating summer and winter conditions.

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KEE 4.5m Diameter RBC – with built in flow attenuation system for plant process optimisation.

Site 1 in Southern Spain (warm sub-tropical climate) The plant in Southern Spain is a site that includes holiday chalets, a golf club, recreation clubs, restaurants and bars. The first phase of the plant had to operate for 10% of the ultimate design load, as the facilities were under construction but, as the facilities were gradually built and occupied, the plant had to keep up with the gradual increase in flows and loads whilst maintaining process performance. In addition, it was also a requirement that the plant was of a modular construction to phase the build programme to spread the capital cost. The first phase module had to be designed to treat 300m3/d of municipal wastewater but also had to cope with gradual increase in load.

The first phase module was required to treat:

  • 300 m3/d,
  • BOD 440 mg/l
  • NH4-N 74mg/l
  • TKN 80 mg/l.

The final discharge consent:

  • SS < 35 mg/l
  • BOD < 25 mg/l
  • COD < 125 mg/l
  • TN < 25 mg/l
  • NO3-N < 13 mg/l
  • PTOT < 2 mg/l

The plant proposed and supplied by KEE included prefabricated Glass-fibre Reinforced Polyester (GRP) Primary Settlement Tanks which provide the facility to separate gross solids as sludge, flow attenuation and sludge storage. This was followed by one 4.5m diameter, five-bank RBC, installed in an in-situ concrete tank. KEE RBCs include a patented flow-management system which provides a flow and load attenuation system for process performance optimisation and also creates the necessary conditions for nitrification – denitrification within the RBC.

The whole RBC is covered with lightweight GRP sectional covers. The RBC was fitted with an automated and fully flexible internal recycle system to manage the nitrification de-nitrification requirement of the plant.

For separation of biological solids generated in the RBC, the system includes a prefabricated hopper bottom GRP radial upward flow settlement tank with effective tank surface area of 19.2m2. The final settlement tank includes a fully automated pump-assisted hydrostatic sludge and scum draw-off system to periodically remove and return the scum and sludge to the head of the PST for co-settlement with primary sludge.

The plant components were built off-site in the UK and delivered, all ready for final assembly on site. KEE built the whole plant and all the internal pipe-work on-site in four weeks and was ready to receive flows shortly after that.

This newly built RBC plant covers an initial build phase on-site. The full development proposed increases over the next few years which will result in 10 systems of this size being built and installed at various times over an agreed time period. The energy consumption for the plant for the current low flow of 200 m3/d is 88 kWh/d. This is projected to be 115kWh/d when the flow reaches the designed high season flow of 300 m3/d.

Spot sample result five weeks after initial process commissioning flow rate of 200 m3/d.

                       INLET              OUTLET
                         mg/l                mg/l

BOD               440                 24.0
COD               716                  79.0
NH4-N               92                   5.2
TN                   98.8               19.2

 

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KEE 4.5m Diameter RBC – drive system.

Site 2 in Northern Spain (Temperate Climate)

The plant in Northern Spain was for a smaller population in a village of 170 PE initially, but the local authorities required that the plant should be capable of treating the future projected load from 400PE. The important features to be included in the design were that the same plant should be designed to comply with the performance for both the current load and future projected load whilst maintaining the minimal operations cost and sludge management cost.

The design criteria for the plant in Northern Spain were:

  • 17 m3/d for current PE of 170 & 40 m3/d for the future projected PE of 400
  • BOD 600 mg/l
  • NH4-N 75 mg/l
  • TKN 81 mg/l.

The final effluent discharge consent:

  • SS < 35 mg/l
  • BOD < 25 mg/l
  • COD < 125 mg/l
  • TN < 15 mg/l

The plant for this smaller contributory PE was designed and built along similar lines as the Phase 1 module  for Southern Spain and all the equipment was totally factory built, including the RBC which was housed in a GRP tank and also covered with lightweight sectional GRP covers.

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KEE 2.35m Diameter RBC unit – on site installation and ready for receiving flows.

KEE supplied a 2.35m diameter RBC, fitted with patented managed flow system for flow and load attenuation, internal recycle, automated pump assisted hydrostatic FST sludge and scum removal system, together with  built-in flexibility to readily adapt the plant for such a large fluctuation in flows and loads, whilst maintaining full compliance with effluent discharge criteria including full nitrification and de-nitrification.

The plant was commissioned in April 2014 and the performance of the plant is significantly beyond the design expectation. The energy consumption of the RBC is 15kWh/d for the current load and is projected to be 35kWh/d for the future PE of 400.

Results for the 28 days test period on 95 percentile basis is detailed below for a flow rate of 17.8 m3/d.

                       INLET               OUTLET
mg/l                  mg/l

BOD               854                   9.1
COD             1,708                  62.0
SS                  518                  13.0
NH4-N             126                   1.3
TKN                135                  12.1

For both the sites, KEE also included a feature within the plant design to aerobically digest the sludge during low load periods to (a) reduce sludge management costs and (b) to keep the plant fully operational biologically and ready for the onset of the full load period.

The benefits for the client are that the ownership costs are reduced, the carbon footprint is reduced by avoiding long sludge tanker journeys and the plant is maintained in readiness for the increase in flows and loads of the peak period.

Author: Suru Nathwani B.Eng (Chem), Group MD of KEE

To see the capabilities of the KEE Group of companies please visit the KEE Group website.

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KEE SERVICES OFFER PLANNED MAINTENANCE AND OPERATION OF WASTEWATER TREATMENT EQUIPMENT BY ANY MANUFACTURER

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The maintenance and operation of wastewater treatment equipment is a specialised task and KEE Services Limited recognises this.

With its extensive experience of on-site servicing of all types of wastewater treatment and pumping equipment, its technicians have the knowledge necessary to protect its customers’ investment and the environment.

KEE Services Limited offers planned maintenance programmes ranging from an annual visit to full plant operation. Its aim is to respond to all of your urgent servicing and maintenance needs. The KEE Services Team of fully trained Technicians operates on both a local and regional basis to ensure a prompt and reliable service.

  • Emergency Services
  • Planned Maintenance
  • Breakdowns
  • Equipment Refurbishment
  • Plant Operation
  • Spares
  • Ancillary Products
  • Plant Hire

Committed to maintaining your environment

  • KEE Service Ltd offers Preventative Maintenance, Process Operation and Breakdown Services for all types of treatment plant and pumping equipment, from all manufacturers.
  • KEE Services Ltd supports its UK customers during out-of-hours emergencies by offering a 24-hour manned call out service.
  • KEE Technicians are trained in long-term servicing and look after over 8,000 installations in the UK. They have sound mechanical and electrical experience, combined with application knowledge, and can identify problems early.
  • Working on a local basis, KEE technicians give a prompt service and have a good understanding of the conditions and legislations in each area.
  • Service and maintenance contracts include routine visits to keep equipment from both KEE Process and other manufacturers in top condition and prolong its lifespan.
  • There is a range of contracts available or a package can be designed specifically.
  • If refurbishment or upgrading is necessary, KEE Services can advise on the alternatives.
  • Site assessment can be made and installations planned for new and existing sites.

For full information on KEE Technologies and Services visit the:
 KEE Services Planned Maintenance site.

KEE GROUP CAPABILITIES – OVER 350,000 WASTEWATER TREATMENT INSTALLATIONS WORLDWIDE

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KEE seeks to identify and satisfy the needs of their customers by providing quality engineered solutions priced to offer value for money. KEE has over 60 years’ experience in wastewater treatment, process engineering, servicing and operation with over 350,000 installations worldwide. 

 The technologies and services offered by the KEE Group of companies are listed below:

Design, Installation and Operation of On-Site Plants

  • Anaerobic Reactors – The KEE Group offer design, installation and operation of on-site treatment plants. Their technologies include anaerobic digestion, aerobic processes including RBC and Submerged Aerated fixed film systems, extended aeration and SBR activated sludge processes, complemented with physical and physio-chemical processes. KEE also have a team of experienced process engineers and project engineers capable of delivering solutions to suit

Rotating Biological Contactor (RBC)

  • NuDisc© Single Piece Packaged RBC Treatment Plants
  • Modular Packaged RBC Treatment Systems
  • Large Diameter RBCs for site erection

Submerged Aerated Filters (NuSAF)

  • Single piece NuSAF© Systems,
  • Modular Packaged NuSAF© Treatment Systems
  • Large NuSAF© – in on-site constructed concrete tanks

Activated Sludge Systems

  • Extended Aeration, Sequencing Batch Reactors (SBR)
  • Oxidation Ditch

Fine Bubble Aeration & Mixing Systems

  • KEE Triton Aerator/Mixer

Attached Growth Airlift Reactor (AGAR®)

  • Moving Bed Biological Reactor (MBBR)
  • Integrated Fixed Film Activated Sludge (IFAS)

Dispersed Air Flotation (DAF)

  • pre-treatment of industrial and food processing wastewater
  • KEE Microfloat® – Dispersed Air Floatation Technology,  for pre-treatment of industrial and food processing wastewater to reduce FOG, BOD, COD & SS. The KEE Microfloat system achieves the same result as conventional DAF systems without the need to use a high-pressure pump and venturi. It incorporates a system to produces extremely fine bubbles 10 to 50 micron air bubbles into the water to float the light fractions

Primary and Final Settlement Tanks

  • GRP Hopper Bottom Settlement Tanks – A range of advanced design Hopper Bottom GRP Settlement Tanks for small wastewater treatment plants.

Grease Management System – Biological Solution to Fat, Oil and Grease (FOG)

  • KEE Bio-GuardThe grease digester that’s the biological solution for the removal of Fat, Oil and Grease.

 

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For full information on KEE Technologies and Services visit the KEE Group website
or call 01296 634500

KEE Services Ltd – A BRITISH COMPANY OFFERING A COMPLETE NATIONWIDE WASTEWATER TREATMENT OPERATION AND MAINTENANCE SERVICE ON A LOCAL BASIS

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  • Process Review and Assessment
  • Sewage and Wastewater Management and Operation
  • Planned Preventative Maintenance
  • 24hr Emergency Call-Out
  • Tankering and Jetting Operation
  • UKAS Accredited Laboratory Effluent Testing
  • Sewage and Drainage Asset Management
  • Plant and Equipment Repair and Refurbishment
  • Installation and Commissioning
  • Forecourt Services
  • Spares and Replacement Parts
  • Commercial and Domestic Sewage Systems
  • Grease Management
  • Plant Hire and Rental

KEE Services recognises that the maintenance and operation of wastewater treatment equipment is a specialised task. With its extensive on-site servicing of all types of wastewater treatment and pumping equipment, its engineers have the knowledge necessary to protect customers’ investment and the environment.

KEE Services offers planned maintenance programmes, ranging from an annual visit to full plant operation. Its aim is to respond to all of your servicing and maintenance needs.

The KEE nationally-based Services Team of over 30 fully trained and certified British Water accredited engineers operates on both a local and regional basis to ensure a prompt and reliable service.

Management and Operation . . . a long-term commitment to you
All mechanical and electrical systems require regular maintenance to ensure a long, trouble-free and cost-effective operational life. Regular servicing can prevent the occurrence of costly problems.

  • KEE Services Ltd offers maintenance, operation and breakdown services for all types of treatment plant and pumping equipment, from all manufacturers.
  • KEE technicians are trained in long-term servicing and are currently maintaining over 8,000 installations within the UK.
  • Sound mechanical and electrical experience, combined with application knowledge, means they can identify problems early on and recommend the best solutions.

24hr Emergency Call-Out . . . a national company with local knowledge
KEE’s nationwide team of technicians operates on a local basis, so that wherever you are in the country, you can be assured of prompt service. Because they work in specific regions, KEE’s technicians have a good understanding of the conditions and legislations in your particular area.

A central call centre is staffed by people who are trained to understand the common problems you may experience and give you advice. From here, the nearest available technician can be contacted, thereby making the most of the extensive resources to solve your problems quickly.

Preventative Maintenance . . . a tailored approach
Focusing on your particular issues, KEE can help prevent potential problems, before they become costly or hazardous situations. From installation of the most appropriate equipment to routine inspections and maintenance, different clients have different needs. However, the aim is always the same – to provide you with competent support for the long-term management of wastewater.

Service, Maintenance and Operations
The KEE service package comprises a complete range of options, from servicing and repairs through to regular maintenance and full plant operation.

Site Assessment
KEE technicians can assess your site if it is not linked to mains drainage and can recommend the most appropriate and effective systems to suit the local ground conditions.

When considering the purchase of a new house, office or industrial unit, KEE can assess the local ground and offer options for the discharge of the wastewater.

Installations and Commissioning
KEE technicians can supervise the installation of your equipment, to make sure it is completed effectively. Correct installation will help avoid problems and unforeseen future costs.

Forecourt Services
From installation and commission of oil level and fuel tank alarms to servicing and routine operation checks, KEE has SPA trained technicians who can provide you with a complete service. They can also carry out routine checks on coalescer and closure devices on Class 1 and 2 separators.

Service and Maintenance Contracts
Routine visits will help keep your equipment in the best order and KEE has a range of contracts to choose from. As well as servicing its own systems, its technicians are trained to maintain those of other manufacturers, giving you a comprehensive service.

Refurbishment and Upgrades
As your needs change, KEE is on hand to offer advice on how to refurbish or upgrade existing equipment to meet those needs, from minor improvements to enhance the functioning of a plant, the addition of extra units, catering for expansion or to provide a higher quality of effluent.

Sludge Tankering and Jetting services
Residential or commercial, customers can save time and money by having KEE Services de-sludge and service your treatment plant.

Plant Hire and Rental
KEE offers one of the largest ranges of Process Equipment, Plant and Technologies for hire in the industry, available to the domestic, industrial and civil engineering markets

Grease Management

  • KEE Class 1 and Class 2 grease separator for physical solids and grease removal.
  • KEE Bio-Guard – for Biological Solution to Fat, Oil and Grease.

Total Management
KEE can offer a bespoke service package, tailored to individual requirements. Its total support means that you can expect peace of mind, knowing that it is working to protect your equipment and your environment.   Whether a single or multi-site operation anywhere in the UK, KEE can design a package to best suit your requirements, including routine inspections, maintenance, operation, emergency call-out services and supply of spares.

For full details of KEE Services visit their website.

KEE AERATION SYSTEM – UPGRADE FOR THE LARGEST CHEESE MANUFACTURER IN THE UK

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KEE Tritons® Dual mode Processor (Aerator/Mixer)

Creamery

Dairy Crest Davidstow Creamery in Camelford is the largest cheddar cheese manufacturer in the UK. The process of collecting and processing milk is a 24/7 operation and therefore in a cheese-making facility like Davidstow effluent is generated round the clock on a daily basis and needs to be treated and disposed of continuously. Effluent from the cheese-making process contains high fat content and BOD/COD concentration.

The Creamery upgraded the effluent treatment plant during 2002/2003 and currently has DAF, a balancing tank, two aerobic reactors and a final clarifier. One of the aerobic reactors is MBR and the second reactor is an extended aeration system.

The original design was based on the MBR treating 60% of the total load and the extended aeration system expected to treat the balance. Due to various operational matters and high power consumption, the site was operating with the extended aeration system, consisting of a 5,000 m3 reactor, treating approximately 60% of the flow. The extended aeration system used helixor aerators for providing oxygen to the mixed liquor and the air was provided by Roots blowers at approximately 0.7bar pressure.

Approximately two-thirds of the helixors were still operational and this meant that one-third of the reactor was not being aerated and consequently was not effective in providing any treatment. The reactor was lacking in adequate mixing and due to the reduced operational volume of the reactor it was necessary to maintain high MLSS at around 7,000mg/l.

A further complication was introduced with high-pressure air at high temperatures increasing the bulk liquid temperature to 23ºC. The combination of high MLSS concentration, high bulk liquid temperature, lack of adequate mixing and the need to operate the reactor at a DO of 3.0-3.5mg/l meant that the blowers were consuming around 150kW of power. It was necessary to replace the disfunctional helixor aerators, as gradually more helixors were beginning to fail and the process was at risk of becoming unstable.

In order to replace helixor aerators, it would be necessary to de-commission the 5,000m3 extended aeration reactor, re-install the aerators and then re-commission the plant.

Whilst this refurbishment was being carried out, the Creamery would have had to make arrangements to dispose of 5,000m3 of mixed liquor and dispose of 850m3/d of high strength effluent for the duration of the refurbishment. Disposal of effluent would need to be continued after the plant had been re-commissioned and until the process was fully established and the effluent discharged from the plant was within consent. In addition to these logistical issues and the high cost of mixed liquor and effluent disposal, the Creamery also had concerns with the ageing Roots blowers, which were consuming approximately 3,600kWh of electrical power, associated maintenance and extremely high levels of noise. It would also be necessary to install 60kW of mixing power to optimise plant performance thereby increasing the power consumption to 5,040kWh/d.

To optimise the process it would also be advisable to introduce lateral mixing in the reactor and again this would have added to the power costs and additional electro-mechanical equipment to be maintained.

Tritons® Dual mode Processor (Aerator/Mixer)

KEE Process has been working with the Davidstow Creamery and their Consultant, Mr. D. Sharpe of Lanson Microbe, for some time to evaluate installation of KEE’s dual-mode Triton® processor which provides efficient mixing and fine bubble aeration for mixed liquors in any activated sludge system configuration. The Tritons® can be installed without de-commissioning the reactor and whilst the existing treatment process is ongoing thereby eliminating the logistics of emptying the reactor contents and finding a temporary solution for disposal of the effluent.

The Tritons® are surface-mounted fine bubble aerators and the aerator operates under water surface, thereby eliminating the atomisation and aerosol effect of the air-water mixture. The blower supplying low-pressure air is a high-efficiency regenerative unit and is quiet in operation. The Triton® injects a plume of fine bubble air and water mixture into the water and this action ensures that air reaches deep into the tank bottom up to a depth of 10m. The air-water mixture forms a cone-shaped plume which increases in its zone of influence with depth and this ensures that all the tank contents are completely mixed. As the Triton® uses low-pressure air, the mixed liquor temperature is not elevated and thus the energy required for process is minimised.

The blower can be controlled using a DO probe and PLC to facilitate effective dissolved oxygen in the mixed liquor as required. During the low-load conditions the blower would switch off but the Triton® would continue to provide efficient mixing to the reactor contents. The benefits of a well-mixed activated sludge reactor are that all the installed volume of the reactor is actively participating in the treatment process, the DO concentration throughout the reactor is homogenised and is always available throughout the tank and all the other tank contents, i.e. activated sludge and the substrate are uniformly distributed and this enables the reactor to operate as a completely stirred tank reactor. The system can therefore be operated at the desired DO set point of between 1.5mg/l and 2mg/l instead of 3.5mg/l previously.

KEE Process provided the necessary process engineering input to the creamery and re-evaluated the reactor design for treating 850m3/d of creamery effluent with influent COD load of 1,682kg/d (2,000mg/l) at a design MLSS concentration of 4,000mg/l, F:M ratio of 0.053, and mixed liquor temperature of 20ºC. The consent for final effluent for the Creamery is BOD < 13mg/l, SS <20mg/l, NH4-N < 5mg/l and PO4-P < 1mg/l/.

KEE concluded that the process required between two and three 48.5kW Tritons® for oxygen requirements but two would suffice for mixing. It was decided to install two 48.5kW Tritons® and these would provide the necessary mixing of the mixed liquor and almost 85% of the oxygen demand. The balance of the oxygen would be provided by the retained existing helixor aeration system as and when necessary. In effect, the Tritons® took over as the primary aeration system and provided the critical mixing vital to any activated sludge process. The Creamery could have installed three Tritons®, in which case the reactor would have been able to handle 30% more load than at present and this option still remains available to the Creamery. In fact the reactor is capable of treating a lot more load with 4 No. Tritons® but beyond that the process becomes limited by the solids handling capacity of the final clarifier.

The Tritons® were installed and commissioned and the existing aeration system was kept switched on to supplement any necessary deficiency in oxygen demand. The Creamery and Mr D. Sharpe monitored the existing variable speed Roots blower operation and concluded that they only need to operate at their lowest speed. They also monitored the D.O. concentration in the reactor and this was found to be consistently uniform compared to before the installation of the Tritons®. They also commented that the Tritons® were extremely quiet in operation.

Power Saving

Since commissioning the Triton® Dual Mode Processors, the power consumption is 2,580kWh/day and this represents a 28.3% drop in energy consumption compared with the previous aeration system. The annual power saving is 372,300kWh. More importantly, the contents of the reactor are now completely mixed thereby providing a true CSTR with uniform distribution of substrate and D.O. With mixing taken into account the annual power saving would be 897,900kWh. In addition to the power saving the noise from the Roots type blower is eliminated.

Conclusion

  • Tritons® can be installed in new plant, or in existing plants for supplemental aeration and/or mixing or for refurbishment.
  • Tritons® can be installed without de-commissioning the aeration reactor.
  • Tritons® are surface-mounted dual-mode processors and provide complete mixing and fine bubble aeration of the reactor whilst operating under water surface.
  • With complete mixing of the reactor contents, the process is completely optimised for performance and energy consumption with lower operational MLSS concentration.
  • The upgraded aeration system enables operation of the reactor at under 2mg/l DO and, apart from saving energy, it also enables control of DO in the anoxic selector tank.
  • Use of Tritons® enables lower MLSS concentration in operation and this will reduce solids loading on the final clarifier which, in turn, improves final clarifier effectiveness in removing solids or enables operation of the reactor at higher SSVI.
  • The use of high-pressure blowers leads to increased temperature of reactor contents thereby increasing energy consumption.
  • It is possible to treat more flow and load in the same reactor by adding further Tritons® to improve mixing or provide additional D.O. or both.

KEE, a BSI Certified Company (IMS, QMS, OHS & EMS) offers domestic and industrial wastewater treatment solutions including lifetime operation and maintenance using RBC, SAF, SBR and Extended Aeration. With 60 years’ experience and over 350,000 installations, KEE have the expertise in design, build and operation of all wastewater treatment plants.

For full information on KEE Technologies and Services call 01296 634500 or visit: The KEE Group Website

KEE SERVICES LIMITED – REFURBISHMENT OF EXISTING TREATMENT SYSTEMS FOR IMPROVED PROCESS PERFORMANCE AND REDUCED LIFETIME COSTS

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KEE Refurbishment of Packaged Treatment Plants

The Anglian Water Systems (AWS) Team undertook such an exercise over a range of small to medium sized treatment plants adapted by the plc from a local council. Instead of abandoning the existing works, KEE Services Ltd with support from their process partners, KEE Process Ltd, were commissioned to survey 11 sites and report the findings. The report was required to include inventory register, feasibility of refurbishment, process implications and improvements with the associated costs of refurbishment. The survey was undertaken and completed over four weeks and a complete report, with a costed refurbishment program for all the sites was submitted to the AWS Team.

The 11 plants varied from 40PE up to 500PE in size and included systems required to reduce BOD and, in some instances, provide fully nitrified discharge with less than 5mg/l ammoniacal nitrogen. All the plants surveyed were of packaged plant construction, single piece or modular, and included primary settlement stage with combined sludge storage, RBC type biological stage and final settlement tank. The report concluded that it was feasible to refurbish all the plants and included a program for refurbishing the plants to a standard where the operators would have the confidence that the plants would provide a reliable and useful life for a further 20 years. Depending on the extent of refurbishment work necessary, the costs associated with the refurbishment varied substantially, but in every case it was much cheaper than replacement. The cost of refurbishment included for supply and installation of new equipment.

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This relates to a cluster of small population equivalent installations where all the plants upgraded were over 20 years old and would now have in excess of a further 20 years life and an improved process performance. With all the sites, the outer GRP structure housing the plant was retained and, with the exception of one or two sites, the internal components including the RBC were replaced by brand new factory built units incorporating the latest concepts in mechanical, structural and process engineering.

All the above plants include sectional GRP covers and were replaced to provide the equivalent of a new plant without the high cost and resource required to build one.

Refurbishing Large Wastewater Treatment Works

The KEE refurbishment concept can also be applied to plants serving larger populations which can be electro-mechanically upgraded to show similar benefits and add 20 years or more useful life to the plant. Scottish Water undertook a similar exercise where an existing 4,750PE activated sludge plant needed to be refurbished to bring the plant back to its full performance requirement without necessarily having to re-build the works.

For more information on Wastewater Treatment Plant refurbishment call KEE Services on: 01296 634500 or visit the KEE Services website.

KEE TRITON AERATOR/MIXER OVERCOMES PREVIOUS LIMITATIONS OF OXIDATION DITCH TECHNOLOGY

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KEE FINE BUBBLE AERATION WITH BUILT IN MIXER

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KEE Process Triton

The KEE Triton Aerator/Mixer overcomes the previous limitations of oxidation ditch technology and can be used to revitalise existing oxidation ditches and extended aeration plant or systems based on activated sludge process.

Using the dual mode processor capabilities of Triton Aerator, aeration basins up to depths of 10m can be completely aerated and mixed. Existing Oxidation Ditches (OD) can be retro-fitted and new OD plants benefit with much smaller footprint. Nitrification and denitrification can all take place in a single reactor. With two propellers and a regenerative blower, Triton is able to operate either as an anoxic mixer with the blower turned off, or an efficient aerator/mixer with the blower on.

Multiple Triton units can be arranged to provide extended contact time between air bubbles and water stream, with greater oxygen transfer efficiency. Improved biological treatment results in Biochemical Oxygen Demand (BOD) removal rates as high as 99% in highly contaminated wastewater.

The KEE Triton is the most versatile fine bubble aeration/mixing device for activated sludge treatment systems available with dual functions – aeration and mixing.

KEE fixed price operation and maintenance contracts are available.

For full information on KEE Technologies and Services visit: KEE Fine Bubble Aeration
or call KEE on: 01296 634500