Monthly Archives: February 2016

KEE Do’s & Don’ts to extend the life of a sewage treatment plant and prevent costly maintenance costs.

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Caring for Your Sewage Treatment Plant

Regular inspections and maintenance will help ensure your plant is operating at optimum performance and will maximise the lifespan of your equipment.


  • Follow manufacturers’ recommended doses for your water type when using household cleaning products. Soft water requires far less detergent concentration than hard water.
  • Try to use cleaning products little and often so your treatment plant is not overloaded.
  • Use liquids (not powders) in washing machines and dishwashers. Powders re-coagulate into clumps and can cause blockages.
  • Try to spread your clothes washing throughout the week.
  • Stick to the same washing, dishwasher and other cleaning products as the bacteria will work more efficiently with products it is used to treating.
  • Think before you put anything down the sink, toilet or drains.
  • Desludge your plant when required. Click HERE to view our one page KEE EXPERT guide on proficient desludging and how regularly your unit should be desludged.
  • Ensure only toilet paper is flushed down the toilet and used in normal quantities.
  • Leave your plant switched on while you are away or on holiday. Switching off your plant can cause damage to the motor and moving parts as well as kill the biomass.
  • Compost all your organic food waste or use your local council bio-degradable waste recycling service (where applicable) to dispose of organic waste. Do not flush organic waste down the sink or drain.


  • Don’t put sanitary towels, tampons, cotton wool or cotton wool buds, incontinence pads or any baby, cleaning or facial wipes down the toilet.
  • Don’t flush rubber products or other non-biodegradable  products down the toilet.
  • Don’t pour fat, grease or cooking oil down the sink or drains. Fats suffocate the bacteria and inhibit the biological process. Everyday products such as milk, wine or beer increase the organic load and should also not be disposed of through the wastewater system.
  • Don’t use neat disinfectant or bleach. KEE recommends that these products are only used at the minimum concentration possible, as they can restrict the biomass growth within the plant.
  • Don’t tip medicine, mouth wash or any chemicals such as photographic fluid or garden products (e.g. Insecticides, weed killers and fungicides) down the drains as they will damage the biological treatment process.
  • Don’t pour DIY products (e.g. paint, thinners, turpentine and white spirit etc.) or car fluids such as engine oil, anti-freeze, brake fluid etc. down the drains.
  • Don’t allow rainwater, groundwater or large volumes of water (such as those from a swimming pool or Jacuzzi) into the plant. Chlorine kills the bacteria and the excessive water will increase the flow rate through the plant, not allowing sufficient treatment time.
  • Don’t fit a waste disposal unit under your kitchen sink. Disposing of organic matter through the treatment system increases the organic load, creating bacterial overgrowth which will inhibit the treatment process. Only use a waste disposal unit if your plant is specifically designed to accept higher organic loads.

KEE who are a member of British Water, have a copy of their:
Code of Practice – A Guide for Users of Sewage Treatment Systems  to download as a good starting point for information.

KEE Services recommend that your Sewage Treatment Plant should be regularly serviced to avoid any serious future costly problems – contact KEE.

Request a quote for a maintenance contract or call 01296 634500




KEE UK Developed RBC Project goes to Europe

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.


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



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.

Image-03       Image-04

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.