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These increase the cost or even prevent the discharge of waste to the  sewer or watercourse and often exclude the recycling of the water. One approach is aerobic treatment in a biological plant.  Traditional processes are very large (with consequential high cost) and are limited in the strength of waste they can handle.

WMEC’s bio plant is particularly suited to  sites which have a BOD problem but who would not have considered a traditional biological treatment plant on the grounds of suitability, cost or space. WMEC’s bio plant employs a unique, patented treatment system using the submerged fixed film principle. In this environment, bacteria grow on the surface of specially structured honeycomb like media and are intensively aerated by a diffuser system.


A diffuser ensures that the entire bio plant is evenly aerated while preventing blocking and creating optimum  mixing conditions. The resulting  oxygen transfer is very efficient and ensures that the biofilm remains thin and active. The diffuser covers the entire floor area of the reactor and, in conjunction with the media, ensures that the entire bioreactor is thoroughly and evenly aerated. The diffusers have no moving parts and form a carpet of constant sized air bubbles.

Packing Media

The bio plant is entirely filled above the air diffusers with specially selected three dimensional media. The specific surface area exposed to the effluent and the oxygen is very high.

Bio plant process characteristics

As a result of WMEC’s unique patented design, a number of significant advantages are obtained, particularly in comparison with the traditional activated sludge process. These may be summarised as:

  • High specific BOD removal: 0.5 – 12 kg/m³/day depending on treatability
  • Low power requirement 1.2 kW blower, continuous rating, inverter controlled
  • Very compact design 4 m x 2 m footprint – ‘one tank solution’
  • Integral sludge, balancing, bio media and post treat settled solids tanks
  • Processes high strength waste
  • Built in air lift pumps for recirculation for periods of very low or no flow
  • Simple automated operation
  • Low capital cost


Modern strains of bacteria can be selected or cultured to digest a wide range of effluents, including many which were previously considered non-biodegradable.  WMEC’s bio is therefore suited to all applications with biodegradable pollutants.


In principle, the bio plant can be used in all situations where activated sludge or similar biological processes have been applied. In many high strength waste streams where anaerobic bio- treatment has been used, the bio plant will also work well in intensive aerobic mode. This means the bio plant can treat wastes of up to 20,000 mg/l BOD.


A small bio suits sites with very limited space and low or intermittent flow rates on account of its very high processing efficiency  and internal recycling loop. Installations in service currently process flow rates from 1m³ per day to 5m³ per day. The size of our bio plants depend on total BOD load, flow rate and treatability.

Existing installations

Existing installations include the following types of sites:

Food processing Fish processing waste
Drink Brewery effluent
Chemicals Multi-purpose speciality chemical synthesis
Paper making Final BOD reduction preceding discharge to watercourse
Engineering High BOD machining coolant
Agricultural Yard wash down waters BOD and ammonia reduction