AEROBIC UNITANK® | ANAEROBIC UNITANK®
As the first Belgian provider of biological wastewater treatment, Keppel Seghers experience dates back as far as 1981, when the first UNITANK® installation was developped.
This unique technology combines all advantages of a conventional, combined activated sludge water treatment station with those of a SBR batch system. The result is one compact, efficient and continuous biological wastewater treatment plant called UNITANK®.
Now 20 years and over 500 satisfied customers later, the 3rd generation UNITANK® still is the absolute reference for biological wastewater treatment.
UNITANK® BASIC
 Applications
The aerobic UNITANK® BASIC is the standard configuration for complete BOD removal of municipal wastewater and of a wide variety of lower concentrated industrial wastewater.
Advantages
Through our advanced control and automation system, the UNITANK® BASIC is highly differentiated from the activated sludge system of our competitors, and offers the following benefits :
- Compact and modular design
- Short plant construction times from engineering to start-up
- Advanced equipment and instrumentation
- Simple and flexible operation
- Stable and reliable purification process
- High treatment efficiency
Description
The UNITANK® BASIC consists of a three compartment activated sludge reactor per line. All three compartments are optimally controlled through time-controlled parameters and act as both aeration and sludge settling tanks.
The UNITANK® BASIC works in a sequence of "left to right" and "right to left" flow pattern keeping an optimal distribution of the biomass over the three compartments. There's no need for a costly racking and pumping system for sludge recycle as required in "continuous flow" activated sludge systems.
On the other hand, the use of three, hydraulically connected compartments guarantees a continuous inflow of wastewater and continuous outflow of purified effluent with a fixed water level, this contrary to the "batch" systems.
Although having a dual function, the outer compartments are particularly designed for optimal sludge settling while the size of the centre compartment depends on the required aeration volume.
The UNITANK® BASIC can be worked out in different shapes (I-shape, L-shape, U-shape or circular) in function of available area, soil conditions or architectural specifications.
UNITANK® ADVANCED
 Applications
Appropriate for municipal and industrial wastewater
Advantages
- Advanced biological removal of nitrogen and phosphorous compounds
- Excess nitrogen removal by nitrifying - denitrifying bacteria
- Excess phosphorus removal by specific phosphate accumulating bacteria
- Optimal ratio aerobic / anoxic / anaerobic conditions when using the Oxydo Reduction Potential as a direct control parameter
Description
Nitrification : NH4+ + 2O2  NO3- + H2O + 2H+ + ENERGY
Conversion of ammonia into nitrate requires:
- autotrophic bacteria (Nitrosomonas, Nitrobacter,...)
- aerobic conditions
Denitrification : 4 NO3- + 5 CH2O + 4H+2N2 + 5CO2 + 7 H2O + ENERGY
Conversion of nitrate into nitrogen gas requires:
- heterotrophic bacteria
- anoxic conditions
- presence of carbon source (CH2O)
Phosphate accumulation :
- By aerobic bacteria that accumulate energy-rich poly-phosphate compounds as an energy source for their survival in anaerobic conditions (if alternated with aerobic conditions).
- Their selection is based on the benefit they have towards other bacteria in aerobic conditions providing themselves with internal carbon sources.
UNITANK® COMET with energy recovery
Applications
The UNITANK® COMET concept is the ideal treatment for many highly concentrated industrial effluents and is perfectly suited for large-scale municipal wastewater treatment projects.
The COMET installation allows you to turn your wastewater into valuable energy.
Advantages
- minimal sludge production (> 65% reduction)
- maximal energy recovery (70 to 120 %)
- intelligent peak flow handling
- ultra flexible and redundant
- construction and operational costs strongly reduced
- high loading rates possible
- no need for oxygen à low energy consumption
- low nutrient requirement
- production of biogas to be used as energy-rich gas source or fuel
- low sludge production
- long preservation possible
Description
COMET = Conditioning & Methanisation
Conditioning:
Solubilisation and hydrolysis of organic matter (carbohydrates, proteins and fats)
Conversion of soluble and particulate organic molecules (like sugars, amino acids and fatty acids) into volatile fatty acids (VFA)
Methanisation:
Conversion of VFA into methane and carbon dioxide
Limitations:
- applied as pre-treatment
partial COD and BOD removal
no nutrient removal
- higher process requirements
more sensitive than aerobic
heating required if water < 20°C
longer start-up times
- undesirable by-products
H2S = malodour compound / corrosive compound
Description
Being a two stage system, it consists of a first ultra-high loaded aerobic activated sludge stage, producing “fat” sludge, followed by a nutrient removing “polishing” second low loaded activated sludge stage.
The “fat” sludge is digested afterwards to produce methane gas and consequently power.
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