Compact WWTP

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Waste water treatment

Compact WWTP

For:towns, villages and industry


Compact WWTPs BioCleaner® are an optimal solution for villages and towns up to 10 000 citizens. These plants may also be applied for treatment of organically polluted industrial sewage water, especially from the food industry.

Technological layout of the WWTP, but also the building and architectural design is always designed exactly to the investor’s requirements and appropriate institutions of state administration.

WWTP can be made as one-line up to four-line (parallel lines) organization, which enables reacting to up-to-date load at the gradual sewerage built-up or reacting to seasonal inequalities in tourist areas. WWTP can be made as an open-air or partially covered or fully covered unit in order to adopt to hygiene and other requirements.


Mechanical pretreatment

It is placed in the technological line of the WWTP especially as protection for the main biological reactor. The choice of technical layout depends on the type and condition of the sewage system, furthermore, on the character of waste water. The following mechanisms are used for removal of mechanical impurities:

  • Coarse screens
  • Fine screens (hand or machine-cleaned), which are in dependence on WWTP capacity (size) suitably completedwith dewatering device and conveyor
  • Gravel trap and sand trap, which may be finished with the sand separator

Biological reactor

The main part of the plant serves mainly for organic pollution removal, but also for removal of nutrients (compounds of nitrogen and phosphorus), which cause unfavorable eutrophication of surface water.

  • Activated sludge process
  • D-N system, that is a system with denitrification situated prior to nitrification organized in one ore more parallel lines


Mechanically pretreated waste water and returned sludge from the settlement tank are led into the denitrification tank. Nitrates, which are reduced to gaseous nitrogen in this tank, are led together with the returned sludge. The process takes place under anoxic conditions, which means without the presence of dissolved oxygen. Homogenization of the activated sludge mixture in the denitrification tank is provided by a submersible mixer. To increase the efficiency of the nitrogen compounds removal, it is possible to integrate the so called internal recirculation, which is based on the recirculation of the activated sludge mixture directly from the nitrification tank into the denitrification tank.


In the nitrification tank in the presence of disolved oxygen, biological oxidation of organic compounds and ammonia nitrogen takes place. Organic compounds are oxidized into the carbon dioxide and the ammonia nitrogen is transformed into the nitrites and consequently into the nitrates. The tank is aerated by a fine bubble membrane aeration system which is placed at the bottom of the tank. Pressured air is provided by air blowers. The activated sludge mixture flows from the nitrification tank into the settlement tank.

Settlement tank

To separate the cleaned water and the activated sludge , there is a circular stainless (plastic) settlement tank, inserted into the nitrification tank. An advantage of the placement of the settlement tank into the nitrification is space and costs saving and furthermore, short distance for the pumpingof the sludge . This enables pumping of returned sludge and excess sludge by means of hydro-pneumatic pumps (air-lift pumps). By the use of air-lift pumps instead of conventional pumps we can reach operating energy savings and high operational reliability.

Machine room

Pressure air supply system

Root air blowers are used to provide pressured air supply for the aeration system of nitrification, for excess sludge stabilization and storage tanks, for air-lift pumps of returned sludge recirculation, excess sludge pumping, internal recirculation and for the sand trap too.

Sludge management

Sludge management fulfills the function of aerobic stabilization, excess sludge gravitational thickening and excess sludge storage. In dependence on the capacity (size) of the WWTP, sludge management can be completed with mechanical dewatering of the sludge.

Chemical management

In case of increased requirements for phosphorus removal, it is possible to integrate installation with phosphorus chemical precipitation by means of inorganic salts (e.g. iron sulphate). The installation consists of dosing membrane pumps modified to dose caustic agents and storage tanks. The storage tank for chemicals is made as a special double-shell tank with supply valve for filling chemiclas directly from the cistern, with a face-level indicator for identification of chemicals quantity and leakage sensor.

Faecal reservoir

In case of requirement to deliver sewage water from other treatment plants or septics, it is possible to incorporate the faecal reservoir. The reservoir is usually equiped with screen cage to trap possible gross dirt. Sewage waters from this reservoir are pumped into the inlet of the WWTP by means of an immersion sludge pump according to the needs.

Tercial clearing

Tertiary treatment is included in case of higher quality requirements for outlet parameters and it is realized for example with the help of:

  • Filtration (gravity or pressure sand filters, micro-sieve drum filters, membrane filters)
  • Hygienization (UV disinfection, chlorination)

Structural design

It is possible to place the whole WWTP BioCleaner inside a brick building, where all the technology is inside in an enclosed space. Another possibility is partial coverage, when is selected larger technological parts (nitrification tanks, settlement tanks, part of mechanical pretreatment) are situated outside of a building. The choice of particular spatial arrangement results from the parameters of the designed plant, selected area, construction costs, also from the aesthetic point of view with respect to the surrounding countryside and built-up area.

Cleaned water quality

Indicator Indicator of required quality at the outlet * BioCleaner® **
  “p” [mg/L] “m” [mg/L] [mg/L]
BOD5 25 50 15
COD 120 170 75
SS 30 60 20
N-NH4+ 15 30 10 ***

*) Required values of pollution indicators at the outlet according to the code of law for WWTP to 10 000 PE
**) Usually reached average values at the outlet by compact WWTP BioCleaner®
***) For the water temperature above 10°C

Approximate dimensions and other values

Number of PE   500 1 000 2 000 5 000 10 000
Dimensions for the built-up area [m] 11.5 × 7.5 12.5 × 10 20 × 15 75 × 50 100 × 60
Quantity of waste waters Q24 [m³/day] 75 150 300 750 1 500
Energy demands* [kWh/day] 45 90 175 400 775
Number of lines   1 to 2 2 2 2 to 4 4

*) Approximate value/quality at full load of the WWTP, real parameters result from used technology

Why choose the compact WWTP BioCleaner®

  • Longterm experience all over Europe
  • More than 100 installed compact WWTP and on the whole more than 12 000 realizations of WWTP BioCleaner® type
  • Waste water from more than 500 000 PE cleaned by means of technology BioCleaner®
  • Self-tested technology supported by development and longtime experience
  • Operational stability and reliability of BioCleaner® system
  • Small bulit-up area, thanks to an inserted settlement tank
  • Low cost of investment (building difficulty reduction)
  • Possibility of complete WWTP covering (reduction of protective zone, winter operation)
  • Optimal choice of technological arrangement „made to measure“
  • Technological support and service all over Europe
  • Cleaned water quality in accordance with EU legislature requirements or with customer’s specific requirements

We’ll be happy to give you advice about any step of preparation or realization.