WALIS certified biological wastewater treatment plants are intended for the treatment of domestic and chemically similar wastewater, i.e. to clean domestic sewage generated in kitchens, bathrooms, WCs and other premises of similar purpose.

WALIS wastewater treatment plants are made of fiberglass. All main external and internal structural elements are durable, corrosion resistant. The capacities of the plant have been tested by hydraulic tests and mechanical resistance tests.

1 Inflow pipe
2 Anaerobic chamber
3 Anoxic chamber - denitrifier
4 Aeration chamber - nitrifier
5 Secondary settler
6 Diffusers
7 Airlift of circulating activated sludge
8 Airlift of denitrified mixture
9 Overflow pipe
10 Overflow ledge
11 Saw-shaped ledge
12 Gutter
13 Outlet pipe
14 Air bubble generators
15 Perforated tubes for air supply
16 Lifting loops
16 Lifting loops
  1. Inflow pipe
  2. Anaerobic chamber
  3. Anoxic chamber - denitrifier
  4. Aeration chamber - nitrifier
  5. Secondary settler
  6. Diffusers
  7. Airlift of circulating activated sludge
  8. Airlift of denitrified mixture
  9. Overflow pipe
  10. Overflow ledge
  11. Saw-shaped ledge
  12. Gutter
  13. Outlet pipe
  14. Air bubble generators
  15. Perforated tubes for air supply
  16. Lifting loops

A biological wastewater treatment process, which is close to the natural decomposition process occurring in nature, takes place in the wastewater treatment plant. Aerobic microorganisms that develop in an oxygen-saturated environment are used for biological wastewater treatment. Activated sludge (aerobic microorganisms and particles of wastewater pollutants) is formed when the wastewater mixes with fine air bubbles, supplied into treatment system. Therefore, organic matter is separated into simpler chemical compounds, which turn into carbon dioxide and water. Under the influence of gravity, the activated sludge separates and settles, and the purified, clear, odourless water is piped to the outlet.

WALIS wastewater treatment plants meet the standards for removing nitrogen and phosphorus from domestic wastewater. The process is based on the AAO technology used in higher capacity wastewater treatment plants, which ensures a higher level of wastewater treatment than is normally regulated for treatment plants with a capacity of up to 5 m3/d.

Through the inflow pipe (1), the wastewater enters the anaerobic chamber (2). The circulating activated sludge from the secondary settler (5) is also returned to this chamber by air lift (7). In this zone, under anaerobic conditions, most of the phosphorus compounds (organic phosphates, polyphosphates, etc.) turn into soluble phosphates, which are used in the further wastewater treatment process and accumulate in the activated sludge. The mixture of wastewater and sludge from this zone enters the anoxic chamber (3) (denitrifier), to which the nitrified sludge mixture from the aeration zone is returned by air lifts (8). In the anoxic chamber, nitrogen is removed from nitrates in the returned nitrified sludge mixture, nitrates are separated into nitrogen and oxygen. Part of the nitrogen is removed from the wastewater in the form of gas. The released oxygen is used for the oxidation and nitrification of organic pollutants.

Later, the mixture enters the oxidation zone – the aeration (4) chamber (nitrifier), where biochemical oxidation of newly introduced pollutants and nitrification of nitrogen compounds proceeds. Diffusers (6), used for aeration, sufficiently finely disperse the air supplied by the compressor and dissolve it well in the mixture of treated wastewater and activated sludge. The air supplied by the compressor is directed to the lower part of the aeration chamber through the supply pipe, where it rises in small bubbles through the diffusers (6), saturating the mixture of treated sewage and activated sludge with oxygen. Organic pollutants are separated and largely oxidized to carbon dioxide or water, while the most of ammonium and the organic nitrogen are converted to nitrates. A part of the treated wastewater and activated sludge mixture is returned from the aeration chamber (4) to the previous stage of wastewater treatment – the anoxic chamber (3) by air lift (8), and the other part enters the secondary settler (5) through the overflow pipe (9). Under the influence of gravity, the activated sludge separates and descends to the lower part of the device, from where it is returned to the initial stage of wastewater treatment – the anaerobic chamber (2). Cleaned water flows through the overflow (10) and saw-shaped (11) ledges, which retain the sludge residues, and accumulates in gutter (12), from which it flows out of the device through the outlet pipe (13). In order to prevent the accumulation of activated sludge particles on the surface of the secondary settler (5), air bubble generators (14) are installed on top of it to break up the raised sludge layer. Air is supplied by the same compressor as for other technological needs. In order to keep the activated sludge floating in the anaerobic (2) and anoxic (3) chambers, wastewater is periodically mixed with compressed air, supplied to the bottom of the chambers through perforated tubes (15). Mixing periods and intensity are determined during the start-up and adjustment procedure of the device.

The start up and adjustment procedure lasts up to 4 weeks, till the wastewater treatment reaches the projected level.

Walis nuotekų valymo įrenginio valdiklis

The operation of the wastewater treatment plant is fully automated. It is regulated by a smart GSM controller designed to control the aeration and circulation processes. According to the programmed time intervals, it changes the position of the electromagnetic valve, regulates the flow of supplied air in the collectors and the operation of the compressor. The controller fixes instantaneous system performance data and possible deviations and informs the manufacturer or the manufacturer’s official representatives, providing technical support services, about system malfunctions.

WALIS biological wastewater treatment plants are completed with HIBLOW (Japan) compressors as standard.

The release of wastewater into the environment, which violates the norms established by legislation or other requirements for the release of wastewater into the environment, incurs criminal liability!

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