Sewage treatment plants Sigmainvest.

The history of tradition and experience started long time ago when numerous projects were accomplished world-wide in the name of Intersigma Ltd and continues up till now when company restructured in more efficient holding organisation. Sigmainvest was founded on 30.4.1991 by its registration in the Companies Register at the District Court of Prague 1. Sigmainvest maintains the tradition of 40 years of experience in water industry with the first Project contracted in the Middle East Region in 1958.

The staff of Sigmainvest Company is formed by the members of the former group 300 - complete investment plants of Intersigma Ltd and as such they have exported and completed many investment plants, the bigger of which are cited below in the list of references.

WASTE WATER TREATMENT PLANTS.

The Sigmainvest waste water treatment plant range include a complete size assortment from small compact units to urban agglomerations with over 100.000 people. Generally, a treatment method is selected according to the type of pollution, degree of purification required, and plant size. Great emphasis is placed on an appropriate design of the plant, whose principal aim is to achieve the maximum economy of the civil engineering part of the waste water treatment plant.

Typical stages of the purification process.

Mechanical pre-treatment of waste water:

* gravel trap
* bar screen
* fine screen
* sand trap
* trap of floating impurities and grease

Biological waste water purification is based on the activated sludge method:

*A single – stage biological purification is used for communal waste water treatment
*A multi – stage biological purification is used for concentrated waste water, mainly from food plants, concentrated cattle - breeding facilities etd.

Technical means of the biological activated sludge purification:

Activation aeration tanks equipped with the following aeration elements or their combinations:

* surface aerators
* deep-submerged aeration grates
* horizontal aeration jets (for circulation tanks)
* biological sprinkled filters
* rotary biodisks
* settling tank
* If there are special requirements as to the removal of solids from waste water, down-draught rotary or belt separators are used.
* depending on concrete conditions of the inflow into the waste water treatment plant, the mechanical pre-treatment stage may include the separation of sufficiently diluted rain water and its separate partial purification in rain retention tanks
* depending on concrete gradient conditions of the inflow into the water treatment plant, the mechanical pre-treatment stage may include an intake waste water pumping station.

Final Treatment of biologically purified water.
Sedimentation tanks:

flat bottom longitudinal rectangular tanks with continuous mechanical removal of sludge deposits
flat bottom circular tanks with continuous mechanical removal of sludge deposits
Dortmundt-type conical tanks with mechanical removal of sludge deposit.

Hygienic treatment of waste water at the waste water treatment plant outlet:

* waste water chlorination
* waste water ozonization

Sludge processing.

The resulting product of the processing of the sludge originating in the separate stages of the waste water treatment process should be a hygienically harmless (= stabilized) product which would be easy to dispose of, or which could be used as a component of other products, mainly in agriculture. Great attention is paid to the utilization of the raw sludge energy potential.

A basic scheme of the sludge processing in SIGMA waste water treatment plants is as follows:

* sludge stabilization
* aerobic
* anaerobic
* thickening of stabilized sludge
* production and utilization of the sludge gas (= biogas) originating during the anaerobic sludge stabilization.

Technical means of sludge processing:
aerobic sludge stabilization.

* taking place concurrently with the biological purification process, in a single activation aeration tank
* separated from the biological purification process, taking place in a separate aeration stabilization tank.

Anaerobic sludge stabilization.

* single or multi-stage sludge septicization with the production of energetically usable
* sludge gas (= biogas)

Thickening of stabilized sludge

* by the sludge own weight in gravity thickening tanks
* by mechanical stimulation in gravity tanks
* by mechanical dewatering using belt filters, filter presses or centrifugal separators etc.
* by flotation using a SIGMAFLOT flotator
* by drying in sludge beds


 


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