Techno Plast

Modular waste watertreatment facilities for up to 1500 population equivalent SBR 12-20

These facilities are joint development with the company Perfect Service EOOD, Sofia:
– 6 Al. Zhendov Street, office 306, tel.: +359887602959, fax +35929173944
– 14 El. Bagryana Street, office 2, tel./fax: +35929714793



The proposed modular treatment facility type SBR reactor consists of 2 plastic tanks, equipped with the necessary pumps, compressors and automation for control of the waste waters treatment processes.

The fats retention, deposition of the undissolved substances and equalisation of the flow of incoming waste waters are performed in the first tank. It can be installed deeper than the second tank, if the waste waters come in from greater depth.

Using the pump installed the waste water is then pumped into the second tank – for a complete biological treatment.

The equalisation volume of the first tank is between 30 and 50% of its volume – adjustable during the start-up and fine tuning of the plant.

The automation system controls the operation mode and cycles of the treatment facility, according to a pre-set program.

The facility operation is fully automatic.

Its servicing is periodic – twice a year the deposits and fats from the first chamber are to be removed and an inspection of the condition of the pumps and compressor is to be performed.

Description of the operation principle of the facility

Biological treatment in the SBR reactors is particularly suitable for modular facilities with great irregularity of incoming waste waters, and permits achieving of high and stable treatment effect. Essentially, treatment in SBR reactors is a variant of the “active sludge” treatment, with the only difference that all phases of the process are performed inside one capacity – i.e. there are no separate units for aeration and for sedimentation.

Operation principle of the SBR reactor


Filling and Stirring Phaseе

The cycle of filling and stirring continues for around 1,5 hours. The process of denitrification is implemented during the period of stirring – it reduces the contents of the dissolved oxygen in the water to below 0,5 mg/l, when microorganisms like the facultative anaerobes begin consuming the oxygen from NO3, reducing it into a free N2, which is then released into the atmosphere.

Aeration Phase

The cycle of aeration has a duration of around 5 hours. Aeration is implemented by means of 3 submersed mechanic aerators in each reactor for a fine-bubble aeration, through which the concentration of dissolved oxygen is maintained within the limits of 2 mg/l. In this stage of the technological process, the microorganisms from the active sludge decompose the organic contaminants, perform ammonification and nitrification of the organic nitrogen.

The sedimentation phase has duration of minimum 1 hour, during which the microorganisms from the active sludge fall on the bottom of the facility, and above them is formed the layer of clarified water.

Phase of pumping of the treated water

The phase of pumping lasts for 0.5 hours. Emptying of the clarified water is performed by a submersible pump. The depth of submersion is adjusted in the process of plant setting-up. The pump supplies the clarified water to a contact reservoir, where there is an option provided (if necessary) to add a 3% solution of sodium hypochloride to the pumped water for disinfection (if required by the healthcare authorities).

The contact reservoir provides the contact of the treated water with the disinfectant to eliminate any pathogenic microorganisms.

Provision for disinfection of the waters can be decided upon in each individual case.

In suitable soil conditions and topography, the treated water can be directed to soak away in the soil via drainage system, or be used for irrigation of green areas or be discharged into a local surface basin (subject to the respective permission).

The drainage system for soaking away of the treated waters is dimensioned for each individual case, depending on the particular soil and hydrogeological conditions.