Industrial waste water treatment plants
The treatment technology takes place subject to the characteristics of the used waters resulted from the industrial activity and to the discharge place (the street sewerage system or the emissary). In case of the existing activities, the design-related data are selected with the beneficiary, based on the quality and the amount of the technological used waters. For the new activities, the design-related data are selected with the beneficiary, based on the suggested technology, taking into account the legal regulations and the similar situations existing in the field.
According to the quality of the inlet water, the treatment technology is designed and implemented in several stages : mechanical, chemical or electrochemical, biological.
Plants for waters with extensive organic charges derived from the food industry
The used waters resulted from slaughterhouses, meat processing factories and milk processing factories contain large amounts of fats and high concentrations of biodegradable organic substances. The treatment technology comprises a mechanical and physical-chemical separation of the suspensions from the used water and a two-stepped biological purification with active sludge.
The used water separated from the solid matters in suspension is equalised and separated from the fats by floatation, after which the water goes into the biological treatment stage, constituted by successive treatment tanks, in two phases followed by secondary decantation.
The excessive active sludge and the sludge derived from floatation are directed into a sludge thickener, from where they are taken over and dehydrated. The purged water is discharged after passing through a sterilisation stage (optionally) and a flow rate measurement stage.
The treatment technology is adapted to the features of the used water and to the discharge requirements (into the sewerage system or into the emissary).
Treatment plants for waters derived from the textile industry
The used waters resulted from the textile industry contain solid matters in suspension in form of fibers, colouring agents, extractable substances and variable alkalinity or acidity.
The residual water treatment technology in case of the waters charged with fibers and variable pH is composed of a physical-chemical stage, a mechanical stage with filters under pressure, a pH correction stage and a biological stage with active sludge.
The treatment technology for waters containig colouring agents is composed of homogenisation, electrocoagulation, coagulation-flocculation, separation by floatation and by a secondary biological phase with active sludge.
The treated water is settled and discharged into the emissary or into the external sewerage system. The active sludge is recirculated in the biological stage.
Waste water treatment plants for waters with a reduced organic charge and waters extensively charged by suspensions (the paper industry)
The technology of treating residual waters is composed of a physical and chemical separation of the suspensions from the used water, a biological purification by active sludge, water disinfection by ozone and water recycling after a high pressure filtering stage.
The used water is pumped into the mixing tank where flocculation reactive agents are dosed, after which it enters the primary decanter where the suspensions are separated. The treated water is pumped into the biological stage and the primary sludge is pumped into the thickener. The biological stage can operate continuously, while recirculating the active ludge, or sequentially (SBR), without the recirculation of the active sludge. After the disinfection by ozone and filtering, the treated water is sent into the storing tanks, in order to be reused in the manufacturing process and the excess – in the emissary, through the flow rate measuring manhole.
Advantages : This system recovers up to 80% of the water used for the process water and the reserves in case of fire, it reduces the amounts of pollutants discharged into the emissary and the sludge form the treatment plant is dehydrated with the sludge resulted from the technological process, in plants of dehydration by means of a press-filter.