SPECTEC is a provider of new generation Effluent Water Treatment Plants for various industrial applications. Process Description & Unit operations.
Dissolved Air Floatation Technique is the technique upon which this proposed effluent scheme is based on. The final parameters are achieved through the conventional activated sludge process and pressure sand filtration and activated carbon filtration.Unit operations:
- Primary Floatation
- Fat Recovery
- Chemical Conditioning
- Removal of Chemical Sludge
- Biological Oxidation by Activated Sludge Process
- Bio-Clarification / Sludge Recycle
- Up Flow Pressure Sand Filtration
- Activated Carbon Filtration
- Reuse Options
In the equalization unit, the variations in the pH and other impurities are checked and stability. The homogeneous effluent is achieved with balanced temperature rate of flow. The homogeneous effluent is pumped into the primary floatation tank, where specific quantity of acid is dosed to split the free floating and emulsified oils and fats & other colloidal impurities. The soluble and insoluble fats and oils arte separated at 3-4 pH. It could be separated promptly by injecting the dispersion water. The water with dissolved air is injected into the floatation tank, where the pressure difference causes air to come our in water as minute air bubbles, which get attached to the suspended and colloidal impurities. This way the impurities float to the surface of the floatation tank. With the help of mechanical scraper, the floated oils and greases are removed and used for making acid oil.
The acidified effluent free from fats and oils is coagulated and neutralized with common coagulants such as hydrated lime solution in flash mixer cum flocculator. Polyelectrolyte can be used for affecting complete coagulation, that combines the flocks and the rate of chemical flocks separation to achieve the maximum clarity. The chemical coagulation process can destabilize the floating, emulsified and suspended contaminants, in a way that the particles contacts and agglomerate, forming flocks that can be easily separated out of the solution. de-stabilization is accompanied by adding chemical coagulants, such as slum and lime. The chemically produced, highly charged hydrolyzed metal ions in the solution minimize the repulsive forces between the contaminant particles. With the force of repulsion suppressed, blending gently causes particles contact and forces of attraction results in the particles to stick to each other, producing progressive agglomeration coagulant for enhancing the flocculation process.
The coagulated effluents its transported from the flocculator to the primary settling tank, where chemical sludge settles at the bottom by gravity. The settled sludge is removed periodically and is de-watered using sludge drying beds. The treated water is carried forward for the further treatment. In the equalization tank, provision is made for effluent recycling and reprocessed till the required characteristics are produced before disposal. These steps reduce 70-80% of COD, BOD, suspended solids and fats and oils. After the primary treatment, secondary system is incorporated to meet the required standards. Single stage activated sludge process is incorporated, since the biological load is high. The primary treated water undergoes activated sludge process for further treatment and bringing down the parameters within the desired limits.
In the aeration tank, the primary treated effluent is aerated by surface aerators by giving enough microorganisms and nutrients. Predator prey reaction is the general biological reaction that takes place. The organic matter is supplied by the waste water and aeration furnishes the dissolved oxygen. The primary reaction is the organic matter metabolism and uptake of the dissolved oxygen by bacteria releasing the carbon dioxide and producing substantial increase in the bacterial population. The secondary reaction results from the oxygen utilized by the protozoa consuming bacteria releasing CO2 and protozoal cells. Around 85-90 % reduction is caused by this process for enhancing the flocculation process.
After the aeration, the effluents enters in the secondary settling tank and the biological sludge settles down. The settled sludge is taken out and re circulated back to the aeration tank for maintaining the biological population in the aeration tank. The excessive sludge is wasted through the sludge drying beds. The water treated is transported to the holding tank and is filtered in an up flow pressure sand filter. This filter traps further suspended solids and other impurities. The water filtered in the filter is passed through an activated carbon filter for absorbing the traces of the organic impurities to prevent color as well as odor. The final treated water is sparkling white in color with no odor. This water can be taken back for indirect cooling and processes, such as general washing, gardening, agricultural, etc.