Treat the Process Condensate + Spent Lees + Blow down water from Boiler & Turbine from the plant to reuse as make-up water in Cooling Tower.
Process Description - The proposed wastewater treatment plant shall consist of following treatment units.
Lime Preparation Tank
A lime preparation tank constructed in RCC. In this tank is used for lime solution preparation and continuous mixing of lime. Lime solution is then feed to equalization tank for pH correction in a required proportion. 1 HP agitator shall be provided for mixing in the tank content.
Equalization tank constructed in RCC Lined lagoon. In equalization tank the raw effluent is collected and equalized for adequate time. The tank content will then be pumped to UASB Reactor for first stage biological treatment. 5 HP Floating mixer shall be provided for mixing in the tank content.
Up flow Anaerobic Sludge Blanket reactor is provided for anaerobic treatment of dairy effluent. The UASB reactor shall be constructed in RCC M-25. The reactor consists of three zones viz. Influent distribution zone, Reaction zone, Gas solid liquid separation zone.
Influent Distribution zone
The raw wastewater enters into the at the bottom through influent distribution zone. A sophisticatedly designed piping net work is provided for uniform distribution of the effluent in the tank. The effluent then travels upward in the reactor.
In the reaction zone the anaerobic bacteria are maintained in the form of sludge blanket. The organic matter in the wastewater comes in contact with the bacterial population and is degraded anaerobically to methane rich biogas, the end product of 5 anaerobic digestion. The process of conversion of organic matter in to the biogas is a two-stage process. In the first stage the organic matter in the raw effluent is converted in to the volatile acids by acid forming bacteria. In the second stage the acid produced in the first stage are converted in to methane by another group of bacteria i.e. methane formers. In UASB process both the stages are completed in single reactor. The biogas so produced is bubbled through the effluent and is separated out in the third section i.e. Gas-Solid-Liquid separation zone. The suspended solids are also separated to prevent escape of solids from the reactor.
Gas-Solid – Liquid Separation
In gas solid liquid separation a hood fabricated in M S and duly painted with corrosion resistant paint is provided. The hood separates the solid from the overflowing reactor content. Gas collectors are provided for collection and conveyance of gas. The treated effluent overflows through a launder and will take to a secondary treatment.
Conventional Aeration tank
The partially treated effluent from UASB shall then be subject to activated sludge process for further reduction of organic matter. Aeration tanks are provided for degradation of organic matter through biological process. Microorganism in the controlled environment carries out the biodegradation process. The container i.e. aeration tank of requisite capacity is provided for this purpose. The tank shall be provided with an aeration mechanism to transfer the oxygen from air to tank content for survival for microorganisms. Diffusers and Aerators are most commonly used for this purpose. The content in the aeration tank is kept under constant aeration and mixing. The aeration thank shall be constructed in RCC and shall be provided with Air Blowers and diffuser for this purpose.
Lamella Clarifier - I
A secondary Clarifier in the form of circular tank shall be provided for settlement of fully aerated Effluent from the aeration tank. The tank shall be provided with PVC lamella plates. Part of the settled sludge at the bottom of the settling tank will be pumped to the aeration tank and part of it will be discharged on sludge drying beds as per operational requirement. This sludge being fully mineralized is suitable for sun drying on sand drying beds.
The effluent coming from lamella clarifier may have certain amount of husk & unwanted suspended materials. If not removed this suspended material may damage the equipments provided down the line & further process. This material is made settable with the help of alum dosed in flash mixer.
The water from flash mixer is then taken to the Flocculator where the suspended material will be converted in flocs using Flocculator mechanism and transferred to the lamella clarifier - II.
Lamella Clarifier - II
A secondary Clarifier in the form of circular tank shall be provided for settlement of flocculated Effluent from the Flocculator. The tank shall be provided with lamella PVC plates. Part of the settled sludge at the bottom of the settling tank will be pumped to the Aeration Tank and part of it will be discharged on sludge drying beds as per operational requirement. This sludge being fully mineralized is suitable for sun drying on sand drying beds.
Sludge Drying Beds
In aeration system the sludge is sufficiently mineralized and does not need any further treatment before dewatering and disposal. Sand filtration drying beds will be provided.