kagal cetp
Effluent Treatment Scheme

In Kagal-Hatkanangle Industries area different type of small , medium and large-scale industries are located. The major part of wastewater generated is from large textile based industries. The data on waste water quality and performance of existing effluent treatment plants for similar waste water indicates that waste water is suitable for biodegradation and hence a treatment scheme based on conventional Biological Degradation of waste water was suggested. In addition to take care of incoming concentration of suspended solids physic chemical treatment followed by clarification process was include after biological treatment to meet the final discharge norms tertiary treatment having oxidation tank was also included in the treatment scheme. The brief process description is as given below.

CETP shall receive the wastewater through MIDC pipeline by gravity at one point with in CETP site.

Equalization and Physical Treatment.

The waste water shall be received in waste collection Sump (T -2) having arrangement of screen chamber (T -3)& grit removal chamber (T – 1) at CETP battery limit Provision of screen chamber and grit removal chamber will facilitate remove coarse grit , other floating foreign impurities as well as any suspended larger particles which can damage internal part of pumps and other rotating equipment. The operation and cleaning of screen is manual Since MIDC will have their own collection and pumping facility for the effluent collection and conveyance before it is reached to CETP site. It is expected that load on screen and grit chamber will be very much minimum.

From waste Water collection sump waste water is pumped using Effluent Feed Pump (P- 1 A/B/Cash ) to Equalization Tank (T-5). Operation of Effluent Feed pump will be automatic using level switch installed in waste water collection sump. Before equalization lank effluent is passed through oil and grease trap (T- ) for the removal of floating and insoluble oil and grease particles from waste oil and grease trap is a baffled wall channel where waste water is subjected to up and down flow for the removal of top floating particles at the top surface. Top separated oil and grease layer is collected from and drain pipe. From oil grease trap effluent is collected in equalization tank(T-5). For successful plant operation it is very essential to have uniform quality and quantity of effluent available to feed for treatment. Equalization tank is provided to take care of variation in effluent quality and quantity. Equalization tank is provided with 8 hours hydraulic retention time. Equalization tank will also be provided with floating type submerged mixer for complete mixing of waste water. Complete mixing will also help to avoid settlement of suspended particles in Equalization tank bottom which in long reduces tank operating condition and develop septic condition at the bottom of equalization tank.

Physico Chemical Treatment and Primary Clarification

Equalized effluent from Equalization Tank is transferred to physico Chemical Treatment Section of the CETP using effluent feed pump (P-2 A/B/C ). Physico Chemical Treatment Plant will consists of treatment of waste water using chemicals and flocculants mainly to precipitate , flocculate and coagulate part of waste water components and to remove this mass by using gravity settling in primary clarifiers. During physico chemical treatment suspended solids, precipitated dyes molecules and soluble oil particles are removed which reduces loan on biological treatment.

Effluent from Effluent feed pump 2(P-2 A/B/Cash ) is first taken to two series of flash mixers 1 & 2 (T-6 A/B) for the reaction of Effluent with lime slurry. The pH of effluent is raised in the range of 8.5 to 9.5 . Effluent from flash mixer is then taken to Flocculator (T-7), where ferrous is added to carry out flocculation and coagulation of suspended and precipitated particles. From Flocculator effluent is passed through reaction channel (T-8) where suitable polyelectrolyte shall be added to increase setting rate of flocculated and coagulated mass. Two flash mixer is series followed by flocculated and reaction channel will ensure complete reaction of time slurry with effluent to achieve desired result before effluent enters into primary clarifier from reaction channel effluent is fed to tube deck type hopper bottom primary clarifier (T-9 A/B/C ) for the separation of precipitated solids from the waste water by setting under gravity. Tube deck packing provides high surface to volume ratio for setting under gravity. Clear overflow from primary clarifier is conveyed to Aeration tank (T-10 A/B) for biological treatment. Settled sludge at the bottom of the primary clarifier is transferred to primary sludge sump (T-16).

Biological Treatment

Activated sludge process is selected for biological treatment of effluent. Here , soluble BOD is stabilized by oxidation of organic matter by microorganism. Microorganism is supplied with oxygen and nutrients (DAP and Urea) necessary of their metabolism. Oxygen required is provided by air blower (BL-A/B/C ) through non-clog type membrane diffusers to achieve higher rate of oxygen transfer efficiency . Mixed liquor overflow from aeration tank is taken in to secondary clarification process(T-11 A/B/C), for the separation of microorganism form treated wastewater under gravity. Bottom sludge from secondary clarifier is retuned back to aeration tank and recycle ration is decided based on the design MLVSS level in the aeration tank .Excess biomass is discharged through sludge handling system. Nutrient and food if required additionally shall be fed to aeration tank from respective tank. In order to achieve efficient suspension of Bio mass in identified dead packets of aeration tank

Mixed liquor from aeration tank in taken into secondary clarification process.(T-11 A/B/Cash ) for the separation of bio mass from treated water under gravity. For secondary clarification tube deck type hopper bottom lamella clarifier is proposed. Tube deck packing provides high surface to volume ratio for setting under gravity. Part of the settled biomass from the secondary clarifier shall be recycled back into aeration tank and excess bio mass shall be transferred into bio-sludge tank (T-17). Bio sludge sump is provided with air maxing to avoid depletion of DO level in bio sludge sump. Clear overflow from secondary clarifier shall be transferred in to the tertiary treatment.

Tertiary Treatment

Clear wastewater after biological treatment shall be subjected to tertiary treatment. The tertiary treatment consists of chemical oxidation, pressure sand filter and activated carbon filters. Effluents from biological treatment shall be passed through chemical oxidation tanks (T-12 A/B/Cash ), where preferably sodium hypochlorite dosing is carried out for chemical oxidation of effluent to enhance colour removal from the effluent. Provision of oxidation with Hydrogen Peroxide and pH correction with acid and alkali is also kept if fount necessary during actual treatment of waste water. Mixing in chemical oxidation tank is provided with air agitation using separate air blowers. Effluent from chemical oxidation tank is collected in intermittent storage tank (T-14) . From here effluent is further subjected to treatment through pressure sand filter (PSF-A/B/C/D/E/F) and activated carbon filter (ACF-A/B/C/D/E/F).

Pressure sand filter removes suspended solids to much lesser level and activated carbon filter provides polishing treatment for color and COD removal from the waste water so that final treated waste water meets the discharge norms specified by MPCB . Both PSF and ACF is required to provide back washing daily for cleaning of filter beds. The back washed water is diverted is taken back to waste water collection sump for further treatment.

After activated carbon filter effluent is collected in treated water storage tank (T-15) , from here effluent shall be disposed of to HRTS site of MIDC using final discharge pumps (P-9 A/B/C )

Sludge dewatering

Sludge slurry fromn bottom of primary and secondary clarifier shall be collected. In primary sludge sump and bio sludge tank respectively. Excess bio sludge is diverted to primary sludge sump. From primary sludge sunmp sludge slurry is transferred to sludge thickener (CLF-1) to increase solid content of sludge slurry. From sludge thickner bottom sludge slurry is sent to sludge drying beds for further water removal and dryibng of sludge. Overflow of thickener is fed to inlet of primary clarifier for further treatment. Leachate collected from the bottom of thickener is collected in leachate collection tank. Leachate from leachate collection tank is directly punped into flash mixed for further treatment in the plant. Dried sludge frim sludge from sludge drying bed is removed packed and then stored in sludge storage area for disposing it to the TSDF site at Ranjangaon/Taloja for secured land filling.