2.35 MLD CETP Unnao

Summary of Step-wise Treatment Methodology at 2.35 MLD Moduleof CETP-UNNAO under IIUS, DIPP:

2.35 MLD sanctioned under IIUS of DoIPP,

working as extended tertiary system added to old CETP Unnao to help achieve the leather tanning industries of this cluster of UPSIDC Industrial
area site-II of Unnao, the prescribed parameters of UPPCB in compliance to their direction 11-8-2010, 18-5-2010& 23-3-2010:

Step-wise Treatment scheme at CETP Unnao:
The wastewater would be equalized first at 4 no equalization tanks in series and pre-aeration through coarse bubble diffuser would also assist partial
oxidation of sulphide due to oxygen available from this stage of pre-aeration as the effluent depth of about 6+ meters in each tank will be a merit for
aeration through air bubbling, this will eventually reduce BD/COD also to the tune not less than 20% as observed from two operational CETPs being run by
industries at Unnao since last many years.


Estimated maximum raw effluent characteristics

Expected quality of treatment from CETP


7 to 9

7 to 8


1000 – 1800 mg/l

20 to 28


2000 – 3000 mg/l

160 to 240


2000 – 3000 mg/l

60 to 100

Total Cr

2 ppm as per CPCB norms

0.5 to 1


5000-10000 mg/l

As it is and be treated at source by tanneries

All values in mg/l except pH

Treatment Units at new module of 2.35 MLD CETP:

1-Bar screen/grit Chamber-1no.-Manual: This will segregate foreign matters/fleshing etc that escape out from tanneries effluent.

MOC—-RCC/M20 fitted with SS screen 10 mm from here effluent will pass to old equalization tank of old CETP as well as 4 nos. circular holding tanks as
per throttling arrangement of inflow line connected.

2-Equalisation cum Holding system—4 nos

HRT—12 hrs-total

MOC—1:4 (Cement: Coarse Sand) Brick work with RCC M20 raft bottom fully plastered with water tight neat plaster inside.

Equalization device:
We would attain good equalization being the main aim of this stage and in addition would also gain to some extent sulphide oxidation and at this stage with
estimated reduction of BOD/COD for about 20%. The bottom catch pits developed on the floor of each equalization tank with a gentle slope towards catch pit
will help de-sludge the heavy settled sludge once in every quarter and be pumped directly to SDBs.

3- Clariflocculation Tank (CLFT also called PST):
The effluent at this unit will be primarily treated where 30 % reduction of BOD/COD and about 80% reduction of SS is estimated.

4-Ist Stage Aeration System (Conventional Aeration Tank CAT):1 no:

Based on 24 hrs HRT under MCRT controlled operational mode we would get atleast 70% reduction of incoming load of BOD/COD/SS in this unit biologically
using the mass of heterotrophic aerobic culture.

5- 1st Stage Bio-Clarifier:
outlet from CAT will move to first stage bio-clarifier through gravity main and solids will be separated and back pumped to Aeration Tank and excess mass
of bio-solids would be discharged to Sludge Drying Beds.

6-IInd Stage Aeration System (Extended Aeration Tank EAT):1 no

The supernatant from 1st stage bio-clarifier carrying recalcitrant and left over BOD/COD reaches here again at 24 hrs HRT extension of
bio-reactor under higher mass of active sludge at about 2 ppm DO contents under MCRT controlled operational mode where we would get at least 80% reduction
of incoming load of BOD/COD/SS in this unit biologically using the mass of heterotrophic aerobic culture. This enables BOD to the tune of 20 mg/l and COD
to the tune of 200 mg/l on average flow characteristics. The young cells of bacterial mass however escape out from open launder which are settled at
tertiary clarifier ahead.

7- 2nd Stage Bio-Clarifier:
outlet from EAT will move to final 2nd stage bio-clarifier through gravity main and solids will be separated and back pumped to Aeration Tank
–II and excess mass of bio-solids would discharged to Sludge Drying Beds.

8-Tertiary Clarifier: 1 no.


HRT—3.5 + hrs

This unit equipped with a flash mixer again along with a chemical dosing arrangement will not only help induce settle the young cells escaped out from 2 nd clarifier here but also we can polish the effluent by using polishing chemicals in case of any deviations of previous characteristics due to
any reason or can continue to use chemicals for polishing as per requirement. The treated effluent from this unit will be sent to MGF and ACF for final
discharge to open channel fitted with online flow meter and a pH meter.

9- Sludge Drying Beds& Mechanical Dewatering System:
There are 16 nos. of SDBs occupying 1600 m2 area as suggested by you to deal with the sludge dewatering and drying. And the SPV would also equip mechanical
dewatering system like Decanter or Chamber Filter Press/Belt Filter Press. Also as suggested by CLRI during Apex Committee meeting on 20th Sep
2012, SPV can develop overhead SDBs too in future if required. At this stage, solids would be separated from all the wet slurries discharged from all the
primary & secondary clarifiers and about 60% dry cakes fully stabilized would be generated after sun drying/mechanical dewatering which would be
directly disposed to the Secured Landfill Facility at Banthar under same SPV.

Proposed pollution reduction of pollutants through new module of 2.35 MLD CETP:

Stage-wise prediction of performance of pollution reduction/effluent treatment at various stages of CETP:


Ist stage Biological treatment system

IInd stage Biological


Tertiary Treatment stage


Quality of treated effluent




30-40% of incoming from equalization tank

60-70% of remaining

Residual coming from physico-chemical stage

70 to 80 % reduction of remaining organic substrate that would be giving

BOD/COD/TSS within prescribed norms




COD=160-240 mg/l