Common Effluent Treatment Plants (CETP)

Common Effluent Treatment Plants (CETP): 

To minimize environmental pollution due to

the small and medium scale industries.

• Cleaner production technologies

• Waste minimization methods and centers

• Collective treatment at a centralized

facility, called as the CETP : A viable

treatment solution.

Innovative Financial Support Schemefor CETP:

• State ‐ 25%

• Central ‐ 25% matching grant

• Loans ‐ 30%

• SME ‐20% of the

project capital cost.

Advantages of CETP

• facilitates ‘economy of scale’ in waste treatment

• addresses the ‘lack of space’ issue

• homogenization of wastewater

• better hydraulic stability

• professional control

• facilitates small scale units

• eliminates multiple discharges

• recycling and reuse

• organization of treated effluent and sludge

disposal

Problems and constraints

• Consistency in operation

• lack of access to

– capital investments,

– working capitals,

– specialized technical skills,

– inconsistent effluent quality from member industries

• improper management of treatment units

• varied nature and scale of the industries, along with

the addition of industries in a haphazard manner,

without proper planning

• no provision to tackle the fluctuations in the pollution

load and quantities, at individual member industries

• no separate treatment units to deal with hazardous

and toxic effluents, etc.

Influencing factors in Planning of CETPs

• categories of effluent generating member industries

• qualitative/quantitative fluctuations of effluent

(equalization/ homogenization /modules)

• pre‐treatment requirements

• segregation of effluent streams at individual member

industry

• collection and monitoring mechanism

• treatability choice of technology and bio degradability,

interferences

• mode of disposal; and

• charging system

Qualitative/quantitative fluctuations of effluent

• Quantity of effluent

• Flow rate

• Effluent characteristics

– Physical characteristics

– Chemical characteristics

The basic principles of Waste minimization

• Avoiding or eliminating the production of

waste

can be carried out by choosing an alternative

process/ advanced technologies when designing a

production unit

• Reduction and minimization of waste within

the industry

can be achieved by considering all the processes

and activities which may lead to production of

waste

Inlet Effluent Quality Standards for CETPs (Source MoEF)Parameter and Concentration:

pH 5.5 ‐ 9.0

Temperature (oC) 45.0

Oil and grease 20.0

Cyanide (as CN) 2.0

Ammoniacal nitrogen(as N) 50.0

Phenolic compounds (as C6H5OH) 5.0

Hexavalent Chromium 2.0

Total chromium 2.0

Copper 3.0

Nickel 3.0

Zinc 15.0

Lead 1.0

Arsenic 0.2

Mercury 0.01

Cadmium 1.0

Selenium 0.05

Fluoride 15.0

Boron 2.0

Radioactive Materials

Alfa emitters, Hc/ml 10‐7

Beta emitters, Hc/ml 10‐8

Modes of disposal

• Surface water bodies

• On land for irrigation

• Marine outfall

• Public sewers

Water Treatment : 5 steps

• Segregation at source of generation.

• Preliminary treatment - It involves a number of unit processes to eliminate

undesirable characteristics of wastewater. Processes include use of screen,

grit chambers for removal of sand and large particles, communitors for

grinding of coarse solids, pre-aeration for odour control and removal of oil

and grease.

• Primary treatment- It involves removal of settable solids prior to biological

treatment. The general treatment units include: flash mixer + flocculator +

sedimentation

• Secondary treatment- It involves purification of wastewater primarily with

dissolved organic matter by microbial action. A number of processes are

available but the ones that are mainly used are anaerobic and /or aerobic

treatment methods.

• Tertiary treatment - This mainly includes physical and chemical treatment

processes that can be used after the biological treatment to meet the

treatment objectives.

Source:Dr. M. Anji Reddy

Professor of Environment

JNT University Hyderabad