The document summarizes Common Effluent Treatment Plants (CETPs) and Zero Liquid Discharge (ZLD) systems. CETPs allow small industrial units to collectively treat wastewater at a centralized facility, reducing treatment costs. ZLD systems completely recycle treated wastewater and convert liquid waste into solid residue, eliminating liquid discharge. Both systems aim to protect the environment while minimizing costs for pollution abatement. Key factors in designing these systems include wastewater characteristics, available treatment technologies, and regulations on wastewater discharge.

1. SUBMITTED BY
SABARINATH C D
Roll no 12
M.Tech process control

2.  Common Effluent Treatment Plant is the concept of treating effluents by means of a
collective effort mainly for a cluster of small scale industrial units. This concept is
similar to the concept of Municipal Corporation treating sewage of all the individual
houses.
 The main objective of CETP is to reduce the treatment cost for individual units while
protecting the environment.
 Reduces the cost of pollution abatement for individual factory.
 To minimize the problem of lack of technical assistance and trained personnel
 To solve the problem of lack of space as the centralized facility can be planned in
advance to ensure that adequate space is available.
 To reduce the problems of monitoring for the pollution control boards.
 To organize the disposal of treated wastes and sludge and to improve the recycling
and reuse possibilities.

3.  Site characteristics- Characteristics such as topography, soils, geology, hydrology,
climate and land use are to be considered while designing a sewer network and a
CETP
 Wastewater characteristics-Flow, Physical characteristics(Solids, Temperature,
Colour and odour), Chemical characteristics-BOD, COD
 Operates on one size fits all basis
 No separate treatment units for hazardous and toxic effluents

5. Advantages
 Strong control over quality and
quantity of effluent received at
CETP
 Effluent not conforming to inlet
norms can be sent back and extra
charges can be imposed to the
member industries.
 Tracking of effluent transpiration
though GPS system will help to stop
illegal disposal of effluent to CETP
 Very effective system to prevent
mixing of toxic and concentrate
effluent with normal effluent
Disadvantages
 Limited transportation capacity.
 Not suitable for industries having
high effluent load i.e. textile
industries.
 Problems of illegal disposal of
untreated effluent if CETP authority
fails to keep an eye on tanker
movement.
 High cost of transportation
 Risks – Spills, Leakages & pilferage .

6.  Zero Liquid Discharge (ZLD) refers to the recycling and treatment process in
which the plant discharges no liquid effluent into surface waters, completely
eliminating the environmental pollution to water bodies.
 Zero Liquid Discharge refers to installation of facilities and system which enables
industrial effluent for absolute recycling of permeate and converting solute into
residue in the solid form by adopting method of concentration an thermal
evaporation. (CPCB Draft Guidelines, January, 2015.)
 ZLD process makes effective use of wastewater treatment, recycling, an reuse,
thereby contributing to water conservation through reduced intake of fresh water.

8.  Stringent environment regulations on discharge of specific pollutants.
 Water scarcity in the area.
 Economics.
 Recovery of useful materials.
 Growing social responsibilities towards environmental issues.
 Technical guidance not available.
 Technology selection is big challenge.
 Difficulty in dealing with very complex streams.
 Need of integration of suitable technologies to achieve reduce, recycle,recovery and
reuse.

9.  Main aim of ZLD is to recover useful products, and salts from rejects, apart from
recovery of maximum water for recycle.
 Major ZLD Technologies:
• Solvent extraction / Stripper.
• Membrane Bio-Reactor Technology (MBR).
• Ultra filtration / Reverse Osmosis.
• Evaporation Technologies
• Agitated Thin Film Dryer (ATFD).
• Incinerator.

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