Zero liquid discharge (ZLD) is a wastewater management technique that eliminates liquid waste discharge going outside of operating plants. This has attracted renewed interest worldwide in recent years.

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Zero Liquid Discharge
• Zero liquid discharge (ZLD) is a wastewater management technique that eliminates liquid waste
discharge going outside of operating plants. This has attracted renewed interest worldwide in
recent years. The concept of establishment of ZLD may be good but it cannot be generalized and
implemented hastily and uniformly over the entire country as it emits more carbon leading to global
warming and generate huge amount of hazardous solid waste occupying more landfill land. Further
ZLD also requires high operation and maintenance cost for its execution and running. In this paper,
we have done comparative techno-economic feasibility study for 2.5 MLD capacity effluent
treatment plant (ETP) to meet the standard discharge norms and to meet ZLD norms based on
environmental parameters considering power consumption, CO2 emission, solid waste generation
& chemical consumption and economic parameters considering capital expenditure & operational
expenditure.

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METHODOLOGY
Wastewater quantity, characteristics & treatment scheme are described below
WASTEWATER QUANTITY & CHARACTERISTICS
The wastewater treatment plant capacity considered in this case is 2.5 MLD. The untreated
wastewater characteristics and treated wastewater characteristics
are shown in the table below.

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METHODOLOGY
EFFLUENT TREATMENT SCHEME TO MEET STANDARD DISCHARGE NORMS
The effluent treatment scheme to meet standard discharge norms is described below
A. Primary Treatment: The primary treatment consists of screening, equalization,
neutralization, coagulation, flash mixing, flocculation and primary clarification for removal of
suspended particles and some organic impurities.
B. Secondary Treatment: The secondary treatment consists of activated sludge process
where effluent will be received after primary treatment. In secondary treatment biological
process take place for removal of organic impurities and further secondary clarification for
solid impurities removal.
C. Sludge Dewatering: The Sludge dewatering technology will be implemented for
removal of moisture / excess water from sludge and collected water will be sent to
equalization tank for further treatment. The dried Cake sludge will be sent to authorized
land filling site for disposal. The treated effluent discharged into Sea/Estuary directly or by
CETP meeting the standard discharge norms. The effluent treatment scheme to meet
standard discharge norms is given in Figure 1

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METHODOLOGY

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METHODOLOGY
EFFLUENT TREATMENT SCHEME TO MEET ZERO LIQUID DISCHARGE NORMS
The effluent treatment scheme to meet zero liquid discharge norms is described below:
A. Primary Treatment: The primary treatment consists of screening, equalization,
neutralization, coagulation, flash mixing, flocculation and primary clarification for removal of
suspended particles and some organic impurities.
B. Secondary Treatment: The secondary treatment consists of activated sludge process
where effluent will be received after primary treatment. In secondary treatment biological
process occurred for removal of organic impurities and further secondary clarification for
solid impurities removal
C. Sludge Dewatering: The Sludge dewatering technology will be implemented for
removal of moisture / excess water from sludge and collected water will be sent to
equalization tank for further treatment. The dried Cake sludge will be sent to authorized
land filling site for disposal

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METHODOLOGY
EFFLUENT TREATMENT SCHEME TO MEET ZERO LIQUID DISCHARGE NORMS
The effluent treatment scheme to meet zero liquid discharge norms is described below:
D. Tertiary Treatment: The tertiary treatment consists of removal of residual organic, TSS
& backwash water by Tertiary clarifier, Filter Media and further treatment by UF & RO for
maximum wastewater recycling then RO reject will be sent to MEE and further ATFD to
achieve the Zero Liquid Discharge norms. Condensate from both MEE & ATFD will be sent
to Tertiary clarifier tank. RO permeate will be used in Cooling tower & other Process. The
dried Salt solid waste will be sent to authorized land filling site for disposal. The effluent
treatment scheme to meet ZLD norms is given in Figure 2

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METHODOLOGY

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RESULTS AND DISCUSSION
Techno-Economic feasibility study of zero liquid discharge plant has been done based on
following parameters
Environmental Parameters : Under environmental parameters we have considered
power consumption, CO2 emission, solid waste generation and chemical consumption
Economic Parameters : Under economic parameters we have considered capital
expenditure and operational expenditure.
The results of our techno-economic evaluation to meet discharge norms and to meet ZLD
norms are tabulated under Table 2

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Summary and Conclusions
Zero Liquid Discharge is not an environmental friendly technique specially in costal area
due to following reasons
4 times higher power consumption in ZLD 4 times higher CO2 emission in ZLD.

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Summary and Conclusions
Zero Liquid Discharge is not an environmental friendly technique specially in costal area
due to following reasons
2 times higher waste generation in ZLD. 2 times higher chemical consumption in ZLD

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Summary and Conclusions
Zero Liquid Discharge is not an environmental friendly technique specially in costal area
due to following reasons
2.5 times higher capital cost in ZLD 3 times higher operating cost in ZLD
UPL as a company suggest, it is good to follow the zero liquid discharge technology only when it is necessary

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ABOUT THE AUTHOR
DR. MRITUNJAY CHAUBEY is sustainability, environment & water technology expert of
international repute. He has done Ph.D. in environmental engineering from Indian Institute
of Technology (IIT) Delhi. He has nearly 23- years of professional working experience in
renowned MNCs Pentair, Shell, Unilever & UPL in field of sustainability, environmental
engineering, water & wastewater treatment. Currently more than 100 environmental
protection technologies are successfully working in Asia, Africa, Europe and America
designed by him. More than 50 technical papers has been published in renowned
international journals & conferences with his name. Dr. Chaubey is currently working as
Global Vice President – Environment, Sustainability & Green Cell with UPL Limited.
Recently Dr. Chaubey is awarded with “Most Influential Sustainability Leader Award” and
“CSO of the Year Award”.

14. Courtesy:https://www.upl-ltd.com/
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