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Wastewater Treatment in the Dairy Industry: Methods, Processes, and Zero Liquid Discharge
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Wastewater Treatment in the Dairy Industry: Methods, Processes, and Zero Liquid Discharge
By PMG Engineering Team
·
Published
January 8, 2021
Introduction: Why Wastewater Treatment Matters in Dairy Plants
The dairy industry generates significant volumes of high-strength wastewater rich in:
Fats, proteins, and sugars Detergents and sanitizers Suspended solids and organic loads (BOD/COD)
Untreated effluent can severely pollute water bodies and soil , making wastewater treatment (WTP) a legal and environmental necessity.
For sustainable operations, food consultants help design and audit wastewater treatment plants (WTPs) tailored for dairy processing.
1. Characteristics of Dairy Wastewater
These values necessitate multi-stage treatment for safe discharge or reuse.
2. Biological Treatment Methods
Activated Sludge Process (ASP) Most common treatment system in dairy plants Uses aerobic bacteria to break down organic matter Units include: Bar screen Skimming tank Equalization basin Aeration tank Secondary clarifier Sludge drying beds
Aerobic Systems Require oxygen for microbial action Types: Trickling filters Aerated lagoons Rotating Biological Contactors (RBC)
Anaerobic Systems Operate without oxygen Break down complex organics into methane and carbon dioxide Types: Anaerobic lagoon Anaerobic digester Up-flow Anaerobic Sludge Blanket (UASB) Moving Bed Biofilm Reactor (MBBR) Up-flow Blanket Filter (UBF)
These systems are ideal for high BOD/COD loads and offer biogas recovery opportunities.
3. Physio-Chemical Treatment Methods
These methods use chemicals to modify and remove suspended or dissolved solids:
⚗️ Coagulation Neutralizes charges on colloids using agents like ferric chloride or aluminum polychloride
⚛️ Flocculation Aggregates neutralized particles into larger clumps for easier removal
💧 Sedimentation Allows heavier particles to settle and separate from the liquid
These processes remove:
Suspended solids Heavy metals Part of the BOD/COD Nutrients (Nitrogen, Phosphorus)
Consultants typically integrate these processes upstream of biological treatment to reduce load.
4. Zero Liquid Discharge (ZLD) Systems
ZLD aims to eliminate all liquid waste discharge by:
Recovering clean water from effluent Extracting usable by-products (e.g., salt) Reducing final waste to manageable solids
Key ZLD Features :
Reverse osmosis units Evaporation and crystallization systems Salt recovery units High-pressure pumps and energy recovery devices
Benefits :
95–99% water recovery Environmental compliance Reduction in wastewater disposal costs
ZLD is increasingly being mandated in greenfield food plants and export-oriented dairy units .
5. Compact Modular WTP Solutions
For SMEs and remote dairy plants, compact modular units offer:
Pre-engineered plug-and-play systems Lower setup cost Rapid deployment Integration with CIP (Clean-in-Place) lines
These solutions include:
Screen chambers Equalization tanks DAF units (Dissolved Air Flotation) Combined aerobic + MBBR tanks Compact sludge drying systems
Conclusion: Future-Proofing with Efficient WTP Systems
A well-designed wastewater treatment plant ensures:
Environmental compliance Cost-efficient operations Sustainable resource use Improved CSR and public image
Food manufacturers and dairy processors must integrate WTPs early in plant design . Whether you're managing a local milk processing unit or exporting dairy ingredients, collaborating with a food processing consultant ensures:
Process flow design Equipment sizing Sludge handling ZLD feasibility Regulatory approvals
PMG Engineering Private Limited
The End-to-End Engineering Company in Food Industry
info@pmg.engineering | www.pmg.engineering
Introduction to Wastewater Treatment
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PMG Engineering Private Limited
The End-to-End Engineering Company in Food Industry
info@pmg.engineering | www.pmg.engineering
Agenda
1. Wastewater treatment
2. Treatment method
3. Zero liquid discharge
4. Conclusion
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PMG Engineering Private Limited
The End-to-End Engineering Company in Food Industry
info@pmg.engineering | www.pmg.engineering
1. Wastewater Treatment
Wastewater from dairy industries is one that
has complex characteristics and is considered
a challenge for environmental engineers in
terms of treatment as well as utilization.
A significantly large volume of waste is
generated from dairy industries and
contains a high amount of pollution
of
load,
terms
in
organic matter
suspended
are
etc.Dairy
produced mainly by cleaning process.
particularly
solids,
industry wastewater
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Competent People. Smarter Work Systems. Exceptional Customer Interactions.
PMG Engineering Private Limited
The End-to-End Engineering Company in Food Industry
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EFFLUENT CHARACTERISTIC OF DAIRY PLANT
The effluent characteristics from a typical Dairy plant are presented in Table:
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2. Treatment Method
Treatment of dairy industry wastewater requires a process that
combines mechanical, chemical, and biological treatment measures.
Screening, Grit removal, flow equalization, sedimentation or
dissolved air flotation are used to reduced suspended solid load from
dairy effluent.
Biological treatment methods are applied for Reduction of soluble
organic matter and disinfection.
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2.1 Wastewater treatment in dairy factory
The pollution load from Dairy can also be reduced with better water by using
the following biological treatment (anaerobic and aerobic).
The conventional system of treating wastewater is by Activated Sludge Process
(ASP) from various units of a dairy plant. The various units include Bar Screen,
Skimming Tank, Equalization Basin, Aeration Unit, Clarifier, and Sludge Drying
Beds.
Treatment method :
1. Anaerobic Lagoon Technique.
2. Anaerobic Digestion.
3. SBR
4. MBBR
5. Up-flow Anaerobic Sludge Blanket (UASB).
6. Up flow Blanket Filter (UBF).
7. Aerobic Bioconversion.
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PMG Engineering Private Limited
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info@pmg.engineering | www.pmg.engineering
Activated sludge process Activated sludge process
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PMG Engineering Private Limited
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2.2 Aerobic Process
• It
involves
generally
the
degradation of organic in the
presence
oxygen.
of
treatment
Conventional
sludge,
indulges
trickling
filter, and aerated
lagoons
activated
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Competent People. Smarter Work Systems. Exceptional Customer Interactions.
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The End-to-End Engineering Company in Food Industry
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Aerobes present in Biological treatment
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2.3 Anaerobic process
Anaerobic treatment is also
widely
sugar
manufacturing industry for
wastewater treatment.
used
in
It has so many disadvantage
over aerobic process which
include the lesser energy
required ,
sludge
production which indirectly
reduces sludge disposal cost.
lesser
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3. Physico-chemical method
• Physico chemical treatment involves using chemicals which can modify the
physical state of colloidal particles which helps in making them more stable and
coagulable for further treatment or filtration purposes.
• Physico-chemical
treatment involves a set of processes which may be
consecutively performed in a single unit or in separate units. These processes
are coagulation, flocculation and sedimentation.
• Coagulation process is integral to neutralizing the charges (usually negative) on
the colloid surfaces by the addition of coagulant while rapidly mixing of
the
wastewater. Ferric chloride, aluminium polychloride, are some of
commonly used coagulants.
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• Flocculation involves the grouping of previously formed flocs or clumps
during slow mixing process. This helps in flocs gaining larger volumes and
density which will eventually prepare them for sedimentation.
• Total suspended solids, biological oxygen demand (BOD), chemical oxygen
demand (COD), nutrients such as nitrogen and phosphorus, heavy metals,
can be successfully removed from wastewater in varying percentages using
Physico-chemical treatment.
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PMG Engineering Private Limited
The End-to-End Engineering Company in Food Industry
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4. Zero Liquid Discharge (ZLD)
of
The
focus
system.
from a
• Zero Liquid Discharge (ZLD) is a treatment process designed to remove all
liquid waste
to
reduce wastewater economically and produce clean water that is suitable for
reuse (irrigation), thereby saving money and being beneficial to the
environment.
Zero liquid
• Zero discharge system is meant to treat effluent water in such a manner that
discharge
water has no TDS (total dissolved solids) and is free from any impurities But
practically this is not correct since some TDS (total dissolved solid) will be
always available in wastewater after the effluent treatment process.
ZLD
is
• Therefore, the main aim is to recover usable materials such as water and salt
from effluent, and; minimize the generation of waste so that it can be safely
stored on-site without the need for discharge into the environment it can be
reused also.
Competent People. Smarter Work Systems. Exceptional Customer Interactions.
Competent People. Smarter Work Systems. Exceptional Customer Interactions.
PMG Engineering Private Limited
The End-to-End Engineering Company in Food Industry
info@pmg.engineering | www.pmg.engineering
Zero liquid discharge
Competent People. Smarter Work Systems. Exceptional Customer Interactions.
Competent People. Smarter Work Systems. Exceptional Customer Interactions.
PMG Engineering Private Limited
The End-to-End Engineering Company in Food Industry
info@pmg.engineering | www.pmg.engineering
5. Conclusion
1. The dairy industry is among the most polluting industries as it produces large
volume of wastewater that may adversely affect the environment if
discharged untreated.
2. Dairy wastewater is characterized by high COD, BOD and nutrient levels.
3. Wastewater can be treated by some Physico-chemical method and biological
oxidation methods such as trickling filters, rotating biological contactor
(RBC), and activated sludge.
4. Compact solutions Such as zero liquid discharge treats wastewater from
industrial processes and recover valuable products during recycling
operations. Materials are efficiently removed from the water, or wet
material, and reduced to solid waste that can be sold, reused, or more
efficiently disposed of.
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PMG Engineering Private Limited
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info@pmg.engineering | www.pmg.engineering
Reference
1. https://www.researchgate.net/publication/332183222_Wastewater_T
reatment_Methodologies_Review_Article
2. https://www.britannica.com/technology/wastewater-treatment
3. https://neoakruthi.com/blog/waste-water-treatment-methods.html
4. https://web.iitd.ac.in/~arunku/files/CVL100_Y16/LecSep1220.pdf
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PMG Engineering Private Limited
The End-to-End Engineering Company in Food Industry
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About PMG Engineering
Competent People. Smarter Work Systems. Exceptional Customer Interactions.
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We deliver End-to-End Engineering Design and Construction Management Projects in Food and Beverage Industry. Meeting Global Benchmarks In ENGINEERING DESIGN and PROJECT MANAGEMENT for FOOD and BEVERAGE Industry with SINGLE POINT ACCOUNTABILITY Process Engineering | Project Management | Mechanical | Electrical | Automation | Food Safety Key Clients We deliver End-to-End Engineering Design and Construction Management Projects in Food and Beverage Industry. Meeting Global Benchmarks In ENGINEERING DESIGN and PROJECT MANAGEMENT for FOOD and BEVERAGE Industry with SINGLE POINT ACCOUNTABILITY Process Engineering | Project Management | Mechanical | Electrical | Automation | Food Safety Key Clients We deliver End-to-End Engineering Design and Construction Management Projects in Food and Beverage Industry. Meeting Global Benchmarks In ENGINEERING DESIGN and PROJECT MANAGEMENT for FOOD and BEVERAGE Industry with SINGLE POINT ACCOUNTABILITY Process Engineering | Project Management | Mechanical | Electrical | Automation | Food Safety Key Clients
