Effluent Treatment Plant (ETP) in the Dairy Industry: A Complete Guide

Introduction: Why Dairy Industry Needs ETPs

The dairy industry is one of the most water-intensive food sectors, generating large volumes of wastewater rich in organic matter, cleaning agents, and fats. Without treatment, this effluent can:

Pollute water bodies
Breach environmental regulations
Harm aquatic ecosystems

An Effluent Treatment Plant (ETP) is designed to treat and purify industrial wastewater before it’s safely discharged or reused.

A seasoned food manufacturing consultant ensures your ETP design complies with local regulations and maximizes environmental performance.

1. Characteristics of Dairy Effluent

Dairy effluents typically contain:

Detergents & sanitizers
Fats, proteins, and lactose
Acids, alkalis, and suspended solids
High BOD (Biochemical Oxygen Demand)
High COD (Chemical Oxygen Demand)

Effluent sources:

Milk spillage
Cleaning-in-place (CIP) systems
Boiler blowdown
Pasteurization losses
Equipment wash water

2. Planning Considerations for ETPs

Key factors in ETP planning:

Characterization of wastewater
Volume & flow variations
Selection of appropriate physical, chemical, and biological units
Discharge standards compliance (CPCB/FSSAI norms)

3. Stages of Dairy Effluent Treatment

A. Pre-Treatment

Screening

Removes coarse solids (plastics, rags)
Equipment: Inclined screens or bar racks (15–40 mm spacing)

Flow Equalization

Uses centrifugal pumps to balance peak loads

B. Primary Treatment (Physical)

Sedimentation & Filtration

Removes suspended solids and some BOD
Equipment: Sedimentation tank or clarifier

pH Control

Chemical dosing (e.g., NaOH, HCl) to balance acidic or alkaline pH

C. Secondary Treatment (Chemical)

Coagulation & Flocculation

Adds alum or ferric chloride to bind fine particles
Forms larger flocs for easier separation

D. Tertiary Treatment (Biological)

Aeration

Introduces air for aerobic microbial breakdown
Systems:
Activated Sludge Process (Suspended Growth)
Trickling Filter (Fixed Film)

Sludge Dewatering

Reduces moisture content of sludge
Methods: Filter press, centrifugation

4. Advanced Systems in ETPs

Dissolved Air Flotation (DAF)

Separates suspended fats, oils, and solids using microbubbles
Enhances removal efficiency before biological treatment

Double Pass Biological Treatment

Two-stage aeration for enhanced BOD/COD reduction
Ensures regulatory discharge limits are met

Automatic Brush Screening

Automates coarse screening and reduces labor costs

5. Final Disposal or Reuse

Treated water can be:
Safely discharged into municipal drains
Reused for non-potable purposes like floor washing or gardening

Sludge is disposed of via:
Composting
Incineration
Landfill (as per local guidelines)

Case Study: ETP in a Modern Dairy Plant

A leading dairy unit implemented:

Automatic screening + DAF + dual-pass biological treatment
Result:
95% BOD removal
Recovered water reused in cooling towers
Sludge composted for agricultural use

A food processing consultant coordinated the ETP installation, ensuring minimal downtime and maximum return on investment.

Conclusion: ETPs Are Crucial for Sustainable Dairy Operations

With increasing scrutiny on environmental performance, ETPs are no longer optional for food and dairy processors. They:

Ensure legal compliance
Reduce environmental footprint
Support water conservation
Improve brand image and CSR performance

For food plants, working with a qualified food industry consultant ensures:

Customized ETP design
Proper technology selection
Regulatory documentation and audit readiness

PMG Engineering Private Limited The End-to-End Engineering Company in Food Industry info@pmg.engineering | www.pmg.engineering Effluent Treatment Plant in Dairy Industry Competent People. Smarter Work Systems. Exceptional Customer Interactions. 1 PMG Engineering Private Limited The End-to-End Engineering Company in Food Industry info@pmg.engineering | www.pmg.engineering INDEX 1. Introduction 2. Treatment scheme and Mechanism of ETP 3. Case study 4. Reference Competent People. Smarter Work Systems. Exceptional Customer Interactions. 2 PMG Engineering Private Limited The End-to-End Engineering Company in Food Industry info@pmg.engineering | www.pmg.engineering 1. INTRODUCTION 1. Dairy industry is among one of the most polluting, in the food industries due to its large water consumption. 2. Effluent generated in a dairy contains highly putrescible organic constituents, which can be removed with help of an Effluent treatment plant(ETP). 3. ETP is a process designed for treating industrial wastewater for its reuse or safe disposal in the environment. In order to have proper processes in the ETP, characterization of 4. wastewater, treatability studies, and planning of proper units and processes for effluent treatment is very much necessary. Competent People. Smarter Work Systems. Exceptional Customer Interactions. 3 PMG Engineering Private Limited The End-to-End Engineering Company in Food Industry info@pmg.engineering | www.pmg.engineering Effluent generation from various unit in dairy DS-Detergents and Sanitizing Agents WW-Wash Water, ST-Steam CW-Cooling Water. 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 Typical characteristic of different dairy plant Effluent COD (mg/L) TS (mg/L) BOD (mg/L) Product ph TSS (mg/L) Sr. No 1. Milk and 5123 10250 8.34 - 5802 dairy products factory 2. Dairy effluent 1200-1800 1900-3000 7.2-8-8 900-1200 500-740 3. Whey 71,526 20000 4. Cheese whey pressed 80000- 90000 120,000- 135,000 4.1 6 56,782 22,050 - 8000- 11000 5 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 Minimal standards for discharge of effluents from the dairy plant Parameter PH BOD5 TSS OIL &Grease Total nitrogen CPCB INDIA max value (except for PH) 6.5-8.5 100 150 10 10 Competent People. Smarter Work Systems. Exceptional Customer Interactions. 6 PMG Engineering Private Limited The End-to-End Engineering Company in Food Industry info@pmg.engineering | www.pmg.engineering 2. Consideration when planning an ETP What national or international standards must you comply with? what volume of effluent do you have? What chemicals does it contain? Do you plan to increase production? How much can you afford to spend on constructing and running an ETP? Competent People. Smarter Work Systems. Exceptional Customer Interactions. 7 PMG Engineering Private Limited The End-to-End Engineering Company in Food Industry info@pmg.engineering | www.pmg.engineering How much land do you have available, or can you buy, on which to build the ETP? Which ETP expert or designer should be used? What type of plant will best suit your requirements? What capacity do you have in your factory to manage the ETP? Do you need to hire more staff or train existing staff? Competent People. Smarter Work Systems. Exceptional Customer Interactions. 8 PMG Engineering Private Limited The End-to-End Engineering Company in Food Industry info@pmg.engineering | www.pmg.engineering 3. Treatment method and mechanics of ETP Description Mechanism Treatment Method Preliminary Primary Secondary in or result and grease Removal of large solids such as rags, sticks, that may damage grit operational equipment problems settleable Removal materials such as suspended solids and organic matter Removal of biodegradable organic matter and suspended solids floating and of Tertiary/adv anced Removal of residual suspended solids / dissolved solids Physical Physical And chemical Biological and chemical Physical, chemical and Biological Competent People. Smarter Work Systems. Exceptional Customer Interactions. 9 PMG Engineering Private Limited The End-to-End Engineering Company in Food Industry info@pmg.engineering | www.pmg.engineering Typical effluent treatment scheme for dairy Industry Fat/oil Equalization tank Dissolved air flotation Biological treatment Disinfection Technology Scum Scum selection Cllection Sludge Handling system Activated Carbon Filteration Competent People. Smarter Work Systems. Exceptional Customer Interactions. Treated Effluent 10 PMG Engineering Private Limited The End-to-End Engineering Company in Food Industry info@pmg.engineering | www.pmg.engineering Physical treatment used in ETP  Screening- Screening is a wastewater pre-treatment, which aims to prevent coarse solids, such as plastics, rags and other trash, from entering a sewage system or treatment plant. Solids get trapped by inclined screens or bar racks. The spacing between the bars usually is 15 to 40 mm, depending on cleaning patterns. Flow equalization- A centrifugal pump is a mechanical device designed to move fluid by means of the transfer of rotational energy from one or more driven rotors, called impellers. Competent People. Smarter Work Systems. Exceptional Customer Interactions. 11 PMG Engineering Private Limited The End-to-End Engineering Company in Food Industry info@pmg.engineering | www.pmg.engineering Sedimentation and filtration- The flocs formed in flocculation are large enough to be removed by gravitational settling, also known as sedimentation. This is achieved in a tank referred to as the sedimentation tank, settling tank or clarifier. Sedimentation suspended to solids, to produce clarified effluent, and to thicken the sludge produced in biological treatment. remove used also and grit is  Flocculation and sedimentation should remove most of the suspended solids and a portion of the BOD. Competent People. Smarter Work Systems. Exceptional Customer Interactions. 12 PMG Engineering Private Limited The End-to-End Engineering Company in Food Industry info@pmg.engineering | www.pmg.engineering Chemical treatment used in ETP pH control- Chemical processes use the addition of chemicals to the wastewater to bring about changes in its quality. Various chemicals are used for pH control. For acidic wastes (low pH) sodium hydroxide, sodium carbonate. For alkali wastes (high pH) sulphuric acid or hydrochloric acid Is added. Chemical coagulation- it is the process of collecting into a larger mass the minute solid particles are dispersed in a liquid. Chemical coagulants such as aluminum sulfate (alum) are added to wastewater to improve the they come together and form attraction of larger particles called flocs. fine particles so that Competent People. Smarter Work Systems. Exceptional Customer Interactions. 13 PMG Engineering Private Limited The End-to-End Engineering Company in Food Industry info@pmg.engineering | www.pmg.engineering Aeration- Aeration is required in biological treatment processes to provide oxygen to the micro-organisms that break down the organic waste. Aeration is the process of adding air into wastewater to allow aerobic biodegradation of the organic materials. The principal secondary treatment techniques used are the trickling filter and the activated sludge process and are often classified as fixed-film or suspended-growth systems respectively. Competent People. Smarter Work Systems. Exceptional Customer Interactions. 14 PMG Engineering Private Limited The End-to-End Engineering Company in Food Industry info@pmg.engineering | www.pmg.engineering Biological treatment operation used in ETP Treatment Process Definition Suspended-growth processes e.g., activated sludge The micro-organisms are maintained in suspension in the liquid Attached-growth processes or fixed-film processes The micro-organisms are attached to some inert medium such as rock or inert plastics Combined processes A combination of suspended-growth and fixed-film Competent People. Smarter Work Systems. Exceptional Customer Interactions. 15 PMG Engineering Private Limited The End-to-End Engineering Company in Food Industry info@pmg.engineering | www.pmg.engineering 3. Choosing an Effluent Treatment plant Every factory that is having an ETP designed and constructed must decide on followings: 1- Type of treatment they are going to follow : • Biological Treatment • Physico -Chemical Treatment • Physico -chemical and Biological 2- Area Requirement Comparison- which mostly depends on • quality of wastewater to be treated flow rate • the type of biological treatment to be used • the orientation of different treatment units Competent People. Smarter Work Systems. Exceptional Customer Interactions. 16 PMG Engineering Private Limited The End-to-End Engineering Company in Food Industry info@pmg.engineering | www.pmg.engineering 3- Cost Comparison The installation costs of ETPs can vary greatly depending on such factors • The materials used, including the quality and source of the equipment(e.g. pumps and air blowers) • Land area • Dimensions for construction, • Quality and quantity of wastewater to be treated, • Quality of the required output Competent People. Smarter Work Systems. Exceptional Customer Interactions. 17 PMG Engineering Private Limited The End-to-End Engineering Company in Food Industry info@pmg.engineering | www.pmg.engineering 3. CASE STUDY Working of Effluent Treatment Plant with Double Pass Biological Treatment with SBR and MBR Technology 1 -Effluent from the dairy industry contains high COD, BOD which is required to be treated by double pass Biological Treatment to produce perfect quality Ultra filtered Treated water for recycling/usage. 2-The dairy effluent treatment plant follows a set of steps: a. The pH is first adjusted to 8.5 using pH controllers such as caustic or acid. Any emulsions are then broken down and solids precipitate with the help of a de-emulsifier. Competent People. Smarter Work Systems. Exceptional Customer Interactions. 18 PMG Engineering Private Limited The End-to-End Engineering Company in Food Industry info@pmg.engineering | www.pmg.engineering b. Other important steps in the treatment of dairy effluent include flocculation and dissolved air flotation. The effluent is flocculated by passing it through a slow mix zone, where the particles are gathered to form larger ones, which are then treated further using the air flotation technique. c. The dissolved air flotation technique works as follows: air flotation system bubbles are propelled by a Recycle Air Dissolving system, which blows the treated effluent, pressurizes it, and dissolves it with air. d. Finally, the sludge batch is pumped through the filter press and disposed of in accordance with environmental regulations. e. Finally, the Effluent Treatment System designed specifically for the dairy industry results in efficient resource use, lower operating costs, smooth dairy functions, compliance with environmental regulations, and peace of mind. Competent People. Smarter Work Systems. Exceptional Customer Interactions. 19 PMG Engineering Private Limited The End-to-End Engineering Company in Food Industry info@pmg.engineering | www.pmg.engineering Automatic Brush screening and collection • • In this unit Effluent is screened through an automatic Motorized Brush screen for removal of fluff and coarse impurities before feeding to DAF unit. Screened effluent after Oil and Grease Trap shall be collected in RCC collection tank. Competent People. Smarter Work Systems. Exceptional Customer Interactions. Competent People. Smarter Work Systems. Exceptional Customer Interactions. 20 PMG Engineering Private Limited The End-to-End Engineering Company in Food Industry info@pmg.engineering | www.pmg.engineering Dissolved air flotation (DAF) • DAF systems are designed to remove total suspended solids (TSS), biochemical oxygen demand (BOD), and oils and greases (O&G) from a wastewater stream. • Contaminants are removed using a dissolved air-in-water solution produced by injecting air under pressure into a recycle stream of clarified DAF effluent. • The recycle stream is then combined and mixed with incoming effluent in an internal contact chamber where the dissolved air comes out of the solution in the form of micron-sized bubbles that attach to the contaminants. • The bubbles and contaminants rise to the surface and form a floating bed of material that is removed by a surface skimmer into an internal hopper for further handling. Competent People. Smarter Work Systems. Exceptional Customer Interactions. Competent People. Smarter Work Systems. Exceptional Customer Interactions. 21 PMG Engineering Private Limited The End-to-End Engineering Company in Food Industry info@pmg.engineering | www.pmg.engineering Dissolved Air flotation system Competent People. Smarter Work Systems. Exceptional Customer Interactions. Competent People. Smarter Work Systems. Exceptional Customer Interactions. 22 PMG Engineering Private Limited The End-to-End Engineering Company in Food Industry info@pmg.engineering | www.pmg.engineering Double Pass Biological Treatment • Double Pass Biological treatment is used to get the high-quality filtered water at the final outlet. This treatment is divided into two biological treatment stages SBR technology - - MBBR technology • Sequencing Batch Reactor (SBR)–is the process of wastewater treatment that uses the activated sludge by the sequencing batch reactor plant.This technology separates the water and activated sludge through the oxygen bubbles.. Competent People. Smarter Work Systems. Exceptional Customer Interactions. Competent People. Smarter Work Systems. Exceptional Customer Interactions. 23 PMG Engineering Private Limited The End-to-End Engineering Company in Food Industry info@pmg.engineering | www.pmg.engineering • Membrane bioreactor- MBR combines conventional biological treatment (e.g. activated sludge) processes with membrane filtration to provide an advanced level of organic and suspended solids removal. • There are two different MBR configurations: (1) submerged membrane bioreactor (SMBR) and (2) side stream membrane bioreactor. • In SMBR the membrane is located inside the biological reactor, submerged in the wastewater. In latter configuration, the membrane is located outside the reactor, as an additional step after biological treatment. Competent People. Smarter Work Systems. Exceptional Customer Interactions. Competent People. Smarter Work Systems. Exceptional Customer Interactions. 24 PMG Engineering Private Limited The End-to-End Engineering Company in Food Industry info@pmg.engineering | www.pmg.engineering Double Pass Biological Treatment 1. Outlet of the DAF unit is directly transferred to the Equalization tank having diffused aeration system with fine bubble diffusers, to be operated as Biological Treatment STAGE-1. This stage reduces the COD by 50%. 2. Auto pH correction dosing unit at the inlet of biological stage-1 is there to maintain the desired pH the at Biological inlet. 3. Outlet of Biological stage -1 is pumped to Biological Stage -2, to produce ultra-filtered water. 4. MBR technology with strong heavy-duty PVDF hollow fiber membranes which are submerged in a tank connected to a biological chamber. Competent People. Smarter Work Systems. Exceptional Customer Interactions. Competent People. Smarter Work Systems. Exceptional Customer Interactions. 25 PMG Engineering Private Limited The End-to-End Engineering Company in Food Industry info@pmg.engineering | www.pmg.engineering 6. The ultra filtered clear ultra-filtered with the help of suction of permeate pumps. Thus, biological outlet passing through the membranes becomes perfect quality free from suspended impurities (TSS < 5 mg/l). 5. Moreover, since the membranes don’t allow any bacteria to pass through its fine pore, it is used to maintain high MLSS in the biological tank for perfect degradation of organic matters Competent People. Smarter Work Systems. Exceptional Customer Interactions. Competent People. Smarter Work Systems. Exceptional Customer Interactions. 26 PMG Engineering Private Limited The End-to-End Engineering Company in Food Industry info@pmg.engineering | www.pmg.engineering Sludge dewatering system • • Screw Press technology is used for dewatering of DAF and biological sludge with minimum moisture content. For the MBR technology in Biological, the generation of sludge is very less and whatever generation of sludge, will be used as manure. Competent People. Smarter Work Systems. Exceptional Customer Interactions. Competent People. Smarter Work Systems. Exceptional Customer Interactions. 27 PMG Engineering Private Limited The End-to-End Engineering Company in Food Industry info@pmg.engineering | www.pmg.engineering Sludge dewatering system • • Sludge from DAF, Biological stage 1 and 2 is collected in a Sludge pit and pumped to an Automatic screw press unit. Small dose of fine flocculant is added to flocculate the suspended sludge for better efficiency of the screw press. Competent People. Smarter Work Systems. Exceptional Customer Interactions. Competent People. Smarter Work Systems. Exceptional Customer Interactions. 28 PMG Engineering Private Limited The End-to-End Engineering Company in Food Industry info@pmg.engineering | www.pmg.engineering Reference 1. https://www.researchgate.net/publication/315435366_Wastewater_Treatment _by_Effluent_Treatment_Plants 2. https://rbnbcollege.com/wp-content/uploads/2021/12/ETP-OPERATING- MANNUAL-.pdf 3. https://web.iitd.ac.in/~arunku/files/CVL100_Y16/Lecture%201%20ETP%20Textil e_verII.pdf 4. https://assets.publishing.service.gov.uk/media/57a08c30ed915d3cfd001216/R8 161-Section7.pdf 5. https://www.netsolwater.com/what-is-effluent-treatment-plant-and-etp- working-process.php?blog=107 Competent People. Smarter Work Systems. Exceptional Customer Interactions. Competent People. Smarter Work Systems. Exceptional Customer Interactions. 29 PMG Engineering Private Limited The End-to-End Engineering Company in Food Industry info@pmg.engineering | www.pmg.engineering About PMG Engineering Competent People. Smarter Work Systems. Exceptional Customer Interactions. Competent People. Smarter Work Systems. Exceptional Customer Interactions. 30 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

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