The document discusses current industrial wastewater treatment processes in the dairy industry. It begins with an overview of dairy operations and the types of wastes generated. It then describes various treatment steps including pretreatment, primary treatment using screens and settling tanks, and secondary biological treatment using activated sludge or oxidation ponds. Tertiary treatment may include coagulation, filtration and disinfection. The document also discusses some modifications to treatment processes like using membranes or organo-zeolites and issues around dairy wastewater treatment.

1. Current industrial wastewater treatment processes
Dairy Industries
Department of Microbiology 19/9/2014

2. What is Dairy
Industry??

3. Operations in a Dairy
Basic process of raw milk.
• Receiving
• Pasteurizing.
Various manufactures
• Bottling
• Condensing
• Dry milk manufacture
• Cheese manufacture
• Butter making
• Casein making

4. Flow Diagram of the Dairy Wastewater
treatment plant

5. Dairy wastes are made up of:
1. Milk solids
• BOD of 1kg of Milk Fat- 0.89kg
• BOD of 1kg of Milk Proteins- 1.03kg
• BOD of 1kg of Milk Sugar-0.69kg
2. Dilutions of Whole milk and by-products
• BOD of Whole milk-90,000-1,05,000mg/l
• BOD of Skim milk-65000-75000mg/l
• BOD of Buttermilk-55,000-65,000mg/l
• BOD ofWhey-25,000-35,000mg/l.

6. 3. Wastewater from : Equipment cleaning.
Tanker washings
Floor washing
Water softening
Boiler house
Refrigeration plant
4. Chemicals and Detergents.
5. Broken glass pieces ,Torn bags and Aluminium foil.

7. Pollution characteristics and conventional
treatment plant

8. Pre-Treatments:
Flow equalization
Oil and grease removal
Treatment:
1. Non Mechanized Methods
Aerobic ponds, Aerobic oxidation ponds, and combination of these two.
2. Mechanized Methods
Trickling filters, aerated lagoons, activated sludge processes.

9. Essential steps in reducing the pollution load in the
dairy include:
1. Allowing the cans and tankers to be emptied completely by keeping them in
inverted position till almost all the milk is drained out.
2. Minimizing spillage and leakage in the bottling section.
3. Attending to leaks in pipes, valves and equipments promptly.
4. Observing good housekeeping practices.
5. Using minimum amount of water for cleaning operations.
6. Segregation of clean streams, recycling of water with or without treatment
to reduce the volume of wastewater.

10. Characteristics of wastewater generated in dairies
• These effluents have the following characteristics-
1. Biochemical oxygen demand (BOD)-0.8 to 2.5 kilograms per metric ton
(kg/t) of milk in the untreated effluent.
2.Chemical oxygen demand (COD)-1.5 times the BOD level.
3. Total suspended solids (TSS)-100–1,000 milligrams per litre (mg/l)
Total dissolved solids (TDS):
•Phosphorus (10–100 mg/l),
•Nitrogen (about 6% of the BOD level).
4. The wastewater may contain pathogens from contaminated materials or
production processes.
5. A dairy often generates odours and, in some cases, dust, which need to be
controlled.

12. Wastewater treatment processes in dairies
•The dairy industry generate on an average 2.5- 3.0 litres of wastewater per
litre of milk processed
•The effluents are generated from milk processing through milk spillage,
drippings, washing of cans, tankers bottles, utensil, and equipment’s and
floors.
•Process in the treatment of industrial effluent may consist of any one or
more of the following processes:
1. Equalization
2. Neutralization
3. Physical Treatment
4. Biological Treatment

13. The dairy is a multiproduct factory and its wastewater treatment
process is based on five steps:
• screening
• sand trap/oil and grease separation in a tank;
• flow equalization in a tank;
• an activated sludge process
• tertiary treatment in three facultative lagoons.

15. •Biological treatment
1. activated sludge
2. trickling filter
3. oxidation ponds
4. A disinfection step is usually included at the end of the
biological treatment- i.e chlorination

16. Activated sludge process – most common
• Primary wastewater mixed with bacteria-rich (activated) sludge and air
or oxygen is pumped into the mixture.
• Promotes bacterial growth and decomposition of organic matter
• Last step is a settling tank where sludge settles out and then the
treated wastewater moves on for tertiary treatment
• Some settled sludge is used to inoculate incoming primary effluent
• BOD removal is approximately 85%
• Microbial removal by activated sludge-
80-99% removal of bacteria (sunlight, temperature, antagonistic
microorganisms, predation by ciliated protozoans, competition from
other bacteria, adsorption to sludge solids) 90-99% removal of viruses
(mostly through solids settling, but also bacterial antiviral products
and predation)

17. Stabilization or oxidation ponds
 Oxidation ponds are a few meters deep, and up to a hectare in size.
They are low cost with retention times of 1 to 4 weeks.
 Types: Aerobic, Aerated, Anaerobic
 Odor and mosquitoes can be a problem
 Pathogen removal:
- Bacteria, 90-99%
- Virus, 90-99%
- Protozoa, 67-99%
 Mechanisms include the long detention time (natural die-off), high pH
(10-10.5) generated by photosynthesis, predation, sunlight,
temperature
 Stabilization ponds are the preferred wastewater treatment process in
developing countries due to low cost, low maintenance. This is
balanced by larger land requirement.

18. Secondary treatment – Trickling filters
• Trickling filters are beds of stones or corrugated plastic. The primary
wastewater is sprayed over the filter and microbes decompose
organic material aerobically.
• Low pathogen removal
- Bacteria, 20-90%
- Viruses, 50-90%
- Giardia cysts, 70-90%

19. Tertiary treatment
Tertiary treatment involves a series of additional steps to further
reduce organics, turbidity, N, P, metals and pathogens. This is for
wastewater that may impact recreational areas, will be used for
irrigation, or will be used for drinking water.
Physicochemical process
 Coagulation
 Filtration
 Activated carbon adsorption of organics
 Disinfection

22. MODIFICATIONS

23. Adaptability of Membranes
• Membranes produce a higher quality effluent than achieved using conventional filtration (sand
filtration) as a final polishing step in dairy industry.
• The membrane process replaces secondary clarifiers.
• Membranes are immersed directly in the bioreactor and operate at high levels of MLVSS (12,000-
15,000 ppm).
• This treatment process allows for long sludge retention times (up to 75 days), decreasing sludge
production up to 70%.
• Membranes are capable of being used with chemical treatment (phosphorus precipitation).
• The membranes form a physical barrier that prevents the passage of biomass and other impurities

24. • The Membrane process offers the ideal solution for wastewater reuse applications,
producing high quality effluent suitable for direct reuse in a single step process.
Conducting membranes
• Development of electrically conducting membranes, will control fouling and separation
properties in the treatment of industrial effluent by adjusting surface charge.

25. Use of organo-zeolites
• Zeolites are microporous, aluminosilicate minerals commonly used as commercial adsorbents and catalysts.
• The adsorbent was formed using granular organo-zeolite.
• The initial used material was Zeolite tuff which is then modified by using quaternary ammonium salt stearin-
dimethyl-benzyl ammonium chloride (SDBAC).
• Superficial modification of zeolites, by means of organic modifiers, allows partial neutralization of the negative
charge of the external surface of zeolite minerals.
• This process produces organo-zeolite, an adsorbent with increased potential for anion adsorption and
simultaneous adsorption of some cationic and organic contaminants.

26. • Zeolites have been introduced to the process purification of dairy wastewater due their large
specific surface area and the selective adsorption of substances, such as ammonia, dissolved
organic matter and many other cations
• Moreover, zeolites have advantageous hydraulic properties, i.e the filtration capacity for large
quantities of water.
• Function of organo zeolite
I. Water softening
II. Removal of phosphate, ammonia, nitrogen
III. Removal of dissolved organic matter and color.
IV.Removal of heavy metals
V. Removal of radioactive substances

27. Electrocoagulation
• Electrocoagulation is an electrochemical technique that consists of the generation of coagulants in
situ by dissolving electrically through either aluminum or iron ions from electrodes.
• The metal ion generation occurs at the anode, when the hydrogen gas is released from the
cathode.
• The hydrogen gas assists in floating the flocculated particles to the surface.
• The dissolved metal ions, at an appropriate pH, can form wide variations of coagulated species
and metal hydroxides which destabilize and aggregate the suspended particles or precipitate and
adsorb dissolved contaminants

28. The Upflow Anaerobic Sludge Blanket (UASB)
• In this process the use of primary treatment and the filter bed is completely eliminated.
• UASB is a hybrid type of reactor, involving both suspended and attached growth
• The wastewater flows upward through a sludge blanket composed of biologically formed
granules or particles.
• Treatment produced under anaerobic conditions (principally Methane and carbon
dioxide) cause internal circulation, which helps in the formation and maintenance of the
biological granules.

29. • Some of the gas produced within the sludge blanket becomes attached to the
biological granules.
• The free gas and the particles with the attached gas rise to the top of the reactor.
• Thus treating under anaerobic condition gives out geese which are collected to
the dome shaped structure and the waste water is collected in the side way
hoods.

30. Modifications in Filtration
Microfiltration:
• It is a low pressure driven fitration process.
• The membrane is with a open structure allowing dissolved components to pass through and non
dissolved components are rejected by membrane.
• Used in bacteria reduction and fat removal
Ultrafiltration:
• It is a medium pressure driven filtration process.
• The membrane is with a open structure allowing dissolved components to pass through and non
dissolved components and large components are rejected by membrane.
• Use in decalcification of permeases and lactose reduction of milk

31. Nanofiltration :
• Medium or high pressure driven membrane filtration process
• Allows monovalent ions to pass through
• Used in partial demineralization of whey and lactose free milk.
Reverse osmosis:
• It is a high pressure driven membrane filtration process
• It is a dense membrane through which only water can pass
• Used for concentration or volume reduction of milk and whey,milk solids recovery and water
reclamation

33. Problems in Dairy Waste Water Treatment:
Disposal of salty whey in the dairy
industry.
1. Biomethanation of a Mixture of Salty Cheese Whey and Poultry
Waste or Cattle Dung.
2. Treatment of Dairy Industry Wastewater by Reverse Osmosis for
Water Reuse.
3. Anaerobic Filter Reactor Performance for the Treatment of Complex
Dairy Wastewater at Industrial Scale.
4. Influence of the Content in Fats and Proteins on the Anaerobic
Biodegradability of Dairy Wastewaters.

34. 5. Influence of Filtration Conditions on the Performance of
Nanofiltration and Reverse Osmosis Membranes in Dairy
Wastewater Treatment .
6. Anaerobic Treatment of Dairy Wastewaters.
7. Electrochemical Technologies in Wastewater Treatment.
8. Hydrolytic Enzymes as Co-adjuvant in the Anaerobic
Treatment of Dairy Wastewaters.
9. Effect of Enzymatic Hydrolysis on Anaerobic Treatment of
Dairy Wastewater .

35. Pollution Prevention and Control
• Reduction of product losses by better production control.
• Use of disposable packaging (or bulk dispensing of milk) instead of
bottles where feasible.
• Collection of waste product for use in lower grade products such as
animal feed where this is feasible without exceeding cattle feed
quality limits.
• Optimization of use of water and cleaning chemicals; recirculation
of cooling waters.
• Segregation of effluents from sanitary installations, processing, and
cooling (including condensation) systems; this facilitates recycling
of wastewater.
• Use of condensates instead of fresh water for cleaning.

36. • Recovery of energy by using heat exchangers for cooling and
condensing.
• Use of high-pressure nozzles to minimize water usage.
• Avoidance of the use of phosphorus-based cleaning agents.
• Odour problems can usually be prevented with good hygiene and
storage practices.
• Chlorinated fluorocarbons should not be used in the refrigeration
system.