• To estimate design and origin of liquid waste
water from various industries.
• To know the quality requirement of various
• To know the wastewater disposal methods
and requirements of treatment plants .
To Understand the quality of water
required for various industries.
To know about the various methods
involved in disposing of liquid
To know the various manufacturing
process and design of liquid
4. Sources of water
• SURFACE WATER
• Lower in dissolved solids
• Higher in suspended solids
• Quality changes quickly with seasons and weather
• GROUND WATER
• Higher in dissolved solids and Lower in suspended
• Higher in iron and manganese
• Low in oxygen, may contain sulfide gas
• Relatively constant quality and temperature
5. WATER QUALITY
• Water quality is a complex subject, which involves physical, chemical,
hydrological and biological characteristics of water and their complex and
• user's point of view, the term "water quality" is defined as "those physical,
chemical or biological characteristics of water by which the user evaluates the
acceptability of water".
• EXAMPLE: drinking water should be pure, wholesome, and potable.
Similarly, for irrigation dissolved solids and toxicants are important, for
outdoor bathing pathogens are important and water quality is controlled
accordingly. Textiles, paper, brewing, and dozens of other industries using
water, have their specific water quality needs.
9. Whether distilled or raw water is used for boiler make-up,
chemical treatment is necessary to counteract harmful
contaminants present in raw water are inorganic sodium
carbonate and the hardness (calcium and magnesium)
Gases : oxygen, and carbon dioxide are present in feed water
Quality requirements for boilers
10. water must satisfy three main objectives:
•Continuous heat exchange
•Production of high quality steam
11. COMMON IMPURITIES FOUND IN WATER
CALCIUM CARBONATE (CaCO3)
Calcium carbonate precipitates from calcium bicarbonate, a much more
soluble form, at the boiling point of water.
But as calcium carbonate it has a measurable solubility in water of
approximately 19 PPM.
This solubility is sufficient to cause it to form scale;
the insoluble precipitate is in equilibrium with that which is in solution,
some therefore dissolving, while some comes out of solution.
In so crystallizing, it cements other free particles of matter not otherwise
scale forming, including precipitated calcium carbonate.
12. CALCIUM SULFATE (CaSO4)
Calcium sulfate precipitates forming a hard scale if the solubility at a
given temperature is exceeded.
For example, at 104oF the solubility is 1551 PPM; at 212oF the solubility is
1246 PPM; and 40 PPM at 428oF. Calcium sulfate has inverse solubility
(becomes less soluble as the temperature increases)
causing deposition problems. This negative solubility characteristic makes
it more prone to crystallize
MAGNESIUM SULFATE (MgSO4)
Magnesium Sulfate is one of the most soluble of salts, having a
solubility of 20% in cold water and 42% in boiling water. It exists only in
water of low pH.
Copper is introduced into the system by corrosion of copper piping and
copper alloys. In cooling systems this may be caused by excessive use of
water treatment, causing highly alkaline conditions.
Copper in the boiler displaces tube steel or “plates out”. This condition
frequently takes place under scale or sludge deposits and is often described
as “under deposit corrosion”. Copper deposits are a serious problem on
new high-pressure boilers.
Any oil film on internal heating surfaces is dangerous, impairing heat
transfer drastically to the extent that comparable heat retarding effects
can be likened.
Oil films therefore cause overheating of tube metal, resulting in tube
blistering and failure, or cracking of engine parts.
14. DISSOLVED GASES
Dissolved Gases are present in distilled water in the form of oxygen and
Each enters the condensate system from leaks in the vacuum side or open
exposure to the atmosphere, the atmospheric drain tank, surge tank, or
feed filter tank.
Due to chemical reactions in water, carbon dioxide can form carbonic acid
(H2Co3), lowering the pH of the condensate, making it corrosive.
Oxygen is highly corrosive causing localized pitting and attack of boiler
metal. Mechanical deaerating equipment, if installed, is designed to remove
the majority of these dissolved gases.
The pretreatment system prepares the raw water before it goes to the boiler.
It could involve several pretreatment steps, Chemical treatment helps you
avoid unwanted impurities.
· Lime-soda softening — Precipitation chemicals are added to react with
dissolved minerals and form heavy suspended particles.
· Filtration — Removes such impurities as silt, clay and some organic materials.
· Ion Exchange — Removes dissolved solids by passing the water through
natural or synthetic resins.
The Nalco Resin Rinse program has been proven to control resin fouling and
reduce operating costs. (Sodium zeolite softening, Dealkalization and
Demineralization are ion exchange processes).
18. · Reverse Osmosis(RO) — RO utilizes a "cross-flow filtration" method that has
three streams (feed, permeate and concentrate). This method uses a
pressurized feed stream that flows parallel to the membrane surface.
Nearly pure water passes through the membrane, which is the permeate,
leaving behind the ions and solids in the concentrate.
Since there is a continuous flow across the membrane surface, the
rejected particles do not accumulate and plug the membrane, but instead
are swept away by the concentrate stream.
20. What is coagulation? What is flocculation?
Coagulation is charge neutralization of finely divided or colloidal impurities.
Colloidal particles have large surface areas that keep them in suspension. In
addition, the particles have negative electrical charges, which cause them to
repel each other and resist adhering together. Coagulation requires neutralization
of the negative charges, providing an agglomeration point for other suspended
particles. Flocculation is the bridging together of the coagulated particles.
What is chemical precipitation?
In precipitation processes, the chemicals added react with dissolved minerals in
the water to produce a relatively insoluble reaction product. Precipitation
methods reduce dissolved hardness, alkalinity and, in some cases, silica. The most
common example of chemical precipitation in water treatment is lime-soda
21. What is ion exchange?
When minerals dissolve in water, they form electrically charged particles called ions.
Calcium bicarbonate, for example, forms a calcium ion with positive charges (a
cation) and a bicarbonate ion with negative charges (an anion).
Certain natural and synthetic materials have the ability to remove mineral ions from
water in exchange for others. For example, calcium and magnesium ions can be
exchanged for sodium ions by simply passing water through a cation exchange
What is the purpose of deaeration?
Before the feed water enters the boiler, oxygen must be removed. Feed water
deaeration removes dissolved oxygen by heating the water with steam in a deaerating
heater or deaerator. A steam vent transports the oxygen out of the deaerator.
There are two basic types of steam deaerators: spray and tray. In the spray deaerator,
22. WATER is important to the FOOD PROCESSING industry
because it is present in all foods.
It is extensively used in most food plants as a processing aid
and for cleaning operations.
When water is used as a food ingredient, its quality (e.g.
impurities) can affect the properties of the food, including
texture, shelf stability, appearance, aroma and flavor.
30. Waste volume Reduction
minimizing effect of industrial wastes.
1] Classification of waste,
 Conservation of wastewater,
 Changing production to decrease wastes,
 Reusing both industrial and municipal
effluents for raw water supplies.
Classification of wastes:
the unpolluted waste stream can be segregated from
the polluted, thus reducing total volume of wastewater.
31. Wastes from manufacturing processes:
e.g. waste from milk can washing, discarded plating solution,
spent wash from distilleries, etc.
b) Wastes used as cooling agents in industrial processes:
• Volume varies from industry to industry
e.g., large refinery discharges 150 MGD of waste out of which
only 5 MGD (3.33%) is process waste, remaining cooling water
with slight contamination due to small leaks, corrosion
products, and little organic matter.
c) Waste from sanitary uses:
• Range from 100 to 200L per person per day.
• Depends on size of plant, amount of waste product washed
32. Conservation of wastewater
Reducing volume of process water is conservation.
• e.g., recycling white water (water passing through wire
screen for wet chipping where paper is formed); reusing
pickling liquid in tanneries, etc.
Concentrated waste streams are treated after usefulness of
Two fold saving: water costs and wastewater treatment cost.
During water storage industries are reducing water
consumption however; after storage is over they are
consuming more water in spite of high water charges.
33. Changing production to decrease waste:
• Effective method of controlling the volume of wastes.
Difficult to convince production people to change process.
The entire unit including production and treatment of
wastewater should be considered to evaluate cost.
e.g., replacement of crome tanning with vegetable tanning.
e.g. balancing quantities of acids & alkalis used in process
in cost of chemicals for neutralization, and time.
34. Reusing both industrial and municipal effluents for raw water
Practiced in water scare area, it is popular and economical
method of conservation.
Not having social acceptance, technical problem such as high
TDS, hardness, aesthetic reluctance, negotiating contract.
35. Waste Strength Reduction
It is a second major objective for an industry.
• Reduction in strength will achieve saving in treatment
cost. (Sometimes due to limitations of hydraulic loading it
may not save cost).
The strength of waste may be reduced by
1. Process changes
2. Equipment modification
3. Segregation of wastes
4. Equalization of wastes
5. By-product recovery
36. Process change: The waste problem of industry
can be resolved by process change.
e.g. In textile finishing starch is traditionally used as
sizing agents before weaving. Replacing starch with
carboxy- methyl cellulose can considerably reduce
pollution (about 50% BOD reduction is possible).
e.g. In metal plating to reduce cyanide pollution.
• Change from copper- cyanide plating to acid-copper
• Replacing soluble oils and other short-term rust-
preservative oils by cold cleaners.
37. EQUIPMENT MODIFICATION
Changes in equipment can effect a reduction in the
strength of the waste by reducing waste- quantity.
e.g., dairy milk cans by eliminating sharp corners and also
installing drip pans to collect milk which drains from the
cans after they have been emptied.
e.g., placing traps on the discharge pipelines in poultry
plants to prevent emission of feathers and pieces of fats.
38. SEGREGATION OF WASTES:
• Segregation reduces strength of waste and difficulty of
Small volume of strong waste can be handled with methods
specific to the problem it present. (e.g. InoTech Pharma,
Bromine wastewater separation)
Segregation results in two wastes
(1) One strong with small volume.
(2) Other weaker with similar volume as non-segregated waste.
• Segregation of cooling waters from process waste will reduce
size of the final treatment plant.
• Some waste like dye can be effectively treated when
39. EQUALIZATION OF WASTES:
Holding of wastes for certain period of time to equalize when
many products using different processes are produced.
• The detention time of equalization basin will be for complete
cycle time of process.
• The effluent from equalization basin is much more consistent
in its characteristics, than separate influent to the same basin.
Stabilization of pH, BOD, SS and heavy metals can be achieved.
• Sometimes no treatment may be required after equalization,
e.g. when acidic and alkaline waste is a problem from the same
40. BY- PRODUCT RECOVERY:
• The use of waste material for by- product will reduce pollution
load and generate revenue through byproducts.
e.g. paper mills recovery of caustic soda from cooking liquors,
methane recovery, sludge digestion and drying and fertilizer, etc.
• Black strap molasses from sugar to alcohol production
• sulphite waste liquor byproduct from paper mills used as fuel,
road binder, insulating compound.
• Waste yeast from brewery as poultry food.
• Dried and evaporated butter milk from milk plant used as
chicken food.• In dairies materials collected on Oil and grease
trap soap manufacturing.
41. Addition of an acid or alkali (base) to a liquid to cause
the pH of the liquid to move towards a neutral pH of 7.0.
Excessively acidic or alkaline wastes should not be discharged without
treatment into a receiving stream. A stream is adversely affected by
low or high pH values. This adverse condition is even more critical
when sudden sludge of acids or alkalis are imposed upon the stream.
43. ACCEPTABLE METHODS OF NEUTRALIZATION:
1. Mixing wastes so that the net effect is a neutral pH.
2. Passing acid wastes through beds of limestone.
3. Mixing acid wastes with lime slurries.
4. Adding the proper proportions of concentrated solutions of caustic
soda(NaOH) or soda ash (Na2CO3)to acid wastes.
5. Adding compressed CO2 to alkaline wastes.
6. Adding sulfuric acid to alkaline wastes.
44. Process and Operation Overview
The process of neutralization involves the following:
• Collection of wastewater resulting from the regeneration of
various ion exchange systems
• Combining and mixing wastewater streams
• Measuring the pH of the combined wastewater streams
• Adjusting the pH of the wastewater so it is within
acceptable limits for discharge to drain
45. Wastewater Collection
The wastewater remaining at the conclusion of an ion exchange
resin regeneration cycle generally has an extreme pH and cannot
simply be sent to drain. Instead the wastewater is directed to a
“batch neutralization” tank.
For complete neutralization to occur in a reasonable amount of time,
the acidic and alkaline waste volumes in the batch tank must be
thoroughly mixed. There are several mixing approaches that can be
Mixing can also be achieved by blowing air into the bottom of the
neutralization tank. This method avoids the use of moving parts and
the associated maintenance concerns, but requires a suitable supply
While the wastewater is being recycled, an inline sensor
continuously monitors its pH. As the wastewater in the tank is being
mixed, the pH is checked to verify that it is within acceptable limits
for discharge. If the pH of the batch is acceptable, the water is sent
46. Components of a pH Neutralization System:
A basic pH neutralization system consists of six basic
1. Instrumentation for monitoring, controlling, and
2. pH electrodes and/or ORP sensors and associated
3. Effluent holding tank
4. Level control
4. Chemical pumps and reagent storage tanks
47. Importance Of pH
1. Lab Analyses
2. Corrosion Control
3. Cyanide Treatment
4. Precipitation Processes
5. Biological Systems
Proportioning means the discharge of industrial wastes in proportion to
the flow of municipal sewage in the sewers or to the stream flow in the
In most case it is possible to combine equalization and proportion in the
The effluent from the equalization basin is metered into the sewer or
stream according to a predetermined schedule.
The objective of proportioning in sewers is to keep constant the
percentage of industrial wastes to domestic sewage flow entering the
municipal sewage plant.
50. FEASIBILITY OF COMBINED TREATMENT OF INDUSTRIAL WASTES WITH
1 It is often possible & advisable for an industry to discharge its waste
water directly into a municipal sewage treatment plant, where a certain
portion of the pollution can be removed.
2 ,A municipal sewage plant, if designed & operated properly can be
handle almost any type & quantity of industrial waste. Hence one
possibility that should be seriously considered is the co operation of
industry & municipality in the joint construction and operation of a
municipal waste water treatment plant.
51. 3. Since the operator of such a large treatment plant usually receives
higher pay than separate domestic plant operators, better trained
people are available.
4. Even if identical equipment is required construction costs are less for a
single plant than for 2 or more. Furthermore, municipalities can apply for
state & or federal aid for plant construction, which private industry is not
eligible to receive.
5. The land required for plant construction & for disposal of waste
products is obtained more easily by the municipality.
6. Operating costs are lower, since more waste is treated at a lower rate
per unit of volume.
7. Possible cost advantages resulting from lower municipal financing cost
& federal grants.
52. 8. Some wastes may add valuable nutrient for biological activity
to counter act other industrial wastes that are nutrient deficient.
Thus bacteria in the sewage are added to organic industrial
wastes as seeding material. These microorganisms are vital to
biological treatment. Also, acids from 1 industry may help to
neutralization alkaline wastes from another industry.
9. The treatment of all waste water generated in the community
in a municipal plant, enables the municipality to assure a uniform
level of treatment to all the users of the river & even to increase
the degree of treatment given to all waste water to the
maximum level obtainable with technological advance.
53. THERE ARE MANY ADVANTAGES TO BE GAINED FROM SUCH A JOINT VENTURE:-
1. Here the responsibility is placed with one owner, while at the same
time, the cooperative spirit between industry & municipality increases,
particularly if the division of costs is mutually satisfactory.
2. Only one chief operator is required, whose sole obligation is the
management of the treatment plant i.e. he is not burden by the
miscellaneous duties often given to the industrial employee in charge
of waste disposal & the chances of mismanagement and neglect which
may result if industrial production men operate waste treatment plants,
54. THIS PROCEDURE HAS SEVERAL PURPOSES:
1. To protect municipal sewage treatment using chemicals from
being impaired by a sudden overdose of chemicals contained in the
2. To protect biological treatment devices from strong loads of
industrial wastes which may inactivate the bacteria
3. To minimize fluctuations of sanitary standards in the treated
4. The rate of flow of industrial waste varies from instant to instant,
as does the flow of domestic sewage system. Therefore the
industrial waste must be equalized and retained, then proportioned
to the sewer or stream according to the volume of domestic sewage
or stream flow