Waste Management K. Pathak

7/31/2019 Waste Management K. Pathak

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Waste Minimization

and

Cleaner Production

Prof. K. Pathak

Mining Engineering Department

IIT KHARAGPUR


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Waste minimization and cleaner production

Waste is generated by activities in all economic sectors and is generally regarded

as an unavoidable by-product of economic activity

Waste is generated from:

inefficient production processes,

low durability of goods and

unsustainable consumption patterns

Waste Generation is associated with:

1. Energy loss

2. Economic loss

3. Environmental degradation

4. Health hazards

5. Opportunity loss

6. Extra expenses on cleaning


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Waste Flow


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Per Capita Waste Generation by countries

The collection of municipal waste varies considerably between countries and

lies in the range of 685 kg/capita (Iceland) to 105 kg/capita (Uzbekistan).

More developed more Waste generation


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Can you identify and discuss waste generation and waste flows in

the following sector?

1. Agriculture

2. Food Processing

3. Chemical Plants

4. Manufacturing industry (Approximately 740 million tonnes of waste aregenerated by the manufacturing industry in Europe every year.)

5. Mining

6. Mineral beneficiation

7. Metallurgical Plant

8. Household and Municipalities

9. Construction and demolishing

Waste Classification:

1. Liquid Waste- Waste water

2. Solid waste-non hazardous and hazardous; also called refuse.1. Garbage : animal and plant residue

2. Rubbish: combustible portion (trash) and non-combustible portion of solid waste

3. Construction and demolition wastes-rubbles

3. Nuclear waste

4. Gaseous waste


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Solid Waste Characteristics

1. Rate of generation

2. Physical characteristics: components, moisture content, density (compaction

ratio, Compaction ratio= compacted density/as-discarded density)

3. Chemical Characteristics : proximate and ultimate analysis (components ofatomic elements)

4. Energy Content

Total Vol= 1.332 m3Density = 100/1.332=75.08 kg/m3 Compacted density =2.5x75.08=187.68 kg/m3

Volume of the vehicle= 1000/187.68 =5.32 m3


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Higher heat of combustion of solid waste is calculated by Dulongs Formula:

Hh= 32,851C+141989(H-O/8)+9263 S KJ/kg


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Industrial Use of Water leads to production of waste water or contaminated water.

Food Processing waste Water: Contaminants in the sewer include

loose meat,

blood,

soluble protein,

inorganic particles,

food waste

Most of this waste adds a high level of biochemical oxygen demand (BOD5) to the

wastewater. Higher the BOD5 level demands more wastewater treatment (andinvestment)

Technical Solution Needed: To reduce Waste production

Provide education on water use and waste load;

Survey the plant for problem areas:

determine where water is used and where wastes are generated, find

how to capture all nonliquid waste and prevent it from entering the wastewater

Evaluate plant processes: find if insufficient waste collection equipment, leaks in some machinery, worn-outequipment and lines;

Promote the use of dry cleanup;

Provide for waste recovery and utilization: identify market for wastes;

Enhance waste pretreatment: grease trap, solids recovery basin, and an activated sludge system with

provisions for pH control.


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Grease Trap:

A grease trap, sometimes called a grease interceptor, is a piece of restaurant equipment which is required

in many regions to keep the sewers functional.

The grease trap acts as a filter to remove fats and oils from water before it enters the municipal waste

system. Since fats and oils can clog a sewer system, the use of a grease trap ensures that the sewer system

runs smoothly.

In a commercial kitchen, a grease trap treats all of the water coming out of the kitchen.

A grease trap looks like a large box or barrel spliced into the water drainage line. When the water enters

the grease trap, it cools down, allowing the lighter oil to precipitate out to the top. A series of baffles in the

grease trap collect oil and chunks of material while the water sinks to the bottom. An exit pipe at the base

of the grease trap allows the treated water to flow out, while the grease remains enclosed on top.

In order to function properly, a grease trap and its lines must be regularly cleaned and maintained. Staffcan empty the grease trap by hand, or a company may be hired to pump out the grease trap. Some grease

traps use automatic systems to skim out the grease and dump it into a container, but these grease traps

still need to be periodically broken down and cleaned. All of the baffles of a grease trap should be

scrubbed, and the drainage lines should be scoured to remove accumulated grease.


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A grease trap is a tank that waste water enters where solids and greases collect. The water

continues to flow out of the other side of the trap and into the sewer system, successfully

leaving the grease behind within the trap.


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Oil Water Separator

The design of the separator is based on the specific gravity difference between the oil and the wastewater because

that difference is much smaller than the specific gravity difference between the suspended solids and water. Based

on that design criterion, most of the suspended solids will settle to the bottom of the separator as a sediment layer,

the oil will rise to top of the separator, and the wastewater will be the middle layer between the oil on top and the

solids on the bottom.

A typical gravimetric API separator

A typical parallel plate separator
http://en.wikipedia.org/wiki/Specific_gravityhttp://en.wikipedia.org/wiki/Specific_gravity


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Activated Sludge

In a sewage (or industrial wastewater) treatment plant, the activated sludge process can

be used for one or several of the following purposes: oxidizing carbonaceous matter: biological matter.

oxidizing nitrogeneous matter: mainly ammonium and nitrogen in biological

materials.

removing phosphate.

driving off entrained gases carbon dioxide, ammonia, nitrogen, etc.

generating a biological floc that is easy to settle.

generating a liquor that is low in dissolved or suspended material.

Activated sludge is a biochemical process for treating sewage

and industrial wastewater that uses air (or oxygen) and

microorganisms to biologically oxidize organic pollutants,

producing a waste sludge (or floc) containing the oxidizedmaterial. In general, an activated sludge process includes:

An aeration tank where air (or oxygen) is injected and

thoroughly mixed into the wastewater.

A settling tank (usually referred to as a "clarifier" or "settler")

to allow the waste sludge to settle. Part of the waste sludge is

recycled to the aeration tank and the remaining waste sludge

is removed for further treatment and ultimate disposal.


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Why are grease traps required and why do they need to be serviced regularly?

Grease traps are required in most areas to prevent fats, oils, and greases (FOG) from flowing

into a city's sewer system. FOG can hinder the sewage treatment process and cause

environmental downfalls. Without regular service, a grease trap will eventually reach

capacity and allow FOG to enter the sewer system. An improperly maintained trap often

causes line blockages, overflows, odors, and costly emergency services. All grease traps will

clog without regular maintenance.


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Iron and steel industry

The production of iron from its ores involves powerful reduction reactions in blast furnaces.

Water is used for cooling.

Cooling waters are inevitably contaminated with products especially ammonia and cyanide.

(During the production of pig iron, potassium and sodium cyanide, KCN and NaCN,

are generated in the blast furnace . These compounds leave the blast furnace

together with the dusty top gas. Prior to further use the top gas has to be cleaned up.

During wet purification, a muddy cyanide-containing waste is created. This waste isreferred to as blast furnace sludge. As the blast furnace sludge is worthless, it is

disposed at surface deposits.

Recently, the crystalline cyanide-containing compound potassium zinc

hexacyanoferrate(II) nonahydrate, K2Zn3[Fe(CN)6]29H2O, was identified by powder X-

ray diffraction in deposited blast furnace sludge as the major component of cyanide)

Production of coke from coal in coking plants also requires water cooling and the use of water

in by-products separation. Contamination of waste streams includes gasification products such

as benzene, naphthalene, anthracene, cyanide, ammonia, phenols, cresols together with a

range of more complex organic compounds known collectively as polycyclic aromatic

hydrocarbons (PAH).

Waste water from Iron and Steel Industry


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The conversion of iron or steel into sheet, wire or rods requires hot and cold

mechanical transformation stages frequently employing water as a lubricant and

coolant.Contaminants include hydraulic oils, tallow and particulate solids.

Final treatment of iron and steel products before onward sale into manufacturing

includespickling in strong mineral acid to remove rust and prepare the surface for

tin or chromium plating or for other surface treatments such as galvanization or

painting. The two acids commonly used are hydrochloric acid and sulfuric acid.

Wastewaters include acidic rinse waters together with waste acid. Although manyplants operate acid recovery plants, (particularly those using Hydrochloric acid),

where the mineral acid is boiled away from the iron salts, there remains a large

volume of highly acid ferrous sulfate or ferrous chloride to be disposed of.

Many steel industry wastewaters are contaminated by hydraulic oil also known as

soluble oil.

Iron and steel industry


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Mines and quarries

The principal waste-waters associated with mines and quarries are slurries of rock particles in water.

These arise from rainfall washing exposed surfaces and haul roads and also from rock washing and

grading processes.

Volumes of water can be very high, especially rainfall related arising on large sites. Some specialized

separation operations, such as coal washing to separate coal from native rock using density gradients,

can produce wastewater contaminated by fine particulate haematite and surfactants.

Oils and hydraulic oils are also common contaminants. Wastewater from metal mines and ore recovery

plants are inevitably contaminated by the minerals present in the native rock formations.

Following crushing and extraction of the desirable materials, undesirable materials may become

contaminated in the wastewater. For metal mines, this can include unwanted metals such as zinc and

other materials such as arsenic.

Extraction of high value metals such as gold and silver may generate slimes containing very fine particlesin where physical removal of contaminants becomes particularly difficult.
http://en.wikipedia.org/wiki/File:Wastewater_effluent.JPGhttp://en.wikipedia.org/wiki/File:Wastewater_effluent.JPGhttp://en.wikipedia.org/wiki/File:Wastewater_effluent.JPG


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Cleaner Production

Cleaner production is the continuous application of an integrated preventative

environmental strategy to processes and products to reduce risks to humans and

the environment.

For production processes, cleaner production includes conserving raw materials

and energy, eliminating toxic raw materials, and reducing the quantity and toxicity

of all emissions and wastes before they leave a process.

For products, the strategy focuses on reducing impacts along the entire life cycle ofthe product, from raw material extraction to the ultimate disposal of the product.

Cleaner production is achieved by

applying know-how,

improving technology,

changing attitudes.


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CLEANER PRODUCTION is Pollution Prevention

China Canada

Cleaner Production means use oftechnology,

processes and

management systemsto avoid the creation of pollution,

to minimise pollution,

needs to treat effluents and emissions

Cleaner Production is thus the efficient use of resources, producing the same, better or more, with less:

less raw materials, less energy, less impact on the environment.

The United Nations Environment Program (UNEP) defines Cleaner Production as the continuous application of an

integrated preventive environmental strategy applied to processes, products, and services to increase eco-efficiency

and reduce risks to humans and the environment. It includes:

Production processes: ... conserving raw materials and energy, eliminating toxic raw materials, and reducingthe quantity and toxicity of all emissions and wastes.

Products: ... reducing negative impacts along the life cycle of a product, from raw materials extraction to its

ultimate disposal.Services: ...incorporating environmental concerns into designing and delivering services.

Cleaner Production requires changing attitudes, responsible environmental management and evaluating technology

options.

CLEANER PRODUCTION HIERARCHY


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Avoid Eliminating the waste altogether. This may need changing parts of the industrial process to

eliminate a particular process waste. Eliminating a waste altogether may involve a major

process change or change to a new process or technology.

Reduce Waste reduction can often be achieved by making small changes to

a process,

a piece of equipment,

a work practice

housekeeping.

The reduction may be in losses of :

a process input,

a waste generated by a process reduction in rework.

Reuse If a waste cannot be eliminated, it may be able to be reused in the process. For example,

wash water may be reused in the process, or one waste stream segregated from another

an reused. A process may be changed to make a waste reusable.

Recycle Recycling may be a cost-saving to the business, or it may be more altruistic. One business's

waste can often be used as another's raw material, and your business may be the donor or

recipient in such an arrangement. (IIT can develop a Waste Exchange Database for Indianindustries to link waste generators and potential waste acceptors, to reuse and recycle

waste.)

Reformulate The disposal cost and/or environmental effect of a waste may be reduced by changing

process inputs or segregating wastes.

Rethink If no solution is found, then a rethink may be in order. The rethink should involve some

basic questioning about the business's processes or even whether a part of the process

can be subcontracted to someone else.

CLEANER PRODUCTION HIERARCHY.


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CLEANER PRODUCTION HIERARCHY.

Cleaner Production Principle:

Housekeeping, Process modification, Recovery, reuse and recycle


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IMPLEMENTATION OF CLEANER PRODUCTION

Phase I: Planning and Organization

Management Commitment

Set up a Project Team

Develop Environmental Policy

Plan the Cleaner Production Assessment Phase II: Pre-Assessment (qualitative review)

Company Description

Process Flow Chart

Walk-Through / Site Inspection

Plan Assessment Phase

Phase III: Assessment (quantitative review)

Collection of Data

Material Balance

Identify Cleaner Production Options

List Options

Phase IV: Evaluation and Feasibility Study

Preliminary Evaluation Technical Evaluation

Economic Evaluation

Non-Economic EvaluationPhase V: Implementation and Continuation

Prepare an Action Plan

Implementation of Cleaner Production Options

Monitor Performance Sustain Cleaner Production Activities


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WASTE MINIMISATION

Process

Modification

Recycle and

Reuse

Conversion of Hazardous to less or Non

Hazardous

Incineration

Air and Aquatic

SystemThermal

Treatment

Chemical,

Physical &Biological

Treatment

Beneficial Use

and Treatment onLand

PERPETUAL STORAGELANDFILLS

UNDERGROUND

INJECTION

WASTE

PILES

SURFACE

IMPOUNDMENTS

SALT

FORMATION

ARID REGIONS

UNSATURATED ZONE

OVERVIEW OF CLEANER PRODUCTION


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Results of Cleaner Production initiatives

Industry Category

of the Plant

Process Change

Fine Chemicals Heat RecoveryChemical Mfg. Vapor loss

Reduction

Food canning Stream Recapture

Brewing Waste as Fertilizer

Furniture Mfg Hazardous waste

reuse

Textile printing Solvent recovery

Metal Finishing Spray paint loss

reduction

Small Appliance

Mfg

Solvent recycling

and substitution

Source: Michael Overcash, Nov 1991)


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CP Audit

In China it is formulated that a formalized CP audit should consist of the following

seven steps:

(1) planning and organization,

(2) Pre-assessment,

(3) assessment,(4) option generation and screening,

(5) feasibility analysis

(6) ) option implementation, and

(7) continuing cleaner production


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Conducting Cleaner Production Assessment

1. Obtain Management commitment

2. Set up a Project Team3. Develop Environmental Policy:

1. Overall Aim

2. Objectives

3. Targets

4. Plan the Cleaner Production Assessment

Planning and organization

Pre-assessment

1. Describe the process: flow chart of the production processes (draw a flow chart of

how meals are prepared in a Hall Kitchen in IIT)

2. Undertake walk-through site inspection poor housekeeping, resulting in excessive waste on floors (amout of flour in the store room

floor); running taps ;

poor hygiene;

insufficient monitoring of yields of wastes/products;

poor maintenance of equipment (find the dirt in the dough making machine in your Hall);

a very damp, cold work environment, with soap water making the floors wet and slippery;

an overall impression of untidiness.

3. Plan assessment phase to find if quality, hygiene and waste treatment could beimproved significantly


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Assessment

1. Collect data: make sketches, measure

1. Water consumption

2. Organic and solid load to the waste water

3. Energy consumption

4. Product yield

2. Identify cleaner Production Options

Evaluation and feasibility study

1. Undertake preliminary evaluation2. Undertake technical evaluation

3. Undertake economic evaluation

4. Undertake environmental evaluation

5. List CP options Select Options


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List of Cleaner Production options

Problem Description Proposed

solution

Expectedimprovem

ent

Time span Capitalcost Operational cost

Excessive

water Use

Solid

Waste

Implementation and Continuation

1. Prepare an action plan

1. Water saving activities

2. Hygienic activities

3. Waste minimizing activities

2. Monitor Performance


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Exercise to learn


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Pounds of Component Pounds of Milk % Component Factor TotalProtein

Fat

Lactose

100

100

100

3.25

3.60

5.00

3.25

3.60

5.00

1.031

0.890

0.691

3.35075

3.204

3.455

Total BOD5 10.00975

Biochemical Oxygen Demand (BOD) is a measure ofeffluent strength in terms of the amount of dissolved oxygenutilized by microorganisms during the oxidation of organic components in the effluent.

BOD is determined by incubating a suitable dilution of effluent in a standard dilution water or specific composition at 68 F (200 C).

After incubation, the amount of dissolved oxygen consumed is obtained by titration and the results expressed as parts per million ofBOD. Complete biological oxidation generally requires about 20 days at 200 C. However, the test has been standardized to becompleted in 5 days, hence the term BOD5.

Knowledge of BOD5 in parts per million of dissolved oxygen and the volume of effluent permits the calculations of pounds of BOD.the pounds of BOD can be calculated by the formula:

Pounds of BOD5 = gallons of water x 8.34 x ppm BOD5 .

If the exact composition of the effluent is known, the pounds of BOD5 can be calculated quite easily by applying the factors 1.031,

0.890, and 0.691 for protein, fat, and carbohydrate, respectively. The exact composition of effluent is rarely known. However, theamount of BOD5 possessed by common processing materials can be calculated from known composition. For example, the BOD5 of100 pounds of milk containing 3.25% protein, 3.6% fat and 5.0% lactose would be 10.00.

The calculation is made as follows:This type of calculation can be used to determine the amount of BOD5 in any product. The calculation is an approximation and willdiffer somewhat from BOD5 levels determined in the laboratory. However, they are sufficiently accurate to estimate the potentialcontribution of a processing ingredient to the total waste load.

Waste Management K. Pathak

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