ECO-COMPATIBILITY: GREEN CHEMISTRY

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ECO-COMPATIBILITY GREEN CHEMISTRY

• Buddhadeb Chattopadhyay
• Government College of Engineering and Leather
  Technology, Kolkata

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HISTORICAL EVOLUTION OF GREEN CONCEPTS

• MODERN ENVIRONMENTAL Rachel Carsons Book
• MOVEMENT (1962) Silent Spring
• GREEN CHEMISTRY MOVEMENT Molina Rowlands
  Book
• (1974) CFCs Ozone layer
• SIGNING OF MONTREAL CFC Phase out
• PROTOCOL (1986)
• FIRST CONCEPT OF ATOM ECONOMY BH Trost
• in Science JL (1991) A search for
  synthetic Efficiency
• TOTAL SYNTHESIS OF A NATURAL Nicolaou
  Sorensen
• PRODUCT (1996) Vitamin B 12
• eFACTOR IN SPECIALITIES (1998) Anastas
  Warner
• (1998) Green Chem Practice

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What is Ecology ?

• Greek, Oikos Logos Ecology.
• Household Study.
• Study of structure function of Nature (Odum,
  1971).
• Distribution and abundance of animals
  (Andrewartha, 1961).
• Interactions that determines the distribution
  abundance of organisms (Krebs, 1985).

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Study of Ecosystem

• Ecosystem is an open system.
• It exchange both matter (mass) and energy.
• This exchange process takes place through
  environment.

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Environment
The complete range of external conditions,
physical and biological, in which an organism
lives. Environment includes social, cultural, and
(for humans) economic and political
considerations, as well as the more usually
understood features such as soil, climate and
food supply.
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Ecosystem
A discrete unit that consists of living and
non-living parts, interacting to form a stable
system.
The term first used by A. G. Tansley in 1935
Fundamental concepts include the flow of energy
via food-chains and food-webs, and cycling of
nutrients biogeochemically.
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Ecosystem components
Abiotic
Biotic
Producers, Consumers (different levels)
Decomposers
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Food- chain
The transfer of energy from the primary producers
(green plants) through a series of organisms that
eat and are eaten, assuming that each organism
feeds on only one type of organism.
E.g. earthworm blackbird
sparrow hawk
At each stage much energy is lost as heat, a fact
that usually limits the number of steps, the
trophic levels.
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Food-chain
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Food chainTwo types
Grazing Primary producers are eaten by grazing
herbivores, with subsequent energy transfer at
various levels of carnivores.
Detritus The living primary producers are not
consumed by grazing herbivores, but eventually
form litter (detritus) on which decomposers
(microorganisms) and detritivores feed, with
subsequent energy transfer at various levels of
carnivores. e.g. leaf litter earth
worm blackbird
sparrow hawk
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Food-web
A diagram that represents the feeding
relationships of organisms within an ecosystem.
It consists of a series of interconnecting
food-chain.
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Essential elements
Vital for successful growth and development of
organisms
Macronutrients (needed in relatively large
amount) C, H, N, O, S, P, K, Mg, Ca etc.
Micronutrients Cu, B, Fe, Zn, Mb, Cr (III) etc.
Non-essential elements Pb, Hg, As etc.
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Dose-effect curve showing the relationship
between concentrations and biological effects of
essential (red) and of non-essential (green)
elements.
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Ecological pyramid
A graphical representation of the trophic
structure and function of an ecosystem.
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3 types of pyramids of Numbers, of Biomass and
of Energy.
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Energy flow
The exchange and dissipation of energy along the
food-chains and food-webs of an ecosystem.
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Hydrosphere
Total body of water which exists on or close to
the surface of the Earth
Hydrological cycle
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Environmental Pollution
The defilement of the natural environment by
pollutant(s).
Pollutants may affect Air, Water, Soil.
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Air pollution
Air pollutants and their consequences

• Gases like, COx, SOx, NOx
• Hydrocarbons and photochemical smog
• Particulates
• Acid rain
• Radioactivity and its effects

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Water Pollution
Water pollutants and their consequences

• Toxic chemicals including heavy metals
• Organic pollutants
• Inorganic pollutants
• Eutrophication
• Thermal pollution

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Tannery Ecology
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Typical Mass Balance

• TYPICAL MASS BALANCE
• 1,000 Kg of hides 30 m3 of water 247 Kg.
  Chemicals
• 150 Kg. of Leather 150 Kg. Splits 700 Kg.
  Solid wastes 30 m3 of Effluent.
• (30 m3 of Effluent contains 400 Kg. of total
  solids)

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Global Water Resources (Est.)

• Earths atmosphere 13,000 km3.
• Earths interior 37,800,000 km3.
• Earths surface 1,320,000,000 km3.
• Total water 1,357,813,000 km3.

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For every kg. of hide processing

• 30 L of fresh ground water is converted into
  effluent and discharged in the ecosystem.
• Who will replenish?

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ADOPTION OF CLEAN / GREEN TECHNOLOGIES IN
DEVELOPING SOCIETIES
CONSTRAINTS

• SCARCITY OF TECHNICAL AND FISCAL RESOURCES
• WEAK REGULATORY INSTITUTIONAL FRAMEWORK

POLLUTION CONTROL
LEGISLATIVE
JUDICIAL
INDEPENDENT DATA COLLECTORS
WATCH DOG BODIES

• LESS PREVALENT STIMULUS PACKAGES
• WEAK RD CAPABILITIES
• MORE FAVOURABLE PUBLIC SENTIMENT TO ECONOMIC
  DEVELOPMENT
• AS COMPARED TO ENVIRONMENT

INDIA IS LUCKY TO HAVE OVERCOME MOST OF ABOVE
CONSTRAINTS STILL LOT TO BE DONE
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INDIAN PRIORITIES TO REALISE GLOBAL POTENTIAL

• Environment driven in tanning sector
• Capability driven in product sector

CAPACITY EXPANSION
TECHNOLOGY

• State of art products / processes
• Ecofriendly

HIGHER GLOBAL MARKET ACCESS
Product and component sectors

• Creating new investments opportunities
• Aggressive global campaigns (FDIs)

PRIORITIES
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ESSENTIALS FOR LEATHER /PRODUCT PROCESSING
MINIMIZE WASTE
INHERENT SAFETY
ATOM ECONOMY
REAL TIME MONITORING CONTROL
LEAST HAZARDOUS SYNTHESIS
THE DOZEN GREEN MANTRAS
CRADLE TO GRAVE APPROACH
SAFER CHEMICAL(s)
EFFICIENT REACTION MEDIA
CATALYSTS FOR HIGHER EFFICIENCY
MINIMUM ENERGY
REDUCE DERIVATIVES
RENEWABLE RESOURCES
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GREENER LEATHER PROCESSING OPTIONS
Chemicals
Hides/Skins
ENERGY
LW SW
SW
Salt

• Galatine
• Petfoods
• Leather Products

• Chrome
• Pickle Liquors
• Dehairing bath

• High Exhaustion
• Enzymatic Processes

• Salt (Reuse)
• SW Products
• Water (Reuse)

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A CASE STUDY
ECONOMIC IMPLICATIONS OF ENVIRONMENTAL ACTIONS

• IMPLEMENTED MEASURES

• Chrome Recycle
• Dye Solution Recycle
• Higher Cr exhaustion
• Segregation of liming and washing waster waters

• ECONOMIC BENEFITS

• Waste Water Quantity reduction 8.5
• Chromium dye bath reduction 55 (Cr)
• 
  25 (Dye)
• Investment USD 25,000
• Annual Savings USD
  98,000

• TECHNICAL BENEFITS

• Improved Productivity
• Quality Enhancement
• Absence of H2S(g) and foul smell

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CHROME DISTRIBUTION ()
GRAIN LEATHER
USABLE SPLIT
SOLID WASTE
LIQUID EFFLUENT
CONVENTIONAL TANNING 34 11 30 25 HIGH
EXHAUSTION TANNING 45 15 38 2 CHROME
RE- TANNING 40 -- -- 60
GLOBAL CHROME RECOVERY BENCHMARKS

• LOWEST ATTAINABLE
• IN LIQUID EFFLUENT 10-19 mg/lit
• ENVIRO LIMIT 1 4 mg/lit

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OUTSTANDING GLOBAL ECO SUCCESSES

• Water consumption by 60
• Chromium Discharge by 90
• Solvent emissions by 90
• Unhairing residue by 50

REDUCTION

• BIOGAS from fat and fleshings
• Galatine /glue/ protein products /Bio-diesel
  from fleshings
• Recycled water for tanning
• Solid waste as dye adsorbents and ashpalt
  additives

WEALTH FROM WASTE

• Water in place of solvent based coatings
• Enzymes in place of chemical agents

VIABLE REPLACEMENTS
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Ecology is the concern of everybody.

• Acid test for any technology to be sustainable
  lies in the ability and efficiency to reconcile
  it to be compatible with ecology.
• This is the major challenge to combat.

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Symbiotic Industrial Ecosystem
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Golden Rules Green Chemistry

• Reduce in-plant pollution load rather than
  efficient end-of-pipe treatment of wastes.
• Optimise Atom Economy. All chemicals needed to
  make leather should be incorporated in it, means,
  look for higher exhaustion either by exhaustion
  aids or by altering application conditions.
• Avoid generation of hazardous substances in situ
  or outside. Risk f (Hazard x Exposure).

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Golden Rules Green Chemistry

• Design use chemicals of lower toxicity. Look
  for ecotoxicological profile of all auxiliaries.
• Minimise use of auxiliary substances that do not
  form a part of the leather. Avoid unnecessary
  loading, replace solvent based system by aqueous
  based system etc.
• Minimise energy consumption.
• Minimise water consumption. Water do costs and
  depletes underground resource.

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Golden Rules Green Chemistry

• Look for by product utilisation. Only 15 of hide
  mass is used as leather and 15 as splits. (70
  precious biomass is wasted.) Todays drainage can
  be tomorrows hidden treasure trove!
• Choose chemicals to provide maximum selectivity
  of function.
• Products to be discarded ultimately should break
  down rapidly into benign compounds.
• Design flawless mechanism for in-process control
  in real time.

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Golden Rules Green Chemistry

• Maintain records at each stage of in-plant
  process control.
• Care for temperature or pressure fluctuation or
  fire hazards (in spray booth, air duct etc.).
• Involve educate shop floor people.
• Discourage tendency for unduly saving time or
  efforts.
• Stop drying Cr-tanned leather under Sun.
• Use computers or microprocessors.

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Need of Energy Audit in Leather Industry

• Pollution has become a major challenge to leather
  industry, energy is now going to become the next
  big issue.
• Steep increase of fossil fuel and electricity
  prices coupled with erratic bulk power supplies
  are causing concern to the Indian tanners.
• A large amount of recoverable waste energy is now
  going up the stack, down the sewer or out through
  the dryer exhausts.

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Energy Consumption Pattern in Tanneries
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Energy Consumption in Tanneries

• Approximately 1400 1800 kcal of energy is
  required to process 1 kg. of hide.
• About 30 50 of waste energy can be conserved
  or recycled through mechanical engineering
  improvements of machinery, readjustment of
  process parameters and process innovations.
• Deployment of solar energy also deserve
  attention.
• So, there is a strong need for conducting an
  energy audit in Indian tanneries.
• Unlike pollution abatement costs, energy
  efficiency pays us back.

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Biomass A Potential Resource

• India predominantly agricultural country.
• Annual production of agro-forest
• and processing residues 350 million tons
• Power generation potential gt 17,000 MW
• Advantages
• Decentralized generation close to
• rural load centers.
• Technology reasonably
• well developed
• Environmentally friendly No net
• CO2 emissions but does emit CH4.

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BIOGAS FROM TANNERY BIO -WASTE (5 ton hides)

• FLESHINGS SLUDGE - 8.5 M3 AT 70 gms/L concn.
• 193.5 M3 BIOGAS (75 METHANE)
• ENERGY EQUIVALENT (1,245,000 Kcal)
• 122 M3 DIGESTER VOLUME
• ACIDOGENISIS (MESOPHILIC) AND METHANOGENESIS

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Energy from Tannery Waste

• Biomethanization of tannery waste offers distinct
  advantages in waste disposal and generation of
  supplementary energy.
• The biodegradability of a pollutant is assessed
  by parameters like 5-days Biochemical Oxygen
  Demand (BOD5) its chemical oxygen Demand and
  their ratio.
• The ratio, BOD5/COD?lt 0.3, the waste is difficult
  to biodegrade.
• If 0.3 lt BOD5/COD lt0.6, the compound (or waste)
  is potentially biodegradable.
• The basis of biomethanation is based on nominal
  pretreatment of solid wastes to get organics in
  liquid form as gelatine and take it for
  biomethanation with additives and nutritives.
• Tannery of Tata International Ltd. in Dewas is
  regularly producing bio-gas from tannery wastes
  (250 m3/d) and the unit is fine since its
  initialization.

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Energy Saving Benefits of Automation in Tannery

• The present century carries on with the
  irresistible march of progress electronics and
  its invasion of various sectors including leather
  industry also.
• Microprocessor control systems have become
  popular in the automation of leather finishing
  operations.
• Microprocessor controlled systems for tannery wet
  operations make sure of the followings
• a) In-process quality control of leather.
• b) Controlled chemical and water dosages.
• c) Drum operation control.
• d) Online colour matching techniques for dyed
  leathers.
• e) Optimisation of spent energy in processing
  leather with
• minimum wastage.

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Simple Action

• Induction motors equal or less than 25 HP are
  energy expensive.
• Motor armature has 1200-1400 r.p.m but drums
  seldom require more than 16.
• There is a huge loss of energy.
• Remedy Replacement by variable frequency
  voltage motors.
• Pay back periods 2 years

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Schumachers Mantra

• Decrease Consumption.
• Wise use of Knowledge is that which leads to
  the well beings of the individual and the
  society. Misuse of science and technology is most
  poignant example of the danger when increase in
  knowledge is out accompanied by an increase of
  wisdom
• E. F. Schumacher.
• (Small is Beautiful)

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Silent Spring Rachel Carson

• There was a strange stillness on the morning
  that had once throbbed with dawn chorus of
  robins, catbirds, doves, jays, wrens and source
  of other bird voices there was now no sound only
  silence lay over fields and woods and marshes

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THANKS FOR PATIENT HEARING

• Acknowledgement Some slides were taken from the
  Lecture of Dr. K. V. Raghavan, former Director,
  CLRI, Chennai.