Presentation on theme: "ECO-COMPATIBILITY: GREEN CHEMISTRY Buddhadeb Chattopadhyay Government College of Engineering and Leather Technology, Kolkata."— Presentation transcript:
ECO-COMPATIBILITY: GREEN CHEMISTRY Buddhadeb Chattopadhyay Government College of Engineering and Leather Technology, Kolkata
HISTORICAL EVOLUTION OF GREEN CONCEPTS MODERN ENVIRONMENTALRachel Carson’s Book MOVEMENT (1962)“Silent Spring” GREEN CHEMISTRY MOVEMENTMolina & Rowland’s Book (1974) “CFCs – Ozone layer” SIGNING OF MONTREALCFC Phase out PROTOCOL (1986) FIRST CONCEPT OF ATOM ECONOMYBH Trost in Science JL (1991)“A search for synthetic Efficiency” TOTAL SYNTHESIS OF A NATURALNicolaou & Sorensen PRODUCT (1996)Vitamin B 12 eFACTOR IN SPECIALITIES (1998)Anastas & Warner (1998)“Green Chem Practice”
What is Ecology ? Greek, “Oikos” + “Logos” = Ecology. Household + Study. 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).
Study of Ecosystem Ecosystem is an open system. It exchange both matter (mass) and energy. This exchange process takes place through environment.
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.
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.
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.
Food chain…Two 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
Food-web A diagram that represents the feeding relationships of organisms within an ecosystem. It consists of a series of interconnecting food-chain.
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.
Dose-effect curve showing the relationship between concentrations and biological effects of essential (red) and of non-essential (green) elements.
Ecological pyramid A graphical representation of the trophic structure and function of an ecosystem.
3 types of pyramids: of Numbers, of Biomass and of Energy.
Energy flow The exchange and dissipation of energy along the food-chains and food- webs of an ecosystem.
Hydrosphere Total body of water which exists on or close to the surface of the Earth Hydrological cycle
The defilement of the natural environment by pollutant(s). Pollutants may affect Air, Water, Soil. Environmental Pollution
Air pollution 1.Gases like, COx, SOx, NOx 2.Hydrocarbons and photochemical smog 3.Particulates 4.Acid rain 5.Radioactivity and its effects Air pollutants and their consequences
Water Pollution Water pollutants and their consequences: 1.Toxic chemicals including heavy metals 2.Organic pollutants 3.Inorganic pollutants 4.Eutrophication 5.Thermal pollution
Typical Mass Balance TYPICAL MASS BALANCE 1,000 Kg of hides + 30 m 3 of water + 247 Kg. Chemicals = 150 Kg. of Leather + 150 Kg. Splits + 700 Kg. Solid wastes + 30 m 3 of Effluent. (30 m 3 of Effluent contains 400 Kg. of total solids)
Global Water Resources (Est.) Earth’s atmosphere: 13,000 km 3. Earth’s interior: 37,800,000 km 3. Earth’s surface: 1,320,000,000 km 3. Total water:1,357,813,000 km 3.
For every kg. of hide processing 30 L of fresh ground water is converted into effluent and discharged in the ecosystem. Who will replenish? Who will replenish?
ADOPTION OF CLEAN / GREEN TECHNOLOGIES IN DEVELOPING SOCIETIES CONSTRAINTS SCARCITY OF TECHNICAL AND FISCAL RESOURCES WEAK REGULATORY INSTITUTIONAL FRAMEWORK LEGISLATIVEJUDICIAL POLLUTION CONTROL INDEPENDENT DATA COLLECTORS WATCH DOG BODIES LESS PREVALENT STIMULUS PACKAGES WEAK R&D 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
INDIAN PRIORITIES TO REALISE GLOBAL POTENTIAL CAPACITYEXPANSION TECHNOLOGY TECHNOLOGY HIGHER GLOBAL HIGHER GLOBAL MARKET ACCESS MARKET ACCESS PRIORITIES PRIORITIES Environment driven in tanning sector Capability driven in product sector State of art products / processes Ecofriendly Product and component sectors Creating new investments opportunities Aggressive global campaigns (FDIs)
THE DOZEN GREEN MANTRAS MINIMIZE* WASTE ATOM ECONOMY LEAST HAZARDOUS SYNTHESIS SAFER* CHEMICAL(s) EFFICIENT REACTION MEDIA MINIMUM* ENERGY RENEWABLE* RESOURCES REDUCE DERIVATIVES CATALYSTS FOR HIGHER EFFICIENCY CRADLE TO GRAVE APPROACH REAL TIME* MONITORING & CONTROL INHERENT* SAFETY ESSENTIALS FOR LEATHER /PRODUCT PROCESSING
Hides/Skins Chemicals ENERGY LW & SW SW Salt High Exhaustion Enzymatic Processes Galatine Petfoods Leather Products Chrome Pickle Liquors Dehairing bath GREENER LEATHER PROCESSING OPTIONS Salt (Reuse) SW Products Water (Reuse) LEATHER PROCESSING LEATHER PROCESSING CONTROLS PRIMARY SECONDARY TERTIARY INTERNAL RECYCLES INTERNAL RECYCLES BY PRODUCT UTILIZATION BY PRODUCT UTILIZATION LESS SALT OR SALTLESS PRESERVATION NEW TECHNOLOGIES
29 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 H 2 S(g) and foul smell
CHROME DISTRIBUTION (%) GRAIN LEATHER USABLE SPLIT SOLID WASTE LIQUID EFFLUENT CONVENTIONAL TANNING 34113025 HIGH EXHAUSTION TANNING 451538 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
Water consumption by 60% Chromium Discharge by 90% Solvent emissions by 90% Unhairing residue by 50% 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 Water in place of solvent based coatings Enzymes in place of chemical agents
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.
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).
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.
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.) Today’s drainage can be tomorrow’s 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.
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.
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.
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.
Biomass – A Potential Resource India predominantly agricultural country. Annual production of agro-forest and processing residues: 350 million tons Power generation potential > 17,000 MW Advantages: – Decentralized generation: close to rural load centers. – Technology reasonably well developed – Environmentally friendly: No net CO 2 emissions but does emit CH 4. FeedstockExamplesPotentialInstalled Agro-forest residues Wood chips, mulberry, coconut shells 17,000 MW50 MW Processing residues Rice husk, sugarcane bagasse 5,000 MW1000 MW
BIOGAS FROM TANNERY BIO -WASTE (5 ton hides) FLESHINGS + SLUDGE :- 8.5 M 3 AT 70 gms/L concn. 193.5 M 3 BIOGAS (75% METHANE) ENERGY EQUIVALENT (1,245,000 Kcal) 122 M 3 DIGESTER VOLUME ACIDOGENISIS (MESOPHILIC) AND METHANOGENESIS
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 (BOD 5 ) & its chemical oxygen Demand and their ratio. The ratio, BOD 5 /COD < 0.3, the waste is difficult to biodegrade. If 0.3 < BOD 5 /COD <0.6, 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 m 3 /d) and the unit is fine since its initialization.
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.
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
Schumacher’s 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”)
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…”
THANKS FOR PATIENT HEARING Acknowledgement: Some slides were taken from the Lecture of Dr. K. V. Raghavan, former Director, CLRI, Chennai.