Glass recycling – An effective way to save energy and environment:
Generally, beer, wine bottles and other food jars etc., are among the few normal household glass items put into landfills every day. The glass in these items can take up space in the landfills for up to 4000 years.
A. The beauty of glass is, it is one of the few materials that can be recycled indefinitely, yet only about 22 percent of the glass produced today is from recycled materials. Glass is generally produced from sand, lime and soda and uses about 40 percent more power to produce from raw materials than it does with recycled materials.
B. It may be noted, “For every ton of glass that is recycled to make new glass products 693 pounds of carbon dioxide is saved”.
C. However, not all the glass items are recyclable. The glass in light bulbs, cook ware and window panes are not recyclable due to some special additives used to the glass. These additives are ceramics and other impurities that generally contaminate the recycling process. The glass that cannot be recycled only plays a small part of the glass that is put into the landfills though.
D. The process of glass recycling is less extensive than the process of making it from raw materials. Once glass is picked up and taken to the recycle center it is separated by color and then broken into small pieces. The broken glass pieces are then crushed and sorted before being cleaned and added to raw materials to make the final glass product. Crushed glass melts at a lower temperature than the raw materials and therefore the more recycled material that is in the mixture the less energy it takes to melt the materials into glass.
E. Producing glass from all raw materials creates nearly 400 pounds of mining waste and by replacing 50 percent of the raw material with recycled glass about 75 percent of that waste is reduced.
F. Reusing glass is another way to recycle - Even better than glass recycling is actually reusing the glass containers, as this uses no energy at all! Whilst returning bottles in exchange for a refundable deposit was at one time commonplace, nowadays milk bottles are one of the few types of glass bottle which are returned for reuse. You can, however, reuse glass bottles and jars yourself, perhaps for homemade jam etc.
G. The benefits of glass recycling are crystal clear - Because glass containers are almost always recycled into other glass containers. Metals or plastics, on the other hand, often become entirely different products. A recycled glass container is just as strong as one made from virgin material, and it can be recycled again and again without any loss of quality. This makes glass recycling one of the best examples of “closing the loop.”
H.Advantages of glass recycling are given in the following points–
(a) Recycling reduces the demand for raw materials. There is no shortage of the materials used, but they do have to be quarried from our landscape, so from this point of view, there are environmental advantages to recovering and recycling glass. For every tonne of recycled glass used, 1.2 tonnes of raw materials are preserved.
(b) The cost savings of recycling is in the use of energy. Compared to making glass from raw materials for the first time, cullet melts at a lower temperature. So we can save on energy needed to melt the glass.
(c) Glass produced from recycled glass reduces related air pollution by 20% and related water pollution by 50%.
(d) Recycling glass reduces the space in landfills that would otherwise be taken up by used bottles and jars.
(e) Using glass for recycling means there are less glass objects lying around in he landfill or bin.
Bio-degradable plastics – development and use are the key for improvement of environment:
A. At present, we make almost 100% of plastics of our requirement from oil and natural gas. Petroleum-based plastics are basically non-degradable. As concern grow about the potential bad effects of petroleum-based non-degradable plastics on the environment, the viability of petroleum-based plastics are in question. At the same time, the increased dependence on oil and gas imports due to manufacture of such petroleum-based products, make us think about the possible solution. In this respect, searching for suitable degradable polymers for various applications as per the need, have become very important aspect in today’s science and technological affair for research.
B. As per reports of various environment protection agencies, plastics alone account for more than 25% (by volume) of municipal waste generated. Plastic’s low density and slowness to decompose makes them a visible pollutant of public concern. Some of the techniques adopted for integrated waste management, which include recycling, source reduction of packaging materials, composting of degradable wastes, incineration etc., may help reduce waste disposal problem; but this will not solve the importation of petroleum products and problem with non-degradability of plastics. As per statistics, about 80% of post-consumer plastic waste is sent to landfill – degrading land masses and causing water pollution, 8% is incinerated – causing unwanted emission and only 7% is recycled. The situation is so acute in some countries of Europe of Japan that today few sites left that can be used for landfill. Since the main bulk of domestic waste is made up of plastics there is a great deal of interest in recycling plastics and in producing plastic materials that can be safely and easily disposed of in the environment.
C. The option to get rid of the adverse effects of non-degradable petroleum-based plastics may be to make bio-degradable plastics suitable for our various applications. Some of the manufacturers in developed countries have already developed some type of degradable plastics made from agricultural products such as corn, potato etc. In fact, bio-degradable plastics can be made from lactic acid. Lactic acid is produced (via starch fermentation) as a co-product of corn wet milling, which can be converted to polyactides (PLA). Alternatively, it can be produced using the starch from food wastes, cheese whey, fruit or grain sorghum.
D. The properties of the plastics changes as per the applications for which it is needed. Some plastics need to be durable like the parts in a car. Yet, there are many plastics that are only used once or have a limited life before being thrown into a landfill or incinerator. Plastics, unlike most organic polymers, are poorly degraded by microbes (although recently some genetically engineered microbes / bacteria have been invented to transform plastic waste into useful eco-friendly plastics – but it is still in research stage). Environmentally degradable polymers are one potential solution to replacing petroleum-based polymers. Potential uses for these polymers are plastics intended for one-time or limited use, for example those used as fast-food wrappers and water-soluble polymers in detergents and cleaners, and for use in the printing industry. Thus, an ideal degradable product would:
(a) Perform the intended task effectively;
(b) Produce little or no side effects in any non-intended target;
(c) Break down, along with any residues of its activity, over a reasonably short time scale;
(d) Produce no harmful substances when it breaks down.
E. Waste disposal: The question now arises, how best to dispose of domestic wastes. The ways of disposing of waste and time required for degradation is very important factors in development of bio-degradable plastics. Current bio-degradable polymers are designed to degrade either biologically or chemically, depending on the disposal environment that they will encounter after use. Ideally, degradation pathways should ultimately lead to the bio conversion of the polymer into carbon dioxide (aerobic) or carbon dioxide/methane (anaerobic) and biomass. Environmental laws and regulations and consumer demands for environmentally friendly products are beginning to have an impact on the use of degradable polymers. As a result degradable polymers, when combined with other degradable plastics, will begin playing a crucial role in helping to solve our waste disposal problems and reducing petroleum imports.
F. Properties of bio-degradable polymers: These new polymers developed from agricultural products described above are truly degradable. These polymers may be used in many applications as well. Some are impervious to water, moisture etc., and retain their integrity during normal use, but readily degrade when they are kept in a biologically rich environment. The amazing part is the full biodegradability can occur only when these materials are disposed of properly in a composting site or landfill. Today, there are three major degradable polymers groups that are either entering the market or are positioned to enter the market. They are
(a) polyactides (PLA),
(b) polyhydroxybutyrate (PHB) and
(c) starch-based polymers.
G. Design for Bio-Degradation of Polymer: Following few points are given to attain bio-degradability. (a) Some organic chemicals degrade only very slowly, and so the level in the environment can rise steadily. These are the persistent organic pollutants (or "POPs").
(b) In contrast, all chemicals produced in nature are 100% degradable and understanding why this is the case is an important part of being able to design synthetic degradable materials.
(c) For example, natural polymers such as carbohydrates, proteins and nucleic acids usually have oxygen or nitrogen atoms in the polymer backbone. If these atoms are included in synthetic polymers, the material is more easily degraded. A carbon-oxygen double bond (carbonyl group) absorbs light energy, and so can make a substance photodegradable.
(d) These features can be seen in the structures of some degradable polymers that are already in use.
H. Bio-degradable polymers are quite new. Only during last five years some bio-degradable polymers for applications have been in use in some of the developed world. Although they are degradable, the industry has not promoted them. One reason is these new polymers are higher priced than the commodity polymers typically in use in plastics applications. However, producers are currently working toward bringing down the price of degradable polymers by increasing production capacity and improving process technology.
I. Price competitiveness and future growth of bio-degradable polymers: The trend observed regarding bringing down the prices of degradable polymers in last five years is quite encouraging. In US, five years ago PLA and PHB sold for more than USD 25.00 per pound. Today PLA, depending on quantities, is between USD 1.50 and USD 3.00 per pound and PHB, in large quantities is near USD 4.00 per pound.
Though recent advances in production technology have helped lower prices of some degradable resins, prices are still higher than for petroleum-based plastics. This suggests that in the short term, companies making degradable polymers will continue to focus on niche markets. As production capacity increases it is expected that future prices to fall to roughly USD 1 per pound. Moreover, due to sharp increase in prices of petroleum-based plastics in recent time, the prices of bio-degradable polymers will become very much competitive soon.
J. Further, several factors, besides cost, will be important in determining the future growth of degradable polymers. One major obstacle is a lack of a composting infrastructure. Large-scale composting would provide the ideal disposable environment for spent degradable. Future legislation will depend not only on the environmental awareness of planners and politicians but also on their perceptions of how degradable polymers may affect the development of plastics recycling.
Steel is the world's most recycled material. Steel's unique magnetic properties make it an easy material to recover from the waste stream, i.e., it can be recycled. The properties of steel remain unchanged no matter how many times the steel is recycled. The electric arc furnace (EAF) method of steel production can use recycled steel exclusively.
Most steel is made via one of two basic routes: (1) Integrated (blast furnace and basic oxygen furnace); (2) Electric arc furnace (EAF).
The integrated route uses raw materials (that is, iron ore, limestone and coke) and scrap to create steel. On the other hand, the EAF method uses scrap as its principal input.
The EAF method is much easier and faster since it only requires scrap steel. Recycled steel is introduced into a furnace and re-melted along with some other additions to produce the end product.
Steel can be produced by other methods such as open hearth. However, the amount of steel produced by these methods decreases every year.
Of the steel produced recently, about 65.0% was produced via the integrated route, 32.0% via EAF and 3.0% via the open hearth and other methods.
Steel is not a single product. There are currently more than 3,500 different grades of steel with many different physical, chemical, and environmental properties. Approximately 75% of modern steels have been developed in the last 20 years. If the EiffelTower were to be rebuilt today the engineers would only need one-third of the amount of steel. Modern cars are built with new steels that are stronger, but up to 25% lighter than in the past.
Steel is very friendly to the environment. It is completely recyclable, possesses great durability, and, compared to other materials, requires relatively low amounts of energy to produce. Innovative lightweight steel construction (such as in automobile and rail vehicle construction) help to save energy and resources. The steel industry has made immense efforts to limit environmental pollution in the last decades. Energy consumption and carbon dioxide emissions have decreased by one-half of what they were in the 1960s. Dust emissions have been reduced by even more.
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