Recyclable materials – What Can Be Recycled

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Recycling and the benefits of recycling have already been discussed in the previous post. Have a look here: What is recycling.

Materials Which Can Be Recycled:

All materials are not considered as good recyclable materials. The biodegradable materials like food items, organic wastes, etc are not considered as the recyclable materials. The materials, which can be picked, cleaned, and reprocessed into new materials are considered as the recyclable materials. The good recyclable materials are:

Municipal Solid Wastes

These municipal solid wastes (MSW) are the post-consumer solid wastes, generated by the domestic units, commercial units, institutions, hospitals, etc. MSWs are not easy to define; however, MSW is considered as the material waste generally (yard waste, papers, glass, metals, etc). Some of the MSW are described under:

o   Paper

Wasted papers are recycled into the new paper products by paper recycling. It is unfortunately a fact that the paper processing requires pulp, which is obtained by cutting down the trees, which is a threat to the environment. Using recycled papers can minimize the new paper requirements, and so are the wood requirements.

o   Glass

Unlike paper recycling, glass recycling needs extra concentration. The glass bottles and the other types of glass (like Pyrex, light bulbs, window glass, auto glass, etc) cannot be recycled together. As glass chemistry is based on its oxide components typically. The most likely recyclable glass is the clean glass.

o   Oil

Oil recycling might be newer for many people. “Oil” refers to variety of combustible liquids, which are not soluble in water and leave greasy stain. The used or contaminated oil (not consumed) can be considered as the recyclable material. Direct combustion of used oil as a burner fuel should always be condemned, because it not only destroys this valuable source, but also cause environmental pollution.

o   Plastic

Plastic recycling has turned a new shape today. There are lots of grades of plastics. And all the grades or types of plastics cannot be recycled together. A very small quantity of the wrong grade of the plastic can ruin the whole processing batch. It is generally not easy to separate different grades of the plastics. That’s why, there are several cryptic markers used in the plastic industries to indicate the type of the plastics.

o   ferrous metals

Recycling of the ferrous scrap is the principle recycling activity worldwide. The ferrous metals refer to the substances made up of iron or steel. Recycling of these ferrous metals gives number of environmental benefits as well including reduction in air pollution, water usage, landfill requirements, etc compared to the use of virgin materials.

o   Non ferrous metals

Non ferrous metals are any metal other than iron or iron alloys. Highly recycled non ferrous metals are copper, aluminum, lead and zinc.

o   Rubber

Rubber recycling is commonly known by the name of “tire recycling”. Used and damaged tires, which cannot longer be used on the roads, are one of the largest sources of the hazardous wastes. That’s why the tires are one the most recyclable materials. Rubber is a very resilient material, and can easily be reused in other products.

Waste Water Recycling

Waste water recycling refers to the process of removing suspended solids, impurities, Ph balancing, color treatments etc. There are various ways, in which waste water can be recycled. The selection of the treatment process depends upon the end use of the treated water. If the water is to be treated for the textile industrial usage, then there might be some of the treatment techniques involved like the sedimentation, filtration, color treatments etc. But, if water is being treated for human consumption, then number of additional processes like ultra-filtration, reverse osmosis, etc should be carried out. However, treated waste water is generally not used for the drinking purposes.

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What Is Recycling And What Are The Benefits Of Recycling?

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The process of manufacturing or producing new, useful and marketable materials from the waste or the junk substances is known as recycling. It is an old aged process, and people have been recycling their household or business goods for thousands of years, to save materials and so is the cost. However, importance and benefits of recycling got noticed in the mid 1980’s on the industrial level. Recycling is not only beneficial for the household level, but also important for the nation’s economic dependence. Also, recycling shares a major part to save the environment.

Although, the trend of recycling is growing, but still there is need to educate a common person about the recycling, and that how a common person can become the active part of the society because of recycling. Recycling doesn’t require huge industrial setups, and can be done on a very small scale; making use of an empty coke tin is also recycling. However, it is important to know that what materials can be recycled. On large scale, Steel and paper industries are the biggest cost saving sectors because of recycling. The basic purpose of this post is to introduce recycling and discuss about the benefits of recycling.

Benefits Of Recycling:

There are numerous benefits of recycling, which can take long time to discuss. However, some of the key benefits of recycling are:

• The basic purpose of recycling is truly the main benefit too. Recycling turns waste materials into useful and valuable resources.


• It conserves the natural resources, like minerals, water, trees, etc.


• It reduces the need of incineration and land filling.


• It is helpful in preventing pollution, caused by in case of using virgin materials.


• Recycling decreases greenhouse emissions, and so is the global climate change.


•  Recycling saves energy.

Some Interesting Recycling Facts:

• A common person makes an average of 2 kg (around 4.7 pounds) daily.


• Every ton of aluminum cans recycling can conserve more than 1500 gallons of gasoline.


• Glass can be recycled again and again for many times. One glass bottle recycling can save up to 400-watt electricity (you can light a 100 watt bulb for 4 hours).


• For the production of 1 ton newspaper, approx 24 trees are needed. In case of recycling, these saved trees can absorb around 250 pounds of carbon dioxide, present in the air, annually.


• The cost of plastic recycling (especially the PET bottles) is almost half of the cost of plastic incineration.

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Air Pollution because of process industries

Being a chemical engineer, you must be aware of the hazards and outcomes of the unmanaged and poorly handled processes in process industries. One of the major disadvantages of these poorly handled chemical processes is the Air Pollution. However energy generation is also considered as the major source of the air pollution.

In air pollution, the air is contaminated with several unwanted substances, which produces direct measurable effect on receptors (receptor may be humans, animals, plants or environment). This situation becomes more dangerous when these substances react with other contents in the atmosphere and form other hazardous compounds, causing harmful phenomena like depletion of ozone layer, petrochemical smog, acid rains, or green house gases (generally known as global warming). We will discuss these phenomena later, in detail.

The original six criteria pollutants, documented by EPA (environmental protection agency) are SO2 (sulfur dioxide), NO2 (Nitrogen dioxide), CO (carbon monoxide), O3 (ozone), suspended particles and VOC (volatile organic compounds). As this is a serious issue against the global environmental protection, so EPA is trying to implement and make several changes in the clean air act.

The clean air act was first passed in 1956 by the parliament of UK, in response of the London smog 1952. This clean air act 1952 was used and effective till 1964, then there were several modifications in this act.

The 1970 clean air act required that EPA provide a safety margin to protect against hazardous air pollutants by establishing national emissions standards for certain sources.

This act was last amended in 1990, which contains national ambient air quality standards for pollutants which are harmful to receptors. This act identifies two types of national ambient air quality standards:

• Primary standards      : for public health protection.
• Secondary standards  : for public welfare protection.

However, it is also the duty of the process industries / organizations, to take serious steps to control air pollution. They must focus on the reduction of contaminant discharge

• by installing control equipments (scrubbers, gravity settling chambers, etc)
• by changing raw materials, operations, or modes of operations
• by diluting the discharge
• by dispersion of sources locations.

Out of all above, the installation of the pollution control equipments is the best option to go for. This is quite an expensive technique, but is very efficient and most of the industries are using these equipments to regenerate the chemicals from the waste stream, so that their process is highly optimized causing very less pollution.

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chloro-floro-carbons

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Chloro-floro carbons are member of halo alkanes [or alkyl halides], which belongs to the group of chemical compound, derived from alkanes, containing one or more halogens. These are generally used as refrigerants, solvents, fire extinguishers, and as pharmaceuticals.

Many haloalkanes, including chlorofluorocarbons are considered as the serious pollutants and toxins to the environment. In actual, CFC's are the hydrocarbons, fully halogenated with chlorine and fluorine, and in the presence of sun light, the chloro-floro carbon molecule breaks into chlorine and chlorodifloromethyl radical. I.e.

.

CCl₂F₂              ----------->        Cl             +            CClF₂

    _{dichlorodifloromethane                 chlorine atom}        chlorodifloromethyl redical   

.

Now this chlorine atom will react with ozone layer, causing ozone depletion, by converting ozone molecule to oxygen.

Cl         +            O₃      ----------->        ClO           +            O₂

_{chlorine atom           ozone                   chlorine monoxide         oxygen}  

_.

This depleted ozone phenomena is a serious issue to environment as well as human health considerations, because less ozone means lesser production towards the highly hazardous ultraviolet sun rays. That’s why; a ban was imposed on the use of CFC’s. However, these gases are still found in refrigerators and in some types of foam packaging.

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