Oral and Written Speech Aspect

Text B

Summarize the texts. Split into groups and exchange the information you have learned with your groupmates.

METHODS OF DISPOSAL

Part I

A landfill

A landfill is a compaction vehicle in action.

Disposing waste in a landfill involves burying the waste, and this remains a common practice in most countries. Landfills were often established in abandoned or unused quarries, mining voids or borrow pits. A properly designed and well-managed landfill can be a hygienic and relatively inexpensive method of disposing waste materials. Older, poorly designed or poorly managed landfills can create a number of adverse environmental impacts such as wind-blown litter, attraction of vermin, and generation of liquid leachate. Another common by-product of landfills is gas (mostly composed of methane and carbon dioxide), which is produced as organic waste breaks down anaerobically. This gas can create odour problems, kill surface vegetation, and is a greenhouse gas.

Design characteristics of a modern landfill include methods to contain leachate such as clay or plastic lining material. Deposited waste is normally compacted to increase its density and stability, and covered to prevent attracting vermin (such as mice or rats). Many landfills also have landfill gas extraction systems installed to extract the landfill gas. Gas is pumped out of the landfill using perforated pipes and flared off or burnt in a gas engine to generate electricity.

Incineration

Incineration is a disposal method in which solid organic wastes are subjected to combustion so as to convert them into residue and gaseous products. This method is useful for the disposal of residue of both solid waste management and solid residue from waste water management. This process reduces the volumes of solid waste from 20 to 30 percent of the original volume. Incineration and other high temperature waste treatment systems are sometimes described as " thermal treatment". Incinerators convert waste materials into heat, gas, steam and ash. Incineration is carried out both on a small scale by individuals and on a large scale by industry. It is used to dispose of solid, liquid and gaseous waste. It is recognized as a practical method of disposing certain hazardous waste materials (such as biological medical waste). Incineration is a controversial method of waste disposal, due to issues such as emission of gaseous pollutants.

Recycling

Steel crushed and baled for recycling

Recycling refers to the collection and reuse of waste materials such as empty beverage containers. The materials from which the items are made can be reprocessed into new products. Material for recycling may be collected separately from general waste using dedicated bins and collection vehicles, or sorted directly from mixed waste streams. Known as kerb-side recycling, it requires the owner of the waste to separate it into various different bins (typically wheelie bins) prior to its collection.

The most common consumer products recycled include aluminum such as beverage cans, copper such as wire, steel food and aerosol cans, old steel furnishings or equipment, polyethylene and PET bottles, glass bottles and jars, paperboard cartons, newspapers, magazines and light paper, and corrugated fiberboard boxes. PVC, LDPE, PP, and PS (see resin identification code) are also recyclable. These items are usually composed of a single type of material, making them relatively easy to recycle into new products. The recycling of complex products (such as computers and electronic equipment) is more difficult, due to the additional dismantling and separation required.

Resource Recovery

Resource recovery (as opposed to waste management) uses life cycle analysis attempts (LCA) to offer alternatives to waste management. For mixed MSW (Municipal Solid Waste) a number of broad studies have indicated administration, source separation and collection followed by reuse and recycling of the non-organic fraction and energy and compost/fertilizer production of the organic waste fraction via anaerobic digestion to be the favoured path.

Part II

Sustainability

The management of waste is a key component in a business' ability to maintaining ISO 14001 accreditation. Companies are encouraged to improve their environmental efficiencies each year. One way to do this is by improving a company's waste management with a new recycling service, (such as recycling: glass, food waste, paper and cardboard, plastic bottles etc.)

Biological reprocessing

Composting, Home composting and Anaerobic digestion

An active compost heap.

Waste materials that are organic in nature, such as plant material, food scraps, and paper products, can be recycled using biological composting and digestion processes to decompose the organic matter. The resulting organic material is then recycled as mulch or compost for agricultural or landscaping purposes. In addition, waste gas from the process (such as methane) can be captured and used for generating electricity and heat (CHP/cogeneration) maximizing efficiencies. The intention of biological processing in waste management is to control and accelerate the natural process of decomposition of organic matter.

There is a large variety of composting and digestion methods and technologies varying in complexity from simple home compost heaps, to small town scale batch digesters, industrial-scale enclosed-vessel digestion of mixed domestic waste (see Mechanical biological treatment). Methods of biological decomposition are differentiated as aerobic or anaerobic methods, though hybrids of the two methods also exist.

Anaerobic digestion of the organic fraction of MSW Municipal Solid Waste has been found in a number of LCA analysis studies to be more environmentally effective, than landfill, incineration or pyrolisis. The resulting biogas (methane) though must be used for cogeneration (electricity and heat preferably on or close to the site of production) and can be used with a little upgrading in gas combustion engines or turbines. With further upgrading to synthetic natural gas it can be injected into the natural gas network or further refined to hydrogen for use in stationary cogeneration fuel cells. Its use in fuel cells eliminates the pollution from products of combustion. An example of waste management through composting is the Green Bin Program in Toronto, Canada, where Source Separated Organics (such as kitchen scraps and plant cuttings) are collected in a dedicated container and then composted.

Energy recovery

The energy content of waste products can be harnessed directly by using them as a direct combustion fuel, or indirectly by processing them into another type of fuel. Thermal treatment ranges from using waste as a fuel source for cooking or heating and the use of the gas fuel (see above), to fuel for boilers to generate steam and electricity in a turbine. Pyrolysis and gasification are two related forms of thermal treatment where waste materials are heated to high temperatures with limited oxygen availability. The process usually occurs in a sealed vessel under high pressure. Pyrolysis of solid waste converts the material into solid, liquid and gas products. The liquid and gas can be burnt to produce energy or refined into other chemical products (chemical refinery). The solid residue (char) can be further refined into products such as activated carbon. Gasification and advanced Plasma arc gasification are used to convert organic materials directly into a synthetic gas (syngas) composed of carbon monoxide and hydrogen. The gas is then burnt to produce electricity and steam. An alternative to pyrolisis is high temperature and pressure supercritical water decomposition (hydrothermal monophasic oxidation).

 

Text C

ENVIRONMENTAL QUESTIONS

Translate the text

Nuclear power is being used increasingly, particularly in Europe and North America. One argument in favour of its use is that it does not produce greenhouse gases, unlike power stations which burn fossil fuels. So is nuclear power 'clean'?

Of course, not. To appreciate the problems, we need to think about the complete fuel cycle, starting with mining. Uranium ore contains only a small percentage of uranium, and extracting it produces large volumes of radioactive waste. The uranium is then usually enriched to increase the proportion of U relative to ' U. More waste results.

Once the fuel rods are spent, they must be removed from the core and replaced. The old rods are highly radioactive, and must be cooled in large tanks of water for several months before they can be taken away and stored. Sometimes the spent fuel is reprocessed; this is what happens at Sellafield in Cumbria. The idea is to extract any remaining U and re-use it; plutonium is also separated for use in reactors or bombs. The most hazardous waste products are concentrated with the intention of storing them safely. However, no-one is sure how to do this in the best possible way. The problem will be around for thousands of years because of the long half-lives of the substances involved.

At the end of its life a power station must be decommissioned. It is dismantled, and the most radioactive parts are taken away for safe storage. The site is eventually levelled and is unlikely to be fit for other uses for several decades.

PROLIFERATING CONCERNS

In practice, nuclear power stations have proved relatively safe. There have been some spectacular accidents — notably the fire at Chernobyl in the Ukraine in 1986 which resulted in thousands of deaths and illnesses. The UK's nuclear stations have been carefully operated, but many are now reaching the ends of their lives. Should they be replaced?

In fact, there is a glut of electricity, and prices have fallen. Most new power stations use natural gas as a fossil fuel, and nuclear power cannot produce electricity as cheaply as these. Are we being shortsighted burning gas which is a non-renewable resource and which contributes to climate change?

 

 

Part II

Writing Skills

Writing Abstracts

I. Definitions

1. An abstract is a condensed version of a longer piece of writing that highlights the major points covered, concisely describes the contents and scope of the writing, and reviews the contents of the writing in abbreviated form.

2. An abstract is a succinct summary of a longer piece of work, usually academic in nature, which is published in isolation from the main text and should therefore stand on its own and be understandable without reference to the longer piece. It should report the essential facts of the latter and should not exaggerate or contain material that is not there.

Writing in chemistry is similar to writing in other disciplines in that your paper must have a clear purpose that explains why you are writing, a thesis statement or main idea that defines the problem to be addressed, and background information wherever necessary. In addition, you should include evidence in the form of figures, graphs, and tables to support your argument. Ideally, the abstract can be thought of as one or two sentences from each section of the paper that form a cohesive paragraph that summarizes the entire paper. The abstract should be single spaced unless you receive other instructions from your professor.

When writing an abstract, you should avoid too much experimental detail (e.g. concentration of stock solutions used) or preliminary results (i.e. " raw" data). In addition, make certain that the purpose of the experiment is stated clearly and early in the abstract. Ideally, it should be stated in the first or second sentence.

Purpose

Its purpose is to act as a reference tool (for example in a library abstracting service), enabling the reader to decide whether or not to read the full text.

Reasons

Two common reasons for writing an abstract are

- to summarize a longer piece of work published as a journal article, thesis, book or web page, an existing article for the purposes of a journal,

- to submit an application to write a paper for a conference.

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