The New Nation - Internet Edition

Water is one of the most essential components for survival of life on the earthThe pressures on our water resources are growing. More houses are being built, our population is increasing, and we are all using more water. Per capita consumption increases but the water supply in Dhaka city is limited. Ground water accounts for nearly 100% of drinking water supply. Overexploitation of ground water has become a common measure to provide water, which has caused a series of environmental problems. The water table is continuously going down in Dhaka city as well as the peri- urban area in Dhaka city.

On the other hand, utilisation of rainfall is at low level .When water becomes more and more critical for human existence and development, it is necessary to pay greater attention to direct use of precipitation, especially in Dhaka city where surface and sub-surface water is short or their abstraction is very difficult and rainwater is the only potential or easy to exploit water source available. Under these circumstances, rainwater becomes a very important and reliable water source because it is accessible almost every where in Dhaka city. Rainwater that is captured and stored correctly is a safe, economical and sustainable source of quality water. Safety measures can be applied to the manner in which rainwater is captured, stored and dispensed. In fact some people argue that rainwater is safer than water supplied through mains or reticulated water systems. Our mains water is typically stored in dams, treated with chemicals such as chlorine to kill bacteria and make it safe, and then pumped through a network of pipes throughout the community. It makes sense to catch the rain that falls for free without chemicals.

Significant economic, social and environmental benefits can be achieved by using rainwater. By using Rainwater Harvesting systems to supply water for some, or indeed all of our requirements, you can reduce your dependence on mains water. Our water supplies are falling and water restrictions are in place in many communities to reduce our overall water usage and protect our supplies.

There is no better quality water available naturally than rainwater. Some say there are health benefits to using rainwater which is not treated with chemicals like our mains water is.

Rainwater falls for free - once you have installed a rain harvesting system, you use less mains water and can reduce your water bills. Rainwater Harvesting reduces the significant damage to our creeks, water habitats and organisms caused by storm water runoff. So we can easily harvest rainwater to mitigate potable water crisis in Dhaka city.

Neelufer Yasmin

MBSTU Tangail.

Industrial pollution

Industrial activities are a major source of air, water and land pollution, leading to illness and loss of life all over the world. The World Health Organization estimates that outdoor air pollution alone accounts for around 2% of all heart and lung diseases, about 5% of all lung cancers, and about 1% of all chest infections.

World sales in chemical products have multiplied nine times since 1970, increasing from 171 billion dollars to 1500 billions in 1998. Among the most polluting products are heavy metals - for example, mercury inside batteries, lead in gasoline - and pollutants made from oil (plastic…). Spreading into water, air, and land, heavy metals contaminate the entire food chain, including humans.

In Europe and in the U.S.A, the rates of testicle cancers have tripled over the last fifty years and breast cancer today hits 1 woman in 8, compared to 1 in 20 in 1960. Despite these facts, humans produce about 1000 new chemical substances every year that add to the 70,000 chemical molecules already available on the market. Although consistent progress in filtering and reprocessing has been made to stop the direct discharging of sewage into rivers or particulate into the atmosphere, industrial pollution still accumulates in estuaries or in the air. Traces of DDT - a very powerful and toxic insecticide that blocks respiratory organs - have even been found in the fat of Antarctic penguins. Moreover, industrial pollutions also last longer periods of time. What must be done with the existing 200,000 tons of nuclear waste and with the 5% that will remain dangerous over periods of thousands of years ?

The largest part of the global pollution comes from industrial countries which produce over 95% of all dangerous products. In these countries, regulations for treatment and elimination of industrial waste became so strict and costly that firms turn to developing countries to get rid of their waste. Countries exporting the largest amount of waste are Germany, the Netherlands, the U.S.A., the U.K., and Australia. After being over-used in the eighties, African countries signed the Treaty of Bamako in 1991 which prohibits the import of dangerous waste onto their territories. South East Asia and Eastern Europe are today's new clients. A recent survey shows that over half of the American " recycled " computers are in reality exported to China.

Here, poorly paid workers reprocess useful materials before burning the rest in the open air, which is source to highly toxic emissions. Furthermore, not only waste, but polluting factories and technologies tend to moves to least constraining world regions. Indeed, a number of products which are either forbidden or progressively banned from Northern markets can still be produced and purchased in the developing countries. Among these, we find 47 medicines and over 500,000 tons of pesticides.

Many countries ask for the creation an international law framework for production and transportation of toxic products. The "Basel convention on the control of trans-boundary movements of hazardous wastes and their disposal" has been ratified by 152 countries (not the USA), and came into effect in 1992. Some efforts are done to ban the most harmful pollutants.

During the Johannesburg Summit of August 2002, a new list of twelve toxic chemical products called POP (Persistent Organic Pollutants) has been prohibited. Also, the European Commission launched a project for a 'white book'. For the first time ever (according to the project) governments won't bear the duty and cost to check, after they have been marketed, if substances are hazardous or not: industrials will have to prove their safety before they become marketable! A revolution which requires effective control procedures even within developing countries. With no doubt such project would represent a positive step to enforce the polluter/payer principle. But other steps still need to be taken. Environmental management in industries is possible as show more and more initiatives. A growing number of industries need to be aware of this embark on environmental certifying process.

Sifat Munim Tanin

MBSTU Tangail.

Carbon capture and storage

The term "carbon capture and storage" (CCS), also known as "carbon capture and sequestration", refers to a set of technologies designed to reduce carbon dioxide (CO2) emissions from large-point sources including coal-fired power plants to mitigate climate change. CCS technology involves capturing CO2 and then storing the carbon in a reservoir other than the atmosphere, instead of allowing it to be released into the atmosphere where its accumulation contributes to climate change.

Several different categories of strategies for storing carbon are possible and have been proposed; these include storing carbon in terrestrial ecosystems, the oceans, and underground in geologic formations. Terrestrial carbon storage refers primarily to biological carbon sequestration in the biosphere relying on the photosynthetic process of capturing and converting atmospheric carbon dioxide into organic carbon.

Ocean storage generally refers to the injection of captured CO2 directly into the oceans but also includes other mechanisms of enhancing oceanic uptake of carbon. Geologic carbon storage refers to the injection of captured CO2 into underground, naturally occurring geologic reservoirs that will trap the gas to prevent it from re-entering the atmosphere. Another proposed approach often referred to as mineral carbonation involves chemical reactions that transform the carbon in gas-phase CO2 into solid-phase carbonate minerals. Among these different carbon storage approaches, geologic storage has emerged as the method with the greatest potential for large-scale CO2 emissions reductions in the near term.

A complete CCS system involving geologic carbon storage includes four basic steps with different technologies required for each step: (1) capture the CO2 from a power plant or other concentrated stream; (2) transport the CO2 gas from the capture location to an appropriate storage location; (3) inject the CO2 gas into an underground reservoir; and (4) monitor the injected CO2 to verify its storage.

Technologies that are commercially-used in other sectors are currently available for each of these components. CO2 capture technology is already widely used in ammonia production and several other industrial manufacturing processes as well as oil refining and gas processing. CO2 gas has been transported through pipelines and injected underground for decades, most notably in West Texas where it is used to enhance oil recovery (EOR) of declining-production wells.

Some 3-4 million tons of CO2 per year is currently successfully stored underground at several locations, including Sleipner in the North Sea, Weyburn in Saskatchewan, Canada, and In Salah in Algeria. Technologies to monitor the carbon dioxide and verify its storage are also available. The integration and the scaling-up of the existing technologies to capture, transport, and store CO2 emitted from a full-scale power plant, however, has not yet been demonstrated, although this is the goal of the US Department of Energys FutureGen project.

The concept of engineering systems to deliberately capture and store CO2 has evolved in the past twenty years from a relatively obscure idea to an increasingly recognised set of potential climate change mitigation options.

While the technical feasibility of CCS involving underground storage in geologic formations has been demonstrated in other applications and several demonstration projects, this technology is unlikely to be used widely until regulations on carbon emissions are instituted so that reducing carbon dioxide emissions into the atmosphere provides an economic benefit that will offset the cost of implementing the technology.

Although studies on the risks associated with injecting CO2 underground have found minimal concerns, widespread of adoption of CCS technology could also be limited by public acceptance due to the novelty of the concept as well as by uncertainties resulting from the lack of demonstrated full-scale integration of the technology.

Sifat MunimTanin

MBSTU Tangail.