Strategies to Control Environmental Pollution
Table of contents
- Introduction to Strategies to Control Environmental Pollution
- Management of Waste
- Types of Sewage Treatment Processes
- Green Chemistry
- Basic Aims of Green Chemistry
Due to increasing human activities pressure on natural resources is increasing day by day and something has to be done to reduce it, because if it continues at this rate life on earth would become unsustainable. Many environmentalist and scientist are working to make certain strategies to reduce environmental pollution. In addition to solid waste which we see in our household garbage bins, there are medical, industrial, agricultural and mining wastes. Environment is polluted mostly by improper disposal of waste. Therefore there is a need to keep a check over waste disposal.
In this article we would study the methods to control various types of pollution caused by different sources. This involves two common strategies:
Management of waste
The production and improper disposal of domestic and industrial wastes are responsible for Environment Pollution. The domestic waste includes sewage and municipal waste while industrial wastes include inorganic and organic suspended particles and inorganic and organic soluble matter.
One of the best methods to manage wastes especially domestic waste is by collecting them in bins. Government of India is promoting the usage of bins, under the Clean India Campaign that is, Swacch Bharat Abhiyan. It is advisable to collect biodegradable and non-biodegradable wastes into separate bins so that the municipal workers do not have to do extra work for separating them. This household waste is transferred to community bins from where they are collected by municipal workers which take the waste to the dumping sites. Municipal workers separate the waste into biodegradable and non-biodegradable waste at these sites. Biodegradable waste consist of households waste like vegetables, left over food etc. while non-biodegradable includes metal scraps, paper, plastic etc. Those which are biodegradable are dumped in landfills and the non-biodegradable are sent for recycling.
If this procedure is not followed and garbage bins are kept unutilized, all of this waste goes into the sewers, and some of it is eaten by stray animals. This waste chokes the sewers and causes various problems. Many times it gets collected at a place and the place becomes breeding ground for mosquitoes and flies which causes various diseases. Therefore, the best practice is to dispose domestic waste properly. These wastes are treated in the following ways:
Now will discuss ways of treating the waste:
This is a simplest method of treating the waste. Recycling of materials saves much of the raw materials cost as well as reduces the cost of disposal. Some common examples of recycling by industries are:
Recycling of Glass
Using scrap metal to manufacture steel
Recovering energy by burning down of wastes which are combustible in nature
The use of waste paper,
In other words, recycling converts waste into wealth.
The sewage treatment involves the following three types of stages
- The first stage known as Primary Treatment involves the removal of large solid particles. This is done by mechanical process consisting of screening and sedimentation. For this, the waste is filtered through different types of screens. In the next step solid waste are separated and then dumped in landfill sites. It is then allowed to flow into sedimentation tanks. This process allows removal solid that settles out (sludge). This process also allows removal of grease which floats to the surface and can be skimmed off.
- The second stage known as secondary treatment involves the biological oxidation of organic content of waste materials by micro-organisms followed by filtration.
- In the third step which is also called as final treatment which includes various specialized physical and chemical processes which help in reducing the quantities of specific pollutants which remains in the sewage even after primary and secondary treatments. Quality of waste water is improved after this process.The common methods used in this treatment involves reverse osmosis, disinfection by chlorine, treatment with activated charcoal, coagulation, filtration, chemical removal of phosphate etc.
During these operations sludge is produced which also poses a problem for safe disposal. The sludge is dried and then damped or digested or may be incinerated, as explained below.
This converts organic materials into CO2 and Water. This is used for biological waste (e.g. from hospitals), chemical waste, household waste etc. Most of such treatment occurs under aerobic conditions, where plentiful of oxygen is supplied and at very high temperature (above 1273 K). The exhaust gases are filtered. This process reduces the volume of the waste and inorganic ash is left behind which is disposed of as land fill.
Using this method we can easily dispose relatively inert PCBs (polychlorobenzenes) and as this method involves endothermic reactions, the high temperature generated allows the breaking of C-Cl bonds in organochlorine compounds. The main disadvantage of this process is that it causes air pollution. Moreover, the ash particles which comes out from the municipal incinerators are of very minute size and easily inhaled by the human lungs. Incomplete combustion of PCBs can cause formation of highly toxic chlorine compounds such as polychlorodiben-zodioxins (PCDDs) and polychlorodibenzofurans (PCDFs).
In the process of digestion the microorganisms degrade wastes in the absence of oxygen and this happens when sewage undergoes anaerobic digestion. By using this process, a wide variety of toxic organic wastes can be degraded. The products of digestion are carbon dioxide and methane, which may be used as a fuel.
This is widely used practice of dumping the sewage sludge in the nearby seas. It is known as ocean dumping. However, the application of sludge to the land is increasing. The sludge contains nitrogen and phosphorus which may be useful as a fertilizer.
Most of the sludge produced by urban areas consiss of toxic substances, so such toxic sludge must be dumped carefully and in a controlled manner.
We know that increasing population, has increased the use of fossil fuels and increasing number of industries and vehicles are polluting our environment to an alarming extent. The increase in pollution adversely affects the health of humans and other living organisms. It is believed that the advancement and modernization of our society is inducing certain types of cancers for our future. These pollutants are being added in air, in water, in our food supply and in soil. As we know because of agriculture revolution i.e. by developing improved methods of farming, irrigation, improving the quality of seeds, and by using fertilizers and Pesticides India became self-sufficient in production of food since late 20th century. But excessive use of fertilizers and pesticides and over exploitation of soil has resulted into deterioration of air, water and soil.
With the growing awareness of the environmental pollution, the international community is under increasing pressure to find methods to save our lives from the increasing pollution. So should we stop using the technology for advancement? NO. Instead we should search for alternative process or technologies which helps in reduction of pollution of our environment. The scientists are searching new alternatives which do not cause environmental pollution. This new approach is called Green Chemistry which was introduced in early 1990s. It means zero discharge of toxic, persistent substances, into the environment guaranteed by the fact that they are never produced. Green chemistry may be defined as a strategy to design chemical processes and products that reduces or eliminates the use and generation of hazardous substances.
The basic aims of green chemistry are:
(i) Restrict all kind of synthetic routes because of which the hazardous substances do not enter into the atmosphere.
(ii) We must select raw materials in such a manner, that they can be converted into product with all most 100% yield. And this can be done only when we perform the process of synthesis at optimum condition.
(iii) The methods like mining, refining, etc. which are used to obtain the basic raw material should have minimum impact on the natural environment.
(iv) To develop various new routes which can be used for producing green chemicals and materials.
(v) The development of environmentally improved methods for the existing industrial processes. The material inputs should be of low or no toxicity or at least reduced toxicity compared with the traditional method.
(vi) The use of starting materials-reagents and solvents that pose less hazard to man and his environment.
(vii) Water having amazing properties like high specific heat and low volatility, must be used for the purpose of carrying the synthetic reaction. Also water is non-inflammable, cost effective and does not have any carcinogenic effects.
(viii) The raw materials and methods should produce less waste to avoid their treatment and problem of disposal.
(ix) To encourage the use of renewable energy sources as an alternative to fossil fuels, wherever possible
(x) Using biotechnological alternatives.
(xi) Develop new tools and methods for evaluating environmental impact.
(xii) To spread awareness among common man, encouraging the use of green products.
The hazards include toxicity, physical hazards (For Examples: explosions, fires), global climate changes, resource depletion. In other words, green chemistry aims to reduce or eliminate toxic, persistent substances from the environment by ensuring their no further releases and destroying existing deposits of these chemicals. So, green chemistry means environmental friendly or no pollution. For example, we have been using organic solvents as a media for many reactions. Now, scientists are planning greener alternative to use water or nonpolluting solvents as a medium in place of organic solvents. Similarly, instead of using synthetic materials for packing, green chemistry plans to use environmental friendly recyclable or safely disposable materials.
Green Chemistry also requires change in our habits and life-style. These days many green products are available in the market in developed countries.
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