Before the decomposition process is completed, these materials cause inestimable pollution to both sea and land environment. The living biological components in the environment as well as the normal cycles and nutrient flows and the interrelationships existing among biotic organisms are disrupted by the toxic presence of these materials.
The illustrations above clearly show the futility of improperly disposing items into our waters and soil. If it takes about 500 years for an object such as tin or can to completely decompose, it therefore means that our health and environment are in great jeopardy and serious risk of pollution for so long, talk less of exposure to such substances as polystyrene for a millennium.
As waste disposal baskets, trash cans and refuse drums are provided on the streets, roads, highways, parks and other public and private places in the metropolis, strong public awareness campaign on the need to properly dispose waste products is vital for positive results. Effective demonstrations and illustrations can be shown over and over again on TV, webs, bill boards, radio jingles and local announcements could be effective in the rural and suburban communities.
The hazardous and toxic effects of environmental pollution could be demonstrated by showing the unpleasant sight and offensive nature of domestic sewage and industrial waste that are thoughtlessly spewed into open waters (such as streams, rivers, lakes), canals, gutters and city drainage. Bio accumulation and bio magnification of heavy metals often occur in living systems, leading to heavy metal pollution, cancer, organ malformation an[d eventual death of organisms. An Italian environmental association estimates the number of years it takes for certain material substances to degrade and decompose completely in the environment (Green Living Tips, 2009). Figure shows some materials and the corresponding approximate period for each of them to undergo complete decomposition in our environment.
The above illustrations simply emphasize the environmental damage and detrimental effects that often result from improper disposal of not-readilybiodegradable materials such as plastics, nylon bags, tins, cans and other not-easily biodecomposable substances such as glass and metal objects (Fig. 4). For effectiveness along these lines, industrialists should initiate or institute promotions/bonanzas and declare incentives for the collection of throw-away packs. They should assist in environmental cleanliness and sanitation programmes by providing along with their products, guidelines on how to properly dispose their by-product/packs (Intergovernmental Panel on Climate Change, 2006). They may also provide the trashcans for doing so.
Recycling and re-cyclable materials: Many more products could be made from materials that could be recycled. This will minimize cost and contribute to a cleaner environment. A recyclable material is one that could be molded and reprocessed with the aim of being reused for the same purpose or another purpose in the future. Recycling involves the concentration of use waste materials, their reprocessing (if required) and their subsequent reutilization in place of new materials (Britannica Corporate Site, 2001). This has also proved to be one of the most promising methods for conservation of mineral resources. If carried out in an organized and consequent manner, recycling can greatly reduce the drain on supplies and utilization of new mineral resources. It is also appropriate for products derived from living resources, such as the reclamation of organic fertilizers from sewage. Recycling can help reduce the quantities of solid waste deposited in landfills, which have become increasingly expensive. Recycling reduces the pollution of air, water and soil resulting from waste disposal. It has a cleansing and refreshing effect on the surrounding environment.
Insects such as ants, termites and dung insect are good biological waste recycling agents. Another notable example is the earthworm (Lumbricus spp.). In nature, these worms consume decomposing organic wastes found in the soil. They, thus produce huge quantities of worm casts that are very rich in plant nutrients. In addition, harmful microbes present in these decaying wastes on which the worms feed, are killed as they pass through the worm’s gut. Because of its outstanding cleansing and recycling ability, it is being harnessed by waste disposal industries, particularly in Australia. The use of some 500 million worms that are fed with pig manure or human waste and shredded wastepaper, numerous waste-processing equipment produce nutrient-rich plant foods that are marketed and utilized in horticultural and agricultural fields for crop production. There are two broad types of recycling operations: internal and external. Internal recycling is the reuse in a manufacturing process of materials that are a waste product of that process. Internal recycling is common in the metals industry. The manufacture of copper tubing results in a certain amount of waste in form of tube ends and trimmings; this material is remelted and recast. Another from of internal recycling is seen in the distilling industry, in which, after the distillation, spent grain (such as castor oil seed) mash is dried and processed into an edible foodstuff (livestock feed) for cattle or processed for organic fertilizers production .
External recycling is the reclaiming of materials from a product that has been worn out or rendered obsolete. An example of external recycling is the collection of old newspapers and magazines for repulping and their manufacture into new paper products such as light cardboard paper and tissue paper. Aluminum cans and glass bottles are other examples of everyday objects that are externally recycled on a large scale. These materials can be collected by any of three main methods: buy-back centers, which purchase waste materials that have been sorted and brought in by consumers; drop-off centers, where consumers can deposit waste materials but are not paid for them; and curbside collection, in which homes and businesses sort their waste materials and deposit them by the curb for collection by a central agency. Society’s choice of whether and how much to recycle depends basically on economic factors. Conditions of affluence and cheap raw materials encourage people’s tendency to simply discard used materials. Recycling becomes economically attractive when the cost of reprocessing waste or recycled material is less than the cost of processing new materials (Britannica Corporate Site, 2001). Many developing countries will do well to consider this. Their governments can also make the needed plans and policies for the introduction and production of the necessary equipment and technology to improve and facilitate their waste management procedures. Proper allocation of funds and other appropriate resources will contribute adequately to such waste management schemes. To reduce environmental pollution and hazards by plastic bags, a remarkable recycling process has been introduced in Australia. Components of cassava/tapioca starch are being used to produce environmentally friendly and biodegradable bags. Tests show that after use and when disposed, these bags can decompose in three months (Green Living Tips).
Treatment, storage and disposal: Several options are available for hazardous waste management. The most desirable will aim at reducing the quantity of waste at its source or to recycle the materials for some other productive use. Nevertheless, while reduction and recycling are desirable options, they are not regarded as the final remedy to the problem of hazardous waste disposal. There will always be a need for adequate treatment as well as for proper storage, transportation or disposal of some amount of hazardous waste from time to time.
Hazardous waste can be treated by chemical, thermal, biological and physical methods. Chemical methods include ion exchange, precipitation, oxidation and reduction and neutralization. Among thermal methods include the use of high temperature incineration, which will not only detoxify certain organic wastes but also destroy them. Special types of thermal equipment are used for burning waste in the solid, liquid, or sludge form. These include the fluidized-bed incinerator, multiple-hearth furnace, rotary kiln and liquid-injection incinerator. One problem posed by hazardous waste incineration is the potential for air pollution.
The use of pollution-free incinerators and other equipment for burning and reducing wastes to ashes are effective when utilized as appropriately. The ash endproduct of incinerator-treated-wastes could be effectively used as components of manure and environmental friendly fertilizers for agricultural and horticultural purposes.
Biological treatment of certain organic wastes, such as those from the petroleum industry, is also an option. One method used to treat hazardous waste biologically is called land farming. In this technique the waste is carefully mixed with surface soil on a suitable tract of land. Microorganisms that can metabolize the waste may be added, along with nutrients. In some cases, a genetically engineered bacteria species is used. Food or forage crops are not grown on the same site. By bioremediation, microbes can also be sued for stabilizing hazardous wastes on previously contaminated zones. Higher plants, insects and earthworm have also been used as biological agents for waste treatment and recycling. Bioremediation is a principle as well as a technique whereby biological resources are utilized to restore a degraded area to its original state (CE-RASE, Arimoro).
The chemical, thermal and biological treatment methods outlined above change the molecular form of the waste material. Physical treatment, on the other hand, concentrates, solidifies, or reduces the volume of the waste. Physical processes include evaporation, sedimentation, flotation and filtration. Yet another process is solidification, which is achieved by encapsulating the waste in concrete, asphalt, or plastic. Encapsulation produces a solid mass of material that is resistant to leaching. Waste can also be mixed with lime, fly ash and water to form a solid, cement-like product (Britannica Corporate Site, 2001. All these methods of treatment and recycling can be introduced and largely utilized in waste management programs in developing nations. The implementation and programs should serve both urban and rural communities. Methods for domestic waste management include the use of pits and burying. Usually, only readily degradable material wastes such as organic litters of plant and animal parts, agric produce, food materials and faecal dropping are best suited for such disposal techniques. In most cases, there is an additional beneficial effect burying gives to the soil environment\, it enhance organ decomposition\, humus formation, nutrient cycling and soil refertilization. The user charges technique is an effective tool for combating and ameliorating the existing waste collection and weak disposal situation in developing countries. In discussing how this methods work, Ikeanyionwu (2000) highlighted its efficiency when all parties cooperate as a team to achieve a cleaner and healthier environment that will undoubtedly contribute to national economic growth. He suggested that users pay a reasonable fee for the services of waste collection and disposal. In this way customer household, individuals or private enterprises (who become users) relieve and assist the government in urban waste management programmes. This technique could also be introduced and incorporated in rural waste management schemes.