Waste disposal is a concern in industrialised countries with high populations. Recent advances in technology provide safer methods for disposing of waste products. Despite these advances, waste remains an environmental health concern. Some types of waste are harmless to the environment, but others are dangerous enough to warrant laws and regulations in certain countries to prevent improper disposal of them.
Incineration reduces waste materials into their base components by burning them. This process generates heat, which is then used for energy. The by-products of this disposal method include various gases and inert ash. Incineration produces various levels of pollution depending on the incinerator design and the waste material being burnt. However, filters can minimise the pollution. Incineration has a higher financial value than recycling because it is cheaper to burn waste for energy than the expenses involved in recycling. However, it is more expensive than disposing in a landfill. Incineration reduces waste volume by up to 90 per cent of the original refuse. If organic waste is incinerated, the resulting ash can provide nutrients for hydroponic solutions. It is the preferred method for disposing of toxic chemicals and hazardous wastes.
Recycling is a conservation method of waste disposal. It involves reusing materials by reprocessing them industrially and turning them into new or similar products. The most common recyclable items are plastic, paper, glass and aluminium. Recycling bins are available for home, office or public use to collect recyclables before being taken to recycling centres. Recycling is the most environmentally friendly method to dispose of waste because it does not add any waste material. The downside of recycling is that only certain items can be recycled, and processing plants are expensive to operate and maintain.
Composting is a natural biodegradation process that converts organic wastes into plant food. This occurs by allowing the waste to sit in one place for months until microbes decompose it. This process can turn unsafe waste products into safe compost. Composting preserves more nutrients than incineration and is the preferred method for organic waste disposal. The disadvantages are that it is a slow process and requires a lot of land.
Waste products that cannot be reused or provide another benefit must go somewhere. That place is usually a landfill. With recent technology, waste can be dumped in a landfill without the danger of polluting groundwater. This is done by placing protective lining beneath the waste to prevent harmful chemicals from leaking into the groundwater and polluting drinking water. Each layer of waste is compacted and covered by a layer of earth. Soil with low permeability is preferred for landfills in order to make the waste materials less susceptible to leakage. Some landfills use hardening materials such as cement or asphalt to seal each layer of waste. Landfills are usually located in areas without flooding or high groundwater levels.