What Is Waste Disposal?
Waste disposal involves the removal, discarding, or recycling of unwanted materials. This process should not be carried out carelessly because it can lead to water pollution, soil contamination, or air pollution.
Fortunately, there are many ways of dealing with waste materials. They include sanitary landfills, which have liners to prevent leachate from polluting the surrounding environment. They also involve material recycling, which involves transforming garbage into useful products. Click here for more info.
Incineration
Many communities have waste-incineration facilities that combust municipal solid waste and hazardous chemical, biological, and medical waste. These systems are designed to reduce the volume, infectious potential, and toxicity of these materials.
The major operations of waste incinerators and industrial furnaces are combustion, flue gas treatment, and emissions control. Pretreatment of wastes is frequently necessary to facilitate homogenization and continuous feed into the incinerator combustor. Typical pretreatment operations include blending, screening and shredding, and liquid-phase decanting.
Incineration processes produce ash and flue gases that contain gaseous and particulate pollutants. The flue gases are typically treated with air pollution controls, such as fabric filters and scrubbers, before being dispersed into the atmosphere through a stack.
Because the emission rates of these pollutants vary with facility operating conditions, the adequacy of ambient monitoring data collected during only a small fraction of operating hours for any given facility is questionable. The most important factors in determining pollutant concentrations in the air are the time of year, weather conditions, and specific waste-incineration plant operating parameters.
Landfills
A landfill is a huge pit where all kinds of solid waste go for disposal. The wastes include animal manure, crop residues, and industrial byproducts, as well as electronics and household chemicals.
Landfills are usually built in open low-lying areas away from populated regions to avoid pollution and groundwater contamination. They are lined with clay or a synthetic liner to protect the soil and groundwater from the leaks that naturally emerge from the trash when it is decomposing. The landfills are divided into cells to keep the different types of waste separated. The wastes are then broken down into organic molecules by bacteria in a process called anaerobic digestion. The result is methane and other gases that can be vented or used to generate energy.
While the landfills are protected by liners, they cannot exclude water completely. As rainwater trickles through the mounds of garbage, it picks up contaminants and becomes leachate. Plastic drainage pipes channel the leachate into collection ponds where it is treated before being released into nearby waterways. The toxins that ooze out of the landfills pollute surrounding lands and can affect people and animals living miles away.
Sewage Treatment Plants
Sewage treatment plants clean and distill sewage and wastewater faster than nature does, returning clean water to the water cycle. Unfortunately, when they malfunction, high concentrations of nitrogen — which acts as a fertilizer on land and in the sea, causing algae populations to skyrocket and deplete dissolved oxygen — pollute coastal waters and cause mass death among fish, turtles, and manatees.
Wastewater flows into centralized sewer systems that convey it to treatment plants. Overflows occur when a plant’s capacity is overwhelmed by stormwater or sewage, which causes poorly treated and untreated wastewater to discharge directly into local waterways.
The first step in sewage treatment is called preliminary treatment, and it involves screening out objects that cannot be easily removed by mechanical means. This includes bar screens that rip out large objects such as sticks, toys, metal scraps, and rags that can clog and damage equipment. Heavier objects with higher densities than sewage, such as rocks and sand, are eliminated via decantation. Next, sewage goes through primary, secondary, and, if necessary, tertiary treatment.
Biodegradation
Biodegradation is a microbiologically mediated natural process that continually recycles biologically essential elements in Earth’s biogeochemical cycles. It is characterized by the conversion of chemicals to completely oxidized products (mineralization) and by the microbial metabolism of unnatural synthetic chemical (xenobiotic) wastes.
Microbial decomposition of organic wastes can result in the formation of water, carbon dioxide, and biomass. It can occur in aerobic or anaerobic conditions. Biodegradation rates can vary significantly, depending on the prevailing conditions and the types of organisms that are involved in degradation.
Some plastics, such as poly-3-hydroxybutyrate and other polyesters and cellulose acetate and celluloid, biodegrade rapidly, while others biodegrade more slowly. In addition, some plastics exhibit very high resistance to biodegradation. To reduce the amount of plastic in the environment, biodegradable alternatives are being developed. Biodegradable waste is often disposed of through composting, which produces nutrient-rich soil. This is a more consistent process than landfills, which can have variable time frames. Read on to find out!
