Solid Waste Management Flashcards
Fundamental Definitions and Waste Terminology
Waste is defined as any material that is thrown away and regarded as useless or unwanted. It arises from the activities of both humans and animals and can exist in a solid or liquid state. In terms of composition, waste is categorized as either hazardous or non-hazardous. Within this broad category, garbage specifically refers to putrescible waste matter that arises from the preparation, cooking, and consumption of food. Refuse is a collective term for solid waste that includes both garbage and rubbish.
Rubbish refers to all non-putrescible wastes with the exception of ash. It consists of both combustible and non-combustible substances. Sewage, by contrast, consists of liquid wastes derived from household effluents, commercial effluents, and industrial liquid wastes, which are transported through a sewage system consisting of pipes and other means of conveyance.
Recycling is defined as the processing of used materials or waste into entirely new products. Recovery is the process of removing materials from the waste stream for the purposes of recycling or composting. To recover a material is to give value to a substance previously believed to be waste, effectively transforming wastes into resources. The best specific example of the recovery process is composting.
Classification Schemes for Waste
Waste can be classified using a multitude of different schemes depending on the focus of the categorization. These schemes include classification by physical state, which identifies waste as solid, liquid, or gaseous. Classification by material distinguishes between substances such as glass, paper, and other materials. Classification by physical properties focuses on whether a waste is combustible, compostable, or recyclable.
Another major scheme is classification by origin, which identifies waste as domestic, commercial, agricultural, or industrial. Furthermore, waste is classified by safety level into hazardous and non-hazardous categories. Hazardous wastes are substances that are unsafe for commercial, industrial, or agricultural use because they possess one or more specific dangerous properties: ignitability, corrosivity, reactivity, and toxicity.
Ignitability refers to substances that are flammable. Corrosivity refers to substances that can rust or decompose. Reactivity describes substances that are explosive. Toxicity indicates that a substance is poisonous. Non-hazardous waste consists of substances that are safe to use commercially, industrially, agriculturally, or economically and do not possess any of the dangerous properties mentioned above.
Sustainability and Concerns Regarding Waste
Wastes must be managed in a specific manner that minimizes risk to human health. Safe waste management must also be sustainable. For waste management to meet the criteria of sustainability, it must be economically affordable, socially acceptable, and environmentally effective.
Environmental effectiveness requires that the waste management system reduces environmental burdens as much as possible, specifically targeting emissions to land, air, and water, such as . Economic affordability means the system must operate at a cost acceptable to the community, including private citizens, businesses, and government entities. The cost of an effective solid waste system depends on local infrastructure but should ideally be little or no more than existing costs. Social acceptability ensures that the management system operates in a manner that the majority of people in the community find acceptable.
Detailed Categories and Sources of Solid Waste
Solid waste is categorized based on its source of generation or its inherent nature. Residential waste, often called household waste, is generated from dwelling apartments and households. Commercial waste comes from businesses, including shops and food or drink establishments. Industrial waste arises from industrial processes like paper manufacture, chemical production, metal processing, and food processing.
Institutional waste is generated by public and government institutions, such as schools, universities, offices, and religious institutions. Its composition is usually very similar to residential and commercial waste. Municipal waste is a broad category covering all the aforementioned wastes produced in an urban area; while similar to residential waste in composition, it generally excludes certain industrial wastes.
Healthcare waste includes any solid waste produced in hospitals, clinics, and health posts. Agricultural waste is waste resulting from farming activities. Waste from open areas includes street sweepings, the contents of roadside dustbins, and waste from ditches or other public places. Construction and demolition waste results from building and demolition activities in urban areas. Electronic and electrical waste, commonly known as e-waste, consists of wastes generated from used electronic devices and household appliances.
Characteristics and Public Health Importance of Solid Waste
Solid waste is classified into two primary categories based on its characteristics: organic and inorganic. Organic solid waste consists of biodegradable materials that decompose, a process that emits offensive and irritating smells if left unattended. These are known as putrescible wastes, with garbage being the primary example. Inorganic solid waste refers to solid matter that does not decompose at any rate. Depending on the nature of the material, these inorganic wastes may be combustible. They are known as non-putrescible wastes, with rubbish being the primary example.
The public health importance of solid waste is significant as it serves as a medium for the growth of microorganisms. It attracts arthropods such as the common housefly and mosquitoes, as well as rodents and other animals like rats, mice, dogs, and cats. Open dumps can contaminate water sources and food supplies, leading to foodborne diseases. Furthermore, hospital and pathological wastes are potential disease-carrying products, while radioactive wastes are highly dangerous.
Solid waste also creates risks for fire accidents and contributes to the degradation of slum areas. It creates nuisances such as bad odors, smoke, and dust, leading to aesthetic problems and physical discomfort such as sneezing and coughing.
Integrated Solid Waste Management (ISWM)
Solid waste management is a complex process involving various technologies and disciplines, including the control of generation, handling, storage, collection, transfer, transportation, processing, and disposal. Integrated Solid Waste Management (ISWM) is a comprehensive program that focuses on waste prevention, recycling, composting, and disposal. Success in an ISWM plan requires positive interdisciplinary communication and interaction between all involved disciplines.
An effective ISWM system considers how to prevent, recycle, and manage solid waste to best protect human health and the environment. The main objective is the improvement of waste minimization strategies and control. The primary steps for integrated waste management are source reduction, recycling and composting, and final disposal through landfilling or combustion.
Source reduction, also known as waste prevention, seeks to prevent waste from being generated. Strategies include using less packaging, designing products for longevity, and reusing materials. This reduces handling and treatment costs and limits the generation of methane. Recycling involves collecting and reprocessing materials like glass, metal, plastics, and paper into new products. Composting is the conversion of organic waste into soil additives. Both generate economic benefits, such as job creation, and environmental benefits, such as reduced greenhouse gas emissions.
Disposal is used for waste that cannot be prevented or recycled. This involves placing waste in properly designed landfills or utilizing combustion. Managed landfills can recover methane to generate energy, while combustion facilities produce steam and water as byproducts for energy generation.
Functional Components of Waste Management
Setting up an effective waste management system requires seven steps: identifying waste types, identifying sources, determining potential health hazards, determining the volume generated, identifying collection methods, identifying transportation methods, and identifying safe disposal methods.
There are five key components of solid waste management: generation, storage, collection, transportation, and disposal. Generation is the stage where a material becomes useless to the owner. Storage involves keeping discarded material prior to collection; on-site storage is critical for public health and aesthetics. Waste handling and separation involve managing waste until it is placed in containers.
Collection includes gathering waste and recyclables and transporting them to a location where the vehicle is emptied, such as a transfer station or landfill. Transfer and transport involve moving waste from smaller collection vehicles to larger transport equipment, usually at a transfer station for long-distance travel. Processing and transformation aim to reduce waste volume and weight and recover energy. Chemical transformation includes combustion, while biological transformation includes aerobic composting.
Processing, Treatment, and Disposal Technologies
Composting is a biological treatment process that converts organic matter into a stable, humus-like material under bacterial action. It is not a final disposal method but a waste minimization tool. The process produces heat at levels of or higher over several days, which destroys fly larvae, weed seeds, and pathogens. The end product serves as a soil builder containing nitrates and phosphates.
Incineration is the hygienic disposal of refuse by burning, ideal for high-calorific waste like paper and plastics. It can reduce waste volume by over and convert it into innocuous material while recovering energy. Although hygienic and space-efficient, it requires high capital and maintenance and raises concerns regarding emissions of particulates, , , and toxic metals.
Open dumping involves dumping refuse in low-lying areas. It is an uncontrolled method common in the developing world due to limited resources. The World Health Organization (WHO) Expert Committee in condemned this as an "insanitary method" that creates public health hazards and pollution. Drawbacks include exposure to rodents, wind dispersal of refuse, and water pollution through drainage.
Sanitary landfilling is an engineered facility designed to minimize environmental impacts by compacting waste and covering it with earth daily. Monofills are landfills for specific constituents like asbestos or ash, while secure landfills are for hazardous waste. Limitations of landfills include high transportation costs, potential water contamination, gas emissions, and explosion risks.
The Waste Hierarchy and the 3-R Concept
The waste hierarchy ranks dealing with waste by desirability. At the top is waste reduction, followed by reuse (e.g., refilling bottles), then recycling. The fourth option is energy recovery via burning or biological treatment, and the final option is disposal in a landfill.
The 3-R concept refers to Reduce, Reuse, and Recycle. Reduction is the best management method and involves buying products with less packaging or buying in bulk. Reuse is the "better" way, involving using items repeatedly or upcycling them. Recycling is the "good" way, involving remanufacturing products to be sold as new. Recycling reduces the consumption of fresh raw materials and limits air and water pollution.
The Philosophy of Zero Waste
Zero Waste is a philosophy that encourages the redesign of resource life cycles so that all products are reused. The ultimate goal is for no trash to be sent to landfills, incinerators, or the ocean. The zero waste hierarchy supports a progression from highest to lowest use of materials: Reduce (the most preferred), followed by Reuse, Recycle, Recover, and finally Landfill (the least preferred).