Waste in the context of Ventilation (physiology)

A sustainable city, eco-city, or green city is a city designed with consideration for the social, economic, and environmental impact (commonly referred to as the triple bottom line), as well as a resilient habitat for existing populations. The UN Sustainable Development Goal 11 defines as one that is dedicated to achieving green, social, and economic sustainability, facilitating opportunities that prioritize inclusivity as well as maintaining a sustainable economic growth. Furthermore, the objective is to minimize the inputs of energy, water, and food, and to drastically reduce waste, as well as the outputs of heat, air pollution (including CO2, methane, and water pollution).

The UN Environment Programme calls out that most cities today are struggling with environmental degradation, traffic congestion, inadequate urban infrastructure, in addition to a lack of basic services, such as water supply, sanitation, and waste management. A sustainable city should promote economic growth and meet the basic needs of its inhabitants, while creating sustainable living conditions for all. Ideally, a sustainable city is one that creates an enduring way of life across the four domains of ecology, economics, politics, and culture. The European Investment Bank is assisting cities in the development of long-term strategies in fields including renewable transportation, energy efficiency, sustainable housing, education, and health care. The European Investment Bank has spent more than €150 billion in bettering cities over the last eight years.

In economics, goods are anything that is good, usually in the sense that it provides welfare or utility to someone. Goods can be contrasted with bads, i.e. things that provide negative value for users, like chores or waste. A bad lowers a consumer's overall welfare.

Economics focuses on the study of economic goods, i.e. goods that are scarce; in other words, producing the good requires expending effort or resources. Economic goods contrast with free goods such as air, for which there is an unlimited supply.

An economic system, or economic order, is a system of production, resource allocation and distribution of goods and services within an economy. It includes the combination of the various institutions, agencies, entities, decision-making processes, and patterns of consumption that comprise the economic structure of a given community.

An economic system is a type of social system. The mode of production is a related concept. All economic systems must confront and solve the four fundamental economic problems:

In economics, the secondary sector is the economic sector which comprises manufacturing, encompassing industries that produce a finished, usable product or are involved in construction.

This sector generally takes the output of the primary sector (i.e. raw materials like metals, wood) and creates finished goods suitable for sale to domestic businesses or consumers and for export (via distribution through the tertiary sector). Many of these industries consume large quantities of energy, require factories and use machinery; they are often classified as light or heavy based on such quantities. This also produces waste materials and waste heat that may cause environmental problems or pollution (see negative externalities). Examples include textile production, car manufacturing, and handicraft.

Resource efficiency is the maximising of the supply of money, materials, staff, and other assets that can be drawn on by a person or organization in order to function effectively, with minimum wasted (natural) resource expenses. It means using the Earth's limited resources in a sustainable manner while minimising environmental impact. Natural resource efficiency is embedded into the work of initiatives like the United Nations Environment Programme (UNEP) and international strategies such as the European Union's "Green Deal".

Waste management or waste disposal includes the processes and actions required to manage waste from its inception to its final disposal. This includes the collection, transport, treatment, and disposal of waste, together with monitoring and regulation of the waste management process and waste-related laws, technologies, and economic mechanisms.

Waste can either be solid, liquid, or gases and each type has different methods of disposal and management. Waste management deals with all types of waste, including industrial, chemical, municipal, organic, biomedical, and radioactive wastes. In some cases, waste can pose a threat to human health. Health issues are associated with the entire process of waste management. Health issues can also arise indirectly or directly: directly through the handling of solid waste, and indirectly through the consumption of water, soil, and food. Waste is produced by human activity, for example, the extraction and processing of raw materials. Waste management is intended to reduce the adverse effects of waste on human health, the environment, planetary resources, and aesthetics.

Cleanliness is both the state of being clean and free from germs, dirt, trash, or waste, and the habit of achieving and maintaining that state. Cleanliness is often achieved through cleaning. In most cultures, cleanliness is considered a good quality, as indicated by the aphorism: "Cleanliness is next to Godliness", and may be regarded as contributing to other ideals such as health and beauty.

The concept of cleanliness emphasizes an ongoing procedure or set of habits for the purpose of maintenance and prevention. In this it differs from purity, which is a physical, moral, or ritual state of freedom from pollutants. Whereas purity is usually a quality of an individual or substance, cleanliness has a social dimension. "Cleanliness", observed Jacob Burckhardt, "is indispensable to our modern notion of social perfection". A household or workplace may be said to exhibit cleanliness, but ordinarily not purity. Cleanliness is also a characteristic of people who maintain cleanness or prevent dirtying.

Mine reclamation is the process of modifying land that has been mined to restore it to an ecologically functional or economically usable state. Although the process of mine reclamation occurs once mining is complete, the planning of mine reclamation activities may occur prior to a mine being permitted or started. Mine reclamation creates useful landscapes that meet a variety of goals, ranging from the restoration of productive ecosystems to the creation of industrial and municipal resources. In the United States, mine reclamation is a regular part of modern mining practices. Modern mine reclamation reduces the environmental effects of mining.

Many abandoned mine sites have no reclamation works undertaken. The majority of mines throughout history have no stringent regulations applied. As a practice, mine reclamation began at the start of the 20th century. Returning the landscape to its original state is not possible in all cases. In most cases the physical and chemical stabilization of mine waste is the limit of mine remediation.

Breathing (respiration or ventilation) is the rhythmic process of moving air into (inhalation) and out of (exhalation) the lungs to enable gas exchange with the internal environment, primarily to remove carbon dioxide and take in oxygen.

All aerobic organisms require oxygen for cellular respiration, which extracts energy from food and produces carbon dioxide as a waste product. External respiration (breathing) brings air to the alveoli where gases move by diffusion; the circulatory system then transports oxygen and carbon dioxide between the lungs and the tissues.

Storage tanks are containers that hold liquids or compressed gases. The term can be used for reservoirs (artificial lakes and ponds), and for manufactured containers. The usage of the word "tank" for reservoirs is uncommon in American English but is moderately common in British English. In other countries, the term tends to refer only to artificial containers. In the U.S., storage tanks operate under no (or very little) pressure, distinguishing them from pressure vessels.

Tanks can be used to hold materials as diverse as milk, water, waste, petroleum, chemicals, and other hazardous materials, all while meeting industry standards and regulations. Storage tanks are available in many shapes: vertical and horizontal cylindrical; open top and closed top; flat bottom, cone bottom, slope bottom and dish bottom. Large tanks tend to be vertical cylindrical, with flat bottoms, and a fixed frangible or floating roof, or to have rounded corners transition from the vertical side wall to bottom profile, in order to withstand hydraulic hydrostatic pressure. Tanks built below ground level are sometimes used and referred to as underground storage tanks (USTs).

A circular economy (CE), also referred to as circularity, is a model of resource production and consumption in any economy that involves sharing, leasing, reusing, repairing, refurbishing, and recycling existing materials and products for as long as possible. The concept aims to tackle global challenges such as climate change, biodiversity loss, waste, and pollution by emphasizing the design-based implementation of the three base principles of the model. The main three principles required for the transformation to a circular economy are: designing out waste and pollution, keeping products and materials in use, and regenerating natural systems. Circular economy is defined in contradistinction to the traditional linear economy.

The idea and concepts of a circular economy have been studied extensively in academia, business, and government over the past ten years. It has been gaining popularity because it can help to minimize carbon emissions and the consumption of raw materials, open up new market prospects, and, principally, increase the sustainability of consumption. At a government level, a circular economy is viewed as a method of combating global warming, as well as a facilitator of long-term growth. Circular economy may geographically connect actors and resources to stop material loops at the regional level. In its core principle, the European Parliament defines the circular economy as "a model of production and consumption that involves sharing, leasing, reusing, repairing, refurbishing, and recycling existing materials and products as long as possible. In this way, the life cycle of products is extended." Global implementation of circular economy can reduce global emissions by 22.8 billion tons, equivalent to 39% of global emissions produced in 2019. By implementing circular economy strategies in five sectors alone: cement, aluminum, steel, plastics, and food, 9.3 billion metric tons of CO₂ equivalent (equal to all current emissions from transportation) can be reduced.

A landfill is a site for the disposal of waste materials. It is the oldest and most common form of waste disposal, although the systematic burial of waste with daily, intermediate, and final covers only began in the 1940s. In the past, waste was simply left in piles or thrown into pits (known in archeology as middens).

Landfills take up a lot of land and pose environmental risks. Some landfill sites are used for waste management purposes, such as temporary storage, consolidation, and transfer, or for various stages of processing waste material, such as sorting, treatment, or recycling. Unless they are stabilized, landfills may undergo severe shaking or soil liquefaction during an earthquake. Once full, the area over a landfill site may be reclaimed for other uses.

Recycling is the process of converting waste materials into new materials and objects. This concept often includes the recovery of energy from waste materials. The recyclability of a material depends on its ability to reacquire the properties it had in its original state. It is an alternative to "conventional" waste disposal that can save material and help lower greenhouse gas emissions. It can also prevent the waste of potentially useful materials and reduce the consumption of fresh raw materials, reducing energy use, air pollution (from incineration) and water pollution (from landfilling).

Recycling is a key component of modern waste reduction and represents the third step in the "Reduce, Reuse, and Recycle" waste hierarchy, contributing to environmental sustainability and resource conservation. It promotes environmental sustainability by removing raw material input and redirecting waste output in the economic system. There are some ISO standards related to recycling, such as ISO 15270:2008 for plastics waste and ISO 14001:2015 for environmental management control of recycling practice.

Waste minimisation is a set of processes and practices intended to reduce the amount of waste produced. By reducing or eliminating the generation of harmful and persistent wastes, waste minimisation supports efforts to promote a more sustainable society. Waste minimisation involves redesigning products and processes and/or changing societal patterns of consumption and production.

The most environmentally resourceful, economically efficient, and cost effective way to manage waste often is to not have to address the problem in the first place. Managers see waste minimisation as a primary focus for most waste management strategies. Proper waste treatment and disposal can require a significant amount of time and resources; therefore, the benefits of waste minimisation can be considerable if carried out in an effective, safe and sustainable manner.

Resource recovery is using wastes as an input material to create valuable products as new outputs. The aim is to reduce the amount of waste generated, thereby reducing the need for landfill space, and optimising the values created from waste. Resource recovery delays the need to use raw materials in the manufacturing process. Materials found in municipal solid waste, construction and demolition waste, commercial waste and industrial wastes can be used to recover resources for the manufacturing of new materials and products. Plastic, paper, aluminium, glass and metal are examples of where value can be found in waste.

Resource recovery goes further than just the management of waste. Resource recovery is part of a circular economy, in which the extraction of natural resources and generation of wastes are minimised, and in which materials and products are designed more sustainably for durability, reuse, repairability, remanufacturing and recycling. Life-cycle analysis (LCA) can be used to compare the resource recovery potential of different treatment technologies.

Hazardous waste is waste that must be handled properly to avoid damaging human health or the environment. Waste can be hazardous because it is toxic, reacts violently with other chemicals, or is corrosive, among other traits. As of 2022, humanity produces 300–500 million metric tons of hazardous waste annually. Some common examples are electronics, batteries, and paints. An important aspect of managing hazardous waste is safe disposal. Hazardous waste can be stored in hazardous waste landfills, burned, or recycled into something new. Managing hazardous waste is important to achieve worldwide sustainability. Hazardous waste is regulated on national scale by national governments as well as on an international scale by the United Nations (UN) and international treaties. A controlled waste is subject to legislative control in its handling or its disposal.