Absorption chillers are refrigerators that use heat energy as an input, rather than mechanical energy. Absorption chillers are useful, where electricity is no available or where there is an easily available source of heat (e.g. sun, hot water). The heat is used to evaporate a liquid to a gas. The gas then moves to the condenser where the heat dissipates and the gas is turned back into a liquid. Then, the cooled liquid is directed into the evaporator, where it turns into a gas and pulls heat from the air. Then the gas moves from the evaporator into the compressor and the process starts again. Synonyms: Absorption Refrigerator
An accumulation tank or a continuously fed batch is characterised by an increasing effective reactor volume with time. When the reactor is full and reaction time is over, it is emptied and refilled again as batch reactors. Synonyms: AC, Accumulation Tank, Fed Batch Reactor
The process by which molecules of a substance, such as a gas or a liquid, collect on the surface of another substance, such as a solid. The molecules are attracted to the surface but do not enter the solid's minute spaces as in absorption.
Learning opportunities for adults exist in a variety of settings, ranging from a formal institution to day to day practical learning at work. It is important to acknowledge prior knowledge and experiences of learners, including their ability to recognize their own skills as lifelong learners. Considerations for adult development and learning include biological and psychological development and socio cultural and integrative perspectives on development.
The term advanced oxidation processes (AOP), describes a series of processes which are used for the chemical treatment of organic and inorganic pollutants in wastewaters. AOPs are based on the generation of reactive oxygen species (ROS) such as hydroxyl radicals. Generating hydroxyl radicals is possible via various ways such as photocatalytic, electrochemical, sonochemical. Typical AOPs are H2O2/hv, ozone/hv, ozone/H2O2/hv, TiO2/hv, (photo-)Fenton systems and electrochemical processes. Synonyms: AOP
Advanced Wastewater Treatments
Advanced wastewater treatments, in opposition to natural systems require generally highly engineered biological processes, which leads to a reduction in space requirement to achieve similar performances. However, due to the complexity of the process and the high requirements for energy and operation and maintenance, advanced systems inhere a higher risk of technical failure.
Advection fog is a certain type of fog, that requires a steady wind that moves a fog layer that has formed upwind of a given site.
Advocacy is the action of delivering an argument to gain commitment from political and social leaders and to prepare a society for a particular issue (DE JONG 2003). Advocacy involves the selection and organisation of information to create a convincing argument, and its delivery through various interpersonal and media channels (e.g. public speaking, project visits, petitions, engaging celebrities, radio and newspaper). Influencing and involving important leaders is one of the essentials of advocacy, because political support together with support from community leaders and religious leaders can give a water-related project or campaign a powerful boost (SCHAAP & VAN STEENBERGEN 2001). Synonyms: Influencing Leaders
Aerobic means ‘requiring oxygen’. Aerobic processes can only function in the presence of molecular oxygen (O2), and aerobic organisms are those that use oxygen to drive cellular respiration and store energy.
Aeroponics is the process of growing plants in an air or mist environment without the use of soil or an aggregate medium. The word "aeroponic" is derived from the Greek meanings of "aero" (air) and "ponos" (labour). Unlike hydroponics, which uses water as a growing medium and essential minerals to sustain plant growth, aeroponics is conducted without a growing medium. Aeroponic equipment involves the use of sprayers, misters, foggers, or other devices to create a fine mist of water to deliver nutrients to plant roots. Because water is used in aeroponics to transmit nutrients, it is sometimes considered a type of hydroponics.
The first UN Conference on Environment and Development in 1992 adopted an agenda for environment and development in the 21st Century. This “Agenda 21: A Programme of Action for Sustainable Development” reaffirmed that sustainable development was delimited by the integration of the economic, social and environmental pillars. The “Agenda 21” is not legally binding, a reason to be criticised by many.
Soil particles can stick together and build aggregates where water can be enclosed.
Agricultural issues provides background knowledge that is necessary to understand loop-oriented approaches in the management of water and wastewater - such as soil properties, plant requirements, etc.
Agricultural wastewater is all waters that have been used in agriculture and are refused. They are either biodegradable (most often) and can be treated and reused similar to blackwater (e.g. manure from livestock); or they are not biodegradable (e.g. water containing a lot of residues from pesticides etc.) and require an advanced oxidation processes for treatment.
Air stripping is the transferring of volatile components of a liquid into an air stream. It is a chemical engineering technology used for the purification of groundwater and wastewater containing volatile compounds. Synonyms: Stripping
A rapid increase in the population of algae in an aquatic system, e.g. as a result of an excess of nutrients (particularly phosphorus and nitrogen). As more algae and plants grow, others die. This dead organic matter becomes food for bacteria that decompose it. With more food available, the bacteria increase in number and use up the dissolved oxygen in the water. When the dissolved oxygen content decreases, many fish and aquatic insects cannot survive. Synonyms: Marine Bloom, Water Bloom
Alkaline is an adjective describing the properties of having a pH greater than 7. It is the opposite of acidic.
The alkalinity measures the capacity of water to neutralise acids. The alkalinity depends on amount of carbonates, bicarbonates, hydroxides, and occasionally borates, silicates and phosphates. Alkalinity stabilises water at pH levels around 7 (neutral). However, high water acidity decreases alkalinity and may cause harmful conditions for aquatic life. Alkalinity is expressed in ppm or mg of calcium carbonate per litre (mg/L CaCO3).
An alluvial river is a river in which the bed and banks are made up of mobile sediment and/or soil. Alluvial rivers are self-formed, meaning that their channels are shaped by the magnitude and frequency of the floods that they experience, and the ability of these floods to erode, deposit, and transport sediment. As such, alluvial rivers can assume a number of forms based on the properties of their banks; the flows they experience; the local riparian ecology, and the amount, size, and type of sediment that they carry. These forms can be meandering, braiding, wandering and (occasionally) straight.
Anaerobic means completely deficient in oxygen and describes environments where there is no molecular gaseous oxygen (O2), neither any other form of oxygen available for metabolic activity. Anaerobicmicroorganisms use other molecules than oxygen for the respiratory activity. Anaerobic processes are either hindered, or halted by the presence of oxygen. Anaerobic processes are often more foul-smelling than aerobic processes.
An anaerobic baffled reactor is an improved septic tank, which, after a primary settling chamber, uses a series of baffles to force the grey-, black- or the industrial wastewater to flow under and over the baffles as it passes from the inlet to the outlet. The wastewater is introduced into the chamber at the bottom, leading to an enhanced contact with the active biomass which results in an increased retention and anaerobic degradation of suspended and dissolved organic pollutants. ABRs are robust and can treat a wide range of wastewater, but both remaining sludge and effluents still need further treatment in order to be reused or discharged properly. Synonyms: ABR
Anal Cleansing Water is water used to cleanse oneself after defecating and/or urinating; it is generated by those who use water, rather than dry material, for anal cleansing. The volume of water used per cleaning typically ranges from 0.5 L to 3 L.
Anoxic describes environments where there is no molecular gaseous oxygen (O2), but other forms of oxygen can still be present (in opposite to anaerobic, which means that there is no oxygen at all). Organisms that can live in an anoxic environment can use oxygen that is bound in other molecules (e.g. nitrate, sulphate). Anoxic conditions are often found at the interface between aerobic and anaerobic environments (e.g. in trickling filters or in facultative ponds).
To protect the immediate surroundings of a well, a concrete slab is installed around the water extraction point. Synonyms: Well cover
The aqua privy is a simplified variation of the septic tank. It is a simple storage and settling tank immediately under the latrine floor. Excreta drop directly into the tank through a pipe. Te bottom of the pipe is submerged in the liquid in the tank, forming a water seal to prevent escape of flies, mosquitoes and smell. Effluent usually infiltrates into the ground through a soak pit. Accumulated solids (sludge) must be removed frequently and enough water must be added to compensate for evaporation and leakage losses (in order to maintain the water seal).
Aquaculture is commonly defined as the active cultivation (maintenance or production) of marine and freshwater aquatic organisms (plants and animals) under controlled conditions. This definition encompasses a broad range of operations, cultivating a wide variety of organisms such as fish, crustaceans and aquatic plants, using a wide variety of production systems and facilities. Aquaculture can be combined with the reuse of wastewater. Nutrients contained in wastewater are removed by feeding animals or plants, which can be harvested. Pathogens can also be removed by natural die-off, solar disinfection (in shallow ponds) or predation (even though the effluent is not pathogenically safe). The combination of aquaculture and wastewater reuse allows optimising the water use for farming of aquatic animals and plants for food production all by increasing the quality of the wastewatereffluent.
Aquaponics is the symbiotic cultivation of plants and aquatic animals in a recirculating environment. Aquaponic comes from the two words aquaculture and hydroponic. The main aim of such systems is the recycling of the nutrients contained in the water from aquatic animal effluent. The system contain of to interlinked compartement, one for growing plants and one for growing aquatic animals. The plants take up the nutrients, allowing them to grow and reducing or eliminating the water's toxicity for the aquatic animal. Thus the water can be recirculated back to the animal pond where it will be charged again by nutrients.
An aquifer is a wet underground layer of water-bearing permeable rock or unconsolidated materials (gravel, sand, or silt) from which groundwater can usefully be extracted using a water well.
Artificial fertilisers are plant nutrients produced through chemical processes to nurture soil and foster plant growth. Artificial fertilisers mainly consist of plant macronutrients such as Nitrogen, Potassium, Phosphorus and Sulphur, but lack other essential substances (micronutrients). Artificial fertiliser are able to improve the chemical properties of soils, but as they contain no organic substances, they are not able to counter the loss of organic substance through harvesting, which is important for soil structure. On the other hand, organicfertilisers produced out of biodegradable waste – such as e.g. kitchen residues, manure and other organic waste – are complete fertilisers that are able to improve both physical and chemical properties of the soil, and that are normally more balanced in their composition, containing macro- and micronutrients.
Artificial Groundwater Recharge
Artificial recharge is the planned, man-made increase of groundwater levels. By improving its natural replenishment capacities and percolation from surface waters into aquifers, the amount of groundwater available for abstraction is increased. Treated effluent and/or stormwater is discharged into aquifers either directly or after pre-treatment (e.g. wastewater stabilisation ponds or constructed wetlands). This is particularly useful in areas where water and groundwater resources are heavily utilised and acute problems with dropping watersheds, soil salinisation, saltwater intrusion in coastal areas or water scarcity in general exist. Synonyms: Groundwater Recharge
An automated irrigation system refers to the operation of the system with no or just a minimum of manual intervention. Almost every irrigation system can be automated with the help of timers, sensors, computers, or mechanical appliances.
Automatic Surge Flow and Gravitational Tank Irrigation System
This is an intermittent gravity-flow irrigation system consisting of a storage tank equipped with one or more siphons. The water in the tank flows to the field because of the siphon effect. As soon as the tank is empty, the flow stops. For the next irrigation process, the tank has to be filled-up to restart the siphon effect again. To learn more about possible siphon designs see VORTECH (2009).
With Awareness Raising Tools, you try to influence social norms, attitudes and values of people so they will change their behaviour because they are convinced that they are doing the right thing and their actions are in line with their personal values. Different types of information, education and communication (IEC) instruments can be used to initiate behavioural change and to stimulate social pressure towards sound and sustainable policies.
Awareness Raising for Demand Creation
Awareness raising includes an array of different technologies to make people aware of a problem, a new approach, a solution etc.