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Activated Sludge Model
Activated sludge model is a generic name for a group of mathematical methods to model activated sludge systems. The research in this area is coordinated by a task group of the International Water Association (IWA). Activated sludge models are used in scientific research to study biological processes in hypothetical systems. They can also be applied on full scale wastewater treatment plants for optimisation, when carefully calibrated with reference data for sludge production and nutrients in the effluent. Around 1983 a task group of the International Association on Water Quality (one of the associations that formed IWA) was formed. They started creating on a generalised framework for mathematical models that could be used to model activated sludge for nitrogen removal. One of the main goals was to develop a model of which the complexity was as low as possible and simple to represent, though still able to accurately predict the biological processes. After four years, the first IAWQ m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Activated Sludge
The activated sludge process is a type of biological wastewater treatment process for treating sewage or Industrial wastewater treatment, industrial wastewaters using aeration and a biological floc (biofilm), floc composed of bacteria and protozoa. It is one of several biological wastewater treatment alternatives in secondary treatment, which deals with the removal of biodegradable organic matter and suspended solids. It uses air (or oxygen) and microorganisms to Biological oxidizer, biologically oxidize organic pollutants, producing a waste sludge (or Flocculation, floc) containing the oxidized material. The activated sludge process for removing carbonaceous pollution begins with an aeration tank where air (or oxygen) is injected into the waste water. This is followed by a settling tank to allow the biological flocs (the sludge blanket) to settle, thus separating the biological sludge from the clear treated water. Part of the waste sludge is recycled to the aeration tank and the r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Water Association
The International Water Association (IWA) is a self-governing nonprofit organization and knowledge hub for the water sector, connecting water professionals and company, companies to find solutions to the world's water challenges. It has Employment, permanent staff housed in its headquarters and global Secretariat (administrative office), secretariat in central London, the United Kingdom, to support the activities, and has a regional office in Chennai, India. The aim of the IWA is to function as an international network for water experts and promote standards and optimal approaches in sustainability, sustainable water management. Its membership is a global mosaic comprising 313 Technology company, technology companies, water and wastewater utilities, 54 university, universities, and wider stakeholders in the fields of water services, infrastructure engineering and consulting as well as 7,791 individuals including scientists and researchers, with 53 governing members (2021). IWA is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wastewater Treatment
Wastewater treatment is a process which removes and eliminates contaminants from wastewater. It thus converts it into an effluent that can be returned to the water cycle. Once back in the water cycle, the effluent creates an acceptable impact on the environment. It is also possible to reuse it. This process is called Reclaimed water, water reclamation. The treatment process takes place in a wastewater treatment plant. There are several kinds of wastewater which are treated at the appropriate type of wastewater treatment plant. For domestic wastewater the treatment plant is called a Sewage Treatment. Municipal wastewater or sewage are other names for domestic wastewater. For industrial wastewater, treatment takes place in a separate Industrial wastewater treatment, or in a sewage treatment plant. In the latter case it usually follows pre-treatment. Further types of wastewater treatment plants include Agricultural wastewater treatment and leachate treatment plants. One common proce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Oxygen Demand
In environmental chemistry, the chemical oxygen demand (COD) is an indicative measure of the amount of oxygen that can be consumed by reactions in a measured solution. It is commonly expressed in mass of oxygen consumed over volume of solution, which in SI units is milligrams per liter ( mg/ L). A COD test can be used to quickly quantify the amount of organics in water. The most common application of COD is in quantifying the amount of oxidizable pollutants found in surface water (e.g. lakes and rivers) or wastewater. COD is useful in terms of water quality by providing a metric to determine the effect an effluent will have on the receiving body, much like biochemical oxygen demand (BOD). Overview The basis for the COD test is that nearly all organic compounds can be fully oxidized to carbon dioxide with a strong oxidizing agent under acidic conditions. The amount of oxygen required to oxidize an organic compound to carbon dioxide, ammonia, and water is given by: :\mbox_n\mbox_a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bacterial Growth
250px, Growth is shown as ''L'' = log(numbers) where numbers is the number of colony forming units per ml, versus ''T'' (time.) Bacterial growth is proliferation of bacterium into two daughter cells, in a process called binary fission. Providing no mutation event occurs, the resulting daughter cells are genetically identical to the original cell. Hence, bacterial growth occurs. Both daughter cells from the division do not necessarily survive. However, if the surviving number exceeds unity on average, the bacterial population undergoes exponential growth. The measurement of an exponential bacterial growth curve in batch culture was traditionally a part of the training of all microbiologists; the basic means requires bacterial enumeration (cell counting) by direct and individual (microscopic, flow cytometry), direct and bulk (biomass), indirect and individual (colony counting), or indirect and bulk (most probable number, turbidity, nutrient uptake) methods. Models reconcile theor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biomass
Biomass is a term used in several contexts: in the context of ecology it means living organisms, and in the context of bioenergy it means matter from recently living (but now dead) organisms. In the latter context, there are variations in how biomass is defined, e.g., only from plants, from plants and algae, from plants and animals. The vast majority of biomass used for bioenergy does come from plants and fecal matter. Bioenergy is a type of renewable energy that the bioenergy industry claims has the potential to assist with climate change mitigation. Uses in different contexts Ecology * Biomass (ecology), the mass of living biological organisms in a given area or ecosystem at a given time. This can be the biomass of particular species or the biomass of a particular community or habitat. Energy * Biomass (energy), biomass used for energy production or in other words: biological mass used as a renewable energy source (usually produced through agriculture, forestry or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyphosphate-accumulating Organisms
Polyphosphate-accumulating organisms (PAOs) are a group of microorganisms that, under certain conditions, facilitate the removal of large amounts of phosphorus from their environments. The most studied example of this phenomenon is in polyphosphate-accumulating bacteria (PAB) found in a type of wastewater processing known as enhanced biological phosphorus removal (EBPR), however phosphate hyperaccumulation has been found to occur in other conditions such as soil and marine environments, as well as in non-bacterial organisms such as fungi and algae. PAOs accomplish this removal of phosphate by accumulating it within their cells as polyphosphate. PAOs are by no means the only microbes that can accumulate phosphate within their cells and in fact, the production of polyphosphate is a widespread ability among microbes. However, PAOs have many characteristics that other organisms that accumulate polyphosphate do not have that make them amenable to use in wastewater treatment. Specificall ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biological Phosphorus Removal
Enhanced biological phosphorus removal (EBPR) is a sewage treatment configuration applied to activated sludge systems for the removal of phosphate. The common element in EBPR implementations is the presence of an anaerobic tank (nitrate and oxygen are absent) prior to the aeration tank. Under these conditions a group of heterotrophic bacteria, called polyphosphate-accumulating organisms (PAO) are selectively enriched in the bacterial community within the activated sludge. In the subsequent aerobic phase, these bacteria can accumulate large quantities of polyphosphate within their cells and the removal of phosphorus is said to be ''enhanced''. EBPR can also integrate biological nitrogen removal through the addition of an anoxic zone where nitrate is present due to the denitrification capabilities of some PAO. Generally speaking, all bacteria contain a fraction (1-2%) of phosphorus in their biomass due to its presence in cellular components, such as membrane phospholipids and DNA. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitrification
''Nitrification'' is the biological oxidation of ammonia to nitrate via the intermediary nitrite. Nitrification is an important step in the nitrogen cycle in soil. The process of complete nitrification may occur through separate organisms or entirely within one organism, as in comammox bacteria. The transformation of ammonia to nitrite is usually the rate limiting step of nitrification. Nitrification is an aerobic process performed by small groups of autotrophic bacteria and archaea. Microbiology Ammonia oxidation The process of nitrification begins with the first stage of ammonia oxidation, where ammonia (NH3) or ammonium (NH4+) get converted into nitrite (NO2−). This first stage is sometimes known as nitritation. It is performed by two groups of organisms, ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA). Ammonia-Oxidizing Bacteria Ammonia-Oxidizing Bacteria (AOB) are typically Gram-negative bacteria and belong to Betaproteobacteria and Gammaproteob ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Phosphorus Removal
Chemical phosphorus removal is a wastewater treatment method, where phosphorus is removed using salts of aluminum (e.g. alum or polyaluminum chloride), iron (e.g. ferric chloride), or calcium (e.g. lime). Phosphate forms precipitates with the metal ions and is removed together with the sludge in the separation unit ( sedimentation tank, flotation tank, etc.). Aluminum sulfate treatment to reduce phosphorus content of lakes One method of eutrophication remediation is the application of aluminum sulfate, a salt commonly used in the coagulation process of drinking water treatment. Aluminum sulfate, or "alum" as it is commonly referred, has been found to be an effective lake management tool by reducing the phosphorus load. Alum was first applied in 1968 to a lake in Sweden. Its first application to an American lake followed in 1970. Today, alum has been utilized with improved effectiveness and understanding. In a large scale study, 114 lakes were monitored for the effectiveness of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Activated Sludge
The activated sludge process is a type of biological wastewater treatment process for treating sewage or Industrial wastewater treatment, industrial wastewaters using aeration and a biological floc (biofilm), floc composed of bacteria and protozoa. It is one of several biological wastewater treatment alternatives in secondary treatment, which deals with the removal of biodegradable organic matter and suspended solids. It uses air (or oxygen) and microorganisms to Biological oxidizer, biologically oxidize organic pollutants, producing a waste sludge (or Flocculation, floc) containing the oxidized material. The activated sludge process for removing carbonaceous pollution begins with an aeration tank where air (or oxygen) is injected into the waste water. This is followed by a settling tank to allow the biological flocs (the sludge blanket) to settle, thus separating the biological sludge from the clear treated water. Part of the waste sludge is recycled to the aeration tank and the r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bacterial Growth
250px, Growth is shown as ''L'' = log(numbers) where numbers is the number of colony forming units per ml, versus ''T'' (time.) Bacterial growth is proliferation of bacterium into two daughter cells, in a process called binary fission. Providing no mutation event occurs, the resulting daughter cells are genetically identical to the original cell. Hence, bacterial growth occurs. Both daughter cells from the division do not necessarily survive. However, if the surviving number exceeds unity on average, the bacterial population undergoes exponential growth. The measurement of an exponential bacterial growth curve in batch culture was traditionally a part of the training of all microbiologists; the basic means requires bacterial enumeration (cell counting) by direct and individual (microscopic, flow cytometry), direct and bulk (biomass), indirect and individual (colony counting), or indirect and bulk (most probable number, turbidity, nutrient uptake) methods. Models reconcile theor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
