What is Wastewater? Wastewater is used water. It includes substances such as human waste, food scraps, oils, soaps and chemicals. In homes, this includes water from sinks, showers, bathtubs, toilets, washing machines and dishwashers. Businesses and industries also contribute their share of used water that must be cleaned. Wastewater contains nitrogen and phosphorus from human waste, food and certain soaps and detergents. Once the water is cleaned to standards set and monitored by state and federal officials, it is typically released into a local water body, where it can become a source of nitrogen and phosphorus pollution. Greywater Greywater is defined as wastewater without any contributions from toilet water It is considered high volume, low strength wastewater with high potential for reuse and application. The composition of greywater is varied and depends on the lifestyle, fixtures and climatic conditions. Reuse of greywater has been an old practice, and it is still being done in areas that are water stressed. This practice if given the needed attention can help reduce the over-reliance on freshwater resources and reduce the pollution caused by discharge of untreated greywater into freshwater resources. It can also be a supplementary source to existing water sources in areas where there is acute water crisis or in arid climatic regions. It’s typically the wastewater from showers, baths, hand basins, washing machines, laundry troughs and kitchens. Blackwater "Black water" can refer to several different things based on the context. In terms of wastewater, it signifies sewage or human waste-containing water that originates from toilets and similar sources. This type of water requires specialized treatment due to its high contamination levels compared to "greywater," which comes from sources like sinks and showers. In a natural setting, "blackwater" might describe bodies of water such as rivers with dark or blackish water resulting from dissolved organic matter and tannins leached from decaying vegetation. It typically comes from toilets and contains human waste (feces and urine) along with water used for flushing. It is considered highly contaminated and poses a greater risk to human health and the environment compared to greywater. Blackwater contains pathogens, bacteria, and other microorganisms that can carry diseases and infections. Sewage water Sewage water is wastewater from people living in a community. It is the water released from households after it has been used for various purposes like washing dishes, laundry, flushing the toilet, and other like purposes, thus the name waste water. The used water, or wastewater, leaves the houses through pipes installed during plumbing. It then moves into sewers, either constructed by the house owner or into a sewer facility set up by the municipality. Sewage water is the combination of greywater, blackwater and trade waste. Industrial wastewater Industrial wastewater is not just a byproduct of oil and gas or mining and chemical manufacturing companies, but also a by-product of food and beverage processing industries, essential in the making of the clothes on your back, the shoes on your feet, the computer at your fingertips, and the car your drive. To comply with existing laws, any organic and inorganic pollutants to water used in industrial production must be managed. Organic matter, metals, and the like found in the wastewater must be removed before the water can be safely discharged back to land, into bodies of water, or reused in plant operations. Some example of industries that produce this type of wastewater are metal finishers, mining, chemical manufacturing and power plants. Environment Untreated waste water can affect ecosystems through oxygen depletion, biodegradation of organic materials, and water-borne pathogens. Every ecosystem relies on water, however big or small. So, if water is polluted with chemicals, toxins, or by products of other human waste, these environments could be put in serious danger. Health If you come into contact with wastewater or its products, you could end up being exposed to harmful microorganisms that can cause illnesses such as: gastroenteritis (diarrhoea or vomiting), giardiasis and cryptosporidiosis (severe stomach cramps, diarrhoea or vomiting), viral infections such as hepatitis (liver infections), infections of the skin or eyes. Society These impacts can include harm to fish and wildlife populations, oxygen depletion, beach closures and other restrictions on recreational water use, restrictions on fish and shellfish harvesting and contamination of drinking water. This may force people to evacuate the place, loose their job because of health issue and a lot more. Wastewater Treatment The removal of impurities from wastewater, or sewage, before it reaches aquifers or natural bodies of water such as rivers, lakes, estuaries, and oceans. Since pure water is not found in nature (i.e., outside chemical laboratories), any distinction between clean water and polluted water depends on the type and concentration of impurities found in the water as well as on its intended use. In broad terms, water is said to be polluted when it contains enough impurities to make it unfit for a particular use, such as drinking, swimming, or fishing. Although water quality is affected by natural conditions, the word pollution usually implies human activity as the source of contamination. Water pollution, therefore, is caused primarily by the drainage of contaminated wastewater into surface water or groundwater, and wastewater treatment is a major element of water pollution control. Biological water treatment This uses various biological processes to break down the organic matter present in wastewater, such as soap, human waste, oils and food. Microorganisms metabolize organic matter in the wastewater in biological treatment. It can be divided into three categories: •Aerobic processes: Bacteria decomposes the organic matter and converts it into carbon dioxide that can be used by plants. Oxygen is used in this process. •Anaerobic processes: Here, fermentation is used for fermenting the waste at a specific temperature. Oxygen is not used in anaerobic process. •Composting: A type of aerobic process where wastewater is treated by mixing it with sawdust or other carbon sources. Secondary treatment removes most of the solids present in wastewater, however, some dissolved nutrients such as nitrogen and phosphorous may remain. Physical water treatment Physical methods are used for cleaning the wastewater. Processes like screening, sedimentation and skimming are used to remove the solids. No chemicals are involved in this process. One of the main techniques of physical wastewater treatment includes sedimentation, which is a process of suspending the insoluble/heavy particles from the wastewater. Once the insoluble material settles down at the bottom, you can separate the pure water. Another effective physical water treatment technique includes aeration. This process consists of circulating air through the water to provide oxygen to it. Filtration, the third method, is used for filtering out all the contaminants. You can use special kind of filters to pass the wastewater and separate the contaminants and insoluble particles present in it. The sand filter is the most commonly used filter. The grease found on the surface of some wastewater can also be removed easily through this method. Chemical water treatment This treatment involves the use of chemicals in water. Chlorine, an oxidizing chemical, is commonly used to kill bacteria which decomposes water by adding contaminants to it. Another oxidizing agent used for purifying the wastewater is ozone. Neutralization is a technique where an acid or base is added to bring the water to its natural pH of 7. Chemicals prevent the bacteria from reproducing in water, thus making the water pure. Sludge treatment This is a solid-liquid separation process where the least possible residual moisture is required in the solid phase and the lowest possible solid particle residues are required in the separated liquid phase. An example of this includes dewatering of sludge from industrial wastewater or sewage plant where the residual moisture in dewatered solids determines the disposal costs and the centrate quality determines the pollution load returned back to the treatment facility. You need to minimize both. A solid-liquid separation device such as a centrifuge is used for removing the solids from the wastewater. Preliminary Treatment Primary Treatment Secondary Treatment Disinfection Sludge Treatment Waste to Energy ACTIVATED SLUDGE PLANT (ASP) An activated sludge plant, also known as an activated sewage plant or ASP, uses a wastewater treatment process that involves adding oxygen and microorganisms to organic pollutants. These microorganisms used in wastewater treatment cause the pollutants to oxidize, creating a sludge type substance biologically. Examples of ASP sewage treatment plants include: Vortex BioPure Crystal EcoConder ASP WPL Diamond Bison Biodigester ROTATING DISC SYSTEM Rotating disc-system wastewater treatment plants offer a reliable and robust solution that delivers high-quality effluent. They are suitable for all applications and can also be retrofit to existing wastewater management systems. They are the ideal solution for populous areas as they offer minimal noise pollution and have a small footprint. Unlike some other types of wastewater treatment plants, rotating disc systems only need to be de-sludged once every 12-18 months. They also do not require a full-time attendant to carry out raking duties. Examples of rotating disc system treatment plants include: •Tuke and Bell •Klargester Biodisc •Clearwater Rotoclear Due to the nature of the mechanical and internal moving parts, rotator disc systems must be maintained by a qualified engineer. Depending on the size of the system, servicing should be performed every 6-12 months. SUBMERGED AERATED FILTER SYSTEM Submerged aerated filter systems, also known as SAFs, are a popular choice of wastewater treatment system. These systems require little in the way of maintenance, have few moving parts, and are simple to operate. For companies looking to reduce overhead without affecting effluent quality, SAF is a good option. SAFs require no regular operator to be present and can be used for both industrial and domestic wastewater processing. Examples of submerged aerated filter systems include: •Falcon •Acorn •Conder SAF •Clearwater Aeroclear •Matrix SEQUENCING BATCH REACTORS Sequencing batch reactors, also known as fill and draw systems, process wastewater using a sequence of steps. All steps take place within the same tank reactor. These systems are extremely flexible and allow the treatment of a range of different wastewater types, from very dilute to very strong. Examples of sequencing batch reactors include: •Fluidyne •Argos •Lakeside Due to their relatively small footprint and ease of operation, these types of reactors used in wastewater treatment require minimal maintenance and also save on capital costs due to the elimination of clarifiers and other equipment.
