Bryant Hu
| Resumen biográfico |
What is Wastewater Treatment With water shortages plaguing the world, water scarcity has become one of the largest threats facing society today, making it one of the UN’s main millennium development goals. Therefore governments have begun to develop new projects and technologies to mitigate its effects on the world. Such projects and technologies include rain harvesting, water location transfers, desalination, and wastewater treatment. Unlike the rest, wastewater treatment presents a sustainable short-term and long-term solution to water scarcity. Wastewater is the water used by residences and commercial/industrial establishments that has become too polluted for further use. The combination between these different types of wastewater causes the resulting wastewater mix to contain both suspended and dissolved organic and inorganic substances such as carbohydrates, fats, soaps, synthetic detergents, as well as various natural and synthetic organic chemicals. Wastewater Treatment Process The treatment process must be divided into different treatment stages to ensure good water and sanitation quality. The preliminary stage of the treatment process uses large filtering screens that remove large solid inorganic material such as paper, plastic, and metal. This is followed by the removal of the grit and silt which are abrasive to plant equipment. In the primary stage, wastewater is passed through a primary sedimentation tank where solid particles of organic material are removed by gravity settling at the bottom of the tank. The resultant primary sludge is then raked to the center of the tank where it is concentrated and pumped away for further treatment. The wastewater then undergoes a biological process known as activated sludge process, which uses natural occurring micro-organisms to break down dissolved and suspended organic solids. The settled wastewater then enters aeration tanks where air is blown into the water to provide oxygen promoting the growth of microorganisms. These microorganisms then consume the organic pollutants and nutrients in the wastewater. From the aeration tanks the mixture of wastewater and microorganisms is moved to a secondary sedimentation tank where the biomass settles to the bottom of the tank and is concentrated as sludge. The clarified wastewater is then passed into a tank where the third stage of treatment, known as the Tertiary treatment stage, takes place. In this stage Chlorine is used to remove any biological pathogens present in the clarified wastewater that could be a risk to human health. In some instances this treatment is repeated more than once if the treated wastewater is reused for purposes such as irrigation of food crops or where close human contact may result. After all these treatment processes are complete, fresh water is produced. Benefits The water treatment process does not only produce clean reusable water, but also has the potential to produce various other benefits. It has the potential to reduce a country’s waste production, to produce energy through methane harvesting, and the potential to produce natural fertilizer from the waste collected through the process. Below is a more detailed explanation of these benefits: Waste Reduction Through the treatment of wastewater, the amount of waste that is usually released into the environment is reduced thus improving environment’s health. By doing so, the government in turn reduces the health risks associated with environmental pollution, and reduces the water loss induced through water pollution. Wastewater treatment also reduces the amount of money spent by a country on environmental rehabilitation projects required to battle pollution. Energy Production The sludge collected during the treatment process is itself treated because it contains a large amount of biodegradable material. It is treated with anaerobic bacteria in special fully enclosed digesters heated to 35 degrees Celsius, an area where these anaerobic microorganisms thrive without any oxygen. The gas produced during this anaerobic process contains a large amount of methane, which is harvested and then burned to generate electricity. This energy can be used to power the wastewater treatment plants making them self-sustainable, andif there happens to be an excess of energy produced, it could be transported into a country’s national grid. This helps lower the reliance on non-renewable energy sourcessuch as fossil fuels, reducing a country’s carbon footprint and a country’s expenditure on energy production. An example of this system being used within the Middle East can be found in al-Samra wastewater treatment plants in Jordan. According to government officials the plant produces 40% of the energy it requires through burning the methane produced by the treatment process. Fertilizer Production Any biodegradable material remaining is dried in “drying lagoons” and is then turned into natural fertilizer. The resulting natural fertilizer is then used in the agricultural sector, increasing crop yields. This decreases the use of chemical fertilizers that pollute the surrounding marine and surface ecosystems. Conclusion In summary, the combination of these benefits along with water production makes wastewater treatment a sustainable short and long-term solution to the world’s water crisis, which will only increase as the world population increases. It is estimated that the world’s population is set to increase to 9 billion people, and this would cause an increase in the amount of water that can be treated. This will cause the production of large amounts of fresh usable water, thus helping battle water scarcity. Step by Step Wastewater Treatment Process The following is a step by step process of how wastewater is treated: 1. Wastewater Collection This is the first step in waste water treatment process. Collection systems are put in place by municipal administration, home owners as well as business owners to ensure that all the wastewater is collected and directed to a central point. This water is then directed to a treatment plant using underground drainage systems or by exhauster tracks owned and operated by business people. The transportation of wastewater should however be done under hygienic conditions. The pipes or tracks should be leak proof and the people offering the exhausting services should wear protective clothing. 2. Odor Control At the treatment plant, odor control is very important. Wastewater contains a lot of dirty substances that cause a foul smell over time. To ensure that the surrounding areas are free of the foul smell, odor treatment processes are initiated at the treatment plant. All odor sources are contained and treated using chemicals to neutralize the foul smell producing elements. It is the first wastewater treatment plant process and it’s very important. 3. Screening This is the next step in wastewater treatment process. Screening involves the removal of large objects for example nappies, cotton buds, plastics, diapers, rags, sanitary items, nappies, face wipes, broken bottles or bottle tops that in one way or another may damage the equipment. Failure to observe this step, results in constant machine and equipment problems. Specially designed equipment is used to get rid of grit that is usually washed down into the sewer lines by rainwater. The solid wastes removed from the wastewater are then transported and disposed off in landfills. 4. Primary Treatment This process involves the separation of macrobiotic solid matter from the wastewater. Primary treatment is done by pouring the wastewater into big tanks for the solid matter to settle at the surface of the tanks. The sludge, the solid waste that settles at the surface of the tanks, is removed by large scrappers and is pushed to the center of the cylindrical tanks and later pumped out of the tanks for further treatment. The remaining water is then pumped for secondary treatment. 5. Secondary Treatment Also known as the activated sludge process, the secondary treatment stage involves adding seed sludge to the wastewater to ensure that is broken down further. Air is first pumped into huge aeration tanks which mix the wastewater with the seed sludge which is basically small amount of sludge, which fuels the growth of bacteria that uses oxygen and the growth of other small microorganisms that consume the remaining organic matter. This process leads to the production of large particles that settle down at the bottom of the huge tanks. The wastewater passes through the large tanks for a period of 3-6 hours. 6. Bio-solids handling The solid matter that settle out after the primary and secondary treatment stages are directed to digesters. The digesters are heated at room temperature. The solid wastes are then treated for a month where they undergo anaerobic digestion. During this process, methane gases are produced and there is a formation of nutrient rich bio-solids which are recycled and dewatered into local firms. The methane gas formed is usually used as a source of energy at the treatment plants. It can be used to produce electricity in engines or to simply drive plant equipment. This gas can also be used in boilers to generate heat for digesters. 7. wastewater treatment Tertiary treatment This stage is similar to the one used by drinking water treatment plants which clean raw water for drinking purposes. The tertiary treatment stage has the ability to remove up to 99 percent of the impurities from the wastewater. This produces effluent water that is close to drinking water quality. Unfortunately, this process tends to be a bit expensive as it requires special equipment, well trained and highly skilled equipment operators, chemicals and a steady energy supply. All these are not readily available. 8. Disinfection After the primary treatment stage and the secondary treatment process, there are still some diseases causing organisms in the remaining treated wastewater. To eliminate them, the wastewater must be disinfected for at least 20-25 minutes in tanks that contain a mixture of chlorine and sodium hypochlorite. The disinfection process is an integral part of the treatment process because it guards the health of the animals and the local people who use the water for other purposes. The effluent (treated waste water) is later released into the environment through the local water ways. 9. Sludge Treatment The sludge that is produced and collected during the primary and secondary treatment processes requires concentration and thickening to enable further processing. It is put into thickening tanks that allow it to settle down and later separates from the water. This process can take up to 24 hours. The remaining water is collected and sent back to the huge aeration tanks for further treatment. The sludge is then treated and sent back into the environment and can be used for agricultural use. Wastewater treatment has a number of benefits. For example, wastewater treatment ensures that the environment is kept clean, there is no water pollution, makes use of the most important natural resource; water, the treated water can be used for cooling machines in factories and industries, prevents the outbreak of waterborne diseases and most importantly, it ensures that there is adequate water for other purposes like irrigation. Conclusion In summary, wastewater treatment process is one of the most important environmental conservation processes that should be encouraged worldwide. Most wastewater treatment plants treat wastewater from homes and business places. Industrial plant, refineries and manufacturing plants wastewater is usually treated at the onsite facilities. These facilities are designed to ensure that the wastewater is treated before it can be released to the local environment. Some of the water is used for cooling the machines within the plants and treated again. They try to ensure that nothing is lost. It illegal for disposing untreated wastewater into rivers, lakes, oceans or into the environment and if found culpable one can be prosecuted. |