Waste Water Purifiers Necessary for a Healthy Environment
The latest data from the National Alliance for Local Economic Development (NALED) shows that in Serbia only 16% of wastewater discharged into sewages is treated annually. With the Urban Wastewater Treatment Directive, the European Union requires that all settlements with more than 2000 inhabitants have a wastewater treatment plant. However, there are only about forty wastewater treatment plants in 168 cities and municipalities, most of which are obsolete, while the Belgrade is the only European capital without a wastewater treatment plant.
Wastewater is full of pollutants, including bacteria, chemicals and other toxins. It is produced by bathing, washing, using toilets, during industrial processes and rainwater runoff. Our mission in environmental conservation is to build a plant that will turn wastewater into water that can be returned to the environment and reused as needed. We want the construction of wastewater treatment plants to reduce the concentration of pollutants to an acceptable (minimum possible) level so that such wastewater, and subsequently purified water, is safe to discharge into rivers or soil.
Wastewater treatment plants operate in four phases:
1) Preliminary phase or pre-treatment
At this initial stage of wastewater treatment, branches, leaves, cans, canvases, plastics, stones, diapers and other waste materials are separated. This is achieved by vertically positioning the grilles, or to facilitate cleaning at an angle of 30 to 60 and even up to 80 degrees. Swimming pools in many wastewater plants are designed to deposit rocks, sand, glass, etc. with water. Some plants already remove oil and grease at this stage, while others do so during the subsequent primary wastewater treatment.
2) The primary treatment
The primary treatment removes the substances that can be easily collected from the raw wastewater before damaging or blocking the pumps and other devices, which are used in the following purification steps. Large basins and sedimentation tanks are essential for this phase, in which wastewater is collected after initial treatment. Reduced water flow rates and gravity allow finer particles to settle, while mechanical scrapers collect solids and direct them to reservoirs connected to sludge treatment equipment.
3) The secondary treatment
The secondary treatment is a biochemical process because it is also under the influence of microorganisms and is applied for the further removal of suspended particles. This phase involves the use of biologically active sludge. The wastewater treatment plant removes residual organic matter and suspends solids at this stage. Therefore, this phase is also called biological purification. Useful microorganisms, natural decomposers, are added to the wastewater, which are used to decompose organic matter into sludge. Drives utilize numerous alternative sludge-breaking strategies.
For example, wastewater plants can grow masses of germs and waste matter transmitted through biofilm. Other plants mix biomass with waste material, creating activated sludge that can be recycled for reuse. Using bacteria removes carbon and nitrogen from organic waste. Oxidation can occur on the surface – in lagoons – or in filter layers containing coke coal and limestone. Some plants create wetlands where organic materials are broken down. Other technologies used include membrane bioreactors and biological aerated filters. The resulting wastewater is collected and deposited in a secondary treatment tank.
4) Sludge treatment
The final phase is the treatment of residual water and sediment. The sludge that has accumulated in wastewater treatment must be processed and disposed of in a safe place. The goal is to reduce the amount of organic matter and the number of pathogens present in the sludge
During the sludge treatment, gravity separates the organic waste from the heavier grain, which can be disposed of in landfill. The remaining primary precipitate is transferred to a thickener, where it is centrifuged and fed into digestion tanks containing anaerobic bacteria. The process takes place in the presence of oxygen. Under aerobic conditions, bacteria quickly consume organic matter and convert it to carbon dioxide.
The sludge can eventually be removed by odors and used as fertilizer on the field. The residual wastewater is treated to remove phosphorus, nitrogen and other additives, disinfected with chlorine, ozone or ultraviolet light, and then discharged or returned for domestic or industrial use.
Conclusion regarding the wastewater treatment plant
For the protection of the environment, wastewater treatment is essential in all areas, both wastewater from homes and workplaces, and from industrial plants. Disposal of untreated wastewater into rivers, lakes or the surrounding area is illegal and can be prosecuted. This is why wastewater in industrial plants, refineries and production facilities is usually treated on site. These facilities are designed to ensure that wastewater is treated before it is discharged into the local environment. Our goal is to build exactly that.