Understanding the Sewage Treatment Plant Process
A Sewerage Treatment Plant (STP) is a complex facility designed to remove sewage waste from community water supplies. Not only does it remove the wastewater but also replaces it with fresh clean water. In larger communities, such as New York and Chicago, there are multiple STPs that serve different communities depending on the severity of their sewer problems. But there is a common misconception about the way the wastewater is treated at these plants.
Most people understand how waste is treated in the garbage system, through collection at a land-based waste transfer station. They do not understand how sewage is treated at STP, or how the wastewater is brought back into the community through a transport line. Sewage treatment plants process all kinds of waste including industrial, municipal and domestic wastewater. Understanding the way these plants operate can help you make better decisions for your facilities.
The three basic processes used in wastewater treatment plants include pretreatment, disinfection and circulation. Pretreatment involves removing contaminants that would otherwise be present in the wastewater. This includes washing and diluting organic materials that cannot be separated from the rest of the material. The wastewater then moves through a variety of filters to make it safer for discharge into the community. Many plants include several stages of treatment to assure that all contaminants are removed, but these are generally not shown on a flow chart.
Disinfection involves adding chemicals to the wastewater to kill any disease-causing bacteria. The most commonly used chemical is chlorine. The idea of using chlorine to kill bacteria in wastewater is that if the wastewater consists of undiluted sewage, it is very easy to cause bacteria to proliferate, resulting in a public health risk. So, by adding chlorine to the wastewater, any pathogenic microorganisms are killed before they can multiply and potentially cause a public health threat. A sewage treatment plant process flow diagram will show how the chlorine is added to the wastewater.
The third stage of the treatment process is where the wastewater exits the treatment plant and enters the community. This is usually done through a sewer line, but can also be through a water pipe or a natural conduit such as a river. When this occurs, it is often referred to as primary sewage processing. The purpose of this step is to remove the bulk of the waste from the sewage in order to allow it to enter any other environment.
Water is then used to de-clog the pipes or channel and to remove solids that may have entered the system during the primary processing stage. Sediment can be very heavy, so it is often passed through filters to ensure that it is removed. When enough water has been filtered through the system, it is discharged into a drain field. The discharge area will vary depending on the volume of water that was released and the size of the pipes that were used.
The last stage of treatment involves the use of chemicals in order to kill any remaining bacteria and ensure that the discharge is at a safe level for human consumption. The most commonly used chemical is chlorine. It is added to the wastewater during the first stage in most plants. After this, other chemicals can be used to help to ensure that the treatment facility is effective in its removal of harmful contaminants.
A flow diagram will help to determine how different treatment plants operate. It will help to ensure that there is consistency in the way that the plants operate as well as in the way that treatment is completed. A flow diagram can also help to keep track of treatment equipment such as pumps, lines, and other equipment. This is especially true if there are multiple sites that need to be cleaned. By keeping track of each stage of the process, it will become easier to complete the entire process as needed.