I know it's probably a topic that has been stewing on your mind for what seems like forever but fret no more. Sewage treatment generally involves three main stages - the primary, secondary and tertiary treatment stages without further ado, here are the 3 stages of sewage treatment that you have always wanted to know, but were too afraid to ask:
The first stage in sewage treatment is the primary sedimentation stage. Sewage including all of the grey and black water from a home flows into a chamber called the primary sedimentation tank and holds waste until it has had enough time for heavy sediment to disperse to the bottom. Lighter waste such as oil and grease floats to the top and can be skimmed off. Once this process has been completed, the leftover wastewater (effluent) then leaves the sedimentation tank and proceeds into a secondary pre-treatment chamber.
The second stage of sewage treatment involves the simple science of decomposition and accelerates it by creating the perfect breeding ground for an aerobic biological process. This involves creating an effective breeding ground for anaerobic bacteria and protozoa to survive. This bacteria feeds on the pollutants within the wastewater and in turn, starts the breakdown process. In order for this process to work effectively you need oxygen a food source for the bacteria to thrive and this chamber is designed to do just that.
Creating small bubbles which aerate the chamber, generates more oxygen in the water which allows for aerobic bacteria to grow rapidly and become way more effective than what would happen outside a treatment tank.
The final main treatment stage is just as important as the others and probably even more so due to the fact that wastewater will be leaving the confines of a treatment facility and will be reintroduced to the environment. The third stage of the process allows for the wastewater to settle, and at this point, it will be lighter and less dense than water was when it entered the system as a sludge. At this stage, aerobic bacteria will settle to the bottom of the tank and then chlorine or UV light will be introduced at this point to remove any unwanted bacteria from the water.
After this, further treatment may be given to the wastewater depending on the use or location it is to be discharged. Regardless of the fact that it's a public or private sewage system, wastewater leaving a sewage treatment must adhere to specific guidelines and industrial standards.