Alfred's Waste Water Treatment Case Study

Alfred’s wastewater treatment plant is not so different from any other plant except in a few regards. It has three main methods of treatment; primary, secondary, and tertiary. These treatments are somewhat standard all around but once the details of each are examined the differences are more apparent. The first process of treatment is primary treatment, which in essence is the physical process of removing pollutants from the influents. (Nathanson and Schneider, 2003). Alfred’s raw sewage is brought to the plant by truck and pumped into their influent building. As it is pumped preliminary treatment begins which involves a bar screen, comminutor and grit basin. The bar screen allows for the removal of materials such as plastics bottles, bags …show more content…
The top of the anaerobic digester floats up and down to account for the fluctuating gas pressure. As previously said the liquid from the sludge is sent to aerobic digesters. As the name implies, these digesters are used as a means to further filter out impurities. Air is sent into the digesters from the bottom of the tanks to move the effluent around evenly. Once this process is complete, the effluent is sent back to the primary clarifier. The primary clarifier is the beginning of the wastewater secondary treatment process. Once wastewater enters, the circular shaped primary clarifier has a rotating arm the length of the clarifier that scopes or gathers solids. The primary clarifier is like a “bucket within a bucket” in the sense that the basin within is meant to overflow into another basin so it will pass through v-notched weirs that work as another screen to remove solids. After the primary clarifier, the effluent is collected and pumped up into the plant’s trickling …show more content…
These stones are covered in bacteria that work to purify and this new effluent is sent to the plant’s biotower. This is another difference between other treatment plants and Alfred’s plant. Normally, this effluent collected from the trickling filter and brought right away to a secondary clarifier but Alfred’s is sent to the biotower. The biotower looks like a large water-holding tank but is it actually a filtration and aeration center. The effluent is pumped to the top of the tower to another rotating arm with nozzles attached that spray the effluent over screens to help remove bacteria. After this, the effluent is collected from the bottom of the biotower and sent to wet wells where alum is applied as a chemical to help make the fine partials stick together or flocculate so they can be removed. The wet walls then release the effluent to the plant’s secondary clarifier. The secondary clarifier is similar in most respects to the primary clarifier, although there are differences in detention time, overflow rate, weir loading, and other details. (Nathanson and Schneider, 2003). This is the end of the secondary treatment. The tertiary treatment begins when the effluent from the secondary clarifier enters the tertiary building and undergoes “polish.” This polish is the final step before the effluent can be released back into the