Presented by Andrea Bruner, Meghan Eade, and Nadia Dastgir. Chipola Junior College, Marianna, FL. Why do we treat wastewater? We treat wastewater in order to remove substances that are harmful or upsetting to the natural environment or man. Process of Wastewater Treatment The New Process Step 1 (Physical Process) Step 2 (Biological Process) Clarifier has 3 sections.. Wastewater is gravity fed to a lift station where paper, rocks, and other bulky debris are filtered out by large metal grates. Sand settles to the bottom where it is Aerobic bugs are introduced in the outer layer. These bugs feed on the nutrients found in the sludge. This portion also contains aerators to supply the bugs with ample oxygen. In the middle circle the aerobic bugs are given time to feed. Phosphorous is then added; it will react with the sludge causing it to settle to the bottom. The innermost circle is the settling basin. Here the sludge settles to the bottom and is pumped out of the clarifier.
Step3 The sludge that was extracted from the clarifier is then run through a belt press or taken to a drying bed in order to remove any remaining water. The dry sludge is taken to either a landfill or a special field to be used as fertilizer. Step 4 From the Clarifier the sludge-free water is transferred to the chlorine contact chamber. The water receives a 15 to 30 minutes contact time. This allows chlorine to kill any harmful bacteria in the water such as diarrhea and cholera
Step 5 Sulfur dioxide is then added to the chlorinated water to lessen the chlorine residual. The chlorine residual must be zero before it can be returned to the environment.
Step 6 Reclaimed water can then be used on spray fields or combined with natural water sources. The Old Process Step 1 (Physical Process) Extraction of debris is performed in the same way as in the new process. Step 2 (Biological process) Anaerobic bugs are introduced into sludge. Notice that there are no aerators here this is because anaerobic bugs do not require a large amount of oxygen to live. A bar rotates from the top of the sludge down to the bottom. This sweeps any remaining debris off the top and pushes settling sludge to the end of the tank to be pumped out.
Step 3 Sludge is pumped from the anaerobic tank and disposed of in the same way as the sludge from the new process. Step 4 Trickle System Water from the anaerobic tank is filtered through granite rocks where microscopic organisms feed on any remaining bacteria. The remainder of the old process is the same as the new: Water is sent to the chlorine contact chamber for a 15 30 minute contact time. As the chlorinated water exits the contact chamber sulfur dioxide is added to bring the chlorine residual down to zero. From there the water is returned to the environment.
Record Keeping Flow charts Flow charts are one of the most important records kept at a Wastewater Treatment plant. They are used to record the amount of water that passes through a plant daily. Any major or minor fluctuations in the volume of water are noted there and then are taken care of accordingly. ph and chlorine residual tests ph and chlorine residual tests are performed daily at a wastewater treatment plant. Chlorine is tested for twice a day, while the other tests (such as cbods, tss, tf, tk, etc) are tested for once. Chlorine is tested for once in the chlorine contact chamber and a second time after the water is treated with the sodium dioxide. Monthly report to DEP (department of Environmental Protections) Data concerning all the tests performed on and off the plant are sent to the DEP for analysis. ph, chlorine, nitrate, ammonia, phosphorus, fecal coliform, and bacteria tests Monthly residual tests are done on sludge fields for they contain nitrates, ammonia, phosphorus, fecal coliform, etc which are toxic in small amounts. Their ions can attach to proteins in the human body and prohibit them from functioning properly. Upon accumulating data from three local area plants, it was found that there is a direct correlation between the amounts of flow that run through a plant and the size of the town. The tests performed were relatively close in numbers. But for those that were not, it was due to the different permitted amounts they were allowed by the state. Federal forms which contain annual averages All the monthly data is summarized into an annual form, which is sent to the state.
Water treatment is very simple Wells are placed across various parts of a town. The water that is drawn up from the wells are then chlorinated, pumped to water towers, and finally distributed to the residents for drinking and other usages. The towns around this area do not have separate water treatment units because they are too small and that would be too costly. One every interesting thing about water treatment is that wastewater can undergo more processes than the ones mentioned above and later be used as drinking water. But the small towns in this area do not do this. Many thanks to Marianna and Cottondale wastewater treatment plants and Dr. Huang for letting us borrow his video.