Aeration is at the heart of wastewater treatment. Whether using pumped air or agitation methods to create an ecosystem for bacteria to grow and naturally break down solids, the O2 level is key to success. Below 2 ppm will kill off the bacteria and reduce plant efficiency, so treatment plants typically run tanks above the required levels of dissolved oxygen (DO), leading to increased energy consumption and costs.
A significant savings can be achieved through optimizing the process. The easiest way to reach optimal conditions is through real-time DO monitoring while incorporating other key parameters to the ecological process.
To reach peak aeration performance, it’s imperative to keep an eye on oxygen, pH, temperature, and suspended solids. These parameters are necessary for maintaining an ecosystem that encourages bacterial growth. It is also beneficial to monitor the Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) in real time so adjustments can be made to the aeration rate and ultimately reduce energy consumption.
COD is a test of the amount of oxygen required to oxidize organic matter in a sewage sample with a powerful oxidizing agent such as potassium dichromate. COD is closely related to BOD. The difference between the two being BOD tests the level of organic matter that is biologically oxidized. Monitoring COD and BOD helps to make sure you are getting the most out of your aeration tank and will ensure that no chemicals are going to waste.
If you have a high BOD level, it indicates more oxygen is needed and, in turn, less for oxygen-demanding species to feed on. It also signifies lower quality of water. Low BOD levels indicate less oxygen is being removed from the water sample and water is generally purer. Unpolluted rivers usually have BOD levels below 1 ppm, while untreated sewage has between 200 – 600 ppm. Higher COD levels mean a greater amount of oxidizable organic material in the sample, which will reduce DO levels. A reduction in DO can lead to anaerobic conditions, which is harmful to higher aquatic life forms.
Why would you want to monitor BOD or COD in real time? COD tests take 2-5 hours to test, while BOD tests take 5 days to complete – making it difficult to optimize the plant. Measuring in real time can maximize your operations. If you have a high BOD or COD your aerators can take a break, resulting in saved energy.
Trending historical data will take your monitoring a step further so you can predict opportunities to save energy, improve your water quality, and gain peace of mind when it comes to compliance with environmental authorities by having that data available around the clock.
Do you have any questions about real time monitoring? Talk to a STREAMETRIC expert today and see how you can optimize your wastewater treatment operation.