Process Control Lab
At the Joint Meeting of Essex & Union Counties we do everything in our power to keep the plant running at top performance. We run extensive analysis on plant samples for process control. Samples are taken daily from every step in the treatment process and analyzed for various parameters. Some of the parameters tested for are Total Solids, Total Volatile Solids, Total Suspended Solids, Total Suspended Volatile Solids, Total Alkalinity, Turbidity, Oil & Grease, Metals, BOD, CBOD, Chemical Oxygen Demand, pH, and various nutrients.
We are always looking for new and better ways of running the analysis. One way we found was to update our balance and computer system to include a program for running all of our solids analysis. This process sends all the information to a spreadsheet and does all of the necessary calculation, thus eliminating the chance of calculation errors and/or transcribed numbers.
Over the past few years, other updates have included such things as Block Digestion for COD analysis. This was switched from the larger scale macro digestion. This newer process uses less chemical reagents and produces less hazardous waste to dispose of. COD is a valuable process control test because it gives us the oxygen requirement results in about 2-3 hours instead of the 5 days that the BOD test requires.
Analysis is performed for various nutrient parameters, such as phosphorous, ammonia, nitrate, nitrite, chloride, sulfate and hardness. Although our permit does not require any nutrient removal, monitoring is done to detect changes within the plant that could cause problems down the line. Changes in the ammonia and nitrate concentrations can be indicators of the biological system heading toward the nitrification or denitrification stage. Nitrite is an oxidizer that could cause interference in our ORP system. Changes in chlorides can be caused by infiltration of salt water from the river during high tides. Results of analysis must be viewed on a large scale. The data received from one part of the plant may be indicators of what is or will be happening at another part of the treatment system.
Most of the nutrient analysis is done by wet chemistry. Pictured is a colorimetric analysis for ammonia. The treatment plant operator, with the help of the lab data must be aware of what is happening in the system. Changes to the process are made based on the data received from the lab. Lab data is entered daily into a computer database to be accessed up to the minute by operations personnel.