In July of 2020, the 0.065 MGD lagoon system in Pax, WV was upgraded with three floating WavTexTM modules and two floating OctopusTM aerators to meet a new effluent requirement of <5 mg/L of ammonia.
Meeting the effluent limit for ammonia requires sufficient fixed-film growth media to support the biology necessary for treatment. The combined aeration from both the WavTex and Octopus modules provides sufficient dissolved oxygen. In the summer of 2021, one year after the installation, samples were taken at various points to evaluate plant performance. The graphic below shows the layout of the equipment and the sample points used.
Wastewater enters the lagoon near sample point #1 and then serpentines through the lagoon due to the two baffles. Locations of the WavTex and Octopus modules are as shown. Sample points #1 and #5 are wet wells for the influent and effluent, respectively. Grab samples were taken at points 2, 3, and 4. The table below shows the performance data for ammonia, nitrate, DO, and pH.
A consistent DO of ~5-6 mg/l across the entire lagoon indicates that the aeration is more than sufficient, especially given that these samples were taken during the warmest part of the year when the solubility of oxygen in the water is at its lowest.
The ammonia concentration drops rapidly in the first of three passes through the lagoon, which is expected during the summer. The fixed film treatment capacity was designed to meet the ammonia requirement in the winter.
As shown above, the effluent ammonia concentration stayed below the limit of 5 mg/l throughout the year.
Although this facility does not have a total nitrogen limit, the nitrate profile was analyzed to measure the rate of simultaneous nitrification within the anoxic zone created within the EnTextile media. As shown in the above table, the nitrate concentration drops to 5.2 mg/l despite the high DO concentration. This highlights a key advantage of the EnTextile media, allowing for a TN of <10 mg/l to be achieved in a fully aerated lagoon.
If we can be of assistance with your lagoon upgrade to improve aeration, BOD removal, nitrification, or total nitrogen control. Send us a note at info@entexinc.com.