Photo: Mayor William Hughes and Operator William Bailey
Back in April, in A Tale of Two Lagoons, we let you know about two upcoming municipal lagoon upgrades, a cold weather lagoon in Pax, WV and a warm weather one in DeQunicy, LA. We followed up by reporting on the installation of three WavTexTM and two OctopusTM modules in Pax in July. The DeQuincy upgrade was on track for installation in September, but was delayed when Hurricane Laura devastated south central Louisiana. We expect to install this system by early November.
Pictured above are plant Operator William Bailey and Town of Pax Mayor William Hughes. I visited them in late September to check on the system and its performance, and also to follow up on some interesting observations reported by Mr. Bailey regarding the die off of the algae and improved clarity of the effluent.
I arrived to find the equipment functioning well, with evenly distributed aeration and vigorous mixing across the lagoon. You can also see in the picture the blowers provided by Entex as part of a complete solution.
As is normally the case for lagoon upgrades, the key challenge was nitrification. For Pax, they needed to produce an effluent with less than 2 mg/L of ammonia. They took their monthly regulatory sample on August the 25th and the ammonia concentration was just 0.22 mg/L, indicating that the nitrifying biofilm on the EnTextileTM media had grown and acclimated in only four weeks.
Prior to my arrival, Mr. Bailey had been reporting that the floating duckweed had been steadily disappearing, that the suspended algae was gone, that the green tint in the effluent had gone away, and that he was surprised to be able to see the gravel on the slope of the lagoon floor. The two photos below are taken from the same vantage point: the first during installation on 7/29/20 and the second during my visit of 9/24/20.
The open water in the first picture is a result of the aeration from the WavTex and Octopus modules pushing the duckweed around, the lagoon was fully covered prior to installation. The second picture clearly shows that depriving algae of ammonia nitrogen (nitrate results are pending) is causing it to die off.
Minimizing algae growth in wastewater lagoons improves their visual appeal and often their odor, both of which can be helpful in community relations. In addition, for lagoons with downstream filters – not the case for Pax – it can dramatically reduce clogging of either sand or cloth filter media, thereby reducing both maintenance cost and hassle.
Mayor Hughes reports that he is quite satisfied with the system. Both he and Mr. Bailey are curious to see what happens in the spring to see if the “algae season” can be eliminated completely. We’ll let you know what happens.
If Entex can be of assistance with aeration, nutrient removal, or algae mitigation for your facility, send us a note at info@entexinc.com.
Article by Jeff Danner, Entex’s VP of Engineering