Operators of the Eureka Springs and North Arkansas Railway recently noticed sludge in Leatherwood Creek downstream from the city’s sewage treatment plant. Public Works Director Simon Wiley said the sludge was found a mile from the treatment plant and could not have come from the facility that treats wastewater for Eureka Springs.
“In our plant, there is no way for sludge to get through the plant into the discharge,” Wiley said. “We don’t allow that. We end up pressing the solids and they go into a dump truck, get dumped into a dumpster at my office and hauled to the landfill at Tontitown.”
Wiley said while they don’t know for certain what happened, a septic pump hauler came to the plant this past week and wanted to dump his load. That is not allowed, and the hauler left.
“I could speculate for days what happened,” Wiley said. “It could have come from a septic tank that overflowed. All I can say with surety is it is not from our plant. There is some turbidity coming out of the plant but there are no solids. It is not possible to get all the color out of the water. All discharged wastewater is disinfected and sanitized with ultraviolet radiation. We have to pull tests all the time. We do things by the book. If we have a problem, we will let people know there is a problem. I’m not in the business of hiding things. If we have an issue, I’m the first to make sure we take care of it ASAP.”
A complaint about the sludge was made to the Arkansas Department of Environmental Quality. The following is the response from Wastewater Treatment Plant Manager Terry R. Long to ADEQ:
“Please allow me to address the complaint of raw sewage leaving our facility and entering Leatherwood Creek. There was not a discharge of raw sewage from our facility. I am not saying that it would be impossible for raw sewage to accidentally or inadvertently escape our treatment facility, but that was not the case as all the evidence found was brown to indicate that we experienced a “solids washout” and nothing was found with a grey color indicating raw or untreated sewage. We take all complaints seriously and investigate every complaint. On a daily basis, we strive to produce an effluent discharge with a quality well below the limits established by our NPDES permit.
“As soon as we were notified about the possible discharge of raw sewage, I came to the plant and performed a complete walk-through of the facility looking for any signs of raw sewage and found nothing to indicate that we had experienced a discharge of raw sewage. In our post-aeration basin, I found an indication (water with straggler floc) that we might have had an instance of “solids washout” from one of our Sequential Batch Reactor (SBR) basins. As a preventative measure, I raised the bottom level for the decant cycle of the SBR basins which causes more vertical space to be between the top of the sludge blanket and the bottom of the decanter tube, thus making it more difficult for solids to exit or “wash out” of the SBR basins.
“It is believed that if, in fact, this was a solids’ wash out event, that it was the result of a combination of issues, all of which have been addressed at this time. The SBR basins were carrying more solids than desired due to being unable to waste enough sludge from the system to keep up with the growth of new micro-organisms. This happened at a time when the temperature was very high, and the micro-organisms were reproducing at a higher-than-normal rate, and we were unable to waste a sufficient quantity of micro-organisms to keep up with their reproduction due to lack of storage space for the waste sludge. During this same time, the mixed liquor settleable solids (MLSS) in the SBR basins was not settling properly which resulted in a larger than normal (typically none) amount of straggler floc in the SBR supernatant to be discharged.
‘In the SBR basins the sludge blanket appeared to be fluffy or feathery which was allowing the top layer of the sludge blanket to be siphoned off during decant cycles.
“Also, during this time, apparently due to the sludge particles having the same electrical charge as the polymer, it was difficult to get a good cake to form on our belt press, so we had decreased the feed rate of sludge to the press to help deal with the problem of no cake forming on the belt press, which compounded the lack of storage space for waste sludge.
“On August 11, 2023, we changed the chemistry being used to aid with settling the mixed liquor in the SBR basins. On August 11, we stopped using an Aluminum Sulfate Solution and started using a Polyaluminum Chloride Solution named AQUA HAWK 15047. This change resulted in almost immediate positive changes with the settling characteristics of the mixed liquor in the basins. The 15047 product is continuing to give good results with the settling characteristics of our mixed liquor and as a side benefit has begun reducing the amount of foam being generated by FOG entering our treatment plant resulting in a more aesthetically pleasing look to our SBR basins.
“As a result of better cake formation at our belt press, we have been able to increase the sludge feed rate going to our belt press which has resulted in freeing up some storage space for waste sludge. It is thought that the belt press is producing a better cake due to a decrease in the ambient temperatures and a slight change in the electrical charges on the sludge molecules. The resulting storage space has allowed us to waste more sludge on a daily basis which is causing the MLSS concentration to decrease, thus decreasing the chances of experiencing another solids washout event.”
Long has a degree in industrial engineering and was named Arkansas Water and Wastewater Manager Association Manager of the Year 2023.