Environmental Stewardship. Cost Savings. BNR.
Reducing the Carbon Footprint of Wastewater Treatment
“Over the period to 2040, the amount of energy used in the water sector is projected to more than double.”
Wastewater treatment professionals strive to be operationally effective and cost-efficient. By the very nature of their profession, they are inherently stewards of the environment. At the same time, however, their responsibilities are challenged by growing populations, aging infrastructure, and limited budgets. With every day of operation, tanks, pipes, and other wastewater infrastructure are exposed to grit and debris.
The aeration process, which can account for 30 to 70 percent of the total energy demand within a wastewater treatment facility, offers a significant opportunity for cost savings. Grit accumulation in aeration basins drives up energy demands. However, by mapping and identifying areas of grit buildup and incorporating targeted cleaning strategies, significant reductions in a wastewater treatment plant’s carbon footprint can be achieved, offering a promising path to cost efficiency without any capital investment.
When equipped with informed data to verify the condition of tanks and other wastewater plant infrastructure, utilities can confidently know where to focus their attention and when to incur or defer operating and capital expenditures.
Biological Nutrient Removal (BNR)
Biological Nutrient Removal (BNR) can play a crucial role in reducing pollutants in wastewater systems. In an environment in which microorganisms can thrive and naturally break down solids, nitrogen and phosphorus are removed from wastewater. The key to a functioning BNR tank is operational capacity. Just as human arteries are sized to allow the heart to pump sufficient blood through the body, biological nutrient removal (BNR) tanks are carefully sized to ensure sufficient retention time for pollutants to be removed from wastewater systems.
But what happens when sediment, grit, sand, and debris build up in BNR tanks?
Plaque buildup in human arteries causes the heart to pump harder to overcome the reduced arterial capacity. Similarly, wastewater plant equipment, such as blowers for aeration tanks, must ramp up speeds to overcome the layers of debris on the bottom of the tanks.
Loss of Capacity in BNR Tanks
The signs and symptoms of lost capacity can be difficult to identify simply because you cannot see into the turbid water of wastewater tanks. Effluent quality at the point of discharge may continue to meet permit requirements because automation keeps pace to overcome the reduced capacity, even though the system is operating with less efficiency. If the accumulation of grit in BNR tanks is left unattended, it will eventually reach a point where systems cannot keep pace. The buildup and infrastructure inefficiency will lead to a decline in effluent quality, signaling the onset of a catastrophic “heart attack” for a wastewater plant.
Until the invention of sophisticated diagnostic tools such as the electrocardiogram and magnetic resonance imaging (MRI), detecting serious health issues was often challenging. That’s why some SediVision clients have described our scanning and mapping process as being like an MRI for wastewater tanks®.
With the introduction of SediVision to the wastewater industry, a full-visibility image of wastewater tanks is now possible. SediVision® technology can scan full tanks and map precisely how much grit and debris have accumulated and where it is located. Wastewater operators can then use this information to diagnose issues with treatment processes and plan, schedule, and budget for tank cleaning.
While the technology behind SediVision and cardiac magnetic resonance imaging differs, both processes deliver valuable, detailed images and informed data for preventative planning and action.
Workplace Safety Commitment
For decades, wastewater operators have used rudimentary tools such as sampling poles to probe the depths of tanks, oxidation ditches, or pipes. Probes provide incomplete insights at best and are limited to only the assessable parts of the structure (See Figures 1 and 2). Grit particles in wastewater do not accumulate uniformly across the tank. Instead, as shown in Figure 3, they tend to build up in piles based on the velocity profile within the tank.
The inadequacies of wastewater tank probing sometimes lead to the use of confined space divers. But the risks to human health and safety from underwater confined space diving can be extreme, and the accuracy of the information the process yields varies based on the knowledge and diligence of the individual diver. Most importantly, penetration diving restricts direct access to the surface, making divers wholly dependent on their equipment. Disorientation in confined spaces, the increased need for oxygen when performing certain tasks in confined spaces, and the risk of exposure to contaminants are some of the many reasons municipalities and corporations are increasingly unwilling to use divers to assess conditions within tanks and other structures. The risk to human safety is too great, and the permitting and added insurance are too costly.
SediVision offers safe and reliable technology that eliminates the need for ineffective probing or hazardous diving. SediVision technology delivers accurate and informed mapping and calculations without posing safety risks to workers or contractors.
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Figure 1. Manually probing wastwater with a sampling pole
Figure 2. Aerial view of probed locations
Figure 3. SediVision® visual overlay of the same oxidation ditch
