What's That Smell? Eliminating Wastewater Treatment Odors

With all this talk about public awareness of hidden water system infrastructure, it is important to point out that there are times when public awareness is definitely NOT on your side. And one of those times is when there is a stink that just doesn't go away.

Odors are generated from every phase of wastewater management including collection, treatment, and disposal, and they can cause all sorts of public relations issues, putting pressure on an utility to resolve the problem in a timely way. Certainly, managing odors is one of the most important - and yet most challenging - aspects of wastewater treatment. 

Why so challenging? Because in part there are many odor control technologies available but no single ideal solution. Some systems, like this Brownsville Public Utilities Board plant in Texas, solve odor problems by placing covers over wastewater tanks and channels and then blowing the smelly hydrogen sulfide gas through a biological tower. Others such as this Bridgeport, CN Water Pollution Control Authority plant, capture odorous offgas with coated fabric covers and treat it with a carbon system. Still others use a combination of  different measures, such as activated sludge diffusion, carbon adsorber sytems, pump station chemical feed systems, coverings and plant operation modifications. 

But fixes like these don't come easily, or cheaply. And sometimes, the problem is even more complex. Consider this story of a system in Saline, MI that has been the subject of neighbor complaints for years. Even after odor studies and abatement work, the smell just keeps getting worse. 

How can a smaller system then, with its limited funding and manpower, address odor problems effectively? The cheapest way to control odors is at their source, according to this Science Daily article, but sometimes that is simply not possible. Fortunately, researchers from the University of British Columbia may have recently developed a solution. 

Many wastewater facilities use anaerobic digestion, but is is expensive to acquire and maintain the associated odor control and biogas safety equipment needed. A much more cost-effective way to mitigate odors, these UBC researchers have discovered, is to revisit metal salts treatment. Simply adding new combinations of these common commercial metal salts during the fermentation process dramatically improves offensive odors, and also improves their ability for remove water from digested sludge. It is these unique doses/formulas and point of addition during the fermentation process that really amplifies the effectiveness of this new approach. Moreover, the cost of adopting their technique is minimal, so smaller systems can afford to test it out. 

In the meantime, if you need a quick primer on odor generation and management, the Water Environment Federation (WEF) has a 7-page factsheet explaining the problem and outlining advantages and disadvantages of various mitigation strategies. 

You can also keep an eye out for odor events right here on WaterOperator.org. For example, this Iowa training later in the month troubleshoots lagoon odor issues. Just type "odor" in the keyword search box on the event calendar page. 

Want to brainstorm with other wastewater professionals? Attend WEF's Odors and Air Pollutants Conference 2018 in Portland, Oregon in March, 2018. With sessions ranging from "Optimizing Hydrogen Peroxide Dosing" to "Odor Control Scrubber System Planning and Design," there will be many opportunities to learn in-depth solutions to any smelly situation. 

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It's Alive! Spooky Sewer Creatures and Things That Go Bump at the Treatment Plant

Every water system has its stories — whether a particularly forceful water main break or sewage overflow, an unwelcome water tower visitor, or a “worse day ever” inside the treatment plant.

This Halloween season, we thought we would share some of the spookiest water operator videos and news stories we have come across, all with one thing in common: they really happened! (Because we all know that truth is scarier than fiction.)

Let’s start with a quick video and resource about a rare, but certainly not unprecedented, hazard. Hopefully, you will never encounter this slow-moving fleshy blob in your wastewater treatment plant or collection system, but just in case you do, you can thank this blog for warning you!  

No, it isn't an alien from another planet. This nightmare blockage is nothing but a nest of tubifex worms. Along with red worms, blood worms and midge flies, these worms are a normal and occasional nuisance to waterwaster operators, as they can clog filters and eat good bacteria. Although it isn't easy to get rid of them, this website offers hope. 

Speaking of blobs, earlier this year a water utility worker fell off a water main and found himself stuck in a blobby, muddy trench. The more he moved, the more stuck he got. Luckily for him, his nightmare didn't last long — fellow workers quickly came to the rescue, using their knowledge of trenching and excavation safety principles.

One thing is for sure: strange encounters are never far away when you work in the water business. In fact, sometimes spooky creatures are as close as the microscope slides in your lab.

Wastewater plants in particular house microbiological zoos of the strangest kind. But don't worry about what you can't see, because these creepy-crawly microorganisms are really the good guys at treatment plants. The predatory suctoria, for example, uses its spines to suck out the nutrient-rich cytoplasm of organisms it has speared, aiding in breaking down and removing nutrients and organic matter. Or the mysterious Tardigrade (aka water bear) seen below in this video whose appearance usually indicates good BOD degradation. Water bears can survive in outer space, extreme radioactive environments and high temperatures, making them one of the "toughest animals on earth".

In addition to strange creatures, strange happenings can also be part of the day-to-day life of a water operator. This Wessler Engineering blog post entitled "Is Your Wastewater Treatment Plant Haunted? describes an acoustic phenomenon known as "water hammer" that can occur inside the walls of a home as pipe fluids suddenly stop or change direction. This same thing can occur at the treatment plant when automated solenoid valves abruptly open or close, causing a sudden loud boom or knocking. It would be enough to make any night-shift operator jump! 

Finally, we leave you with a story that is sure to give you the shivers. Recent hurricane flooding in Houston has jarred many manhole covers out of place (more than 65, in fact), and somehow a man fell into a pit that feeds underground sewer lines carrying residential wastewater. After over a week underground, the man was finally discovered by utility workers who were nearby making repairs and heard a disembodied voice crying, "I am here, I am here!". After tossing the man snacks from their lunches, rescuers were able to haul the man to the surface. Thankfully this story has a happy ending, but be sure to watch where you are walking this Halloween. 

The Unique Challenges of Wildfires for Water Systems

Recent wildfires in California’s Sonoma and Napa Counties have caused loss of life and significant damage not only to over 5,700 homes and businesses, but also to critical water infrastructure in the region.

In Santa Rosa, residents have been instructed to use only bottled or boiled water for drinking and cooking. According to the city's water engineer, the system is currently experiencing unusually low water pressure, due either to high volumes being used by firefighters or damage to infrastructure. She explains that when water pressure drops below a certain level, backflow prevention devices – particularly in the higher elevations of the system – many not work properly.

Loss of pressure is only one of the many unique and harmful effects wildfire can have on water systems. This 2013 Water Research Foundation report on the effects of wildfire on drinking utilities lists many more, especially the dramatic physical and chemical effects on soils, source water streams and water quality that would necessitate changes to treatment operations and infrastructure. In fact, according to the US EPA, long-lasting post-fire impacts (especially flooding, erosion and sedimentation) can be more detrimental to water systems than the fire itself. 

The WRF report also suggests mitigation and preparedness strategies for utilities, including using fire behavior simulators to identify areas to target for fuel reduction activities, such as this goat grazing program in California. The idea behind such collaborative programs is that the less vegetation fuel available for fires to consume, the better. 

The increase in wildfire incidents such as these across the country make it all the more important for water systems of all sizes to be prepared for the unique challenges of wildfires. A good way to start your preparation is by checking out WaterOperator.org’s listing of free wildfire resources by typing in the word “wildfire” in the search box.

No time to lose? The US EPA has a page of "rip & run" resources including this Wildfire Incident Action Checklist.

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Hurricanes, Flooding and Wastewater Plants: What Have We Learned?

In recent months, there have been dozens of reports of wastewater treatment plants that have flooded due to heavy hurricane rains and storm surges in Florida, Texas, Puerto Rico and beyond. Both the sheer number of plants affected, and the extent and duration of the flooding have posed significant public health and technical challenges, often stretching communities to their limits. 

To add to these problems, many rural utilities were already struggling to keep their systems operating before the storms struck, so costly, complicated repairs or replacements of damaged infrastructure is simply not an option. For example, Patton Village, Texas had just completed a new wastewater plant — the first of its kind in their community — before Hurricane Harvey struck. Now they can only hope that USDA/FEMA emergency funding will be available to help repair the damage. And even once the systems are up and running again, it is not a given that water systems can count on water rate income to help with their O&M bills - many residents have fled their flood-damaged homes for good.  

The sad truth is that lately, floods have been affecting wastewater plants with unfortunate regularity, and not just in hurricane-prone areas. For example, in Central Illinois, the small town of Hutsonville's wastewater treatment plant has flooded 3 times in the last 2 years, up from once every 5 years, according to its contract operator Shannon Woodward of Connor & Connor, Inc.

Woodward's first piece of advice is not to build on a floodplain, but he also acknowledges that many communities do not have the capital funds for effective protective measures or relocation, and so operators must deal with the hand they are given. His second piece of advice: "Make sure all electrical controls, switch gears and transformers are above the flood stage. That way, when the flood waters subside, you don't have equipment loss and can get back into operation — even if it takes 3 to 6 weeks for the waters to recede." 

Mason City, another small town in Illinois, was able to fund improvements after a flood in 2008 cut off the town’s water supply and nearly overflowed the capacity of its wastewater system. The following year, the city built a stone wall around the water plant, installed flood sensors on the local river, and built effluent pumping stations for the wastewater plant. 

And this article tells the damage and recovery stories of two flooded wastewater plants in Rhode Island. According to the operators of these plants, it is essential to have a flood plan, even if you think your facility is protected. In addition, they maintain it is important to involve wastewater treatment personnel in emergency response exercises or in the incident command structure. On a practical level, the operators encourage SCADA systems to be elevated on the second floor in the operations building if possible. And lastly, they recommend you back up your files and documents electronically. Papers get wet, they say: move them to a dry storage facility. 

Finally, while every community has different characteristics and needs, there are some universal preparedness strategies for wastewater plants. The US EPA recommends practicing mitigation options as the best way to prevent floodwater from invasively appearing. Some of these options include crafting barriers around key assets, having an emergency back-up generator, and keeping key electrical equipment elevated. You can learn more about these options here, or you can watch this helpful video. In addition, many states have their own guidances, such as this one from Minnesota’s Pollution Control Agency.

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