Sewer Nozzles and Recycled Water Sewer Cleaning Systems
The latest trend in sewer cleaning is using recycled water, which has impacted the sewer nozzle market. The use of recycled water trucks for sewer cleaning is currently limited, though it’s becoming well established in Europe and in the western and southwestern United States where drought is a major factor. And that’s understandable.
Reduction of the use of treated water in sewer jetter trucks, which typically fill their tanks at fire hydrants or municipal yards, can be enormous. A traditional jetter, running for six hours at 80 gpm, can use about 30,000 gals of treated water in a day, and perhaps as much as 7 million gals annually. And all that cleaned water will go into sewers to be cleaned again.
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By contrast, a recycled water truck will often head out for the day with an empty tank, and can work in sewers with moderate flow without ever filling the tank, or using treated water at all. That’s a big difference, and a compelling reason for any sewer maintenance department or contractor, working in drought stricken areas, to use recycled water simply for sustainability reasons.
But according to Scott Paquet, president/CEO and owner of sewer nozzle firm NozzTeq Inc., the emphasis on sustainability obscures economic reasons for the use of recycled water jetter that are potentially even more compelling, for any sewer cleaning done in any region. “Recycled water trucks are simply more efficient,” he explains. “They don’t just save water, they save money and labor as well. More lineal feet of sewer can be cleaned, every single day. We don’t have really good measures yet, but we know they’re significant — based on what our customers are reporting, and what I’ve observed in field visits, I think three times as much sewer can be cleaned in a day, compared to conventional trucks. Figures from a study done by the city council of Dublin, Ireland, go even further than that; recycling trucks, the council says, can “… typically carry out three to four times the production per day.”
Here are some of the factors contributing to that enormous productivity gain:
• Recycled water trucks rarely drive around with full water tanks. That weight savings means that less fuel is used for transport, and that there is less wear and tear, physically, on recycled water trucks.
• Since they don’t have to refill tanks, recycled water trucks don’t have to break down and leave job sites to go find a hydrant. That can save hours a day, especially in areas where hydrant access is limited, forcing truck operators to drive farther to refill tanks.
• Recycled water trucks are effectively unlimited in the amount of water that can be used. That means higher flow rates can be used as needed, so sewers can be cleaned more efficiently and more quickly. Wear and tear per lineal foot of sewer cleaned is also reduced.
• Since recycled water trucks typically filter out sludge and grit, and transport it as a relatively dry material to landfills, overall strain on sewer networks and treatment plants is reduced. Complementing this, drinking water that has already been treated is not reintroduced into the system for a second cleaning. And of course, if there’s an option, it’s hard not to see the use of treated water for sewer cleaning as wasteful. Put another way, treated water is obviously more expensive to use than sewer water on the way to be treated.
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Of course, there are potential downsides to consider. For one thing, recycled water trucks are considerably more expensive than comparable conventional jetter. “It’s definitely a ‘pay more now, save more later’ technology,” Paquet says. “Still, capital costs are higher, at least currently, and that’s a factor.”
And the quality of recycled water can also be problematic. “The onboard filtering and cleaning systems are definitely getting better, and the day may come when recycled water trucks will supply jetting water that is very close in quality to treated water, at least in terms of grit and particulates,” Paquet explains. “But for now, and the foreseeable future, recycled is definitely grittier, and harder on sewer nozzles. If they’re not made for recycled water, they’ll wear out faster.”
This last factor explains Paquet’s interest in recycled water sewer cleaning. His company, NozzTeq Inc., specializes in highly engineered, high quality sewer nozzles that clean more efficiently and last longer than cheaper conventional nozzles, and he’s been making the case for years that better quality sewer nozzles are a good investment.
“Too often, contractors and sewer network operators will invest hundreds of thousands of dollars in their jetter and other major cleaning equipment and then spend less than a hundred bucks on a nozzle,” Paquet says. “But really, the nozzle is the endpoint of a very complex system, and it’s so important to use nozzles that maximize the available pressure at hose ends, and produce smooth, powerful jet streams that clean efficiently. And of course they should be durable too, with jet orifices and other elements that are replaceable.”
This advice applies even more obviously when using a recycled water jetter. More grit in recycled water means more wear on nozzle interiors, and NozzTeq has already introduced a new nozzle, the MANTA 350-RC Sewer Nozzle, and redesigned its classic BL-Swiper series nozzles, to work well with recycled water. “Our nozzle interiors have always been top tier technology, made from stainless steel and ceramic materials. But recycled water adds significantly more stress,” Paquet says. “Fortunately, we’ve figured out tweaks in the MANTA and BL Swiper series to make these nozzle interiors even more resistant to internal wear. And we’ll be introducing these options to most of our nozzles.”
These tweaks include carbide coated stainless steel, specially formulated ceramics, and replaceable elements that extend nozzle lifespans. And the MANTA also incorporates a jetting plate that is interchangeable and replaceable, so that the MANTA, a heavy duty bottom cleaner, can be used in configurations of 8, 10, and 12 jets. “It’s important to have options in jet configuration,” Paquet says. “That way, the cleaning can be adopted to local conditions, in the pipe being cleaned or in available pressure. It’s another way to clean more efficiently.”
These nozzle interior changes are urgent now, due to the high grit in recycled water. But Paquet is quick to point out that they’ll be important even when technology improves and water is cleaner. “We know that filtering systems are going to get better as this technology is more widely used and manufacturers innovate and bring costs down. And that will lead to even more use of recycled water,” he says. “But keep in mind, that also means that sewer water cleaning crews will be doing a lot more work in a day—and so they’re going to want more durable nozzles. The economic benefits of longer lasting, better designed, nozzles will be even more obvious than they are now.”
Paquet says he is already seeing an increase in the use of recycled water for sewer cleaning. “That’s why we worked with customers and nozzle designers to make the MANTA,” he says. “Demand isn’t huge now, but it’s increasing steadily and we have more interest every month. Recycled water sewer cleaning is definitely here to stay, and will eventually become common.”
He’s surely right. More sustainable and more economically effective is a combination that always wins in the marketplace, and it’s good to know that sewer nozzle technology is keeping pace.
Angus W. Stocking, L.S. is a licensed land surveyor who has been writing about infrastructure since 2002.