Reduce, Reuse, Recycle: Managing Industrial Water Resources

The idea of a circular economy, where today’s manufactured goods and byproducts become tomorrow’s resources, is gaining ground. With 7.3 billion people and counting, the world’s resources are becoming increasingly scarce and traditional consumption patterns more costly and unsustainable. Nowhere is that more evident than with water.

While the extreme drought in the western U.S. has raised awareness in this country of the need to use less water, countries and companies around the globe have been dealing with water scarcity for years. Many industries are also finding that operating more sustainably helps them reduce costs.

Built on recycling

The sustainability mantra—reduce, reuse, recycle—has been standard operating procedure at Charlotte Pipe and Foundry for decades. The family-owned company, based in Charlotte, N.C., is one of the nation’s largest manufacturers of plumbing pipe and fittings, and the only U.S. maker of both cast iron and plastic versions.

Sustainable water use is critical for Charlotte Pipe and Foundry, which uses and reuses tens of thousands of gallons of water every month in its processes.
 

In fact, Charlotte Pipe couldn’t exist without recycling. Its cast iron products are made with a minimum of 95 percent scrap iron and steel—more than 350 million pounds are recycled every year. Even some of its PVC products are made with a significant amount of recycled content.

Water is a critical part of the company’s manufacturing process, from quenching hot iron to mixing the sand used to cast iron fittings. “For many years, we were able to recycle and reuse all the water from our production processes,” says David Waggoner, technical director at Charlotte Pipe. “But with the addition of an electrocoating process for corrosion resistance that uses a reverse osmosis (RO) system, the plant now has to discharge about 900,000 gallons of pre-treated wastewater every month into the city’s sewage system. We haven’t yet found a way to economically use our recycled water for RO input.”

Although a large amount of the water used in production evaporates during the process, Charlotte Pipe operates its own water treatment plant for reusing the remaining water, including rainwater. “One of our biggest challenges was getting employees to follow new practices and use the recycled water in the production process,” Waggoner explains. “We did it by putting higher-pressure pumps on the recycled water flow.” Once they started using the recycled water, they didn’t want to go back to using city water.

To make it easier for other companies to distribute reclaimed, gray and rainwater within a building, Charlotte Pipe recently introduced a new pipe made from chlorinated polyvinyl chloride (CPVC). Colored purple and clearly marked “WARNING: NON-POTABLE WATER,” the ReUze pipe ensures that contractors don’t cross pipes carrying water fit for human consumption with non-potable water lines. Non-potable water can be used for many industrial applications, including cooling tower makeup water.

In addition to water recycling and reuse, Charlotte Pipe also gives away the slag and spent sand from its manufacturing processes. These materials are used to make concrete blocks lighter, which reduces transportation costs for the manufacturer, and are also mixed with asphalt for road construction. “Our waste disposal bill is $1 million annually, but it would be double that without recycling and reuse,” Waggoner says.

“We’ve spent at least $40 million over the last two decades to stay ahead of the environmental compliance curve,” he adds, “although that’s getting harder to do with ever-stricter EPA requirements. Many foundries that didn’t make that kind of investment over the years are now out of business.”

Tighter process controls

Along with stricter environmental regulations comes the need for tighter process control. It’s an area where mobile technology can play an important role.

“Cities are requiring a lot more remediation of industrial wastewater, even shortening the amount of time water can spend in pipes because it affects oxygen levels,” explains Matt Wells, general manager of GE’s Automation Software business. “To maintain compliance and reduce energy, water and steam use, companies need to make their processes more efficient.”

Wells points to the experience with mobile technology at Cornell University in Ithaca, N.Y., using a system that combines GE’s Proficy visualization and control software—Proficy Mobile—as well as the Internet and mobile devices such as iPads. It gives managers and maintenance workers greater visibility into their processes as they move around geographically dispersed facilities. Off-hours troubleshooting is now 40 percent faster, uptime has been increased through proactive equipment maintenance, and the university has reduced energy usage by 80 percent and lowered operational costs.

The software integrates HMI, SCADA, historian and analytical tools to monitor and control cooling water from nearby Cayuga Lake, water filtration, and steam and power generation processes at the on-campus central energy plant. It creates steam for heating more than 270 campus buildings and electricity to run the chilling units and building power. The 24/7 data access helps the university deal with a number of unique maintenance challenges, such as lake debris or zebra mussel buildup that can clog piping and reduce water flows.

There are many ways that improved data access and analytics can help significantly lower the cost of managing water, according to Wells. “If you have to move water with pumps rather than gravity feed, that’s an energy-intensive application,” he says. “One water plant in Australia, for example, schedules their pumping activity when spot prices for electricity are at their lowest.”

Analytics is where the magic is “because you’re able to see data within context,” Wells says. “Rather than looking at the data by individual asset, the power comes from being able to see the specific measurement points within a process that indicate when it’s performing sub-optimally. The key is defining which multi-variable data sets are most relevant for predicting a specific problem.” For a pump failure, for example, vibration levels and outlet temperatures might be the most relevant measurements.

“By continuously pulling from a wide range of data sources, you can present information to operators that enables them to dig deeper to find out what’s really happening and why,” Wells adds. “As more of today’s workers retire and new ones without the domain expertise are hired, it will be essential to be able to quickly draw operator attention to what information they need to focus on most.”

Intelligence, not just data

Analytics that provide the context for improved decision-making are just as important for breweries, says Doug Bellin, senior global manager, manufacturing and mining, for Cisco. “Breweries want to prevent losses and that means turning every ounce of water they use into beer. To do that, operators need to know what’s happening at all times in every area of their process.”

Bellin sees the industry moving to Ethernet and wireless to better understand when an abnormality is happening in a process so operators can act to correct it quickly. “One important trend is to enable analysis on the edge, where data is being generated, to reduce latency in the system.”

Mining is another industry where process intelligence can make the difference between profit and loss, particularly when it comes to environmental compliance. “Tailings ponds for oil sands drilling are a big issue in Canada, and operators can be fined up to $1 billion for violating standards such as water content, dam pressure or ground movement,” he explains. “Operators used to have to send a guy out in a truck to take measurements from a pond and record them on paper. With the dramatic decline in sensor prices, however, it’s easier to get live information. Now all you have to do is press a button to find out what’s happening in real time. The ROI has become almost instantaneous. It changes how people work and what they do.”

Emerging trends

Energy management, security, chemical use and labor reduction are four major trends changing traditional practices for water and wastewater treatment, according to Thomas Schaefer, industry manager, water and wastewater, at Rockwell Automation. “These trends are being driven by cost reduction and environmental compliance efforts.”

Schaefer points to one example, the growing use of peracetic acid to replace chlorine in water treatment. The organic acid, really industrial-strength vinegar, has long been used in the food industry. It can also serve as an antimicrobial treatment for cooling tower water. “Water facilities are often located near population centers, where large tanks of chlorine can pose a serious danger in the event of a leak,” he says. “Peracetic acid is an alternative that’s consistent with sustainability.”

The environmental and resource impacts of industrial processes have long been a subject of public debate. “Take the fracking industry, where an average frack uses 3 million gallons of water, and then you have to deal with the aftermath in terms of chemical- and acid-laden water,” Schaefer says. “The question is whether this is sustainable long term in the face of growing costs, declining water resources and stricter environmental regulations.”

Schaefer predicts that the western drought “may prompt water utilities to do things they should have done years ago. We need to learn from countries like Singapore, where 70 percent of the water they use is either reused or desalted.”

Although modern automation technology is being used more widely in the water industry, Schaefer says adherence to traditional practices still poses a drag on the pace of change. “If we’re going to reduce raw material use, whether it’s energy, water or chemicals, and run plants that are more efficient economically, we’re going to have to really ramp up new technology,” he says. “We just can’t get the job done with what’s previously been installed.”

New technologies such as model predictive control (MPC) can tap into the intelligence of devices to help humans make better decisions, says Schaefer. “This mathematical process-modeling tool takes into account all the different factors needed for tighter process control,” he says. “By embedding MPC within a ControlLogix PAC, a separate server is no longer needed, there’s greater industrial reliability, and it’s easier to install and maintain.”

EnWin, a Canadian water utility with an aging infrastructure, was experiencing an average 238 main breaks a year, primarily caused by pressure spikes and dips in the system, at roughly $5,000 for each break. Since water is a non-compressible fluid, a change in pressure anywhere in the system is felt throughout the entire infrastructure.

EnWin was working to rapidly modernize, but couldn’t replace the entire system at once. Operators had to stop and start pumps manually to adjust to system flows. The PID logic based on outlet header pressure at the pumping stations had significant limitations because it could only control a single input and generate a single output.

By using Rockwell Automation’s MPC technology, which can react to multiple variables, the utility was able to maintain consistent pressure system-wide while accommodating fluctuations in flow demand. System pressure was reduced by 2.8 psi and standard deviation by 29 percent. Annual water main breaks also declined by 21 percent for an approximate cost savings of $125,000 and an additional $125,000 in savings for electricity and system leakage.

Automating for efficiency

“Industrial water systems are not the core process at most industrial facilities, so operational efficiencies and the ability to rapidly react to adverse conditions with minimal resources is absolutely essential,” says Jeff M. Miller, a water solutions architect at Schneider Electric. “Increased automation can not only free up resources for other tasks, but reduce waste, energy and other costs.”

Sustainable water practices can more than pay for themselves, according to Miller, but it’s unrealistic to expect this to be achieved with one project. “A roadmap of how to migrate to technologies over time is best for acting on improvements,” he says. “You need to make technology decisions based on the lifecycle costs of assets.”

“Water and energy are at the nexus of conservation efforts because you need one to produce the other,” says John Masters, vice president of sales, water, for Danfoss Drives. “In an industrial water system, you need to evaluate the process streams to understand where water is being wasted and where water reuse might be an alternative.”

The use of flow or pressure monitoring in conjunction with variable-frequency drives allows the monitoring and control needed to match process requirements, Masters adds. “Maintaining historical usage records of each process stream can also tell you whether a process is performing optimally and identify the heavy water usage processes that can be better managed to reduce water/energy consumption.”