The Philadelphia Water Department (PWD) and Ameresco (Framingham, Mass.) recently announced a public–private partnership to design, build, and maintain a new facility that will convert biogas into electricity and thermal energy. The $47.5 million Northeast Water Pollution Control Plant Biogas Project will produce 5.6 MW of power — enough to supply 15% of PWD’s annual energy usage — and is expected to reduce energy expenses by approximately $12 million during the term of a 16-year contract.
During the initial planning phase, one of the biggest drivers for implementing a biogas-to-energy project at the PWD facility was impending energy deregulation, which began in 2011, said Chris Crockett, deputy commissioner of planning and environmental services at PWD. “For years, we were interested in utilizing our excess biogas in some capacity, but financially, it didn’t make sense for our ratepayers; with electrical costs as low as they were, the payback wasn’t there,” Crockett said. “However, with energy deregulation approaching, we were expecting a 15% to 30% immediate increase in electrical costs. That alone would have forced us to raise sewer rates and was enough of a reason to pursue the project.”
Taking into account the new energy-purchasing scenarios, onsite energy generation enables PWD to shave peak loads, diversify its energy portfolio, and mitigate risks associated with the volatility of energy markets, according to Crockett. “Essentially, we know what our rate is going to be for the next 16 years for 15% of our total electrical load,” he said.
Importantly, the biogas project will enable PWD to address air emissions at its facility. Currently, half of the total biogas produced from digester processes is flared, but following project implementation, this excess biogas instead will be used, reducing carbon emissions by an expected 20,000 Mg/yr (22,000 ton/yr). “We owe it to our citizens to address this source of air pollution,” Crockett noted. “In terms of environmental responsibility, flaring does not send the right message. But moreover, with tightening air regulations expected in the future, we view this project as an opportunity to eliminate that liability.”
Additionally, if the electrical grid were to go down due to a disaster, cogeneration would allow “extra flexibility, reliability, and redundancy beyond the existing backup generators for keeping the facility fully operational,” Crockett added.
Pepco Energy Services (Arlington, Va.) and DC Water (Washington, D.C.) recently signed an agreement for Pepco Energy Services to design, build, and operate a $170 million combined heat and power (CHP) plant at the site of DC Water’s Blue Plains Advanced Wastewater Treatment Plant (AWTP). The CHP project will utilize biogas generated from anaerobic digesters at the AWTP facility to produce up to 13 MW of electric power.
The sheer amount of clean energy that will be produced on a long-term, permanent basis was a critical, driving factor behind the DC Water board’s decision to pursue biogas-to-energy, said George Hawkins, DC Water general manager. “The ability to generate our own power offers us independence from fluctuating energy prices,” he said. “If the economy becomes robust, there is no telling where prices could go. Having control over those costs in the long term is significant and worthy of an investment at this scale.”
The CHP plant will include a clean-burning recuperative turbine to generate electricity and supply the AWTP facility with nearly 30% of its average power needs. A heat-recovery stream generator will pull heat from the turbine to produce high-pressure steam.
“The steam, in turn, will be sent back to the AWTP facility and will be used for powering the plant’s new thermal hydrolysis process, creating a closed-loop system,” said DC Water biosolids manager Chris Peot.
DC Water’s new thermal hydrolysis project, set to be the largest in the world, will effectively reduce biosolids production by half and also create a Class A product instead of the Class B biosolids that currently are generated.
Aside from the energy-producing benefits, one of the most significant results of the project includes the ability for DC Water to mitigate long-term liabilities associated with its biosolids recycling program, according to Hawkins. “Our existing treatment process generates an enormous quantity of Class B material — approximately 1200 tons [1090 Mg] of biosolids are trucked from the facility on a daily basis, with the majority of this material land-applied under very strict circumstances,” he said. “Potential new regulation limiting wintertime land application would have meant storing this material. If the recycling limitations were ever to increase, the consequences to our enterprise would have been extraordinarily expensive.”
Class A biosolids are high in nutrients and organic matter and present a potential revenue source for DC Water, according to Peot. “We anticipate that this product can be sold for use in street tree planting and urban restoration initiatives, including as a soil source for stormwater low-impact development projects,” Peot said.
“Instead of a serious liability, we will have a potential asset while at the same time cutting hauling costs significantly,” Hawkins added.
In terms of quantifiable savings, the project is anticipated to reduce energy costs by as much as $15 million per year while also cutting hauling expenses by the same margin, resulting in a total annual savings of $20 million to $30 million, according to Pamela Mooring, DC Water communications manager.
While sustainable energy generation remains a significant motive for municipalities to pursue biogas projects, the biogas-to-energy market is increasingly being driven by biosolids management, according to Greg Chung, San Francisco regional office manager of GHD, an international engineering, architecture, and environmental consulting company. “With landfill space diminishing, energy recovery projects that can reduce biosolids volume and lower disposal requirements are viewed with higher importance,” he said.
Another driver at work influencing the energy recovery market includes the availability of outside feedstock supplies for generating biogas. “Many municipalities have excess digester capacity and want to supplement their biogas production by bringing in and digesting outside waste sources, such as fats, oils, and greases or the organic waste-
streams from bottling industries, breweries, or large food processers,” Chung said. “Even more sources on the forefront include biodiesel or algae-to-energy residuals.”
The long-term sustainability of projects that rely on alternative sources other than wastewater solids, Chung continued, is dependent on securing consistent, dependable, and high-quality waste sources. “However, because of pressures to deal with wastes in different ways and the development of new technologies that destroy the waste or reduce volume, the potential volatility of the feedstock market moving forward will likely cause more competition for waste sources,” he said.
Drought in the Lone Star State
New supplies of water are increasingly needed in Texas as a safeguard against severe shortages
Last year, Texas experienced what has been widely characterized as the worst 1-year drought in the state’s history. According to state climatologist John Nielsen-Gammon, a record-dry March 2011 brought widespread extreme drought conditions to the state, and the period from October 2010 to September 2011 was the driest 12 months on record. Heat and resulting evaporation from record warm weather during the summer further depleted streamflow and reservoir levels. Water use data for 2011 from the Lower Colorado River Authority (LCRA; Austin, Texas) revealed that lakes Buchanan and Travis, the water supply reservoirs for central Texas, dropped to their third-lowest levels on record.
Although higher-than-average winter precipitation has helped alleviate conditions in eastern Texas and the metropolitan areas of the state, the western portion of Texas remains extremely dry, with “many of the reservoirs in west and central Texas not showing significant recovery,” Nielsen-Gammon said. “Widespread drought from last year has eased into more localized drought this year, but moving forward this summer, it is difficult to predict if overall conditions will improve or become more severe.”
New sources and supplies of water are actively being developed by LCRA, which has a goal to “add 100,000 ac-ft [123 million m3] of new water over the next 5 years,” said LCRA general manager Becky Motal. “Texas is in the second phase of a drought that really began back in 2008 and included a very dry year in 2009,” she said. “Last year was even more intense in the sense that lakes Buchanan and Travis received the lowest inflows on record.”
Compounding this shortfall was an unusually hot summer that contributed to more water loss from evaporation in lakes Buchanan and Travis than the entire annual water demand of Austin, Motal added.
“Last year, it looked very apparent that we could potentially be approaching a combined storage of less than 600,000 ac-ft [740 million m3] in those reservoirs, which would have required us to consider declaring a drought worse than the drought of record,” Motal said. “That backdrop prompted us to create a water supply resource plan and to pursue a number of water development initiatives. In addition to the conjunctive use of groundwater, we are looking into developing off-channel reservoirs downstream of Austin, which could supply water for agricultural uses and allow us to save water in Buchanan and Travis lakes.”
Another strategy in the works includes recharging aquifers with surface water to prevent losses from evaporation. Additionally, LCRA recently implemented a pilot project that involves testing the feasibility of utilizing gravel pits located in the lower basin region of Colorado County as downstream water supply reservoirs. If feasible, the gravel pits would be capable of storing about 2.47 million m3 (2000 ac-ft) of water, according to LCRA.
Texas Water Plan
Earlier in the year, the Texas Water Development Board (Austin) released its 2012 State Water Plan, which forecasts a widening gap between water demand and existing water supplies, and emphasizes that if Texas does not implement new water supply projects or management strategies, then homes, businesses, and agricultural enterprises throughout the state are projected to need 10 billion m3 (8.3 million ac-ft) of additional water supply by 2060.
In the event of severe drought conditions, according to the plan, the state would face an immediate need for additional water supplies of 4.4 billion m3 (3.6 million ac-ft) per year. Not meeting water supply needs could result in income reductions of approximately $11.9 billion annually if drought conditions approach the drought of record.
The plan also highlights the need for long-range water resources planning and recommends an extensive number of water management strategies, including plans and unique water supply projects for meeting water needs during severe drought. The estimated capital costs associated with designing, constructing, and implementing these strategies and projects total $53 billion. However, the plan stresses that this amount only represents about a quarter of the total $231 billion that is needed for water supplies, water treatment and distribution, wastewater treatment and collection, and flood control for the state during the next 50 years.
With such intensive long-term capital costs required, financing the State Water Plan is a top priority, said Carol Batterton, executive director of the Water Environment Association of Texas (Austin). Last year, the association joinedH2O4TEXAS, a coalition of diverse stakeholders that was created to increase public awareness of the critical water shortfalls facing Texas and to mobilize support for full implementation of the State Water Plan.
“We are working together to develop an acceptable means for funding the State Water Plan so that all of the different entities with water development strategies can move forward,” Batterton said.
Funding strategies have tobe in place before the next Texas legislative session begins in January, according to Batterton. “The H2O4TEXAS group is exploring a wide range of fee-based funding alternatives, such as water conservation development fees, water use fees, water rights fees, and tap fees on retail public utility connections,” she said. “The challenge is how to create and distribute a water-based fee that is equitable. For instance, tap fees would be inclusive for connections to the public water system but would miss homes and business supported by water wells. We also have to consider how a proposed fee would relate to the geographical diversity of Texas. The eastern part of the state might view the problem differently as compared to the drought-stricken regions of central and west Texas.”
James Keffer, a representative in the Texas Legislature and member of the natural resources committee, said Texas now needs to embrace the same vision that was taken back in the late 1950s, when the state was emerging from a multiyear drought that was the worst in recorded history. Policy-makers and agencies were driven to develop new supplies and new sources of water. “We need to not only look at building new reservoirs but also to explore new and relatively untapped sources of water,” Keffer said. “The technologies are available and the resources local for pursuing desalination projects that utilize Gulf seawater and brackish groundwater.”
One initiative already under way includes the San Antonio Water System (SAWS) brackish groundwater desalination project, which will use reverse osmosis for generating water to drinking standards. The first phase of the project, scheduled to come on-line in 2016, will produce about 38,000 m3/d (10 mgd). According to SAWS, brackish groundwater is a plentiful, previously untapped local source of water that will help diversify San Antonio’s supplies.
The timing is increasingly urgent for funding water-related projects, according to Keffer. “A reservoir is a 20- to 30-year process, and a desalination plant can take up to 5 years to build. If the state has truly entered into a long-term drought cycle, then we need to get very serious about financing more projects so they can get under way,” he said.
While very costly to industries reliant on water and particularly affecting to many of the state’s reservoirs and aquifers, the drought also has helped inspire a sort of consensus view toward the need and urgency of securing future water supplies, Keffer added. “If there was one positive that resulted from last year’s drought, it was that the impact of water shortage was felt statewide, which helped build broad knowledge and concern for taking the necessary steps forward,” he said.
— Jeff Gunderson, WE&T
Not so secure
A former employee allegedly accesses a Florida wastewater treatment plant’s computer system illegally
When it comes to cybersecurity at water or wastewater treatment plants, the threat to supervisory control and data acquisition (SCADA) systems can come from outside or within the utility. But based on the way “utility SCADA systems are typically built, I would say that you always have the greater threat from an insider in terms of attack, especially if you factor in which kind of attack could cause the most damage,” said Ron L. Booth, vice president at Westin Engineering (Rancho Cordova, Calif.).
Though its system was not attacked, the Key Largo (Fla.) Water Treatment Facility experienced its own security scare earlier this year when Sal Zappulla, the former finance officer for the water district, allegedly accessed computers illegally that belonged to the treatment facility. Zappulla was later charged with nine misdemeanor counts and 21 felony counts, according to the Monroe County Sheriff’s Office.
According to the sheriff’s office website, the facility’s computer manager, Paul Christian, contacted the Monroe County Sheriff’s Office in February to report that during a routine check of employee e-mail, he noticed several e-mails from an employee’s account being sent to an address he recognized. Christian alleged that the e-mail address belonged to Zappulla, who once worked for the facility but whose contract had not been renewed. Christian continued his investigation and allegedly discovered that Zappulla had been illegally accessing the facility’s computers.
When Zappulla was confronted by a sheriff’s office detective, he allegedly bragged about using passwords belonging to other facility employees to access the facility’s computers from home.
“He told Detective Dosh he accessed the computers illegally to prove the computer system was not secure,” the Monroe County Sheriff’s Office website states. “Zappullo [sic] told the detective he accessed the computers and downloaded e-mails and other documents pertaining to him. Further investigation revealed he also deleted some information as well.”
To combat something similar from happening at other facilities, the U.S. Department of Homeland Security (DHS) Industrial Control Systems Cyber Emergency Response Team has some security recommendations for control system owners and operators. In addition to using the DHS Control System Security Program’s cybersecurity evaluation tool to determine where improvements can be made, owners and operations staff should take the following steps:
- Minimize network exposure for all control system devices by not making them accessible via the Internet.
- Place control system networks and devices behind firewalls and isolate them from the business network.
- If remote access is required, use secure measures, such as virtual private networks, or VPNs, recognizing that a VPN is only as secure as its connected device.
- Remove, disable, or rename any default system accounts wherever possible.
- Implement account lockout policies to reduce the risk from brute-force attacks.
- Implement policies requiring the use of strong passwords.
- Monitor the creation of administrator-level accounts by third-party vendors.
— LaShell Stratton-Childers,
More than just a chip
Frito-Lay installs groundbreaking industrial wastewater treatment process, helping the facility run almost entirely on renewable energy and recycled water
Whenever someone thinks of Frito-Lay (Plano, Texas), corn chips and potato chips are probably the first things that come to mind. But now, the name also will be associated with water reuse and alternative energy, thanks to a groundbreaking industrial wastewater treatment process at the company’s snack-manufacturing plant in Casa Grande, Ariz. The facility became not only the first U.S. food processing plant to produce drinking-water-quality process water to be used in food production, but also the first snack-food manufacturing facility in the United States to be awarded LEED Existing Building Gold Certification from the U.S. Green Building Council (Washington, D.C.), according to a CDM Smith (Cambridge, Mass.) press release.
CDM Smith designed and constructed the 2460-m3/d (650,000-gal/d) process water recovery treatment system. Prior to the construction of this system, Frito-Lay had a land application facility, said Al Goodman, principal at CDM Smith. “The treated wastewater was being used for crop irrigation,” he said.
Frito-Lay did not have the initial goal of building a nearly zero-waste facility that runs almost entirely on renewable energy and recycled water, Goodman said. “They needed land space to insert solar panels, [and] ... they had the location in the Southwest that was optimal for light exposure for the solar arrays.” But in order to build the arrays, the company had to upgrade its facility to the next level of treatment, because it no longer would have the extra land for land application of the treated wastewater, he said.
So, CDM Smith designed an advanced purification process that “incorporates screening, sedimentation, membrane bioreactor, activated carbon, ultraviolet, low-pressure reverse osmosis, water stabilization, and chlorine disinfection to treat the effluent to U.S. Environmental Protection Agency primary and secondary drinking water quality standards, allowing it to be reused to wash and move potatoes and corn,” according to the press release. A 5-MW photovoltaic solar panel system that produces all the plant’s daytime electricity was built next to the plant.
During the design–build process, CDM Smith used a 3-dimensional and 4-dimensional design approach that “allowed for a future computerized maintenance management system to maintain equipment and track costs — adding to the client’s confidence in the sustainable water reuse system,” according to a CDM Smith fact sheet.
“The 3-D [approach] allowed for easier visualization of drawings,” Goodman said. The engineers could see exactly what the plant would look like onsite. “The 4-D [approach] allowed us to see into the future,” Goodman said, by providing additional information on specifications and the ability to update it. For example, 4-D diagrams of pumps could include such information as what the pump is made of, its dimensions, etc. “This is called intelligent design,” Goodman said.
In total, it took 4 months to design the facility and a little more than a year to construct it, Goodman said.
The final product now recycles as much as 75% of the facility’s process water, enabling Frito-Lay to reduce its annual water use by 380 million L (100 million gal), according to the press release. Also, the facility reduced its overall waste. Eighty percent of the construction debris was recycled for beneficial use, dewatered potato peelings and corn kernels are routinely sent to local farms for feedstock, recovered potato starch is sold for other manufacturing uses, and the facility now sends less than 1% of its overall waste to landfills, according to the fact sheet.
Goodman said Frito-Lay has 39 manufacturing facilities in North America, and this is the first facility in which it has used the new advanced treatment process. It could be used at those other plants in the future, but for now, the company is waiting.
“They have several facilities where water cost is more than the cost of the advanced treatment facility, but they want more run-time first to see how the system performs before they consider having it at different facilities,” Goodman said.
©2012 Water Environment Federation