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BC WATER NEWS

Sept. 29, 2014 — Change is in the air — and the water.

As industry professionals gather in New Orleans this week for the Water Environment Federation's Annual Technical Exhibition and Conference, with 22,000 attendees and a comprehensive technical program of more than 1,000 presentations, there remains one constant: WEFTEC always showcases the latest in water quality developments, research, regulations, solutions and cutting-edge technologies.

The theme of the Opening General Session keynote is "Embracing Change in a Disruptive Age," something water experts have been doing with new, transformative thinking that is leading to innovative solutions for today's most vexing water challenges.

Keep reading to learn how utilities in Oakland, Calif., Seattle and Cleveland are going beyond thinking outside the box and reinventing the box altogether.

 
 
WEFTEC 2014




 

 In 2012, EBMUD became the first wastewater treatment plant in the United States
 to produce more renewable energy than the utility needs to run its facility.



EBMUD's resource recovery program in Oakland, Calif., advances net-zero energy

Faced with the challenge of using existing digestion infrastructure in new ways — whether for Class A digestion, resource recovery, or other forward-thinking processes — utilities around the country are searching for new solutions. The East Bay Municipal Utility District in Oakland, Calif., has taken it a step further with a resource recovery program that advances the concept of net-zero energy.

In 2012, EBMUD became the first wastewater treatment plant in the United States to produce more renewable energy than the utility needs to run its facility. This monumental accomplishment was made possible by an energy-efficient, low-emission gas turbine that was installed in 2011. Excess renewable energy is sold back to the electrical grid to cut fossil fuel use and greenhouse gas emissions, and EBMUD ratepayers reap the savings. Biogas production saves the district about $3 million each year by reducing electric power demand.

"EBMUD is at the forefront of the concept of acting as a resource recovery facility rather than a wastewater treatment facility," says Adam Ross, Brown and Caldwell engineer and co-author of the paper being presented at WEFTEC this week, "Modifying 20th Century EDMUD Digestion System for 21st Century Needs."

"This mindset is a paradigm shift from disposal of waste to production of recycled water, energy or nutrients," Ross said.

EBMUD collects biodegradable wastes in sewage, food scraps and grease from local restaurants that are mixed together in large tanks and "digested" by microorganisms. The biogas emitted by the microorganisms is captured and used to generate renewable energy to power the wastewater treatment plant.

EBMUD's rejection of old-school thinking that would lead to mitigation instead of innovation started with a small receiving program for fats, oil and grease (FOG).

"They had everything they needed to ramp up the program — lots of available digestion capacity, available cogeneration capacity, and a great location in the middle of an urban area," Ross said. "Once EBMUD saw the promise of the overall program, they made a conscious push to see how far they can go with it."

As EBMUD has become less reliant on utility power and the overall program has been a win financially, other facilities are beginning to follow suit, although none are at the same level yet.

"There are so many interrelationships between wastewater, energy, water, solid waste and organics," Ross said. "Anaerobic digestion — and cogeneration using the resulting digester gas — is a key process in treating traditional wastewater solids, but also as a process that allows for organics to be diverted from more energy-intensive disposal pathways or from landfilling."

California's goal of reducing solid waste to landfills by 75 percent and getting to 33 percent renewable energy means that anaerobic digestion will play a key role, he added. So while the traditional model of planning for gradual shifts has yet to become a thing of the past, these kinds of special technologies and developments can cause a disruption to tradition.

"The anaerobic digestion of things-other-than-traditional-wastewater-solids is a good example," Ross said. "It has excited folks about the net-zero-energy concept and has wastewater agencies collaborating more with solid waste and industrial companies."

 

  NEORSD is moving ahead with a groundbreaking project for advancing the future of
  wet-weather treatment at their plants.

 

Advancing wet-weather treatment using a proven technology in a new way

As extreme weather events continue presenting challenges to wastewater agencies, wet-weather solutions are in high demand, and traditional treatment technologies remain tremendously expensive. The Northeast Ohio Regional Sewer District (NEORSD) has risen to the challenge by taking a tried-and-true treatment technology in an innovative direction, and now has a viable wet-weather solution that is already demonstrating promising results.

On Tuesday, WEFTEC attendees will have a chance to learn more about how NEORSD is moving ahead with a groundbreaking project for advancing the future of wet-weather treatment at its plants. In response to an EPA consent decree, the district is implementing one pilot- and two full-scale demonstrations for the chemically enhanced primary treatment (CEPT) and high-rate disinfection (HRD) for its wet-weather flows at its three wastewater treatment plants in the Greater Cleveland area. Together, these technologies are referred to as Chemically Enhanced High Rate Treatment (CEHRT).

"We are using an old technology in a new way that really represents some transformational thinking," said Dan Davis, Brown and Caldwell's project manager. "CEPT is being repurposed for wet-weather treatment. Our mission is to reliably demonstrate and document the effectiveness of CEHRT on treating wet-weather wastewater flows."

During CEPT, a coagulant is added to screened plant influent, followed by a polymer flocculant to consolidate the floc created during the coagulation process. Using CEPT instead of the more costly ballasted flocculation alternative is estimated to save the district millions of dollars. This is accomplished at one of the facilities by using plants existing primary clarifiers in a dual use mode. They operate as normal during dry weather; however, only during wet weather are chemicals turned on to improve performance.

HRD uses high-rate mixing along with higher doses of a chemical disinfectant to reliably meet effluent bacteria requirements in much shorter contact times than conventional disinfection. Results have shown that by using HRD, the district will be able to minimize the construction of costly contact tanks required for disinfection of its wet-weather flows and achieve the disinfection requirements in five to 10 minutes.

"By demonstrating the performance criteria can be met, NEORSD will be able to maximize existing infrastructure during full-scale implementations. This will potentially save hundreds of millions of dollars when compared to the consent decree stipulated alternative treatment technology," Davis said.

Successful implementation of the eventual full-scale CEHRT systems requires smart decisions and forward thinking during the pilot and demonstration phase. The district is working to validate the effectiveness of CEHRT and consider the latest innovations in chemically enhanced CEPT and HRD that maximize performance.

During wet-weather conditions, operations staff members are deployed to operate and measure the performance at each of the facilities. The work presents a number of challenges, including intermittent operations, unpredictable wet weather, and changing influent water quality characteristics — all of which can impact performance.

Despite the challenges, the facilities have performed well at the midpoint of the demonstration program and have met targeted effluent requirements over a range of events tested. The team has been able to combine the latest technology of long-range meteorological forecasts with sophisticated methods of local weather tracking and team deployments for the most advanced notice of imminent storm events and plant response.

"We're midway through the program and have met the targeted effluent requirements over the 34 events we've tested," Davis said. “This project represents some really groundbreaking work for our industry in terms of the scale of the facilities tested and the amount of data we’re generating. All of this work makes the most of existing plant infrastructure and brings tremendous cost savings.

"NEORSD’s investment in this project should be applauded," he said. "This approach allows them to prove the efficacy of these technologies on their wastewater to meet their requirements and to provide the necessary data for regulatory acceptance."

 

 Seattle is one of the first cities in the United States to develop an Integrated Plan to prioritize
 and coordinate stormwater and combined sewer overflow projects.

 

 

Seattle demonstrates the value of an integrated approach for water management

The City of Seattle is one of the first cities in the United States to develop an integrated plan to prioritize and coordinate stormwater and combined sewer overflow projects as part of a consent decree.

"Seattle saw that the traditional regulatory approach for dealing with wet-weather quality was not efficient," said Mike Milne, Brown and Caldwell's project manager. "Regulatory requirements are outpacing revenues, so it is more and more important to get the most bang for the buck, while still maintaining compliance.

"The old school thinking was, 'Here's your permit, you have to control CSOs according to your permit.' The CSO and stormwater requirements were kind of siloed," Milne said. "The integrated planning approach allows the city to look at things more holistically and prioritize its investments to get the most benefits in terms of water quality improvements."

The IP team was faced with the challenge of identifying stormwater projects that will provide significant water quality benefits beyond those provided by the approved CSO control measures alone.

"The bottom line is that the stormwater projects chosen would provide much greater pollutant load reductions than the deferred CSO projects, primarily because the stormwater projects would treat much larger volumes than the deferred CSO projects," Milne said.

Because so much had been done with CSOs already, the remaining projects included the expensive and particularly tricky ones — those that were deferred initially because the value wasn't there. In the case of stormwater, which is a major potential source of pollution to receiving water bodies around the city, including Puget Sound, "there was plenty of low-hanging fruit left," Milne said.

This turned out to be good for SPU, better for the environment and beneficial for the citizens of Seattle.

"It provides significantly better water quality habitat improvement than would have been achieved otherwise," Milne said, "and it's better for people who use the water for fishing, kayaking, shell fishing, swimming, you name it, as well as being better for ecological receptors, including endangered and threatened species."

Other municipalities are moving toward integrated planning, applying the concepts and methods SPU has developed as they work with regulators to comply with regulations and prioritize investments to improve water quality in their communities.

"There's ever-increasing pressure to get the most out of every dollar that we invest in stormwater quality and water quality in general, and this type of approach allows jurisdictions and utilities the ability to get the best return on their investments," Milne said.

 


© 2014 BROWN AND CALDWELL