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Sunday, 07 July 2013 22:00

Wastewater project looking to squeeze more value out of biosolids

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Biosolids from the Wyoming Clean Water Plant are pumped to the Dewatering Facility by a series of pumps and motors, shown above. The GVRBA wants to revisit an earlier proposal for an anaerobic biodigester at the plant to help get ahead of increasing costs. Biosolids from the Wyoming Clean Water Plant are pumped to the Dewatering Facility by a series of pumps and motors, shown above. The GVRBA wants to revisit an earlier proposal for an anaerobic biodigester at the plant to help get ahead of increasing costs. COURTESY PHOTO

A partnership involving the cities of Grand Rapids and Wyoming wants to double down on its past investments in wastewater treatment facilities to help get ahead of cost increases the partners see on the horizon.

The Grand Valley Regional Biosolids Authority (GVRBA), a partnership between the City of Wyoming and the City of Grand Rapids that formalized in 2004, is trying to get closer to net-zero energy consumption at the cities’ two wastewater processing facilities.

The reason: They expect to see continue indefinitely the increased capacity needs and rising costs to both send biosolids to the landfill and to treat wastewater.

In late May, the authority released a request for qualifications for firms that could ultimately help the cities improve their biosolids processing systems. Biosolids are the nutrient-rich organic materials resulting from the treatment of sewage or wastewater. Now, the authority is reviewing submissions from seven companies, including several local firms.

Anaergia, Chevron Energy Solutions, Fleis & VandenBrink Engineering, HESCO, Swedish Biogas International, Synagro and United Water Environmental Services partnering with Kohlberg, Kravis, Roberts & Co. all responded to the request.

The GVRBA expects to issue a request for proposals for project plans as soon as August.

“As part of the GVRBA’s Vision 2020 framework, we are trying to look at ways we can further reduce our costs to taxpayers and maximize energy capture,” said Haris Alibasic, director of legislative affairs and the energy and sustainability office at the City of Grand Rapids.

Grand Rapids and Wyoming are “pushing for net-zero consumption” at their respective wastewater treatment facilities and have a wishlist of improvements and additions, including an anaerobic digester that repurposes gases into energy to offset the costs of operating the facilities in the long run.

Initially, GVRBA came together so both cities could jointly manage the biosolids each produced in the treatment of sewage. Prior to this, the two cities had individual programs for dewatering the biosolids and sending that material to the landfill.

The group’s early plans looked into a sophisticated system to convert the biosolids into energy and other usable byproducts, but that $112.5 million proposal was scaled back because its cost was too high.  

Now an anaerobic biodigester could be back in the plans, although the authority must first evaluate all its options, Alibasic said.

There are a number of solutions and processes that could allow the GVRBA to decrease costs and make its product more valuable, said Aaron Vis, operations project manager for the authority and environmental services inspector for the City of Wyoming’s Clean Water Plant.

“All of these projects are capital intensive,” Vis said.

The original project was built in four phases and included a pumping station at the City of Wyoming’s Clean Water Plant, a mixing and equalization tank for chemically reacting and blending the solids at the City of Grand Rapids’ Waste Water Plant, a pipeline in between the two plants, and the centrifuge dewatering facility located at the Grand Rapids plant.

At a cost of $34 million, the operation still wasn’t cheap. However, meeting expected capacity needs over the next 20 years will help provide a better payback on the investment, GVRBA officials said.

With improved technologies emerging in energy recovery systems since the installations first occurred, GVRBA is looking to further maximize its investment as landfill costs continue to rise, the need for treatment capacity increases and current infrastructure ages.

Wyoming operates a “liquid land application” program, which uses the biosolids to fertilize some 30 acres of farmland. The city sends the remaining 25 percent of its biosolids to the centrifuge dewatering facility in Grand Rapids. Residuals from the dewatering facility, which handles all of Grand Rapids’ biosolids processing, are currently being sent to the waste-to-energy plant in Grand Rapids or to a compost facility.

In 2012, approximately 18,350 dry tons of biosolids were handled by the GVRBA. The organization’s annual budget is about $7.9 million.

Even with the sophisticated system, it’s still costly for the municipalities to manage their biosolids. Wyoming’s land application costs approximately $293.49 per dry ton. Meanwhile, the authority pays $337.35 per dry ton for the waste-to-energy operation and $317.02 per dry ton for the composting program.

The current operation has an annual debt service of roughly $2.1 million that Grand Rapids and Wyoming share at a roughly 60-40 ratio, respectively.

“Right now, it still costs us a lot of money to get rid of these biosolids,” Vis said.

With RFQs in hand, the GVRBA is set to evaluate companies’ capabilities and potentially issue a project RFP by the end of summer. 

Read 4332 times Last modified on Friday, 19 July 2013 11:53

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