May 2010, Vol. 22, No.5

A ‘Perfect Storm’ of Upgrades 

Wisconsin treatment plant expands capacity without adding tanks


feature 1 Kenneth Sedmak, Thomas Krueger, Aric Bergstrom, Gary Cressey, and William Marten

As wastewater treatment plants age and communities grow, facilities must be improved to keep up with demand. However, capital improvements are an expensive means of increasing treatment plant capacity. Finding and modifying the capacity-limiting treatment processes can be a much more cost-effective solution.

Grafton, Wis., a village 40 km (25 mi) north of Milwaukee, is a growing community. In 1997, the Grafton Water and Wastewater Utility had to decide whether and when to abandon its existing wastewater treatment facility and build a new one jointly with a neighboring utility. Before making this decision, Grafton staff needed to know the plant’s current capacity, its capacity-limiting treatment processes, and how much margin was left.

The project team evaluated the existing plant and found unused capacity that would enable the utility to postpone major capital improvements. Minor modifications to the existing plant would not only increase capacity but also improve effluent quality and reduce energy costs. Read full article


Aerate for Less

Turbo blowers can cut energy costs by more than 35% 

feature 2 Katherine Bell, Jason Sciandra, and Kevin Wagner

Most of the electricity used at wastewater treatment facilities powers aeration systems that deliver air to biological treatment processes and mix wastewaters to suspend solids in process tanks. Aeration processes can account for 60% or more of a facility’s overall power consumption, so making them more energy-efficient would greatly reduce energy consumption and costs. Blowers, in particular, are often high priorities when improving energy efficiency. Read full article


Energy Efficient MBRs

A well thought-out design can minimize a membrane bioreactor’s energy demand

feature 3 Sudhanva Paranjape, Roderick Reardon, and Joe Cheatham

Although membrane bioreactors (MBRs) continue to gain popularity because of their compact size and exceptional-quality effluent, these systems tend to be energy hogs. So, when upgrading the Lake Bradford Road Water Reclamation Facility (Tallahassee, Fla.) to an MBR, the project team implemented measures that could reduce the facility’s overall energy use by 20% while still meeting effluent requirements. Read full article


Operations Forum Features

A Biosolids Process With a Renewable Power Bonus

Landfill gas dries biosolids, generates green energy 

Feature 4 art Sandy Warren

Ventura County, a multihued California quilt of laid-back beach towns, fertile farmland, and sparkling suburbs just north of Los Angeles had a problem — what to do with the 8000 ton (7260 Mg) of biosolids produced by local wastewater treatment plants every month. For years, the answer had been to load the treated solids onto trucks and haul them more than 150 mi (240 km) to Kern County, Calif., where it was given additional treatment and then land-applied as soil conditioner and fertilizer.

But in 2006, a Kern County voter initiative threatened to halt the hauling for good. Faced with the need for a more reliable biosolids disposal solution, the management and engineers at Ventura (Calif.) Regional Sanitation District proposed a creative idea: Use methane gas produced from decaying refuse in a local landfill to fuel a regional biosolids drying system and simultaneously drive a network of microturbines to generate power for the facility and the local grid. Read full article



Permit-Safe, Energy-Smart

Greening wastewater treatment plant operations 

Feature 5 art Bhavani Yerrapotu, Medi Sinaki, Steve Colby, and Issayas Lemma

The San Jose/Santa Clara (Calif.) Water Pollution Control Plant is an advanced wastewater treatment facility with a rated capacity of 167 mgd (630,000 m3/d). During the past several years the plant has been quite active and successful in identifying and implementing energy-saving projects without compromising its effluent quality.

The projects have produced significant sustained savings in operating costs. In addition to energy savings, financial incentives in the form of rebates from its electric and natural-gas utility helped drive these projects. In many cases, the rebates covered the entire expenses of the projects, making the final implementation cost zero. Read full article


Testing a Nutrient Removal Option

IFAS enables Virginia plant to meet permit demands 

Feature 6 art Bob Rutherford

When Hampton Roads Sanitation District (HRSD; Virginia Beach, Va.) received a tough new nitrogen wasteload allocation nitrogen limit — 6 million lb (2.7 million kg) per year — the James River Treatment Plant (JRTP; Newport News, Va.) — one of HRSD’s nine large plants — set out to perform a full-scale demonstration study of an integrated fixed-film activated sludge (IFAS) system. The 20-mgd (760,000-m3/d) JRTP estimated it could remove about 760,000 lb (340,000 kg) of nitrogen by switching to a moving-carrier IFA S process from its conventional single-stage activated sludge process.

Through the demonstration study, JRTP staff members were able to gain experience operating a moving-carrier IFA S system, confirm the ability of the process to meet the needed requirements, and identify ways to improve the performance, operability, and economy of the full-scale design. Read full article


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