Features

July 2011, Vol. 23, No.7

What you know can save you 

Understanding your options for purchasing electricity is the first step toward managing costs more effectively 

Moore art Travis Moore and Jeffrey Buxton

The water and wastewater industry consumes approximately 7% of the electricity generated in the world, according to the U.S. Department of Energy. Since electricity costs often are one of the largest operation and maintenance costs for water and wastewater utilities, they merit substantial scrutiny. But anyone who has ever tried to understand the intricacies of an electricity bill or wondered how to manage rising electricity costs in an age of stagnant or declining budgets knows it can be difficult to implement cost-cutting strategies.

Many utility managers have found ways to cut their electricity costs with little or no capital investment. Large consumers of electricity often are afforded a variety of options for purchasing electricity from their local electric utilities. Options for pricing and the corresponding opportunities for cost reduction generally increase with increased energy consumption. Managers who understand how electricity is priced and purchased and who know their alternatives can identify and take advantage of opportunities to reduce energy costs.  Read full article (login required) 

 

Powerful predictions

Choosing the best wastewater technology based on estimated energy costs 

Curtis art Betty-Ann Curtis and Mark Pamperin

Approximately 20% to 25% of a typical municipality’s energy budget is allocated to water and wastewater treatment. According to U.S. Environmental Protection Agency data, of all the processes in a treatment plant, aeration consumes the most energy at 50% to 60%, followed by pumping and heating for the anaerobic digester process. Choosing energyefficient biological treatment processes, pumps, and blowers has become an industry best practice. But in doing so, it is necessary to balance the capital cost of the equipment with the predicted future power cost.

By using an accurate inflation rate for power over the 20-year expected operating life of the plant, a municipality can be assured that the technology selected is the most economical investment. Historical energy data can be used to accurately select inflation rates and future power costs so that true energy efficiency can be selected. Read full article (login required)

 

Back to nature

Rehabilitating aging infrastructure in environmentally sensitive areas

Nilsen art Kenneth H. Nilsen and Peter Sanchez

In King County, Wash., the Southwest Suburban Sewer District (SWSSD) faced a potentially catastrophic situation when it found that a sewer line beneath a stream was in danger of becoming completely separated from the trunk line. Within 3 months, SWSSD was able to successfully rehabilitate the sewer line and protect against future environmental impacts in the area. Read full article (login required)  

 

Operations Forum Features

Side steps

Battling infiltration and inflow in side sewers 

pottinger art Diane Pottinger, Scott Christensen, and Michael Derrick

The Ronald Wastewater District (RWD) serves about 53,000 customers in northwestern King County, Wash., with a collection system that was installed primarily during the 1950s and 1960s. The district, which was formed in 1951, collects and transfers wastewater to King County Wastewater Treatment Division (KCWTD) and the City of Edmonds (Wash.) Wastewater Treatment Plant.

Throughout the region served by KCWTD, infiltration and inflow (I/I) is a concern. Preventing and removing I/I provides increased capacity for wastewater in the system, reduces annual operating costs, and can prevent or postpone expansion projects.

I/I reduction efforts typically involve repairing or replacing aging and leaking sewer lines, but one area often overlooked or deemed too difficult to address are side sewers — the portion of the lateral that sits on private property. But as RWD found, replacing side sewers can significantly reduce the I/I in the wastewater system, as well as provide a benefit to the property owner. Read full article (login required) 

 

Revisiting a wet weather option

Optimizing chemically enhanced primary treatment 

Melcer art Henryk Melcer, Adam Klein, Greg Land, Rick Butler, Pete Carter, Mike Ciolli, and Ron Lilienthal

The past decade has seen a great interest in the treatment of peak wet weather flows. The regulatory induced redirection of combined sewer overflows (CSOs) for treatment at wastewater treatment plants (WWTPs) has increased peak flows at these plants. Accordingly, chemically enhanced primary treatment (CEPT) has experienced a renaissance as communities have sought economic alternative treatment technologies for WWTPs with existing conventional primary clarifiers. Read full article (login required) 

 

The smell of success 

Overcoming operational challenges to commission and operate a biofilter system 

Hibbard art Craig Hibbard, Jeffrey Hlad, Shelley Trujillo, and Perry Holland

In 2002, the Fort Collins Utilities (FCU) set out to measure and control the odors coming from its 87,000-m3/d (23-mgd) Drake Water Reclamation Facility (DWRF). An extensive odor study provided the information needed to evaluate odor control technologies. In the end, the utility chose to install organic compost/woodchip biofilters.

When construction was completed in 2008 on two sets of biofilters — one each for odors from solids and liquid processes — FCU staff realized that starting up, maintaining, and optimizing these biofilters in a dry climate requires extra attention and knowhow. Read full article (login required) 

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