July 2007, Vol. 19, No.7

Asset Management: Just Do It

Engaging your greatest asset — people — is the key to organizational change

assetmanagement.jpg Mary Snyder and Jim Keary

 As U.S. water and wastewater utilities face rapidly urbanizing development, increasingly stringent regulations, and increasing pressure to minimize rates, many are adopting asset management as part of a long-term business strategy.

Once Sacramento County Sanitation District 1 decided to move forward with asset management, it quickly made significant progress in training staff, making the organizational culture more customer-focused, and reducing costs.  Read full article (login required)  


Reduce Sewer Congestion 

Well-designed FOG management programs help minimize SSOs

reducesewercongestion.jpg Carrie R. Mero and Jessica L. Wilkerson

To manage fats, oils, and grease (FOG) effectively and thereby reduce sanitary sewer overflows (SSOs), municipalities need ordinances and programs with strong education, training, and enforcement components. These will save money, time, and resources, as well as protect environmental and public health, by reducing FOG accumulation in wastewater utilities.  Read full article (login required)  


A Dam Good Idea

Inflatable dams help control wet weather flows in Detroit-area sewers

adamgoodidea.jpg Karen E. Ridgway and Mirza M. Rabbaig

As part of its long-term combined sewer overflow (CSO) program, the Detroit Water and Sewerage Department (WSD) installed 13 in-line, in-system storage devices (ISDs) in large WSD-owned combined sewers in Dearborn, Detroit, Hamtramck, and Highland Park, Mich.

ISDs are inflatable dams that consist of top and bottom sheets of reinforced rubber that are laid on a new concrete pad, clamped together around the perimeter, and bolted to the sewer. When deflated, the top sheet of each dam lays on the bottom sheet. When inflating, air blown into the dam lifts the top sheet to impede the flow of wastewater in the sewer. The dams are controlled based on upstream and downstream wastewater levels and dam pressure.  Read full article (login required)  


Operations Forum Features

The Nitty Gritty 

Grit sampling and analysis

nittygritty.jpg George Wilson, George Tchobanoglous, and Jimmie Griffiths

Grit is defined as inorganic settleable solids ranging in size from 50 to 1000 µm. Grit deposits throughout a plant, gradually reducing processing and operational capacity in mechanically cleaned screens, aeration basins, pipes, channels, and digesters. Grit will abrade pumps and sludge-handling equipment.

To prevent those problems, most treatment plants have processes in place to remove grit from influent at the headworks. But to understand how to remove grit from wastewater most effectively, it is important to understand how grit behaves in that medium and how much grit is there in the first place. Surprisingly, though, there are no published standard methods for sampling and analyzing grit from wastewater treatment plants. For this reason, consideration of the methods used in sampling and characterizing grit must be made to ensure that data generated represent actual conditions.

This article explains why grit settles and why it doesn’t, and discusses the procedures required for municipal grit sampling and sample analysis to obtain accurate data.  Read full article (login required)  


The Industry's Finest 

Operators share their experiences with the new breed of wastewater finescreens

theindustrysfinest.jpg Alec Mackie and Kenny Oyler

The industry is full of legendary finds at the preliminary stage of wastewater treatment where screens remove inorganic solids and grit removal settles out sand, egg shells, and abrasive material.

Some of the odd finds from our files include the front end of
an old Volkswagen Beetle, a swimming turtle rescued by an operator, diamond rings, and currency and casino chips. Then there’s the story of the old lady who visited her local treatment plant to inquire about lost dentures. Once they were found, the story goes, she took them home, gave them a good cleaning, and gave new meaning to the term reuse.

Far from a punch line, however, wastewater inlet works are undergoing a quiet and revolutionary shift to finer and finer screening, a move helping to improve efficiency, lower operating costs, extend the life of downstream machinery and meet stringent requirements for membrane bioreactors.  Read full article (login required)  


Hitting the Mark 

Development and Field Testing of a New Intelligent Sequencing Batch Reactor Control System

hittinghtemark.jpg Andrew Shaw, Andrew W. Fairey, October McConnell, and John B. Cook

Daniel Island, located near Charleston, S.C., is experiencing rapid development. This growth is causing the plant influent flows at the local wastewater treatment plant (WWTP) to increase dramatically. The rapid increase in flows, coupled with difficulties in getting access to an easement to put in a
new outfall necessary for a future permit, caused some consternation for the Charleston Water System. To optimize and rerate its 0.5-mgd (1900-m3/d) sequencing batch reactor plant to buy time to provide additional capacity, the utility installed an intelligent sequencing batch reactor control system.

The optimization steps described in this article enabled the utility to increase the plant capacity to 0.75 mgd (2800 m3/d) with the addition of extra aeration and additional ultraviolet disinfection units, and then to 1.0 mgd (3800 m3/d) with an influent equalization tank. Read full article (login required)