Denitrification Takes a BAF
Jon R. Pearson, Dennis A. Dievert, Donald J. Chelton, and Matthew T. Formica
Starting up the first separate-stage biological anoxic filter in Connecticut requires some problem-solving and know-how
The 13,200-m3/d (3.5-mgd) Water Pollution Control Plant (WPCP) in the town of Cheshire, Conn., was facing significant expenditures to purchase nitrogen removal credits under Connecticut’s nitrogen credit trading program. After evaluating various approaches to nitrogen removal, the town selected the
separate-stage biological anoxic filter (BAF) process with methanol feed. This installation, the first in Connecticut and the second in the New England region, is also the first application to add a separate denitrifying BAF to an existing nitrifying plant in the United States.
One of the main reasons for selecting the BAF process was its compact size, resulting from higher loading rates than those for more conventional filter techniques. The upflow BAF has proven successful in achieving the targeted high level of denitrification during the initial operating period, consistently reducing effluent total nitrogen to less than 3 mg/L. In general, the denitrification system operates automatically, with little operator attention except for observation of the filter and minor preventive maintenance of the on-line analyzer. Read full article (login required)
An Ounce of Prevention
Susan E. Moisio and Peter L. Caldwell
Cincinnati’s ‘Water in Basement Prevention Program’ boosts customer service, worker morale with simple solutions to backups
Many customers of the Metropolitan Sewer District of Greater Cincinnati have experienced basement backups due to surcharging of the sanitary and combined-sewer systems. As part of a consent decree that the district signed with the U.S. Environmental Protection Agency in 2003, the district
developed a program to address this problem: the Water in Basement Prevention Program (WIBPP).
The goal of WIBPP is to isolate affected homes from the sanitary and combined-sewer system. Five-hundred homes participated in this $37 million program from January 2004 to October 2006. Solutions include installation of backflow valves, whole-house grinder pumps, basement-only grinder pumps, and ejector pumps. The program has now entered into caretaker status — solutions that have been installed will be maintained. Each home is tracked as a separate project with an individual design and construction. This article focuses on the steps taken to achieve the 500 completed projects and the lessons learned from identifying and eliminating private-property infiltration and inflow. Read full article (login required)
Saving the Planet With Bars of Soap and Trucks That Smell Like French Fries
An Alabama utility enlists its customers’ help to remove FOG from sewers
Imagine the following scenario: You and your family are walking through a fun-filled street festival. Children are playing. Local artists are displaying their wares. Sips of ice-cold lemonade fend off the summer heat. Suddenly, you turn and exclaim, “Hey, there’s the guy who runs the sewer system! Let’s ask him what
they’re doing to protect the environment and how we can help.”
Sound far-fetched? Well, it doesn’t have to be. A sweet-smelling truck and a tiny bar of soap have transformed the way Daphne (Ala.) Utilities interacts with customers to combat sewer problems. As Daphne’s story illustrates, you can get your customers’ enthusiastic help, improve your sewer system’s overall function, build powerful public relations, and save money, all at the same time. Read full article (login required)
Operations Forum Features
The Rock Box
R. Mark Pearson and Shaun O’Kelley
Diversion structure protects headworks of Missouri wastewater treatment plant
The Kansas City (Mo.) Water Services Department (WSD) operates the 105-mgd (397,000-m3/d) Blue River Wastewater Treatment Plant (WWTP) located near the confluence of the Blue and Missouri rivers. The plant serves both combined and separate sanitary sewer systems. Part of the plant’s flow comes from the Blue River Interceptor Sewer, which carries large quantities of grit, silt, rock, and other
debris that are washed into surface drains, curb inlets, and other stormwater collection devices throughout Kansas City, especially during wet weather events.
As the wastewater enters the plant through a connecting sewer, it slows down, dropping tons of heavy, coarse grit and debris. The weight of this material was warping and damaging bar-screen scraper mechanisms and even buckled some of the screens. The coarse material also was overwhelming the augers and bucket elevators in the grit-removal process.
WSD needed to address this overloading issue and repair and upgrade Blue River’s bar screens. WSD and a contract engineering firm analyzed the available in-line and off-line technologies. Nothing they saw seemed to be a good fit, so they devised their own solution: the Rock Box. Read full article (login required)
Odors Get the Chute
Articulating and automating a biosolids discharge chute
Operators at the Vallejo (Calif.) Sanitation and Flood Control District used a do-it-yourself approach to build an articulated chute that would be the solution to evenly loading their biosolids transfer trucks and controlling odors. As part of a plantwide odor-control project, the district needed to find the most cost-effective solution to controlling odors while filling its hauling trucks from the biosolids storage hopper.
District staff evaluated designs and chose to test their own prototype. The automated articulating discharge chute was completely built, automated, and testet in-house during 3 months. This project is a great demonstration of the technological achievement made possible by relying on the knowledge and experience of the district staff. This hinge has now been in use for more than 2 years with no problems. Read full article (login required)
Tips for Maintaining and Troubleshooting Your SCADA System
Maintaining the various components that comprise a supervisory control and data acquisition (SCADA) system isn’t always easy. And troubleshooting them can be even trickier.
While your system manufacturer is a good source for answers, you’re sometimes the one who has to figure out what to do. Below are some do-it-yourself tips for maintaining
and troubleshooting your SCADA system’s power supply, battery backup system, analog loops, discrete digital inputs and outputs, and communications. Read full article (login required)