June 2008, Vol. 20, No.6

The Power of Digester Gas 

As this California utility demonstrates, biogas-derived electricity can reduce our dependence on foreign fuel supplies

The Power of Digester Gas Mark McDannel and Ed Wheless

There are many benefits in using wastewater and solid-waste management byproducts to generate electricity. These byproducts are low-cost sources that can provide enough local power to displace imported power, thus reducing the expense and environmental consequences of burning fossil fuels.

The County Sanitation Districts of Los Angeles County (CSD) has a long history of using biogas to produce
electricity. In 1938, digester-gas-fueled onsite internal-combustion engines provided all the power a CSD treatment facility needed. It was so successful that the facility was disconnected from the local electric utility. Ever since, CSD has pursued the economic and environmental benefits of “waste gas.” At wastewater treatment plants, CSD personnel use digester gas to generate the electricity needed for plant operations. At landfills, CSD personnel use landfill gas to generate electricity and then sell it to the local power utility.  Read full article (login required)  


The Future Looks Bright 

Ultraviolet irradiation systems are rapidly gaining traction in the water treatment, wastewater treatment, and water reuse markets

The Future Looks Bright Bertrand W. Dussert

Although ultraviolet (UV) irradiation technology has been available for more than a century, it only gained prominence in the water management field during the last 2 decades. Now, UV irradiation is a hot growth area in the water
treatment market.

The worldwide water market for UV technologies currently is estimated to be worth a total of $500 million. This includes municipal wastewater treatment ($120 million), municipal drinking water treatment ($120 million), industrial pretreatment ($100 million), commercial use ($80 million), and consumer–residential use ($80 million). This market is forecast to grow to more than $900 million by 2010 (assuming a 10% growth rate for the industrial, commercial, and consumer–residential markets and a 15% to 20% growth rate for the municipal water and wastewater treatment markets).   Read full article (login required)    


Advanced Treatment to Remove Microconstituents

Studies indicate several technologies show potential to remove endocrine disrupting compounds and pharmaceutical and personal care products.

Advanced Treatment to Remove Microconstituents Gary Hunter, Dan Buhrmaster, Tom Walz, Jim Coughenour, Peter Ruiz–Haas, and Karl Linden

Microconstituents, which include such chemicals as endocrine-disrupting compounds (EDCs) and pharmaceutical and personal-care products (PPCPs), have earned considerable attention from the public and regulators in recent years. Most of these concerns stem from their known aquatic and environmental impacts and potential human health effects at very low (part-per-trillion or part-per-quadrillion) concentrations. Unfortunately, traces of EDCs and PPCPs are not easily removed by conventional wastewater treatment processes.

The City of Phoenix has conducted two studies to examine technologies for the removal of pathogens, EDCs, and PPCPs. The first phase, which at press time was due to be completed this spring, included a pilot study to evaluate various combinations of disinfection processes at the city’s 91st Avenue Wastewater Treatment Facility. The pilot test included evaluation of the germicidal effectiveness of these disinfection technologies while also removing various types of microconstituents. The second study compared the removal of microconstituents at four wastewater treatment plants, including the 91st Avenue plant. Results from these studies indicate that various technologies can achieve pathogen and microconstituent removal.  Read full article (login required)  


Operations Forum Features

Rooting Out SSOs 

Evaluating popular root-control methods in a pilot-scale sanitary sewer

Rooting Out SSOs Joel Ducoste, Justin Wood, Tarek Aziz, John Groninger, Leon Holt, and Kevin Keener

Root intrusion in sanitary sewers is a significant contributor to the alarming rate of sanitary-sewer overflows (SSOs) occurring in the United States. About 40,000 wastewater overflows occur annually, according to the U.S. Environmental Protection Agency (EPA) 2001
fact sheet, EPA Takes Action To Protect the Nation’s Beaches From Health Threats Posed by Raw Sewage Overflows. A significant percentage of these overflows are facilitated by root intrusion.

A better understanding of popular root-control methods is required for the development of an optimal root-removal and pipe-maintenance protocol. To that end, researchers from several universities, as well as the town of Cary, N.C., designed a pilot-scale sewer environment in Oxford, N.C., and compared the effectiveness of popular root-control methods. They tested two herbicidal chemicals, as well as mechanical removal. The research, which was sponsored by the Water Environment Research Foundation (Alexandria, Va.; Project No. 03-CTS-16T), explored the extent to which the treatments stop root growth, induce root decay, and inhibit regrowth so that an effective treatment and maintenance protocol can be developed for both municipalities and private landowners.  Read full article (login required)  


Saving for a Rainy Day 

The importance of budgeting operations and maintenance staffing and nonstaffing needs for SSO and CSO control facilities

Saving for a Rainy Day Gary Fujita and James Sherrill

As long-term wet weather control plans are developed and implemented, the operations and maintenance (O&M) manager is often faced with developing a budget with little to no background information. Implementing long-term wet weather control plans can be daunting, costing upwards of $1 to $2 billion for large, older communities with combined sewers. Capital funds can be raised via revenue bonds or
state revolving loans, which are paid off over a 20- to 30-year period. However, unlike the capital funding for wet weather facilities, O&M costs can significantly affect sewer rates, since those costs must be allocated on an annual basis. Without consideration of the O&M costs associated with each control option, the “least-cost” capital alternative may result in a higher overall cost when O&M is accounted for.  Read full article (login required)   


Collaborate to Educate 

Collaborate to Educate

Collaborate to Educate Aisha Niang, Richard Cardazone, Patrick O’Connor, Nat J. Federici, and Frank Giardina

Clear documentation, effective training, and appropriate knowledge-sharing mechanisms are crucial for the successful startup and long-term operation of any new process. That’s why the New York City Department of Environmental Protection (DEP) used a programmatic approach to prepare the staff for its new egg-shaped digester facility at the Newtown Creek Water Pollution Control Plant in Brooklyn, N.Y. Due to the complexity of the system — 3000
valves, five different process loops, and 29 million gal (110 million L) of solids capacity — and a continually shifting work force assigned to operate it, effectively preparing plant staff to operate the facility was critical.

To that end, DEP hired a three-way joint venture (JV) team from Greeley & Hansen (Chicago), Hazen & Sawyer (New York), and Malcolm Pirnie Inc. (White Plains, N.Y.) to provide startup and operations services and ensure a smooth transition during construction of the system. The team’s duties included acting as a liaison for the plant with designers, vendors, and construction management representatives. The team also was tasked with preparing plant staff to operate the new digester system.  Read full article (login required)