BioCycle May 2007, Vol. 48, No. 5, p. 47
A national survey using 2004 data finds about 55 percent of the biosolids generated in the U.S. are beneficially used.
FOR THE past 10 years, agencies regulating wastewater solids (biosolids), scientists, engineers, concerned citizens, policy makers and other interested stakeholders have relied on limited and aging sources of information about biosolids management in the United States. Recognizing the need for updated, accurate information on biosolids regulation, quality and end use and disposal, the Office of Water in the U.S. Environmental Protection Agency (EPA) funded a proposal submitted by the Northeast Biosolids & Residuals Association (NEBRA) to conduct a national survey. The Northwest Biosolids Management Association (NBMA), BioCycle, and the Wisconsin Department of Natural Resources (DNR) were part of the survey team.
Methods for the national survey included: Literature review to learn from past data collection efforts; a Data Needs & Availability Survey to learn from state agencies, EPA regions and others about what information is desirable and what information is readily available; and a comprehensive survey of biosolids regulation, quality, end use and disposal in each state, completed by state biosolids coordinators and others. Additional data were collected from EPA regions and from individual wastewater treatment facilities (referred to in this project as TWTDS, Treatment Works Treating Domestic Sewage).
As BioCycle has experienced in its past national biosolids management surveys (e.g., “State of Biosolids In America,” December 2000), consistent data is difficult to obtain and compile. It is not because the data isn’t reported. In fact, a great deal of data on biosolids is generated at individual TWTDS, in accordance with regulatory requirements. And each year, treatment works provide this data to EPA (and in many cases, to states) in paper reports. While these are reviewed for enforcement purposes, only some states and some EPA regions (around 30 percent) compile them electronically – which poses a challenge to any national data collection initiative.
Despite the lack of “easily” accessible data, the survey team was able to collect biosolids management information for all 50 states. In some cases, the major TWTDS in a state were surveyed (representing at least 60 to 70 percent of the state’s estimated total wastewater flow), which helped provide a fairly accurate assessment. The national survey requested biosolids management data for calendar year 2004.
A more complete article on the survey results will appear in a summer issue of BioCycle, to be authored by the survey team, which included Ned Beecher and Kristy Crawford of NEBRA, Maile Lono Batura of NBMA, Greg Kester of Wisconsin DNR and Nora Goldstein of BioCycle. A preliminary report can be downloaded from the NEBRA and NBMA websites (www.nebiosolids.org; www.nwbiosolids.org). This article provides highlights of the findings.
Treatment Infrastructure: There are an estimated 16,583 TWTDS in the U.S. The vast majority are small – 13,261 treat wastewater flows equal to or less than one million gallons per day (MGD). That leaves 3,322 TWTDS that treat flows greater than 1 MGD, of which only 551 treat flows greater than 10 MGD. The 3,322 “major” TWTDS treat 93 percent of the existing wastewater flow and, given the significant correlation between flow and solids production, an equivalently high percentage of the biosolids production.
Data Reporting: Ten states (Illinois, Massachusetts, Minnesota, New Hampshire, New Jersey, New York, Rhode Island, Vermont, Washington and Wisconsin) and the District of Columbia were able to efficiently provide comprehensive data on wastewater solids end use and disposal. Delaware, Georgia and Maryland efficiently provided somewhat less comprehensive estimates. For other states (California, Colorado, Hawaii, Montana, Nevada, North and South Dakota, Wyoming) it was relatively easy to compile robust data with the added help of EPA regional offices (Regions 8 and 9) that track biosolids closely using electronic data bases. A combination ofsources were used to compile adequate data from most of the other states. For a few states, estimates of biosolids generation were required in order to tally national totals.
Total Biosolids Generation: Total estimated wastewater flow in the U.S. in 2004 (based on EPA’s Clean Watershed Needs Survey) was 34,201 MGD. Reported wastewater solids used and disposed in 2004 were 7,180,000 dry U.S. tons.
Biosolids Use And Disposal: Figure 1 illustrates biosolids use and disposal practices in the U.S. in 2004. Of the 7,180,000 dry tons reported used or disposed, 3,507,000 (49%) were managed via beneficial use (applied to land for agronomic, silvicultural or land restoration purposes); 3,252,000 (45%) were disposed; and 421,000 (6%) were stored, or their final use or disposal was not reported. It is likely that most of that six percent was destined for beneficial uses, which means that the rate of beneficial use of biosolids tracked in 2004 was probably close to 55 percent. (It also should be noted that biosolids reported as used for daily landfill cover were included in the disposal side of the equation, even though California, Washington and some other states define daily cover as beneficial use.)
Beneficial Use Practices: Figure 2 illustrates the break out of how the 3.5 million tons of biosolids were beneficially used in 2004. Agricultural applications dominate; they make up 74 percent of all biosolids going to beneficial use. Most of this is traditional Class B land application, but a good portion (at least 613,000 tons) is Class A. Distribution of Class A “Exceptional Quality” biosolids makes up 22 percent of the U.S. total of beneficially used biosolids, and includes significant amounts of biosolids compost and heat-dried pellet fertilizer. Reclamation (3%) and forestland application (1%) comprise the other beneficial uses.
Disposal Practices: Figure 3 illustrates biosolids disposal practices in the U.S. in 2004. Of the 3.2 million tons disposed, 63 percent go to municipal solid waste landfills. Thirty-three percent is incinerated and four percent goes to dedicated surface disposal units. – N.G.
May 23, 2007 | General
Biosolids Management Trends In The U.S.
BioCycle May 2007, Vol. 48, No. 5, p. 47