December 2007, Vol. 19, No.12

Wastewater Reveals Illicit Drug-Use Patterns

wastewaterreveals.jpg A new automated monitoring method for analyzing raw wastewater flowing into treatment plants is so sensitive it can detect cocaine use spiking on weekends. If the method pans out as its developers think it will, wastewater treatment plants could one day be enlisted as frontline surveillance monitors in the war against illicit drug use. 

Preliminary tests conducted in several midsize U.S. cities show that the method can simultaneously quantify methamphetamine and metabolites of cocaine and marijuana, as well as legal drugs, such as methadone, oxycodone, and ephedrine, according to lead researcher Jennifer Field, an environmental chemist at Oregon State University (Corvallis).

“Every community’s got something,” Field said, and being able to reliably identify emerging drug-usage patterns at local, state, or even regional levels could help law enforcement officials develop preventive interventions. “You can examine individual communities over time, look at different communities distributed over a region, and look at spatial or temporal trends within that region or at individual municipalities,” she added. The findings then can be used to alert different authorities to problems that occur in certain communities or at a particular time.

Field’s team presented their results at the August meeting of the American Chemical Society (Washington, D.C.) in Boston.

Drug Screening Test

Wastewater is often tested for contaminants after it is treated to measure potential environmental impacts. This new approach, however, tests raw influent as it enters a treatment plant to obtain a profile of the drugs being used in the community. It involves a sensitive and selective analytical method based on large-volume injection and liquid chromatography–tandem mass spectrometry to quantify the presence of a drug in minute wastewater samples — on the order of a few nanograms per liter — taken automatically during a 24-hour period.

“We take advantage of the fact that municipal wastewater treatment plants already have equipment that takes 24-hour composite samples,” Field said.

The chemical analysis can detect the presence of a long list of illicit drugs, Field noted. So far, they have been targeting their efforts on about 20 recreational and illicit compounds known to have the greatest human health impacts. These include methamphetamine, cocaine, LSD, marijuana, and their precursors and metabolites. Subsequently translating the resulting tiny traces of drug into the number of individual users is problematic, according to the researchers, and so they are focusing on the community level, ensuring the anonymity of individual users.

“It’s like a very diluted urine sample collected from an entire community,” Field explained. “Essentially, we’re trying to understand population use of a variety of chemicals and their discharge to municipal systems,” she noted, emphasizing that the work to date is preliminary.

Field and her colleagues tested the method on wastewater from 10 municipalities, calculating the concentrations of individual drugs and using the volume of wastewater flowing into the treatment plant and the municipal population to estimate the community load of each drug. They found patterns over time of drug occurrence in wastewater, with higher concentrations of recreational drugs, such as cocaine, on weekends. They found no change in concentrations of either prescription drugs or methamphetamines in their samples over time, which suggests more consistent use of both.

To address the potential for false positives, the researchers are working to identify common indicators, or biomarkers, such as caffeine or nicotine, that can be used to sharpen their calculations.

“A lot of things contribute to the flow in wastewater, including agricultural and industrial processes,” Field explained. “By linking our illicit-drug measurements to biomarkers related to measurable human activities, we could compensate for differences in flows that aren’t related to human excretion.”

Real-Time Surveillance Tool
Drug abuse is a widespread public health problem, but there are several limitations to the current methods for documenting and anticipating the distribution of illicit drugs over time and across regions of the country, according to Caleb Banta–Green, a research scientist at the University of Washington (Seattle) Alcohol and Drug Abuse Institute, who is part of the analytical method development team.

Estimates of illicit drug abuse in a particular community are based largely on surveys, medical records, and crime reports, “all of which just give you little slices of the population,” Banta–Green explained. Moreover, they don’t offer real-time information about what happened last week, “so you really can’t predict or look forward,” he added.

By providing a fast, reliable, and inexpensive way to track drug consumption patterns, “this method could potentially give us a really valid community snapshot of what’s going on right now,” Banta–Green said. Public health and social service agencies then could compare the findings to see what changes are occurring in the community, as well as across communities. The tool also could be used as an early warning system.

“The detection of a new drug in wastewater might be the very first sign that a drug’s being used in a community,” Banta–Green noted. “It’d be nice to try to nip that in the bud at the front end, when you have just a few users.”

Until now, most conventional studies of community-level drug abuse have been conducted in a few very large cities. Another advantage this new method offers, according to the researchers, is that because it is automated and relies on tiny samples from municipal treatment plants, it can be used in more and smaller communities, making it possible to portray patterns of drug use across much more of the population.

“It’s a fascinating new development,” said Adam Krantz, managing director of government and public affairs for the National Association of Clean Water Agencies (Washington, D.C.). “To the extent that this information could somehow be obtained from treatment plants and improve law enforcement capability in certain areas is intriguing.”

— Kris Christen, WE&T 


Energy Star Launches Benchmarking Tool for Wastewater Industry

Energy Star, a U.S. Environmental Protection Agency (EPA) program, recently developed a benchmarking tool designed for wastewater utilities.

Using Energy Star’s Portfolio Manager software (www.energystar.gov/benchmark), wastewater utility managers can input energy use and operations characteristics, and the tool will track energy efficiency over time and compare performance to others. The tool, which became available Oct. 1, uses sophisticated statistical methodologies to rate a utility’s performance.

Developed as part of Energy Star’s Water and Wastewater Focus Initiative, a new effort to determine what tools and resources are needed to help the industry improve energy management, the tool is designed to help individual facility managers and operators learn how energy-inefficient their facilities or plants may be and help motivate them to pursue energy-efficiency improvements.

Benchmarking Best and Worst Performers
More than 30,000 organizations, including offices, schools, hotels, and supermarkets, have been using Portfolio Manager to rate performance.

“Portfolio Manager can be used to establish a baseline for energy use, prioritize investments, set goals, and track energy use and carbon emissions over time,” said Caterina Hatcher, Energy Star national manager for public-sector partnerships.

According to EPA, the tool provides a secure environment to share facility-specific energy information, with features that group facilities, view ratings, control access to building data, and more. The tool helps users manage multiple plants to determine top energy performers within an organization.

Portfolio Manager applies EPA’s Energy Performance Rating System to assign ratings to utilities. By comparing data inputs to a national data set, the tool rates a treatment plant’s energy efficiency on a scale of 1 to 100.

How It Works
First facility data are entered into Portfolio Manager — including data on all energy consumption at a facility for a 12-month period and specific details about operational characteristics. The user enters data about a facility’s average influent flow, design flow rate, biological oxygen demand removal, and more.

Portfolio Manager then computes the actual source energy-use intensity, or source EUI, from the metered energy data entered into the software. The source EUI is the sum of source energy across all meters, divided by total flow area.

Next, Portfolio Manager computes the predicted source energy intensity, or predicted source EUI, using a statistical regression equation specific to the wastewater industry. For each operating characteristic entered by a user, the tool calculates a value that represents the difference between an individual facility and the mean value, based on the nationally representative data. The prediction reflects the expected energy use for a facility, given its specific operational constraints.

The tool then computes an energy-efficiency ratio, which is the actual source EUI divided by the predicted source EUI. This figure expresses how much energy a plant uses relative to its predicted energy use. A lower ratio indicates that a plant uses less energy, while a higher ratio indicates the opposite. The tool compares the ratio of the actual source EUI to the predicted source EUI and assigns a rating. Thus, two plants with similar actual source EUIs can end up with very different performance ratings in Portfolio Manager.

Factors That Affect Ratings
“If a treatment plant rates below the average of 50 on our scale, there are likely to be many opportunities to increase energy efficiency in that plant,” Hatcher said.

Plants with atypical and older equipment may score lower, compared to plants with more standard equipment. For example, one small plant involved in the pilot receives wastewater from multiple industries and requires an energy-consuming, compressed-air system to dry residuals prior to disposal. The atypical system affected its rating in Portfolio Manager. 

EPA advises that a plant’s low rating in Portfolio Manager could work to convince superiors to fund more energy-efficient diffusers and other equipment.

Conversely, facilities that use renewable energy — wind, solar, methane gas recovery, and hydropower — will have a higher performance rating because the figures entered in Portfolio Manager for metered sources and flow rates will automatically reflect that energy efficiency.

In order for Portfolio Manager to provide meaningful performance ratings to users, the tool must be built to provide an accurate and equitable assessment of a wastewater facility’s energy performance — so as not to introduce bias with respect to various operating constraints and other variables affecting the industry.

Creating an Equitable Rating Scale
Energy Star technical staff regularly reviews the technical approach used to develop its rating system and its statistical methodologies to ensure that Portfolio Manager users of many industries are provided with statistically robust ratings. The rating system developed for the wastewater benchmarking tool in Portfolio Manager uses the latest methodology, according to EPA.

Portfolio Manager’s ratings are not based on information from other plants entered into the software. The national data is used to determine the distribution of energy performance across the entire population of plants; also each plant type has unique features that have an impact on energy efficiency. EPA then adjusts the ratings separately for each plant type based on unique operational characteristics.

In general, plants are not penalized based on size, treatment processes, or weather, according to EPA. “Once you input characteristics, then [a plant is] measured against the average plant with those same characteristics,” said Jason Turgeon, a member of EPA Region 1’s Energy and Transportation Team.

Statistical Analyses Considers Industry Characteristics
EPA staff perform a statistical regression analysis on the national dataset to identify key drivers of wastewater facility energy consumption and provide the best equation for rating individual facilities. Multiple statistical tests and analyses approximate the average relationship between plant flow and source energy in a wastewater facility. Industry variables affect the rating system, and an equitable rating scale should not penalize for operational variables outside of a plant operator’s control.

The tool normalizes for several variables — load factor (ratio of average flow to daily flow), nutrient removal, presence or absence of trickle filtration, design flow, and weather type by zip code — to get an estimate of an average plant’s energy use given the variables. Then the tool compares user-entered metered data against the normalized estimate to get a score. Variables excluded from normalization include specific technology factors, presence or absence of onsite generation, and solids disposal practices.

For example, Portfolio Manager accounts for temperature-based energy use, which is calculating how hot or cold each month is and adjusting ratings accordingly.

“That’s how we compare facilities in Boston with facilities in Arizona, and still have [the comparison] be apples to apples,” Turgeon said.

Quantifying Multiple Energy Sources, Regional Attributes
In general, a building’s energy performance is compared in terms of source energy consumption — which includes energy consumed at the site, as well as energy used in generation and transmission. According to EPA, this is the most equitable approach for comparing properties that use different fuels.
 
Because different fuel types are used, Portfolio Manager converts all figures to primary, or source, energy (heat and electricity are considered secondary energy — energy that is converted from a raw source).

To estimate regional environmental attributes, Portfolio Manager locates a user’s facility in one of 27 subregions of the U.S. power grid. These subregions, defined by EPA’s Emissions and Generation Resource Integrated Database, represent a portion of the U.S. power grid that is contained within a single North America Electric Reliability Council region. Subregions of the power grid have similar emissions and resource mix characteristics of the electricity consumed.

Energy Star Ratings
Portfolio Manager’s ratings are created by and based on the ratio of a user’s actual energy consumption, compared to that predicted by the tool’s statistical analysis. This enables the software to apply ratings to individual facilities where one point equals 1% of the population — hence the 100-point rating scale.

EPA also is considering recognition opportunities for wastewater utilities through the Energy Star program. There is a possibility that eventually, as Energy Star’s wastewater initiative develops, some wastewater utilities might be eligible to apply for Energy Star status. However, wastewater utilities cannot currently earn the Energy Star label, mostly due to the freshman nature of the wastewater initiative, according to EPA. 

Andrea S. Bistany, WE&T