[Pharmwaste] Biological Treatment Provides an Efficient Option for Reducing HPV (High Production Volume) Household Chemicals

Fri Sep 19 16:40:54 EDT 2008

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Biological Treatment Provides an Efficient Option for Reducing HPV Household Chemicals

Look inside the cabinets and cupboards of the average U.S. home and you will find dozens of household cleaners, paints, solvents, and pesticides containing one or more of the 500 high production volume (HPV) consumer product chemicals identified by the U.S. Environmental Protection Agency. Manufactured in quantities of one million pounds or more per year and used in an array of products, these HPV chemicals regularly end up in wastewater treatment systems. Yet, despite the pervasiveness of these chemicals, there is a shortage of readily available information concerning both their ability to affect wastewater processes and the quality of effluent. This lack of information poses a major challenge to the water quality community. 

A three-year WERF research study, led by Professor Jörg Drewes of the Colorado School of Mines and Shane Snyder of the Southern Nevada Water Authority, examined the fate of select HPV household chemicals during wastewater treatment. Their findings show just how effective traditional wastewater processes can be at achieving a high degree of removal for many household chemicals. 

Know Your HPVs 

Knowing what to treat is as important as knowing how to treat it, so the project began with a comprehensive review of HPV organic chemicals in household products and their contributions to wastewater treatment systems. The result is a database of HPV chemicals and organic compounds in household products that have the potential to adversely affect wastewater processes and effluent qualities. It includes 720 compounds that fall within eight commodity categories: 

auto 
inside-the-home 
pesticides 
home maintenance 
personal care 
pet care 
arts and crafts 
landscape and yard 
The team then developed a two-tiered ranking based on production volumes, environmental relevance, and feasibility for analytical quantification, which led to a short list of 26 compounds for further study that represents a broad range of product lines, chemical properties, and toxicities. The complete list of Tier and Tier 2 compounds, as well as the comprehensive list of 720 compounds is included in the report, Contributions of Household Chemicals to Sewage and Their Relevance to Municipal Wastewater Systems and the Environment (stock no. 03CTS21UR). 

Conventional Treatment Proves Effective 

The project team studied the occurrence of select HPV target compounds during wastewater treatment by collecting composite samples of raw influents and final treated effluents at seven full-scale treatment plants employing different treatment processes and operational conditions. Of the 26 HPV household chemicals targeted in this study, the team consistently detected 20 compounds in raw influents. Most were personal care and cleaning products with 2-phenoxyethanol (a preservative with various uses) and menthol (a fragrance) consistently exhibiting the highest concentrations. In general, concentrations of target compounds varied from the micrograms per liter (parts per billion) to as little as several hundred nanograms per liter (parts per trillion). The team noted that similar concentration ranges of these compounds among the treatment facilities suggests that HPV compounds are more likely to be contributed by general consumers and households, rather than specific industries. 

The team assessed the removal efficiency of selected HPV chemicals by conventional treatment processes such as activated sludge and disinfection, as well as advanced wastewater treatment processes-membrane bioreactor, ozone, advanced oxidation. 

The results are encouraging. Biological treatment resulted in partial (greater than 80 percent) or complete removal  indicating that biological treatment is an efficient treatment option for HPV household chemicals (Figure 1). For conventional disinfection processes, chlorination represents a process for partial transformation of remaining HPV compounds and an additional barrier. However, the research team noted that halogenated byproducts were likely formed during this process. 

Where higher effluent quality is desired, ozonation and ozone/hydrogen peroxide treatments performed similarly and are additional barrier options, although they do not represent a 100 percent treatment barrier for all compounds (e.g., vanillin). 

Chloramine and UV disinfection processes were not effective in removing HPV compounds. 

In treated wastewater effluents, the target HPV compounds dibutyl phthalate (found in plastics), benzophenone (perfumes and soaps), 2-phenoxytethanol, vanillin (artificial flavoring), and triclosan (soaps, deodorants, and toothpastes, among others) exhibited average secondary treated effluent concentrations exceeding 200 ng/L, with dibutyl phthalate exhibiting the highest average concentration of approximately 600 ng/L. 

Ensuring the Removal of Tomorrow's Household Chemicals 

As manufacturers incorporate new synthetic organic chemicals in household products, wastewater treatment facilities will be faced with the need for costly studies of the fate, transport, and removal of these emerging contaminants. It is essential to develop tools to determine how effectively a given compound can be removed during conventional and advanced wastewater treatment. Such a tool can quickly screen an organic compound of concern and provide a meaningful response in regards to its fate and, if needed, suggest the degree of treatment upgrade required for removal or recommend appropriate source control. 

To that end, the research team examined quantitative structural property relationship (QSPR) models to determine their ability to predict the fate of organic chemicals through specific treatment processes. After conducting a comprehensive literature review on existing QSPR models that aid or could aid in predicting the removal of certain compounds by individual wastewater treatment processes, the team identified the most viable QSPR components, which can be connected as modules-as part of a toolbox-to predict the removal of individual compounds through wastewater treatment trains. More information on how to use QSPR models for predicting the removal of target compounds can be found in the full report. 

September 8, 2008

Deborah L. DeBiasi
Email:   dldebiasi at deq.virginia.gov
WEB site address:  www.deq.virginia.gov
Virginia Department of Environmental Quality
Office of Water Permit Programs
Industrial Pretreatment/Toxics Management Program
PPCPs, EDCs, and Microconstituents
Mail:          P.O. Box 1105, Richmond, VA  23218 (NEW!)
Location:  629 E. Main Street, Richmond, VA  23219
PH:         804-698-4028
FAX:      804-698-4032

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