New article on contaminants of emerging concern in wastewater

In response to recommendations from the Southern Resident Orca Task Force, Ecology is sharing research on the potential benefits of wastewater treatment technologies for reducing the amount of contaminants of emerging concern (CEC) entering Washington water. In preparing this new article, we have gathered and reviewed previously published research findings, case studies in Europe, numerous studies in Washington, and consulted with regional experts to provide an overview of the science behind the elimination of CECs from waste. We have reviewed over 280 scientific studies and compiled the results on the effectiveness of some wastewater treatment technologies in removing common CECs.

We concluded that technologies that increase the duration of treatment also increase the chances of clearing more CEC. This is because CECs tend to be large and complex chemicals that take longer to break down. Some of the technologies that reduce nutrients in wastewater are also likely to reduce CECs, as many nutrient removal technology options increase wastewater treatment time.

Read our article on Contaminants of Emerging Concern and Wastewater Treatment Technologies.

CECs are chemicals, both natural and synthetic, found in common products, such as pharmaceuticals and personal care products. There are over 40,000 chemicals in commerce, each of which has the potential to become a new area of ​​concern. The problem is, we just don’t know enough about all of these chemicals to understand whether they are harmful to the environment.

SCCs can end up in sewage during routine activities such as washing clothes, flushing the toilet, bathing, and maintaining and cleaning a home or business. CECs also reach wastewater from industrial processes, hospital wastes and recreational activities or places such as parks (i.e. boat wash and rinse stations).

There are more than 2.8 million homes in Washington that produce wastewater. This number does not include industrial sectors, office buildings and other commercial areas that are connected to wastewater treatment facilities and may contribute to SCCs other than pharmaceutical and personal care products.

There are over 20,000 prescription drugs and personal care products approved by the Food and Drug Administration (FDA). While these products have a positive impact on the quality of human life and provide vital treatments, an unexpected result is that some of these products are also found in Washington waters. The introduction and accumulation of personal care products is becoming an environmental concern in the state. Many of them can be toxic to aquatic life and / or bioaccumulate in the food chain, like mercury. When exposed to toxic chemicals, aquatic life can also experience lethargy, reduced fertility, cancer, and death.

In our article, we looked at 15 different types of treatment technologies and compared the amount of four common CECs they removed (measured by percent removal).

We chose the CECs listed below because they are commonly used as representative CECs in many studies and have published elimination rates for many types of technologies. In addition, these CECs are common in wastewater and range from easy to remove (caffeine, ibuprofen), to difficult to remove (triclosan), to extremely difficult to remove (carbamazepine):

  • Caffeine (which many of us know and love) is a naturally occurring chemical used as a brain and central nervous system stimulant. Caffeine is often used in studies of wastewater treatment technologies because it is ubiquitous.
  • Ibuprofen is a nonsteroidal anti-inflammatory drug that works by reducing hormones that cause inflammation and is used to reduce fever and pain.
  • Triclosan is an antibacterial and antifungal agent that has been added to many personal care products such as toothpaste, antibacterial soaps, and body washes. The FDA banned the use of triclosan in consumer products in 2016, but it can still be found in clothing, cookware, toys, and as a pesticide.
  • Carbamazepine is an anticonvulsant / pain reliever medicine used to treat seizures, mania and neuropathy. It is often used in studies that test the effectiveness of the technology because it is well known that it is extremely difficult to remove from wastewater.

For each type of processing technology, we’ve summarized how it works, what the research says about how it eliminates CECs, and listed the pros, cons, nutrient removal capabilities, and CEC removal rates. published.

There are over 300 domestic wastewater treatment plants in Washington, and they use many types of treatment technologies and processes to meet water quality standards. Modern treatment plants do a good job of removing most of the waste that people throw down the toilet or down the drain. They generally remove over 85% of solids, biodegrade certain pollutants that enter the facility and disinfect the water to kill most pathogens (bacteria and viruses). Although treated wastewater meets appropriate water quality standards, it is not free from pollution.

Treatment systems range from small passive systems to large advanced treatment systems in wastewater treatment plants.

Rural communities or small communities often do not have centralized wastewater treatment systems. Centralized systems are not practical in these areas due to the smaller amounts of wastewater created, distance or terrain which makes it difficult to transport waste. These communities treat their wastewater closer to the source and rely on smaller decentralized systems like septic tanks, which are not complicated to operate.

Large communities have wastewater treatment plants that use a combination of technologies and processes.

Biological processing uses bacteria and fungi to break down materials. You can think of “activated sludge” as a sourdough starter that you keep alive separately and add to your dough to make bread.

Conventional wastewater treatment usually involves primary treatment to remove most of the solids, biological treatment in which microorganisms such as bacteria and fungi break down the material, secondary clarification to recycle and remove microorganisms in excess for solids treatment and disinfection. Some wastewater treatment plants are now using advanced treatment technologies that have additional processes to remove more nutrients and CEC. Advanced wastewater treatment refers to any treatment beyond conventional (secondary) treatment, such as enhanced nutrient removal, addition of chemicals, filtration and advanced oxidation.

We have found that some of these advanced treatment technologies such as carbon filtration, ozonation, and reverse osmosis are the most effective in removing CECs.

Washington residents can prevent CECs from entering even sewage by properly disposing of pharmaceuticals, avoiding the use of harsh chemicals when cleaning, and purchasing EPA Safer Choice products.

When the EPA’s Safer Choice logo is displayed on products, it indicates that they contain only the safest ingredients possible.

We have found that most treatment systems reduce the amount of CEC in wastewater (although the amount is different for each type of technology). However, the chemicals are not completely removed.

There is no “one size fits all” approach to CEC removal because CECs have very different chemical characteristics and there are so many CECs in common use that there are often not enough CECs. data on chemicals and their quantity in wastewater. Additionally, available treatment technologies can have widely varying removal rates for the same compound depending on the season, day, location of the treatment plant, or the chemical composition of the wastewater entering the plant. Some compounds are extremely difficult and can only be removed by complex and expensive advanced processing technology like granular activated carbon, reverse osmosis and ozonation.

While we may not be able to remove all CECs, many wastewater treatment technologies exist that have the capacity to remove a certain amount of CEC from wastewater.

We continue to review the latest available science on this issue, work with state universities to develop a Washington-specific list of priority CECs, learn from other states as they address these issues, and support the ‘EPA as they continue to provide the information needed to control SCCs in local waters.

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