Measuring Organic Chemical Pollutants In Drinking Water

Organic chemicals in drinking water are a serious problem for many communities. They can enter drinking water through human activities such as industrial and agricultural waste, improper disposal of household products, or even from domestic animals. Some organic chemicals are also naturally occurring, while others are man-made. These chemicals can cause various health issues, including an increased risk of cancer, liver and kidney damage, birth defects, and other chronic diseases. To protect those who rely on potentially contaminated water sources, it is essential to measure and monitor the levels of organic pollutants. This can be done through testing private well water for volatile organic compounds (VOCs) and petroleum products, which can cause an oily sheen on the water or a taste and smell of gasoline or solvents. Additionally, regulations such as primary maximum contaminant levels (MCLs) and Vermont action levels (VALs) are in place to ensure the safety of public water systems.

Sources of organic chemical pollutants in drinking water

The depth of the well is another factor, with shallow wells being more susceptible to contamination than deeper ones when spills or the application of contaminants occur on surface soils. The local geology can also impact the movement of contaminants, with groundwater covered by thin, porous soil or sand layers being more vulnerable to contamination. Additionally, the treatment of drinking water with chlorine can lead to the formation of certain volatile organic compounds (VOCs) known as disinfection byproducts.

VOCs are a significant group of organic chemical pollutants that include substances like benzene, toluene, and perchlorate. These compounds are easily vaporized and can be released into the environment through the burning of fuels such as gasoline, wood, coal, or natural gas. They are also found in products like paints, cleaners, and fuels, and their improper storage or disposal can lead to groundwater and drinking water contamination. VOCs have been linked to various health issues, including an increased risk of cancer, liver and kidney damage, and birth defects.

Brominated flame retardants (BFRs) are another type of organic chemical pollutant. These compounds are added to various consumer and commercial products, such as electronics, furniture, and textiles, to enhance their fire resistance. However, BFRs can end up in the environment and enter the food chain, potentially causing negative health effects, especially during pregnancy, where they have been associated with congenital defects.

Natural sources of organic chemical pollutants in drinking water also exist. For example, crude oil and coal are organic compounds formed through natural chemical processes. Additionally, certain organisms can synthesize organic compounds, such as sugars, proteins, and alcohols, which can also find their way into water sources.

Methods for detecting organic chemical pollutants

There are various methods for detecting organic chemical pollutants in drinking water. Firstly, it is important to understand the sources of these pollutants, which can include human activities such as improper storage, disposal, or spills of products containing volatile organic compounds (VOCs) and synthetic organic compounds (SOCs). Other sources include pesticides sprayed near water sources, industrial or commercial areas, gas stations, landfills, and agricultural activities. These organic chemicals can contaminate groundwater and drinking water supplies, posing significant health risks, especially when consumed over extended periods.

One method for detecting organic chemical pollutants is through the use of multi-parametric sensor arrays. These sensors have become more cost-effective and user-friendly, allowing for the detection of contaminants such as aldicarb, glyphosate, colchicines, and nicotine. Additionally, low-cost sensor networks, incorporating multiple electrochemical optical sensors, can detect the presence of harmful bacteria like E. coli and heavy metals such as arsenic (As) in real time. These sensors can simultaneously monitor various water quality parameters, including flow rate, temperature, conductivity, pH, oxidation-reduction potential (ORP), and turbidity.

Another technique is capillary electrophoresis (CE), which is a separation method based on molecular polarity and atomic radius. It involves analyzing the movement of ions through electrolyte solutions, with their mobility directly influenced by the applied voltage. CE can be performed in capillaries with diameters ranging from millimeters to microfluidic and nanofluidic channels. This technique has been employed to detect trace chloroanilines in water samples, achieving low detection limits within a short time frame.

To address the challenge of reference compound availability, synthesis is often necessary for structure verification and rapid detection and quantification procedures. This includes investigating properties such as molecular size distribution using selective membranes or gel permeation chromatography, absorbance and fluorescence of UV and visible light, bonding configurations through nuclear magnetic resonance (NMR) and infrared spectroscopy, and acidity via potentiometric titrations.

Additionally, regulatory agencies have established maximum contaminant limits (MCLs) for hazardous organic compounds, including pesticides, aromatic hydrocarbon compounds, disinfection byproducts, and chlorinated solvents. These MCLs, such as those set by the Environmental Protection Agency, represent the highest permissible levels of specific chemicals in public drinking water supplies. HPLC/MS in conjunction with ESI is also emerging as a standard method for organic trace analysis, offering advantages in terms of cost and time efficiency.

Health effects of consuming organic chemical pollutants

Organic chemicals are human-made compounds that are used in a variety of products, such as pesticides, gasoline, dry-cleaning solvents, and degreasing agents. These chemicals can contaminate groundwater and drinking water supplies through improper storage, disposal, or spills. While short-term exposure to these chemicals may not cause significant health issues, long-term consumption of contaminated drinking water can lead to various health problems.

The health effects of consuming organic chemical pollutants depend on several factors, including the type of contaminant, its concentration in the water, individual susceptibility, the amount of water consumed, and the duration of exposure. Some of the potential health impacts of consuming organic chemical pollutants in drinking water include gastrointestinal illnesses, nervous system disorders, reproductive difficulties, and chronic diseases such as cancer.

Volatile organic compounds (VOCs) and synthetic organic compounds (SOCs) are particularly harmful. VOCs, which include substances like PCE, TCE, and atrazine, can increase the risk of liver problems and cancer if consumed over many years. Atrazine has also been linked to an increased risk of cardiovascular issues and reproductive problems. Di (2-ethylhexyl) phthalate (DEHP), a commonly used plasticizer, has similar health risks. Consuming water with high levels of DEHP over a long period can lead to liver problems, reproductive difficulties, and cancer.

It is important to note that the presence of organic chemicals in drinking water is not always due to contamination. In some cases, these chemicals can be formed during the water treatment process, such as when chlorine is used for disinfection. The chlorine can react with organic materials in the water, forming certain VOCs known as disinfection byproducts. While disinfection has successfully reduced the prevalence of waterborne diseases like typhoid, cholera, and hepatitis, it can also introduce new chemical contaminants into the water.

To protect public health, regulatory agencies like the Environmental Protection Agency in the United States establish legally enforceable standards, known as primary maximum contaminant levels (MCLs), to regulate the levels of chemicals allowed in public drinking water supplies. These standards aim to minimize the potential health risks associated with consuming contaminated drinking water. However, it is worth mentioning that the effects of some drinking water contaminants are not yet fully understood, and ongoing research is necessary to ensure the safety of our water supplies.

Treatment methods to remove organic chemical pollutants

Membrane Filtration

Membrane filtration is a method that uses membranes with different permeation characteristics to separate and remove pollutants from water. There are three main types of membrane structures: conventional nanostructured, thin-film nanostructured (TFN), and localized surface nanocomposite. Membrane filtration can be used to remove organic chemical pollutants, with studies showing that modifications to the manufacturing process or the incorporation of nanomaterials can improve their performance.

Activated Carbon Filtering

Activated carbon, in powdered (PAC) or granular (GAC) form, is an effective media for removing organic pollutants such as pesticides, phenols, pharmaceuticals, organic halogens, and non-biodegradable compounds. It can be used before or after other treatment steps to ensure the complete removal of micropollutants. However, activated carbon has some disadvantages, such as expensive regeneration methods and the loss of adsorbent during the process.

Bioremediation

Bioremediation is a natural treatment process that uses microorganisms found in the soil to digest and convert chemical contaminants into water and harmless gases like carbon dioxide. It is effective, inexpensive, and less intrusive than other forms of treatment. However, it can take anywhere from a few months to a few years to remove contaminants.

Phytoremediation

Phytoremediation uses the roots of plants and trees to remove pollutants, including organic chemicals, from water. It is a natural process that can take several months to a year to finish, similar to bioremediation.

Chemical Oxidation

Chemical oxidation is an expensive and time-consuming treatment process that can take several months to a year to complete. It involves using chemicals to oxidize and break down organic pollutants into water and carbon dioxide. Electrochemical oxidation (EO) is a type of chemical oxidation that can remove a wide range of pollutants and is commonly used for industrial wastewater treatment.

Regulations and guidelines for organic chemical pollutants

The presence of organic chemical pollutants in drinking water is a pressing issue, and various regulations and guidelines are in place to address this concern. One key regulation is the National Primary Drinking Water Regulations (NPDWR) in the United States, which sets legally enforceable primary standards and treatment techniques for public water systems. These standards aim to protect public health by limiting the levels of contaminants, including organic chemicals, in drinking water. The Environmental Protection Agency (EPA) plays a crucial role in this process by setting legal limits on over 90 contaminants, including organic chemicals, in drinking water. These legal limits are based on the levels that protect human health and that water systems can achieve using the best available technology.

The EPA also establishes water-testing schedules and methods that water systems must follow to ensure compliance with the regulations. One important concept in drinking water regulation is the Maximum Contaminant Level (MCL), which represents the highest level of a contaminant, such as organic chemicals, that is permitted in drinking water. MCLs are enforced by the EPA and are designed to protect public health by minimizing potential risks associated with contaminated drinking water. In addition to the federal regulations, the Safe Drinking Water Act (SDWA) empowers individual states to establish and enforce their own drinking water standards, as long as they meet or exceed the minimum standards set by the EPA.

At the state level, California has implemented its own set of regulations for drinking water quality. The California State Water Resources Control Board has established Maximum Contaminant Levels (MCLs) for various chemicals, including organic contaminants. These MCLs are outlined in Title 22 of the California Code of Regulations and address both health concerns (primary MCLs) and aesthetic aspects such as taste and odor (secondary MCLs). The state of Vermont has also taken proactive measures by establishing Vermont Action Levels (VALs) for specific organic chemicals that are of particular public health concern. These VALs complement the federally mandated MCLs and provide additional protection for Vermont residents.

It is important to note that organic chemical pollutants in drinking water can have significant health impacts, especially when consumed over an extended period. Therefore, proactive monitoring, regulation, and treatment of these contaminants are crucial to safeguard public health. While the EPA and state governments play a pivotal role in setting standards and enforcing regulations, individuals should also remain vigilant and test their private water sources if they suspect contamination. By working together and adhering to established guidelines, we can minimize the presence of organic chemical pollutants in our drinking water and mitigate potential health risks.

Frequently asked questions