Bacteria: Water Pollution Control Warriors

Water pollution is a pressing issue, with 1.8 million deaths attributed to it in 2015, according to a study in The Lancet. It is caused by a range of chemical and industrial pollutants, including heavy metals, pesticides, and fertilizers, which contaminate our water supplies. While bacteria are often seen as the problem, they can also be part of the solution. Scientists are studying the ability of various bacteria to remove harmful pollutants from water, such as perchlorate, a chemical found in rocket fuel, munitions, and fireworks, which can impair thyroid function in humans and animals. This process, known as bioremediation, has been successfully implemented in a groundwater treatment plant in Rialto, California, which can decontaminate over a billion gallons of perchlorate-polluted water per year.

Bacteria as indicators of water pollution

Bacteria are often perceived as the cause of water contamination. However, they can also be used as indicators of water pollution, helping to identify contaminated water sources and prevent waterborne diseases.

Fecal indicator bacteria (FIB) have been used for over 150 years to indicate the presence of faecal contamination in water and the associated health risks. FIBs are typically harmless Gram-negative bacteria that are part of the natural gut microbiota in humans and other warm-blooded animals. They are used as "indicator organisms" because of their high concentrations in sewage and ease of culture, making them a simple and reasonably reliable tool for diagnosing sewage pollution in water samples.

Coliform bacteria, including Escherichia coli (E. coli), are commonly used as indicators of faecal contamination. The presence of E. coli in water sources is often indicative of other harmful bacteria and pathogens that can cause waterborne illnesses. The Minnesota Pollution Control Agency (MPCA), for example, uses the presence of E. coli to identify water bodies that may be contaminated with faecal waste.

However, using indicator bacteria to assess the presence of pathogens is not a perfect process. The behaviour of bacteria and pathogens in the environment is complex and depends on various factors such as weather, current, water temperature, and other sources of contamination. Additionally, some bacteria may be injured or damaged during the water treatment process, leading to an underestimation of faecal contamination levels.

Despite these challenges, advancements in molecular methods have improved the detection capabilities, analytical sensitivity, and data quality of FIBs. Alternative indicators, such as fecal streptococci, Clostridium perfringens, and fecal sterols, are also being explored to address the limitations of traditional FIBs.

Using bacteria to remove perchlorate

Perchlorate is a chemical that comes from rocket fuel, munitions, and fireworks. It is dangerous to humans because it can impair thyroid function by inhibiting the uptake of iodine. It can also affect the thyroid in freshwater animals like fish and amphibians, even altering gonad development in some animals. Perchlorate can contaminate the environment through leaks or explosions near manufacturing plants.

Certain bacteria, including several species of Dechloromonas and Azospira, have evolved to use perchlorate to make energy-storing molecules. In the process, they turn it into harmless chloride and oxygen. Scientists like Coates are working to harness the ability of various bacteria to remove harmful pollutants from water.

One method of removing perchlorate from water is through the use of bioreactors. A bioreactor is an ex situ biological treatment system that uses microorganisms to degrade perchlorate from contaminated groundwater and surface water. The bacteria in the bioreactor can break down perchlorate under certain anaerobic conditions.

The bioreactor-based groundwater treatment plant in Rialto, California, is capable of decontaminating 2,000 gallons (over 7,500 liters) of perchlorate-polluted water per minute, making it one of the largest-scale bioremediation projects in the world. Other technologies used for removing perchlorate from groundwater include ion exchange, in-situ bioremediation, and permeable reactive barriers (PRB).

In situ biodegradation (ISB) is another approach that involves delivering nutrients to the subsurface to promote the biodegradation of perchlorate by indigenous bacteria. This method requires the ability to transmit and mix liquids in the subsurface effectively. Overall, the use of bacteria to remove perchlorate from water is a promising solution to water pollution caused by this harmful chemical.

Bacterial removal of industrial chemicals

Bacteria are often seen as the cause of water contamination, but they can also be part of the solution. Scientists are working to harness the power of various bacteria to remove harmful pollutants from water. This process is known as microbial cleaning or bioremediation, and it involves taking advantage of naturally occurring microbes that have an affinity for hydrocarbons. These microbes digest the hydrocarbons, turning them into harmless carbon dioxide.

One example of bacterial removal of industrial chemicals is the work being done by the Coates lab. They are growing different kinds of bacteria that can break down perchlorate, a chemical found in rocket fuel, munitions, and fireworks. Perchlorate is dangerous to humans as it can impair thyroid function, and it can also affect freshwater animals, altering gonad development. However, certain bacteria, including several species of Dechloromonas and Azospira, have evolved to use perchlorate to create energy-storing molecules, converting it into harmless chloride and oxygen in the process.

The bacterial removal of perchlorate is one of the largest-scale bioremediation projects globally, with a bioreactor-based groundwater treatment plant in Rialto, California, capable of decontaminating over 3.7 billion liters of perchlorate-polluted water per year. Additionally, a bioreactor designed by Bruce Rittmann can remove not only perchlorate and trichloroethene but also uranium and other metals from water.

While microbial cleaning has proven effective in various industries, including petrochemical, chemical, food processing, and oil spill cleanup, it is not a perfect solution for water contamination. Each type of bacteria has specific survival conditions, which can make it challenging to incorporate them into water treatment systems. Furthermore, with thousands of different pollutants, it is impossible for a single microbe to break down all of them. Despite these challenges, researchers remain optimistic about the potential of bacteria in remediating industrial chemical pollution.

Bacterial removal of agricultural chemicals

Bacteria are often seen as the cause of water contamination, but in some cases, they can be part of the solution. Scientists are working to harness the ability of various bacteria to remove harmful pollutants from water.

Bacterial removal, or bioremediation, of agricultural chemicals is an eco-friendly, cost-effective, and efficient method compared to more expensive and toxic chemical and physical methods. The microbial activity of microorganisms, primarily bacteria, can transform pesticides into less complex compounds, carbon dioxide, water, oxides, or minerals.

Several bacterial species, including Dechloromonas and Azospira, have evolved to use perchlorate, a chemical found in rocket fuel, munitions, and fireworks, to make energy-storing molecules. In the process, they turn it into harmless chloride and oxygen. A bioreactor-based groundwater treatment plant in Rialto, California, for example, can decontaminate 2,000 gallons (over 7,500 liters) of perchlorate-polluted water per minute.

Overall, bacterial removal of agricultural chemicals is a promising approach to controlling water pollution, but it is not without its challenges. Different bacteria have specific conditions under which they can survive, and incorporating them into water treatment systems can be difficult.

Bacterial removal of human and animal waste

Bioremediation is an effective and environmentally friendly technique that utilizes bacteria, algae, fungi, and yeast to remove toxic waste from polluted environments. It is particularly useful in breaking down persistent organic compounds that are difficult to degrade through chemical and physical methods of remediation. By employing microorganisms, bioremediation eliminates, degrades, detoxifies, and immobilizes hazardous wastes and pollutants, converting them into less toxic forms.

In the context of human and animal waste removal, bacteria play a critical role in breaking down organic matter and facilitating its decomposition. This process helps in the treatment of wastewater and the maintenance of water quality standards. For example, bacteria can be used to break down fecal waste, which contains harmful bacteria such as E. coli, and can serve as "indicator organisms" to denote the potential presence of fecal matter in a body of water.

Additionally, bacteria have been cultured to break down dangerous chemicals that pollute waterways, such as perchlorate, which is commonly found in rocket fuel, munitions, and fireworks. Certain bacterial species, including Dechloromonas and Azospira, have the ability to utilize perchlorate to generate energy-storing molecules, simultaneously converting it into harmless chloride and oxygen. This bacterial removal of perchlorate is considered one of the largest-scale bioremediation projects globally.

While bacterial removal of human and animal waste offers promising solutions, it is important to acknowledge that incorporating bacteria into water treatment systems can be challenging due to the specific conditions bacteria require to survive. Nevertheless, with ongoing research and advancements, bacterial applications in waste removal continue to evolve, contributing to more sustainable and eco-friendly waste management practices.

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