Microorganisms: Water Polluters And Their Harmful Impact

Microorganisms are a natural form of water pollution, with many types living in water sources and causing illness in humans, land animals, and fish. The main source of microbial water pollution is sewage, which can contain harmful bacteria, viruses, and parasites, known as pathogens, that can cause serious diseases such as cholera. Other sources of fecal matter include septic systems and animal waste, which can contaminate drinking water and cause waterborne infections. Waterborne bacterial infections are a significant concern, leading to deaths worldwide due to a lack of access to clean drinking water.

Sewage and waste

Wastewater contains a variety of contaminants, including pathogens, pharmaceuticals, microplastics, heavy metals, and endocrine disruptors. Pathogens, in particular, pose a significant risk to human health, as they include disease-causing bacteria and viruses from human and animal waste. These waterborne pathogens can lead to illnesses such as cholera, giardia, and typhoid, which affect about 1 billion people annually.

The treatment of sewage and wastewater is crucial in preventing water pollution and the spread of diseases. Wastewater treatment plants use bacteria and other microorganisms to clean and decontaminate polluted water. These microorganisms act as natural cleaners, treating pollution without creating new contamination. They use organic waste as a source of food and energy to grow and reproduce, which helps in the biodegradation process.

However, the effectiveness of wastewater treatment plants can be influenced by various factors. For example, the temperature of the water affects the development of microorganisms, with higher temperatures generally promoting faster growth. Additionally, the selection of the right bacteria is crucial, as it depends on the specific conditions of the treatment area.

In rural and urban settings, septic tank systems are used for individual sewage treatment. These systems consist of a sewer line, a septic tank where microorganisms anaerobically decompose organic solids, and a drain field where clarified water is further purified by bacteria. Malfunctions in septic tank systems can lead to water pollution, usually due to incorrect soil types or poor maintenance.

Bacterial infections

Fecal matter, which contains many pathogens, is a common source of water pollution. Sewers, septic systems, and animal waste are all sources of fecal matter that can contaminate water. Fecal streptococci and Clostridium perfringens are used as indicators of fecal pollution, with the presence of these bacteria indicating potential harmful pathogens in the water.

Coliform groups of bacteria, including E. coli, are also used as indicators of fecal contamination in water. The presence of coliform bacteria can suggest the water may contain pathogens that can cause various illnesses, including diarrhea, vomiting, cramps, nausea, headaches, fever, and fatigue. In some cases, waterborne bacterial infections can even lead to death, particularly in infants, children, the elderly, or those with weakened immune systems.

Some of the most common bacterial diseases transmitted through water include cholera, typhoid fever, and bacillary dysentery. Foodborne bacterial infections can also occur, such as Salmonella gastroenteritis, which is caused by contaminated food and can result in diarrhea, vomiting, and fever.

Improving access to safe drinking water and implementing proper sanitation practices are crucial to preventing waterborne bacterial infections. Regular testing of public water systems for coliform bacteria and E. coli is essential to ensure the safety of drinking water and mitigate the risk of waterborne bacterial infections.

Cholera and other diseases

Cholera is an acute diarrheal disease caused by infection of the intestine with the bacteria Vibrio cholerae, which is often found in contaminated food or water, especially in areas with poor sanitation and water treatment. It is transmitted when the feces of an infected person come into contact with food or water. The bacteria accumulate in a person's stomach and produce toxins that affect the cells of the gastrointestinal tract, causing the person to lose large amounts of fluids (up to one litre per hour). This can lead to severe dehydration and shock, and even death within several hours if left untreated.

Cholera outbreaks have occurred in various regions, including Uganda and India, and are often linked to contaminated water sources. For example, in March 2016, an outbreak in the Bulambuli District of Eastern Uganda was attributed to drinking water from the Cheptui River. Similarly, in June-July 2015, an outbreak in the Kasese District of southwestern Uganda was traced back to drinking water collected from a lakeshore site. In both instances, public health interventions, such as distributing water chlorination tablets and advising water boiling, helped control the spread of the disease.

Other waterborne diseases caused by microorganisms include those caused by bacteria, viruses, and protozoa. For example, E. coli, a type of bacteria, is a common indicator of fecal contamination in water and can cause gastrointestinal disorders. Fecal streptococci and Clostridium perfringens are also used as indicators of fecal pollution and can lead to water contamination. These microorganisms can enter water bodies through sewage, effluent from hospitals, industrial activities, and cattle farms, increasing the bacterial load and posing risks to human health.

To prevent waterborne diseases, it is crucial to ensure proper sewage treatment and water sanitation. This includes treating drinking water through chlorination or boiling and improving overall sanitation practices. By addressing these issues, the risk of waterborne diseases, including cholera, can be significantly reduced.

Testing water for pathogens

Indicator Organisms

Indicator organism testing is a common method for detecting potential pathogenic contamination. Indicator organisms are microorganisms that are not necessarily harmful but suggest the possible presence of pathogens. For example, coliform bacteria, particularly E. coli, are often used as indicators of fecal pollution and the potential presence of harmful pathogens. Fecal streptococci and Clostridium perfringens can also be used as alternative indicators of fecal pollution. Testing for these indicator organisms helps assess the overall sanitation and safety of water.

Sampling and Testing Methods

Water samples are collected to test for the presence of pathogens or indicator organisms. Standard plate count (SPC) of heterotrophic bacteria and biochemical oxygen demand (BOD) techniques are traditional methods to determine bacterial and organic pollution load in a water sample. Molecular methods, such as Polymerase Chain Reaction (PCR), are also used for pathogen detection. PCR-based approaches, like BACGene, amplify bacterial DNA, allowing for accurate detection and quantification of pathogens. Enzymatic methods, such as esculin hydrolyzing or catalase-negativity tests, are also employed for rapid detection of indicators and enteric isolates in water samples.

Testing Frequency and Recommendations

The frequency of water testing depends on various factors. The New York State Department of Health recommends that well owners test their water for coliform bacteria at least once a year, especially if there have been previous bacteria-related issues. Late spring or early summer is the ideal time for testing, as wet weather increases the likelihood of bacterial contamination. It is important to understand that a single test is just a "snapshot" of water quality, and more frequent testing provides a more reliable indication of drinking water safety.

Regulatory Requirements and Food Safety

In the context of food safety, the Food Safety Modernization Act (FSMA) mandates that companies test for known pathogens to prevent foodborne illnesses. Foodborne pathogens like Salmonella and E. coli can contaminate food products at any stage of production, emphasizing the importance of pathogen testing to ensure consumer safety and prevent harmful outbreaks. Regulatory requirements for pathogen testing vary across industries, with some facing stricter pressure due to a history of failing to control pathogens in their products.

Microorganisms in animal waste

Animal waste, especially from concentrated animal feeding operations (CAFOs), can contain harmful microorganisms, including bacteria, viruses, and protozoa. These pathogens can cause diseases such as cholera and other waterborne illnesses. For example, swine wastes can contain over 100 microbial pathogens that pose risks to both human and wildlife health. Furthermore, the routine addition of antibiotics to animal feed to promote growth has led to increased antibiotic resistance among microbial populations, potentially impacting the effectiveness of treatments for waterborne illnesses.

Fecal bacteria and other pathogenic microorganisms from animal waste can contaminate water through direct runoff or when CAFOs are flooded and in direct contact with surface waters. These microorganisms can settle into sediments, thriving at high densities for extended periods. This can lead to unsafe conditions for human recreation and adverse health effects, as indicated by World Health Organization (WHO) guidelines for cyanobacteria in recreational water.

To mitigate the impact of animal waste on water quality, proper waste management practices are essential. Livestock manure, when exposed to the weather, can be a source of water pollution, as the bacteria can contaminate shellfish and make water unsafe for drinking or swimming. Collecting and storing manure in covered, sheltered areas can help prevent runoff and reduce the risk of water contamination. Constructed wetlands and riparian zones can also act as natural filters, retaining and reducing pathogens before they reach adjacent watercourses.

While animal waste is a significant contributor to water pollution, it is important to note that other sources, such as human sewage, hospital waste, and industrial effluent, also play a role in microbial water pollution.

Frequently asked questions