Major Pollutants

Organic pollutants, inorganic pollutants, pathogens, suspended solids, nutrients and agriculture pollutants, thermal, radioactive, and other pollutants are all types of water pollutants. Organic and inorganic contaminants are mostly discharged into water bodies through industrial effluents and sewage.

The United States’ Environmental Protection Agency (EPA) has compiled a list of water quality indicators that can be used to assess water quality. Inorganic materials include arsenic, antimony, boron, beryllium, barium, chloride, calcium, copper, cadmium, chromium, cobalt, lead, iron, fluoride, manganese, molybdenum, magnesium, mercury, nitrate, nickel, nitrite, phosphates, potassium, phosphorus, salmonella, selenium, silica, sodium, silver, sulphate.

These materials, whether in the form of elements or in combination with other compounds, can be classified as inorganic pollutants if their limit surpasses allowed levels, causing environmental harm. Heavy metals and other inorganic contaminants contaminate water sources, including trace elements, mineral acids, sulphates, inorganic salts, metals, metal complexes with organic compounds, and higher quantities of cyanides. These nonbiodegradable inorganic contaminants endanger aquatic flora and animals, as well as human health. Eco-technologies, activated sludge technologies, anaerobic technologies, biofilm technologies, advanced oxidation processes, and membrane technologies are the most common types of wastewater treatment technologies.

Sources

There are various sources which contributes and are responsible for the major pollutants such as pathogens, organic wastes and chemical pollutants, they are as follows:-

1. Basic chemical manufacturing industries such as inorganic/organic chemicals, bulk petrochemicals, pharmaceutical goods and intermediates, polymers and their derivatives, agricultural chemicals, acids, alkali, dyes, paper and pulp, and fertilisers make up the chemical and related industries. 

2. Due to pollution difficulties, the chemical industries have a considerable impact on the environment. 

3. Organic and inorganic contaminants predominate in wastewater from the chemical industry. These contaminants are poisonous, mutagenic, carcinogenic, and nonbiodegradable in the majority of cases. 

4. Complete treatment of effluents generated in various chemical industry units in effluent treatment plants is necessary, and process intensification (PI) concepts can be applied to effluent treatment. 

5. For the treatment of wastewater from the chemical, biological, food, pharmaceutical, pulp and paper, dye, and textile industries, a variety of physical, chemical, and biological procedures have been studied. 

6. The type, nature, and concentration of contaminants influence the procedures used to treat wastewater. The treated effluent should be recyclable and environmentally beneficial.

7. The primary contaminants in wastewater are inorganic and organic pollutants. Bacteria and other organic pollutants from sewage, fertilisers, agricultural runoffs, forestry, food processing, tree and brush debris, industrial waste, and other sources are all examples of organic water pollutants. Inorganic water pollutants include inorganic salts, mineral acids, metals, trace elements, metal compounds, metal complexes with organic and compounds, sulphates, cyanides, acid rain from industrial or volcanic discharges, acid mine drainage, acid pollution of lakes from acid soils, volcanic or mineral, carbon dioxide discharges and runoff, chemical waste industrial byproducts, and so on. 

8. One of the largest contributors of wastewater is the chemical sector. Heavy metals such as lead, mercury, chromium, vanadium, arsenic, copper, nickel, cadmium, molybdenum, and zinc are major inorganic pollutants with sources in industrial coolants, mining, leather tanning, chromium salts manufacturing, e-waste, paints, smelters, ceramics, bangle industry, thermal power plants, chlor-alkali plants, fluorescent lamps, electrical appliances, hospital waste.

Organics that are biodegradable

Biodegradable organics, which are mostly made up of proteins, carbohydrates, and lipids, are most usually assessed in terms of BOD (Biological Oxygen Demand). BOD is the amount of oxygen necessary for bacterial action to oxidise organic matter in the presence of oxygen. The greater the demand for oxygen (and thus the more organic pollution), the less oxygen is available to support life. The BOD of urban sewage is typically 500 mg/litre. BOD levels in the harbour basin should be between 50 and 150 mg/litre.

Pathogens

1. Contamination of drinking water, either directly or indirectly, by sewage, other wastes, or human or animal excrement is the most common and ubiquitous threat. 

2. If the contamination is recent, and there are carriers of infectious enteric diseases among the contributions, some of the living causative agents may be present. 

3. The consumption of polluted water or its usage in the production of certain foods may lead to the spread of infection. 

4. The microbiological quality of natural and processed waters differs. 

5. Drinking water should be free of germs that are pathogenic to humans. In reality, this means that the presence of any coliform bacteria in any 100 mL sample should be impossible to prove.

6. Humans who are affected with disease or who are carriers of a particular disease may discharge pathogenic organisms found in contaminated water. Bacteria, viruses, protozoa, and helminths are the four main types of harmful organisms.

Organic Waste

Organic waste is simply any biodegradable material that comes from a plant or animal. Organic waste is everything we used to throw in a compost pile. Organic waste includes the following items:

1. Food that has been left over.

2. Coffee grounds, apple cores, egg shells, and other food wastes are just a few examples.

3. Yard trimmings, fallen leaves, branches, weeds plucked, and other landscape detritus are all acceptable.

4. Food for pets.

5. Manure from livestock.

6. Wood that has not been treated or painted, such as coffee stirrers and toothpicks.

7. Paper/packaging that has been discoloured by food, such as greasy pizza boxes and dirty paper plates. (Note that this does not include food packaging made of foam or plastic, even if it is discoloured with food residue.)

Chemical Pollutants

Chemical pollutants that enter the human body through inhalation, ingestion, or dermal absorption can have a local effect on specific organs (e.g., the lungs, the gastric system, or the skin), or they can have a systemic effect due to absorption, circulation in the blood, and distribution throughout the body. Damage to the liver, kidneys, neurological system, blood, cardiovascular system, immunological system, or reproductive system are examples of systemic impacts. Certain pollutants can be carcinogenic (cause cancer), teratogenic (cause birth deformities), or mutagenic (create mutations) in nature (affect DNA). Hazardous effects of chemical pollution on humans are dependent on the nature of the pollutant (and its fate and effects on the human body) as well as the level of exposure. 

Conclusion

Pollutants or Toxicity refers to the degree to which a chemical pollutant can harm humans. It is determined by the reactions and interactions between the pollutant and the human body, as well as the dose of the chemical that enters the body. Certain pollutants only have an effect above a certain dose, and at low doses, they can be innocuous or even beneficial. Dose–response analyses are used to identify critical levels of exposure to a pollutant that, if exceeded, could result in unacceptable health consequences.