Wastewater Pollutants

Human activities generate wastewater, which is treated and discharged through sewage systems. Wastewaters contain pollutants which can cause environmental and health impacts if not properly treated. According to Environment Canada, these impacts include damage to fish and wildlife populations, beach closures, and restrictions on fish consumption and drinking water consumption. Wastewater pollutants include heavy metals, sulfates, phosphorus, nitrogen and organic materials.

Heavy Metals

• The textile and other industries produce wastewater with high concentration of heavy metals, reports the Turkish Journal of Fisheries and Aquatic Sciences. Lead, chromium, nickel, arsenic and cadmium are examples of heavy metals in industrial wastewaters. According to a study published in the European Journal of Scientific Research, concentrations of metals well above health limits showed up in vegetable samples collected in the Kano metropolis area of Nigeria. Such high concentrations of heavy metals can be attributed to the used of untreated wastewater in the farms.

Sulfates, Phosphorus and Nitrogen

• Although sulfates, phosphorus and nitrogen are not considered toxic to plants, animals or humans at low concentrations, they become toxic when in high doses. Phosphorus and nitrogen can cause over-fertilization of lakes and other receiving waters, reducing available oxygen, promoting excessive plant growth and leading to a decline in certain species, according to Environment Canada. Sulfates also contribute to the acidification of waters.

Organic Materials

• Wastewaters from sewage that contain feces and other organic materials can be contaminated with bacteria, viruses and other pathogens, says Environment Canada. If such pollutants reach beaches or other natural areas, they can contaminate shellfish and other seafood and cause infectious diseases. Decaying organic matter in excess can exhaust the dissolved oxygen of a lake, killing fish and other aquatic animals.