Why do we need to treat wastewater?
If you just bought a property with a sewage treatment plant, you may have questions related to its operation. However, before you start learning about wastewater treatment processes, take some time to get the answers to two basic questions:
In the simplest terms, wastewater is any amount of water that has been polluted by human activity. This includes water contaminated as a result of:
- flushing toilets and urinals (this waste is known as blackwater)
- bathing, showering, and washing clothes and dishes (greywater)
- commercial and industrial activities
As you would expect, wastewater is almost entirely water. The remaining portion — roughly 0.1% — contains organic matter, inorganic compounds, nutrients, and microorganisms that need to be explored in more detail.
Organic matter in wastewater includes proteins, carbohydrates, fats, oils, greases, and synthetic compounds found in certain detergents.
Without appropriate treatment, organic matter enters lakes and rivers and becomes a food source for the microorganisms that live there. The problem is that these tiny creatures pull dissolved oxygen from water when they break down pollutants. The more pollutants that are present in the water, the greater their demand for oxygen (often presented as BOD and/or COD).
This process spins out of control in lakes and rivers with high concentrations of organic matter. In these watercourses, oxygen levels fall so low that animals like fish, frogs, and turtles suffocate and die.
Inorganics in wastewater include compounds with copper, lead, magnesium, nickel, potassium, sodium, or zinc. In many cases, these harmful substances are the by-products of commercial and industrial activities.
Inorganics do not break down easily. If they enter lakes or rivers via untreated wastewater, they remain there. As their concentrations increase over time, the water quality becomes a hazard for humans and animals alike.
Nutrients in wastewater include nitrogen and phosphorus compounds. These often come from human waste and cleaning products like laundry detergent and dishwasher soap.
It is no secret that nitrogen and phosphorus are common compounds in fertilisers. They do wonders in plant growth and reproduction. However, this benefit becomes a serious threat if nutrient-rich wastewater is allowed to enter lakes, rivers and streams.
High concentrations of nitrogen or phosphorus can lead to "dead zones" in watercourses. The process goes like this:
- Excess nutrients feed the growth of large algae blooms.
- Algae blooms prevent sunlight from reaching plants below the water's surface.
- Native plant species decay without sunlight.
- Bacteria that feed on decaying plant matter uncontrollable multiply.
- Growing populations of bacteria consume more and more dissolved oxygen from the water.
- Fish and other aquatic species that need oxygen evacuate the watercourse or die from hypoxia.
Nitrogen in partially treated wastewater can cause another problem. If excessive nitrate (a nitrogenous compound) pollutes our drinking water, it can reduce our blood's ability to transport oxygen. For infants, this can lead to what is commonly known as blue baby syndrome. In extreme cases, the condition is fatal.
Not all microorganisms are pathogenic. Numerous microorganisms are helpful because they break down organic matter in wastewater that would otherwise pollute the environment.
Pathogens in untreated wastewater are a different story. These bacteria, parasites, and viruses can contaminate clean water sources. If they do, they undermine human health by causing serious and sometimes deadly illnesses.
A closer look at wastewater makes it easy to see why we must treat it before it is released back into the environment.
Think of your on-site wastewater treatment plant as a water conservation tool. By removing suspended solids and other pollutants, your system prevents groundwater and water pollution that could lead to:
- tainted drinking water
- water scarcity and water shortages
- foul lakes and rivers
- lower numbers of aquatic species
- dangers to livestock
- reduced waterfront property values
Now that you understand the basics of wastewater, take your knowledge to next level. Discover our range of wastewater treatment systems and find out how they protect your property, our communities, and planet we share.