Wastewater Management Systems: How they work

Water that has already been used and is no longer fit to be used again is called wastewater. Daily human activities like brushing, bathing, using the toilet, cooking, cleaning, etc. produce wastewater. Industries using water for their processes also produce wastewater. No matter what the source is, it is important to treat wastewater before releasing it into the water bodies. Wastewater management is the process by which water that is no longer usable is treated to remove toxins, bacteria, particulates, etc., making it safe to be released into the environment.

Wastewater usually contains 99.9 percent water by weight and 0.1 percent waste that needs to be removed. The waste is usually dominated by organic matter, germs (even dangerous pathogens), particulates and dissolved solids, chemicals like ammonia and nitrate, and, of course, it has a bad odour. If left untreated, wastewater will find its way back to the surface or to the water bodies and will get back into circulation. This, in turn, can pose a serious health risk for the general population.

There are two main methods of treating wastewater: chemical or physical, and biological processes. Biological plants use certain bacteria to treat waste, whereas chemical plants use physical processes and chemicals to eliminate contaminants.

How do wastewater systems work?

Improvement in technology has allowed wastewater management systems to evolve and advance. Today, many companies, like Reflections Wastewater Systems, offer state-of-the-art systems to suit every need. Here is a brief explanation of how wastewater is treated:

Pre-treatment:

In the first stage, wastewater enters the treatment chamber where it flows through a screen. In this ‘pre-treatment’ phase, all large solid items like bottles, plastics, branches, etc. are removed. Next, it is sent to the grit chamber where smaller particles like sand, glass, small stones, etc. settle to the bottom. At this stage, some treatment plants skim grease and other oils from the surface of the water by turning them into froth using air blowers.

Primary Wastewater Treatment:

At this point, wastewater still contains organic and inorganic matter along with some solids. The pre-treated wastewater is sent to a number of basins and tanks for further clarification. This separates the contaminants from water, allowing them to settle at the bottom of the tank as ‘sludge’. This ‘sludge’ is processed further in a ‘digester’. At this point, about half of solid waste, organic matter and germs are eliminated. Oils and grease will also be removed now if they haven’t already been removed. Some systems will have no further stages, and the water will be treated with chlorine to kill bacteria and odour and discharged. The solids will be removed and dumped in a landfill.

Secondary Wastewater Treatment:

Water is moved to an aerated tank where plants and beneficial microorganisms are added to break down the organic compounds in the sludge. This happens over several hours. This activated sludge is used again to treat fresh sludge in the aeration tank, or it is sent to another tank where it is disinfected which kills any remaining pathogenic bacteria.

Tertiary Wastewater Treatment:

In some systems, this is the final stage where treated water is sent to yet another tank where more sludge settles at the bottom of the tank. Nitrates and phosphates are removed from the water; it is disinfected with chlorine and sent back into circulation. The resulting solid ‘sludge’ from this stage is treated to be used as fertilizer or to produce methane that can power the plant.

Of course, wastewater management systems could use many more processes than these three, but the basics of treating the water remain the same.