There are a number of ways in which wastewater can cause pollution problems, considering not all waste makes it to wastewater treatment plants. Many cities , particularly older ones, have combined sewer systems CSS , which collect domestic sewage in the same pipes as storm water runoff. After heavy precipitation, street gutters collect more water than the system can hold and a combination of raw sewage and storm water is released directly into the environment, otherwise known as a combined sewer overflow CSO.
There are two main levels of wastewater treatment: primary and secondary treatment. In the primary stage, solids are allowed to settle and be removed from wastewater.
The secondary stage uses biological processes to further purify wastewater. Sometimes these stages are combined, and in some cases additional treatment such as tertiary treatment and advanced wastewater treatment are used. Primary treatment removes material that will either float or readily settle out by gravity. This treatment includes the physical processes of screening, comminution—the act of reducing a material to minute particles or fragments—grit removal and sedimentation.
As wastewater enters a plant for treatment, it flows through a screen. This removes large floating objects, such as rags and sticks, which clog pipes or damage equipment. Once the wastewater has been screened, it passes into a grit chamber, where cinders, sand, and small stones settle to the bottom.
Once the screening process is complete and grit has been removed, the wastewater still contains organic and inorganic matter along with other suspended solids. Fish and aquatic life require fresh water. When their water environment is laden with wastewater, they cannot survive. If chemicals, such as nitrogen and phosphates, enter streams, rivers or large bodies of water in excessive amounts, it causes excessive plant growth which release toxins into the water.
This leads to oxygen depletion and dead zones; areas where fish and other aquatic life can no longer exist. While Mother Nature does her best to naturally process wastewater, there is too much for her to handle.
Because the global population is so large and growing, so is wastewater. And, as the population grows, so does the amounts of wastewater. In fact, Sweden actually ran out of its own waste and it now imports over , tonnes of waste from other countries. The reuse of treated wastewater has become a viable option to minimising water scarcity problems. Having said this, with some smart thinking, wastewater treatment and some generous open mindedness something previously almost unheard of from corporations we can turn this around and make much needed changes all around the globe.
We consider wastewater treatment as a water use because it is so interconnected with the other uses of water. Much of the water used by homes, industries, and businesses must be treated before it is released back to the environment. The gas produced during this anaerobic digestion process contains a large amount of methane, which is harvested and then burned to generate electricity.
An example of this system being used within the Middle East can be found in al-Samra wastewater treatment plants in Jordan. The resulting natural fertilizer is then used in the agricultural sector, increasing crop yields. This decreases the use of chemical fertilizers that pollute the surrounding marine and surface ecosystems.
This will cause the production of large amounts of fresh usable water, thus helping battle water scarcity. Pingback: What About Water? Pingback: Wastewater treatment plants in India - Why install?
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