Sewage systems are a modern marvel – and perhaps the most undervalued modern convenience we enjoy today. From garbage disposal to bathroom needs, our sewage systems make life easier. However, treating our waste is a significant undertaking.
Why Do We Treat Sewage?
Firstly, you might be wondering why sewage and wastewater is treated in the first place. If it is already being disposed of, why bother any further with it? It’s a fair question, but the answer is a simple one: wastewater filters back into the natural environment, where contaminants – whether biological or chemical – can have a profound effect on the delicate balances found there.
If left untreated, sewage from even basic household activities, from using the toilet to taking a shower, can negatively impact wildlife, and potentially even human life a little further down the line. Without treatment, wastewater can allow dangerous pathogens to propagate, increasing the risk of disease outbreak. Meanwhile, chemicals from household cleaning products can harm aquatic life where wastewater is drained, and inorganic waste can present an ecological hazard.
The Stages of Sewer Treatment
Preparation
The first stage involves the preparation of wastewater for proper treatment. Here, larger materials are removed from the sewage via a series of large mesh filters. Complete items and larger non-dissolved materials are prevented from passage via the mesh, enabling conventional disposal later on.
Primary Treatment (Removal of Solids)
The sieved wastewater is fed into tanks which settle the water, enabling any suspended sediment to either sink or float. Lighter sediment is removed from the surface of the wastewater, while more refined filtration methods are used to separate the remaining elements by type. Heavier solids, or ‘sludge’, are then separated from the wastewater for separate treatment.
This stage requires extensive use of powerful pumps and airflow units, which are prone to blockage and breakage. As such, sophisticated alarm systems utilizing buzzers can alert sanitation workers as to any issues in treatment.
Auxiliary Treatment (Decomposition)
The separated sludge aerated with an air pump, before storage in a decomposition tank. Here, aerobic microorganisms are introduced to break down organic matter in the sludge, making it easier to separate and producing valuable methane in the process. The remaining sludge is dried and removed for conventional disposal.
Sterilization
With the wastewater largely free of sediment, the last step is to eliminate any microorganisms that may be proliferating in the water. This is done by a process of sterilization, which includes the introduction of chemicals such as chlorine. A final stage of filtration occurs before the wastewater is safely pumped out.
Improving Efficiency
Environmental concerns are at the forefront of sewage treatment, but there may be some ways in which efficiency can be improved – in turn, saving energy and resources:
- Methane produced in the decomposition stage can be used for its energy, to power the plant.
- Pumps can be serviced and replaced on a more regular basis, ensuring everything works at spec.
- Automation of more processes can eliminate the chance for human error, reducing downtime.