How Do Wastewater Treatment Plant Operate?
The main purpose of a treatment plant is to clean the sewage and water so that it can be used again. So what a treatment plant does? It removes the solids, pollutants, and any broken down organic matter but most importantly it restores the oxygen of the treated water. Once the treatment is done, it can support water-life again.
A Look into Its Operation
This cleansing is done in usually four stages, so the wastewater treatment plant operations have preliminary, primary, secondary and sludge treatments. The treatment plant is connected to the drainage system from where it gets the continuous supply of waste-water that has to be treated. Now let’s take a look at the various phases:
First Is Per-Treatment of Sewage
In this phase, the water-plant removes the easy pickings. Bar screens take away large items like branches, garbage, leaves, cans, rags, plastic bottles diapers and other waste materials that are there in the water. In many plants, there are grit chambers of various types. Their main purpose is to control the inflow of sewage water. In this way stones, sand and glass settle out. The basin continues to hold the sewage unit until it is ready for treatment. In some water treatment plants, you may find blower as well. Its main purpose is to remove the oily material by making a wroth out of it by blowing. But in some plants, grease is removed during primary treatment.
Now Water Is Given Primary Treatment
Once the primary treatment is done, the wastewater collects in primary clarifies. These are large basins and sedimentation tanks. Smaller particles settle down due to gravity. The mechanically driven scrappers collect any solid matter that is still present. They then direct it to a hopper that’s connected to sludge treatment equipment. If the grease removal is not done in the per-treatment phase, it’s done in this phase using surface skimmers. There are certain plants which recycle the collected fats with special equipment and saponify it to make soaps and glycerol.
Secondary Treatment Is the Next Phase
In this phase, the semi-treated water from the previous phase is aerated and agitated, and the micro-organisms are added to it so that organic matter can easily be broken down into sludge. In some plants, biomass is mixed with waste material. It leads to the creation of activated sludge which can be easily recycled for re-use. In this way, carbon and nitrogen are removed with the help of the biological flock. The oxidation occurs in filter beds that contain coking coal and also limestone. In some treatment plants, you may find wetlands where the organic material may be decomposed. The water treated in this stage is collected in secondary clarifies tank from where it goes to sludge treatment.
Now the water is treated for sludge. The heavier material gets separated due to gravity, and it is usually deposited in a landfill. Rest the sludge moves to a thickener for further treatment in a digestive tank which contains bacteria. These tanks produce methane which can be used to power the plant. The final solid product after deodorization can be plowed into the soil and may be used as fertilizer. The rest of wastewater is then treated to remove phosphorus, nitrogen and other nutrients.
Environment Protection Standards Need To Be Followed
There is an environmental protection agency in almost every country which defines the standards for discharged water and the equipment that may be used. Wastewater treatment plant operations have to conform to these standards as well.
In The End
These are simple phases that are used in wastewater treatment, but some plants may perform additional steps as well.