How Wastewater Treatment Plants Work: A Comprehensive Look (Part 1)

Too often, we pay no mind to where the water we use comes from, or where it goes after we’re finished with it. At Dutchland, our business revolves around the storage and processing of wastewater. Today, we want to take a look at the structure of a wastewater treatment plant, what goes on inside, and how water goes from being deemed “waste” to being usable again. This is going to be a two-part blog series, so stay tuned for the second half next month!

There are two broad, overarching categories under which wastewater can be placed:

  • Sewage water – this is water stemming from a domestic or office setting (toilet, shower, sink, etc.)
  • Industrial wastewater – this is wastewater produced in an industrial or commercial setting, and has a different chemical composition than sewage water due to its usage

Next, we’ll describe the steps involved in treating wastewater. We’re going to break these steps up into two separate blogs, with part two being continued for next month. They are:

  • Preliminary Treatment
  • Primary Treatment
  • Secondary Treatment (Biological Stage)
  • Digestion Stage
  • Second Digestion Stage
  • Deep Inspection

In the preliminary treatment, wastewater is passed through “bar screens”, which remove excessively large debris from the water that pass through the main sewer system. Coarse screens are used first, followed by fine screens, which remove much smaller objects such as matches or cigarette butts.

overhead view of a wastewater treatment plant

After all the larger objects are removed, the next contaminant to be removed is grit, caused by sediment buildup in the water. The aptly named “grit chamber” allows for the grit to settle to the bottom of the water. It is then removed from the tank and disposed of properly, since gravel and grit cannot be reused.

The next step is primary treatment, in which wastewater goes to the primary settling tanks to be further processed. Within the settling tanks, a hopper arm moved around the edge of the tank. Treated water is pushed outwardly toward the edges of the tank, while sediment particulates are driven down to settle at the bottom of the tank to be removed.

After the sediment is removed, the level of wastewater pollution is down to roughly 60%. The water then moves on to its secondary treatment, also called the biological stage. As the name suggests, this stage in the treatment process relies heavily on natural processes involving bacteria to break down remaining organic residues and transform it into a sludge.

This sludge is then pumped out of the tank and goes off for its own treatment, leaving the water to move on for its own separate scouring. The sludge settles to the bottom of the tank and is then transported to digestion tanks for even more processing.

Come back next month for the rest of the wastewater treatment plant tour; if you have questions in the meantime, feel free to give us a call at 717-442-8282 or send us an email at info@dutchlandinc.com. We look forward to hearing from you!