Power in wastewater

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We all follow a morning routine, which typically consists of some combination of visiting the lavatory to brush teeth, use the loo, and take a shower. The water quickly disappears down the drain and we don’t once wonder about its fate. For those curious to find out where the water travels, let’s go on an adventure to DC Water – the Washington DC wastewater treatment plant. The facility averages 370 million treated gallons per day, and over one billion gallons at peak flow. Put in perspective, that is enough to fill the RFK stadium…daily!

First the water is pumped into the plant for preliminary treatment, aka big item removal. You could see things such as basketballs (not kidding), wedding rings, fish (yes, this happens sometimes)…feel free to get as creative as you want here. The next process is primary treatment, where a metallic slow moving arm skims the fats and oils from the top and the solids settle and fall to the bottom. The wastewater generated from that step goes on its way to the secondary process, which uses microbes to treat organic matter – the picture that reads chocolate milk depicts the process in which microbes consume the organic water in bubbling, oxygen infused water.

The process does not end at the secondary treatment and moves to nitrification, denitrification, filtration and disinfection. End goal? Biosolids, also known as fertilizer. Class A biosolids are heated sewage sludge that meet EPA guidelines for land application. That is the type of product that DC Water works to produce.

And there you have it – a quick summary of an important process of converting our waste into energy. And just to think that before 1937 DC residents saw their excrements typically flow through open sewers and discharged to nearest waterways. The uncleanliness of that process led to dysentery and sparked epidemics of cholera. Now, this plant not only helps keep the customers happy, but also generates energy. The energy generation will definitely go far to reduce the almost ~$1M energy bill that the plant generates.

The next time you see the water going down the drain you will know exactly where it’s headed!


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