I can remember asking myself this question many years ago at my first environmental laboratory job. I was manually shaking out separatory funnels for EPA 625 and 608 and each sample looked drastically different from the next as I was pouring them into each separatory funnel. At the time, I thought the term wastewater meant anything that came from a sewer pipe and that it mainly consisted of human waste. When I looked deeper into the possible sample categories for these methods, I was very surprised by the different sample types required to be tested as wastewater. With that, it prompted me to ask myself well where does it come from?
So, where does wastewater come from?
Well, of course, there are the obvious sources such as our homes and our offices at work. This would be categorized as domestic wastewater. It consists of any water used in showers, baths, toilet sinks, and to do laundry.
Another source of wastewater that is impactful is from industrial or manufacturing facilities. These operations have liquid waste that can be in any process that is used to clean food, equipment, or even cooling down machines. This type of wastewater is categorized as industrial wastewater and has a long list of facilities that must have their wastewater treated and tested. Examples of such sources of wastewater include coal mining, explosive manufacturing, organic chemicals manufacturing, petroleum refining, plastic and synthetic material manufacturing, pulp paper and paperboard mills and steam electric power plants.
I have firsthand experience with one of those examples in my home state of New Hampshire. On the bank of one of our river systems stands the last coal-burning power plant in New England. This facility uses the water from the river to cool its system down and then discharges the warm water back into the river. This action is really a sight to see when all the ice has covered the bodies of water here in NH except for the river section this power plant is on. In the winter you can launch a boat and navigate to the discharge area and fish in the river. The water is significantly warmer in that river stretch as the warm water that is discharged from the cooling system into the river warms up the surrounding area. The discharging of the warm water triggers many of the fish in the area and they will navigate to this area in December through February while all other bodies of water have a few feet of ice covering them. This wastewater must be monitored and tested as it is going back into the environment and will impact ecosystems in and around the riverside.
Another source of wastewater I didn’t consider when I was just starting in the lab was stormwater. This is a form of wastewater because excessive water from runoff can gather into stormwater drains and sewer lines. Just look outside on a rainy day. All that water flowing must go somewhere and as it flows it touches whatever is in its path and will eventually flow untreated directly into storm drains, streams, rivers, and potentially into the ocean.
With all the wastewater sources, it will need to be tested and monitored at the source and wastewater facilities periodically. These pollutants range from metals, volatiles, inorganic and organic compounds. Some organic pollutants are acid/base neutrals, pesticides, polychlorinated biphenyls (PCBs), and oil and grease. Testing for these toxic pollutants will ensure wastewater discharges; sewer lines and runoff are safe and kept within the environmental guidelines for toxic pollutants. If the water samples are over the environmental limit corrective actions at the source or wastewater facility will take place.
With all these sources of wastewater I realized not all samples are equal and that is because they are all from different sources that make each of them unique. From clean-looking samples to very dirty-looking viscus samples with unique smells. One word of advice I would like to pass on with uncapping wastewater samples is always uncapping them in a working ventilation hood; you never know what is in that bottle.
All this wastewater testing at the source and before and after wastewater treatment is to sustain the safety of humankind, for now, and in the future.
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