Humans are animals. We eat food, breathe the air, and generate waste. According to theGuardian.com, Americans generate roughly 300 million pounds of feces each and every day. These feces have to go somewhere in order to keep the surface clean and liveable, so they are transported to a network of wastewater treatment plants. At the wastewater treatment plants, the feces, water, toilet paper, and any other flushed objects, are treated and cleaned. After the water treatment process is done, the input is reduced by almost 99%, leaving behind a substance called sludge or biosolids. The leftover sludge is simply concentrated feces. Humans are then left with the challenge of disposing of the sludge. The problem is, in today’s world, the sludge is filled with harmful substances like heavy metals, pharmaceuticals, and the PFAS mentioned in the last civic issues blog.

In the past, there have been many methods of disposing of the sludge. The three most widely known methods were, landfill dumping, incineration, and land application (Stehouwer). These methods all had their pros and cons, but let’s begin by talking about their pros. The most common way to handle biosolids was through landfill dumping. The sludge was removed from the wastewater, loaded into trucks, and driven to the nearest landfill. The sludge would then be mixed in with the rest of the trash. Companies preferred landfill dumping to other methods because the cost of transportation was low along with the low dumping costs. Companies also preferred landfill dumping because they knew that they could continue to dump years into the future. Landfills had no end in sight since no one was working hard to find other ways of waste disposal. Finally, landfills were preferred because they seemed to have few known environmental risks.

Another method wastewater companies used to dispose of sludge was through land application. This method consisted of sludge being transported to farms for the farmers to fertilize their crops with. Sludge is packed full of plant-growing nutrients. It allowed farmers to grow more food in less space, and greatly increased the yield farms had. This method was also liked because of the scalability it seemed to have. Below is a picture of biosolids being land applied.

The final major method of sludge removal is through the use of incineration. Wastewater companies will haul sludge to massive incinerators where the sludge is incinerated. This method of sludge reduction is good because it greatly reduces the volume of the sludge. The output of an incinerator is between 10% and 20% of the initial sludge input. The output sludge has been stripped of its organic compounds and pathogens. Incineration also generates a small amount of energy out of the sludge. This means that more sludge can be put into a landfill before it gets full.

These methods are great, but now that we are learning so much more about PFAS, the quality of our waterways, and the hidden dangers of our wastewater, we are forced to rethink these methods. To start, landfilling the sludge is no longer a viable option. Over the years of landfill dumping sludge, the structural integrity of the landfills is degrading. Biosolids are organic compounds and they break down over time. The breakdown of the sludge releases methane gas. This is a problem for two reasons. For one, the methane gas creates pockets of air deep inside the landfill, this causes risk of cave ins. Landfill operators and their machines are no longer being supported well by the lack of structural support. In addition, the release of methane is not helping the problem of global warming. Methane is a greenhouse gas and greatly contributes to the rise in global temperatures. Besides the methane problem, landfill dumping biosolids is smelly and potentially harmful for groundwater and the surrounding ecosystem. Finally, landfills aren’t accepting sludge anymore. Waste water companies have been seen shipping their sludge all of the way from NYC to Texas just to dump their sludge in a place that accepts it.

Land application also has its newfound problems. Because our sludge is now filled with such high concentrations of harmful pharmaceuticals and PFAS, the crops grown in the sludge are unsafe to eat. The USDA is now regulating the levels of PFAS and pharmaceuticals found in farmland (Machno). Because of this, farmers are no longer accepting sludge because they will get shut down by the government if they do. In addition, the harmful chemicals get transported into the waterways via runoff. This causes ecological problems in the waterways and surrounding lands.

Finally, incineration also has its discovered drawbacks. The biggest problem of incineration is the cost. Incineration is incredibly expensive because the sludge needs to be shipped to an incineration facility, incinerated, shipped to a landfill, and then dumped. Besides the reduction in size and organic matter, the sludge is still the same as regular landfill dumped material. The process of incineration is known to release heavy metals into the atmosphere, as well as carbon dioxide. The heavy metals and gasses in the atmosphere are harmful to life and can have long term effects on population health. The carbon dioxide released into the atmosphere contributes heavily to global warming. Also, due to the nature of incineration, all nutrients and energy in the biosolids are lost.

Now that you have an understanding of chemicals like PFAS and their harm to humans, as well as the pros and cons of traditional methods of sludge removal, you can see the problem that we face. Our waste is harmful to the world. We need to find better ways of producing things, and we need to be kinder to our own bodies. In the next civic issues blog, we will discuss the solution to these problems!

Works Cited:

Machno, Peter S, and Peggy Leonard. “Biosolids.” Pollution Issues, http://www.pollutionissues.com/A-Bo/Biosolids.html#:~:text=Landfilling%20of%20biosolids%20usually%20occurs,the%20nation’s%20biosolids%20are%20landfilled.

Perkins, Tom. “Biosolids: Mix Human Waste with Toxic Chemicals, Then Spread on Crops.” The Guardian, Guardian News and Media, 5 Oct. 2019, https://www.theguardian.com/environment/2019/oct/05/biosolids-toxic-chemicals-pollution#:~:text=Spreading%20pollutant%2Dfilled%20biosolids%20on,everything%20from%20pharmaceuticals%20to%20PFAS.&text=It%20often%20includes%20PCBs%2C%20PFAS,flame%20retardants%20to%20hospital%20waste.

Stehouwer, Richard. “What Is Sewage Sludge and What Can Be Done with It?” Penn State Extension, 1 Feb. 2022, https://extension.psu.edu/what-is-sewage-sludge-and-what-can-be-done-with-it.

“Technology.” Ecoremedy, 12 Nov. 2021, https://ecoremedyllc.com/technology/.