Sewage Sludge

The human waste we produce and the way we handle it has consequences on our health and the environment. Some of our waste is more dangerous than others; it can cause disease and illness in addition to poisoning our drinking water. While special attention needs to be given to how we handle those types of waste, the vast amounts we produce sometimes leads to less than ideal methods as we simply just try to manage the flow. 

 

This brings us back again to the subject of human waste. As a nation, we are full of sewage sludge, which is the semi-solid product left at the wastewater treatment plant after it processes the sewage we send down the drain. According to information from the United States National Sewage Sludge Repository, we produce an astounding 7.18 million tons of sewage sludge in a year. It needs to be disposed of someplace. 

 

Once the treatment plant has processed the sludge as far as it can, the next step is disposal. Up until the end of 1991, sewage sludge would be hauled out to the ocean and dumped. For states not near the ocean, any large waterway or body of water was used. This method of waste disposal is sometimes described with the phrase “the solution to pollution is dilution.” Fortunately, the practice of ocean dumping was finally halted, mostly due to public outcry, especially over continuous beach and lake closings due to high coliform bacteria counts. The end to this method of disposal forced the industry to find more eco-friendly (and therefore more expensive) methods to dispose of human waste.

 

Currently, the most common methods of sludge disposal are landfills, land application, incineration, and deep well injection. Depending on where you live, your local sewage treatment plant is doing one or more of these, and each comes with its own consequences and drawbacks. You would want to check with the water district to find out how they dispose of the sludge. Otherwise, you may find yourself in a rather unpleasant smelling situation.

 

1. Landfills

 

Disposing of sewage sludge at the landfill along with regular solid waste presents a few issues, especially for the people living nearby. When the sewage sludge is trucked into the landfill, it first needs to be unloaded from the transport vehicle. Depending on the sludge thickness, it will usually be transported in either a vacuum pumper truck if it’s wetter or in an open top cargo trailer if it’s drier. State regulations usually require the sludge in the transport vehicle to be completely covered with tarps if the truck has no top, such as with dump trucks and open trailers. This is to prevent sludge from blowing away, getting rained on and creating leachate, or creating overly powerful odors. When the trucks arrive at the landfill, they usually are directed to an active area on the landfill to dump their loads. While the landfill is required to cover the sludge as quickly as possible to minimize odors and keep down the flies, this sometimes may not happen until the end of the day and all the trucks of sludge have completed their deliveries to the landfill. Many times the landfill dumps trash on top of the sludge to save money on using cover dirt, so hours go by while the sludge sits exposed. 

 

While landfilling sludge is not the preferred method, it is widely used because it is the easiest disposal method for the sewage plant. Landfills were not made to take the enormous quantities of sludge that most plants need to dispose of, so the overabundance of waste being dumped causes the landfill to give off a much stronger odor. When the weather is warm and especially humid, the smell lingers in the air for days and permeates into everything nearby. 

 

Sewage sludge decomposes more rapidly than solid waste due to the processes of bacteria in it. This gives off a much larger amount of gas. Unfortunately, the gas smells like rotten eggs, and the landfill may not have the ability to control the excess gas. As a result, anyone living near the landfill isn’t just breathing in a bad smell; they’re breathing in sulfur, pathogens, and other harmful substances.

 

In Parrish, Alabama, the residents wound up with a train nicknamed “The Poop Train.” It seems that New York City had been sending their sewage sludge to a landfill 20 miles away for the past year or so. While the courts battled over whether or not the train could proceed to the landfill as planned, the waste sat and sat, all the time the stench growing more rank.  

 

In Coventry, Vermont, the state Department of Environmental Conservation has been receiving dozens of complaints from its neighbors about strong odors, some of which would linger. The landfill accepts sewage sludge from the treatment plant for disposal, so locals expect the situation to only get worse. In addition, due to pathogens and bacteria in human sewage sludge, monitoring the water in the area is of critical concern. Many residents and towns get their water supply from wells in the area. 

 

2. Land Application

 

The application of animal manure to the land is an ancient practice. Before the birth of chemical fertilizer, farmers routinely returned the waste from their animals back to the land to add nutrients. Using manure with its natural nutrients and organic matter reduces the need for other fertilizers to be used. The nutrients contained in the manure help build the soil up to help the crop grow. Unfortunately, over the past 20 years, the effective use of that practice has been compromised by the creation of factory farms (as was discussed in an earlier chapter) and millions of pounds of animal manure recklessly overapplied to the fields. While there are some small family farms using the practice responsibly, most farms are not.

 

Sewage sludge from human waste is different because it contains more materials that are harmful to us. Sewage treatment plants process waste sent through the sewage system from many more places than residential homes. Offices, stores, restaurants, hospitals, and industrial operations all share and dispose of their wastes through the same system. Spreading human sewage on agricultural land is usually only done with sludge that has gone through additional treatment to remove as many of the toxins and heavy metals as possible. That treatment process, however, is woefully inadequate to deal with the range and volume of chemicals, metals, pathogens, and other waste which enter the treatment plant. The sludge that comes out the other end of a sewage treatment plant is dangerous. 

 

The term the industry likes to use is “biosolids.” No matter what we call it, biosolids or sewage sludge, it still smells and attracts flies. It still contains toxic chemicals and materials which pollute the land and groundwater and affect the people living near where it is applied. For example, the government recently discovered high levels of PFOS, a likely carcinogen, in sewage sludge. The likely carcinogen has been there all along, but finally now is openly being discussed as millions of pounds of contaminated sludge has been spread over farmland for years all over the country. 

 

Even with these known dangers, many states use land application as the preferred method of disposal. In some, about 60% of the volume of sewage sludge is disposed of this way. In addition to agricultural land, sludge is also used for mine reclamation areas to build the soil back up. It’s also used In forestry projects and public works projects such as parks.

 

There are strict federal regulations and guidelines that are supposed to be followed when anyone disposes of sewage sludge on the land. On top of that, many states that allow this method also have their own additional requirements as to how the sewage sludge is to be applied. Many of the restrictions deal with what uses the land can have and what is allowed to be grown on that land. Even though the land it is applied to is regulated, the sludge has a large impact on the surrounding area as well. 

 

Nitrates are found in large amounts in sewage sludge. While they are good for the soil and add needed elements, nitrates also have the potential to contaminate the groundwater with levels harmful to infants and may cause blue baby syndrome. Some studies are now suggesting there are some negative health effects on adults as well, but more research is being done. 

 

As if that weren’t enough, the sludge still contains many pollutants even after treatment. That leaves open the possibility for pathogens to be present in the sludge that were not destroyed during the treatment process. The sewage sludge contains high amounts of bacteria from the feces and urine that make it through the treatment process, including Listeria, salmonella, E. coli, and clostridium. All of these harmful bacteria have been found in sewage sludge tested after treatment. 

 

The problem is widespread. In 2019 almost 60% of the sewage sludge from over 16,000 treatment plants was disposed of on the land. Used on farm fields, parks, schoolyards, lawns, and many other places, millions of tons were spread. The use of sewage sludge on land is allowed by the EPA based on the claim it is a beneficial use of a waste product because the sludge contains phosphorus, nitrates, and some heavy metals considered good for the soil even though the agency has no testing requirements for other chemicals in the sludge before being applied. The waste may contain thousands of dangerous chemicals and other heavy metals. Pesticides, lead, mercury, radioactive wastes, microplastics, dioxins, PFAS, pharmaceutical wastes, and many other substances are found in the sewage sludge being applied to lands across the country. 

 

Even with all of these known dangers, because there is an almost limitless supply of sewage sludge available to farmers and other places, at times they put down too much. This presents several new problems. If over-applied, the sludge will not be absorbed by the ground but will instead run off into nearby properties and waterways.  Along with the organic matter and nutrients, however, these nearby locations also receive whatever pollutants and pathogens were in it. If not properly monitored and managed, these could adversely affect human and animal health, soil quality, plant growth, and water quality. 

 

In Lancaster County, Pennsylvania, for years my family found ourselves living in a farming community that not only spread the manure from the pigs and cows they raised on the fields, but also brought in sewage sludge from the local wastewater treatment plant to apply to the fields as well. The stench of the entire area during spreading time was unimaginable. In addition to the stench, we had constant sore throats, headaches, and much more frequent colds due to the airborne pathogens in the sludge. 

 

In Franklin County, Alabama, farmers are suing Synagro, a sludge spreading company, as well as several industrial operations who sent toxic, carcinogenic chemicals through the sewers to the treatment plant. The chemicals PFAS and PDOAs were in the sewage sludge applied to the farm fields in the area. Five thousand acres of farmland and water were contaminated. The company said it was unaware of the hazardous chemicals and didn’t test before spreading. 

 

The town of Lapeer, Michigan, had disposed of much of their sewage sludge the past 20 years by offering it to the local farmers as free fertilizer. It was good for the farmers as it cost nothing and contained nutrients they could use to enrich their soil. It was also very good for the town as it saved them a large amount of money on other disposal methods for the sludge. However, the newly-suspected hazardous chemicals PFOAs and PFOS started turning up in tests. Concerns are now growing that the fertilizer that was applied to the lands all these years, has contaminated not just the soil, but possibly the water as well. 

 

In Edmond, Oklahoma, according to a new report, over a million gallons of sewage sludge has been applied to a 44 acre site of local farmland in a seven day period. The sludge was injected into the ground. Putting 28,000 gallons of sludge in one acre of land in a single week isn’t a good decision. Authorities are assuring people the sludge has been tested for safety; the Director of Water Resources for the town told the people and the news reporter, “I wouldn’t do anything that would not be safe to do at my own house.” Given the gravity of the situation, the director’s words ring hollow with the locals who still have concerns.As a bare minimum, better testing for certain chemicals such as PFAS is required. The way the situation is now,there may well be some unpleasant surprises in store. 

 

3. Incineration

 

At the time of this book’s writing, there are 217 sewage sludge incinerators operating in various communities in the United States. Because sewage sludge contains a variety of toxic chemicals and heavy metals, the EPA regulates the emissions of these incinerators. There are actually two sets of regulations, depending on the age of the incinerator. There was a change made by the EPA in 2016 to lower the quantities of certain very hazardous emissions. However, due to how expensive it would be to upgrade the older incinerators built before 2014, the EPA allows a different amount of pollution to continue. Very unfortunately, though, the amount of hazardous materials incinerators were allowed to emit prior to tighter regulations was extremely concerning to communities affected by the operation of the incinerators. Some already have quite a few residents whose health was impacted as a result of delay. 

 

Incineration of sludge reduces its volume to about 15% of the original amount. This creates a new problem for the 15% remainder, which needs to be landfilled. Because of the chemistry behind waste incineration, the incineration process increases the percentage of most of the toxic chemicals and metals to five to ten times their original concentration: many of these are not destroyed during the combustion process. In other words, the remaining sludge has even higher hazardous levels of heavy metals and toxic compounds. While some people such as Tony and I say this should qualify the incinerated sludge as hazardous waste and disposed of as such, it gets dumped in a landfill. There is no financial incentive to dispose of it otherwise, and there are no governmental restrictions against doing so.

 

Mercury is one of the most dangerous chemicals found in sewage sludge. When the sludge is incinerated, much of the mercury is emitted from the smokestack. There are guidelines for the amount of mercury pollution allowed, but many times the incinerator and its pollution control equipment are not capable of meeting the standards. Unhealthy and dangerous amounts of mercury are released into the neighborhood and community. Sludge incinerators also emit dioxins, furans, cadmium, and lead into the surrounding area as well.

 

In Manchester, New Hampshire, the sludge incinerator emitted so much mercury that the EPA needed to step in to force the city-owned incinerator to comply with The Clean Air Act. The city settled with the EPA by agreeing to spend more than $6 million to install pollution control equipment, which will meet the standards needed. The amount of mercury the plant had been emitting was exposing residents to dangerous levels of mercury emissions. Inhalation of mercury vapors in emissions can harm the nervous and digestive systems. It also causes damage to the lungs and kidneys. Too much exposure to mercury can even be fatal in extreme cases. 

 

In Bridgewater, New Jersey, the sewer authority was fined over $200,000 for multiple violations of the Clean Air Act involving the incineration of sludge at its facility. Among the violations was non-compliance with emission standards, not having a plan to comply with emissions, especially the highly toxic chemical mercury. The sewer authority operates two incinerators at the site. They agreed to bring one of them up to standards to meet EPA requirements. They told the EPA that the second incinerator had a catastrophic failure and would no longer be using it at the current time. While there were no details about what this failure was, it certainly was obvious it was not running in compliance at the time of the catastrophe. 

 

4. Well Injection

 

Sewage sludge is one of the many waste products we like to dispose of in injection wells. Simply put, the sewage sludge is injected into the ground using a reverse-powered well. While many companies and municipalities like to talk about how scientific this all is, it is a method that will come back to haunt us at some future time. For years these injection wells have been sending millions of gallons of human waste down into cavities and porous rocks below the surface. Most of these wells extend down a thousand feet or more. Some go down several thousands. However, scientists and engineers cannot possibly predict when something below the surface may shift or rupture, sending millions of gallons of waste into a nearby aquifer and poisoning a water supply for years to come. Given the physics involved in injection wells, it is not a matter of if they will leak, but a matter of when.

 

In Los Angeles, California, there is an experimental project known as the Terminal Island Renewable Energy. The project has already injected over 200 million gallons of waste down several injection wells 5,300 feet deep. The project hopes the wastes will break down due to the heat in the Earth at that depth and cause the waste to produce large amounts of methane gas that will be pumped back to the surface and used for energy.  Nobody can say with 100% certainty that all of the waste will stay sequestered where it is put until it breaks down to less harmful materials and that it won’t at some future point contaminate underground water needed for the city. Because this isn’t based on hard science, they are gambling with the health and drinking water of millions of people for quick and easy disposal. 

 

Florida is trying to lead the nation in this disposal method with several very deep, newly-drilled injection wells. The hope is the waste they send down these holes will not return anytime soon and pollute the water. However, as discussed in the chapter on Injection Wells, Florida has a history of injection wells backing up on them. Back in the late 1990s, 20 injection wells were detected as having leaks, 17 of them in Miami-Dade County. The 3,000 foot deep injection wells showed evidence of treated sewage migrating upwards towards potential drinking water aquifers and not staying impounded as were supposed to. 

 

On the islands of Hawaii, Maui is sending their sewage waste into underground injection wells. Daily, three to five million gallons of treated wastewater is being injected down below the surface into supposed impoundment areas. Environmental groups sued to stop the injection of waste after dyes placed in the wastewater showed over half the waste from two of the wells was leaking into the ocean. The U.S. Supreme Court recently ruled that was a violation of the Clean Water Act. However, the ruling wasn’t a complete win: the court only sent the case back to lower courts to reconsider some issues but stopped short of totally banning the practice. 

 

The piles of sewage sludge we have all over are not going away anytime soon, nor are they going to get any smaller. For now, according to the experts, these disposal methods are the best options. However, many scientists and environmental groups dispute that, saying we are simply moving the problem from one place to another without really doing long-term planning. Like ocean dumping before it, our waste is really still there however we try to get rid of it. It still has the capacity to harm our health and environment.

 

Be cautious and thoroughly check out how your community handles the waste from its sewage treatment plant. Doing so is simply being smart and potentially preventing you winding up in an area or situation which is placing your health at risk. Research into better methods of disposal is ongoing. Maybe one day soon they will figure out a process to deal with the incredible volume we create.