A Brief Look at the Bacteria Found in Sewage Sludge
Monday, January 11, 2021

Have you ever seen the sludge that builds up in sewers? Its smell and appearance and inherently repulsive and with good reason. It's chock-full of dangerous bacteria and other microorganisms.

American sewage treatment plants generate nearly 14 million tons of sewage sludge each year. So, what is it made of, and how is it formed?

Sewage treatment is vital to maintain a growing population. Today, we are taking a closer look at the bacteria that live and make up part of the sludge. Read ahead to learn more.

You Are What You Eat

More than ever, we have an interest in bacteria, viruses, and other pathogens that can make us sick. On the other hand, we know about the importance of 'good bacteria' for our GI and skin health.

So, which bacteria cause the greatest harm in the food industry? This varies depending on the geographic location. However, a sewage leak is likely to contaminate surrounding areas with my kinds of bacteria.

Here are some most commonly found types of bacteria, with important examples from each group.


In most cases, proteobacteria are the most abundant bacteria in sewer water. They are an important phylum of Gram-negative bacteria that includes many medically-significant species.

Well-known examples include E. coli, Vibrio spp., and Salmonella spp. Other important include genera Helicobacter, Yersinia, and Legionellales, and others.

E. coli is commonly found in the GI tract but can cause serious disease and death if ingested. Cholera is an infection that follows the consumption of contaminated and water and food. In war-torn Yemen, there has been an ongoing cholera outbreak since 2016 that has claimed thousands of lives.


Another Gram-negative phylum, the Bacteriodetes, are a diverse group. They can be found in water, soil, on the skin, and in the GI tract of different animals.

In fact, they form an important component of the intestinal microbiota.

B. fragilis is the most medically significant species. It can cause peritonitis, abscesses, appendicitis, and other infections.


Unlike the previous groups, Firmicutes consists of Gram-positive bacteria. Many species have the ability to form endospores. This allows them to go dormant and avoid dissection and death in hostile environments.

One interesting example is Heliobacteria. They use anoxygenic photosynthesis, meaning they create energy from light, similar to a plant.

Clostridium, however, is quite dangerous. These bacteria cause tetanus, botulism, and other serious infections.


Treponemas are spirochetes (spiral-shaped bacteria) commonly found in sewage. T. pallidum, the most well-known spirochete, causes yaws and syphilis.

Propionibacterium is a genus of actinobacteria that are commonly found on the skin and sweat glands. Their overgrowth predisposes to acne.

Dealing with Sewage Sludge

Whether or not you find it pleasant or interesting, proper management of sewage sludge to vital.

No other industries can function without proper sanitation and wastewater processing.

When it comes to monitoring sludge levels and analyzing drinking water, you want the best. Visit this page to contact us to learn more about our water treatment solutions.