Bacteria and Your Septic Tank


Bacteria are the least understood and least appreciated organisms on earth. Humans seem to have an excessive fear of these little guys, but in many respects, we are just giant cargo ships for the thousands of species of bacteria that live in intimate association with us. Hundreds of different types coat our outer skin, and our insides also carry over a thousand species that do all kinds of jobs to keep us healthy. For us, the trick is to ensure that we have plenty of the “good” bacteria in and on us. These species are the best defense we have against the few organisms out there that are dangerous.

It is no accident that taking a course of antibiotics can disrupt our intestines. The antibiotics kill off the good guys as they go after the bad. Sometimes you can get pretty bad infections, and there is no choice but to use antibiotics, but our society has gone over the top with its obsession with cleanliness. “Anti-Bacterial” is omnipresent in our various cleaning products. But we must be much more cautious about how we use these products.

Our waste is full of bacteria, so naturally, a sewer line or septic tank will also be full of them. And, of course, we use bacteria to treat that waste. But when we consider the types of bacteria in the waste, it becomes pretty clear that virtually none of them are the type of organism that would be suited to “treating” waste. They are intestinal bacteria, and when you think about where they live inside warm-blooded animals, you realize they have some adaptations that make them probably the least suited for wastewater treatment.

First, any bacteria in our gut has spent its entire existence at 98.6o F. When they hit the toilet as your feces, they go into temperature shock. These bacteria can’t operate at average ambient temperatures. Second, these bacteria have co-evolved with us. We give them a warm home, and the bacteria pre-digest our food for us in exchange. They break large chunks into smaller molecules we can absorb through our intestines. But in a waste treatment system, we want bacteria to digest the organic waste down to CO2 so it can escape as a gas. If they did that in your gut, not only would they be stealing your food, but you would also be in constant pain from the gas. So, these bacteria have evolved delicate appetites, and we can keep them on board. Again, you want something else in a sewage digester.

Finally, gut bacteria live in a soup of enzymes and acids, so they must secrete a mucus coating to protect their cell membrane. All bacteria do this, but gut bacteria secrete a lot. This mucus is a problem. It makes everything slimy. It goes out into the septic tank and the soil, clogging the pores. Over time the leach trench can no longer soak away the effluent, and it comes to the surface right in your back or front yard.

But some bacteria can digest our wastes. Most of them live in the soil. After all, the soil receives billions of tons of dead material every year in the form of leaves, grass, animal bodies, you name it. These bacteria have big appetites, especially in temperate zones. Think of what happens in the forest. Each year during the summer, huge quantities of plant materials accumulate. The leaves fall to the ground and then are covered by snow. Nothing happens all winter, but as soon as spring and the snow melt moisten the soil, spores of bacteria start to germinate. What happens is a race. The first ones to emerge get a head start. They grow by dividing, and many of these species will divide every 30 minutes. The object is to eat as much as possible, reproduce, use up the food and then create a spore to wait for the following year. The bacteria that do this the fastest win the evolutionary race.

But there is another feature in the ecology of these organisms. They need oxygen and typically get it from O2 in the air. But in the leaf litter, you will get pockets that occasionally are anaerobic, like a bunch of soaked leaves packed together. This is a problem for “strict” aerobes that can only use O2 from the air. But many species of soil bacteria are “facultative” species. They grow fast with O2, but if that’s not available, they can get oxygen from other compounds that have oxygen in their makeup, especially sugar molecules. The cellulose of the leaves is a long-chain sugar, but so is the mucus that causes problems in leach fields. They do this using the process of fermentation.

Fermentation is more efficient than anaerobic digestion, but still, half the carbons get converted to CO2, and the rest become alcohols or esters, which are small molecules. The slimy, long-chain mucus molecules disappear, and clogged soil opens up.

We created the SludgeHammer to grow some of the best of these soil species inside a septic tank. If you just add aerobic bacterial spores to the tank, the bacteria go into the anaerobic septic tank and never even germinate.

With the SludgeHammer, we provide the oxygen these spores need to develop. We also designed it to use the air to mix and pump the liquid in the septic tank through the ABG column. The interior was engineered with fixed film media to provide a place for the bacteria to attach and form a colony. The liquid entering the SludgeHammer transports with it the food that the bacteria need, and, voila, the bacteria can grow in a septic tank.

Now we can send these bacteria out into the soil and clear out the clog, no mess, no fuss—just biology working for us instead of against us.