Lagoon Sludge: Causes and Effects

Lagoon sludge naturally builds up over time and has to be dealt with sooner rather than later to keep your water treatment facility operating efficiently.

While these collection sites don’t have to present a big issue, they can cause big problems if left unattended for too long. Worst-case scenario: it can result in a complete shutdown of your plant’s water treatment process. 

One of the not-so-serious issues can simply be an unpleasant stench. This usually means you’ll have to deal with some angry neighbours (you can’t blame them, though).

The good news? There are ways to prevent, or at least slow down, the process of sludge build-up. And once it inevitably gets to the point when you have to take action, there are methods to remove all the excess sludge.

Let’s dig deeper into what the sludge even is, how it’s formed, and what potential effects it has.

 

What Is Lagoon Sludge?

Sludge is the body of biosolids that collect at the lagoon’s bottom and are mainly composed of dead bacteria, algae, plants, sand, silt, gravel, and insoluble metals. The volatile (biodegradable) components will degrade over time, while the remainder will need to be removed by dredging.

Sludge is formed when suspended particles settle or float in water. A variety of industrial processes that include water treatment generate this kind of industrial waste.

There are two types of sludge — organic and inorganic.

Organic sludge is produced by treatment facilities that handle organic contaminants in wastewater, such as sewage treatment plants, food processing plants, paper mills, and pulp mills. 

On the other hand, inorganic sludge is produced by wastewater treatment facilities, such as civil engineering sites, water purification plants, and metal plating factories that handle wastewater containing large quantities of sand and metal components.

Sludge storage is incorporated into the cell capacity; thus, most lagoons don’t need dredging for years or decades. However, sludge accumulations of greater than 18 to 24 inches may lead to a variety of issues.

 

Causes of Sludge in Lagoons

Various factors can cause sludge to build up in your lagoon. Here are some of the potential causes.

The Age of Your Lagoon

The majority of wastewater lagoons are designed for sludge build-up, which means that a certain degree of sludge accumulation is not only anticipated but intended. 

Typically, the lowest 1–2 feet of a wastewater lagoon are classified as “sludge storage,” where sludge is expected to collect throughout the lagoon’s lifetime.

In theory, this sludge storage region should function as an anaerobic zone, in which some solid influent materials, such as plastics, may degrade anaerobically over time. 

Unfortunately, this does not change the fact that sludge build-up may harm 

effluent levels.

Inefficient Lagoon Mixing System

Your lagoon aeration system will influence the pace at which lagoon sludge accumulates.

When it comes to mixing the first six feet of water, surface aerators, for example, do an excellent job. By the time you get to this stage, the water will be much more challenging to maintain well-mixed.

Consequently, influent particles sink to the bottom of the wastewater lagoon, where they begin to accumulate. Lagoons that use surface aeration often have an excessive accumulation of sludge.

 

Effects of Lagoon Sludge

Allowing an excessive build-up of wastewater lagoon sludge may have some not-so-great effects. Here are some of them.

Impede the Treatment Process

Allowing an excessive build-up of wastewater lagoon sludge may short-circuit your whole treatment process. 

Because the build-up of sludge reduces the amount of water a lagoon can store, it also forces the retention period to be shorter. Shorter retention means shorter time available for proper treatment, which leads to overall longer and inefficient treatment processes.

This may result in higher effluent concentrations of biochemical oxygen demand and total suspended solids. If lagoon sludge levels continue to rise, the effluent levels will most likely exceed what’s allowable. 

In the worst-case scenario, this can cause entire sludge islands, leading to complete system failure.

Odors From Your Lagoon

When an excess amount of sludge accumulates in the lagoon, it means that the breakdown of the organic matter will start anaerobically. Dealing with that alone is a highly time-consuming process.

For starters, everything will move at a slow pace. And to make everything even nastier, toxic fumes will evaporate during the entire process. Once the poisonous vapors leave the lagoon’s confines, they can cause a lot of trouble for the people who live nearby. 

The equation is simple — the more lagoon sludge there is, the more foul smells there will be. 

Rise in Ammonia Levels

The slow breakdown of sludge may leak ammonia into the lagoon’s water column under certain conditions. As a result, the effluent ammonia content may be greater than the influent content — which is frowned upon by government regulators.

 

Don’t Ignore Your Lagoon Sludge Removal Needs

Aeration and mixing are the best defenses against sludge build-up and the problems it may bring. 

A well-aerated lagoon prevents biodegradable organic materials from sinking to the lagoon’s bottom as sludge by keeping them suspended and in continuous contact with dissolved oxygen and microbes.

There are mechanical devices called aerators that do just that. They bring more air into the body of water — in this case, industrial lagoons.

Even with all prevention, sludge will inevitably build up, as that is what it’s designed for. There are several technologies that will safely remove all the excess sludge from the lagoon, such as mechanical dredges, vacuum trucks, and yellow iron applications.

With the tech world expanding every day, you can also opt for the newest technology, and dive into the world of robotic cleaning systems. Robots are a fresh and innovative addition to the industry and by far the most efficient option. 

Regardless, not every method suits every sludge removal project. Factors such as lagoon size, budget, and waste reduction goals all play an important part in making the best decision for your situation.

When it comes to the green battle for our planet, we are used to seeing machines on the opposite side. But maybe it’s time to start looking at how new technology can also help us cut back on the damage to our home.

Robots are a critical part of the environmental revolution.