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What Is Wastewater BOD And Why Does It Matter?

For those that are less familiar with the intricacies of dealing with wastewater treatment, exactly how much goes into treating it may be a surprise. Wastewater commonly contains multiple characteristics that need to be removed or treated before it can be successfully turned into drinking water or discharged back into the environment. If not, the environment may suffer irreparable damage and the company that is responsible to face serious consequences.

Wastewater needs to be filtered and processed in multiple steps before it reaches the clean rating needed to be safe enough to drink or release into the environment.


Some of the most common contaminants that need to be removed from wastewater include:


  • Total Suspended Solids, known as TSS

  • Fats, Oil, and Grease, known as FOG

  • High nitrogen levels, measures as TKN or TN


But the physically visible contaminants are not the only potential hazards that lurk in the depths of untreated wastewater. There is also the question of the BOD, also known as the Biochemical Oxygen Demand (also sometimes called the Biological Oxygen Demand). This is a standard test used to measure the levels of organic water pollution by checking the number of pollutants the water contains.


BOD describes the measurement of the total amount of dissolved oxygen being used by the microorganisms when organic matter decomposes in the water. To put it more simply, the bacteria and other microorganisms in the wastewater need oxygen to break down biosolids through a process known as oxidation. If the pollution levels are high, too much activity from these microorganisms reduces the quality and oxygen level of the water.


This measurement can either be done in real-time or can be detected using sensor-based equipment installed in wastewater treatment plants.

Keep reading below as we go into more detail about BOD and why it’s an essential part of the wastewater treatment process.

Wastewater BOD And Pollution

BOD is considered to be one of the most important measurements to be taken in wastewater treatment and is a key indicator of water health and safety.


Think about it this way - oxygen and water already go hand in hand in terms of molecular makeup, and it is also used by the microorganisms that form in the water to break down any organic solids. The microorganisms are typically bacteria, yeasts, and others that form naturally in the wastewater. The degree of contamination they bring is measured in mgO2/L.


The measurement takes place in a temperature-controlled biological process, one that needs to be conducted very carefully. The rule is that the higher the BOD is, the greater the rate of pollution will be and the lower the general water quality. A low BOD amount on the other hand means that the water product is less polluted and purer, making it more suitable to be reused.


As cold water tends to have a better oxygen-retaining capacity than hot water, dissolved oxygen in wastewater tends to be lower as a whole during warmer months of the year. This can make wastewater treatment a greater challenge since BOD measurement is time-sensitive and the time that a BOD sample can be kept is limited to just two days. Wastewater treatment is a delicate process and this test is just one more place where plants need to be ultra-careful not to introduce overly high levels into the water.


The Role BOD Plays In Water


Dissolved oxygen plays a big role in natural water sources. Without the right concentration of dissolved oxygen, aquatic life and water quality start to deteriorate.


That’s why BOD measurement is an essential part of maintaining and managing natural water quality. Some environmentally stressing factors like high temperatures during the summer, or the introduction of man-made materials like fertilizer to a primary water source can decrease the amount of dissolved oxygen available. This, in turn, causes additional stress on the aquatic wildlife and ecosystem.


The “Demand” part of BOD can have several different sources - natural materials like leaves and animal manure or man-made pollutants like waste from industrial activity are just a few examples of places anaerobic bacteria are borne from in our sewer collection systems. In recent times, higher levels of phosphate solution coming from residential homes around the country have also left an impact on water source quality.


Phosphorous is a common chemical found in cleaning solutions during the 1960s and onwards. Used as a drain cleaner and more, large amounts of this element introduced into natural water bodies have been found the be responsible for a phenomenon known as algal bloom. Algal bloom describes a situation in which a population of algae found in a natural water source will experience explosive growth and cause an imbalance by releasing toxins as a byproduct.


This is why the BOD test plays such a crucial role - without it, we’re at risk of repeating past mistakes and causing further hazards to an already fragile aquatic ecosystem.



BOD In Wastewater Treatment Plants


As mentioned, BOD is a key indicator of organic pollution in wastewater. This means that the industrial sector is tasked with discharging their final water product only if it meets the right level of BOD.


A high concentration of wastewater BOD can lead to regulatory penalties and serious financial repercussions for the plant in question as they need to take extra measures to fix the problem. That’s why wastewater treatment plants are in need of a system that helps them to ensure that the BOD in the wastewater they process is reduced as much as possible.


This is achieved by putting the wastewater through multiple treatment steps of various intensities. This part of the process sees all of the solids and other bigger materials be filtered out of the raw wastewater, the water is subjected to UV light treatment, and more.


The majority of BOD suspended solids, and FOG will be removed during this initial step of the treatment process. Some of the other heavier chemicals like nitrogen, phosphorous, and others are also removed during this step, but they are further captured in the secondary part of wastewater treatment.


In the majority of states, the primary treatment as described above is the minimum level of processing needed for wastewater irrigation. If the wastewater is going to be used for non-drinking purposes like irrigation or industrial work this is more than sufficient. But for cleaner water needs, secondary and tertiary treatment is required to prevent any potential issues and hazards.



The In-Pipe Difference


Wastewater treatment is a careful biological process. The microorganisms already naturally present in the wastewater do the majority of the work when it comes to reducing harmful nutrients and push clean water back into the waterways. The problem with this is that these microorganisms only come from what is already in the sewer collection system - mostly biosolids, kitchen food waste, and other effluents.


Why is this a problem? Well, the majority of these microorganisms are anaerobic, making them difficult to maintain and inefficient. The few that do work with oxygen require air to be injected into the wastewater to create the right conditions for them to perform. This process, while effective, is costly as it requires a lot of electricity to run these processes.


This is where In-Pipe comes in. In-Pipe is improving wastewater treatment by allowing plants to decrease the number of organic materials coming in in the first place. It also:


  • Strengthens the microorganism community by introducing more efficient bacteria

  • Enables plants to improve their rated capacity

  • Reduces the amount of aeration needed


The In-Pipe difference is that our technology works on the biofilm during the initial collection stage using bacteria already present in the surrounding soil. This bacteria is special because it’s able to facilitate the wastewater treatment process with or without oxygen, making the microorganisms within the plant more effective and less expensive to maintain.


The bacteria In-Pipe technology uses grow in number rapidly when added in high concentrations on a continuous basis until they are rulers of the sewer collection system. As less oxygen is needed to keep this bacteria going, the wastewater treatment plant can greatly reduce its operation costs by eliminating its high electricity usage. Our work has been shown to process a larger amount of carbon and nitrogen per gram of mixed liquor suspended solids (MLSS), as well as significant reductions in BOD, TSS, total nitrogen levels, and phosphorus uptake rates to name a few.


In-Pipe And FOG


In-Pipe is also effective when it comes to dealing with FOG. Food-related industries are some of the most notorious sources of FOG in sewer collection systems, and the build-up can cause serious issues. These blockages require regular, labor-intensive cleaning which can be costly to do on a consistent basis.


Case studies of In-Pipe in real wastewater plants across the city have found that the introduction of our technology has completely eliminated the need for expensive FOG clean-up crews because these blockages no longer appeared. That means no more overflow and no more bad odors. That’s why we believe in creating proactive solutions that will drive long-term performance.


Our FOG bacteria is completely natural and safe to introduce into your system without worrying about damage to your pipes or other infrastructure. Our solution is quick to implement, more cost-effective, and offers a higher ROI - even better, the In-Pipe FOG solution is flexible enough to be customized to specific needs. It’s free of harsh chemicals, meaning less bad stuff makes it into the environment and into drinking water sources. Working with In-Pipe also comes with additional support in the form of monthly site visits.


Contact In-Pipe to start transforming your wastewater treatment process or to introduce more natural and effective FOG control by clicking here.


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