Biological method can be used to reduce waste contaminants, clogging and odor problems.
by Julie Holmquist and Tonya Decterov
September 11, 2019

Industrial waste discharge can be a big problem when contaminants build up on a large scale from clogging pipes and systems, racking up high discharge fees and causing bad odors. Interestingly, natural biological processes can counteract these problems by means of “good” microbes/bacteria that instinctively work to clean out the contaminants in the system.

This natural technology is already widely accepted in septic systems and municipal wastewater treatment where secondary digesters, lagoon systems, trickling filter beds and other forms of natural biodegradation are used.

image 1 adding target microorganismsImage 1. Adding targeted microorganisms and nutrients to sewage has shown promising results for natural contaminant degradation. In addition to helping avoid discharge fees, bioaugmentation also has practical benefits like reducing sludge and odors. (Images courtesy of Cortec/Adobe Stock)

These systems typically rely on naturally occurring microorganisms to do the work of degradation but can also benefit from the addition of microorganisms targeted to degrade specific contaminants.

This method is called bioaugmentation and can also be used on a localized level to reduce the amount of contaminants being discharged by industries and institutions before they reach the treatment plant or re-enter the ecosystem. Bioaugmentation has been performed with repeated success in a variety of industries and provides a maintenance plan to promote the efficient flow of wastewater without unwanted interruption and odors.

High Contaminant Concentration

Institutions and industries produce waste on a large scale. This often results in a high concentration of certain types of contaminants depending on the normal activities of the industry. For example, food processing industries release high amounts of fats, oils and greases (FOG) that are more difficult to degrade and can clog a system. To avoid excess discharge, restaurants are often required to install grease traps. However, if these become overloaded, the excess FOG can overflow anyway, and the problem continues. Chemical companies may release excess chemicals in their waste, and high starch processing plants release starch into the wastewater.

image 2 discharge levelsImage 2. Discharge levels at a Moscow shopping mall before and after bioaugmentation (Chart information courtesy of OOO Kozhuhovskaya-Invest/IB T.A. Kashirskaya.)

The level of contaminants in the waste discharge is measured by BOD—biological/biochemical oxygen demand. During the aerobic digestion process, contaminants require oxygen in order to degrade, so this measurement is an indicator of how many oxygen-demanding contaminants are present in the waste and need to be degraded biologically. Industries often use another indicator that is easier to measure—chemical oxygen demand (COD)—that shows the amount of organic and inorganic chemicals that require degradation. Industries and institutions of all types usually have a cap on the amount of BOD or COD they can release before they will be charged an extra fee for processing the extra contaminant load.

The Biological Prescription

Fortunately, industries have some effective natural options to avoid this problem. Microbes are naturally present in the environment and wastewater. As previously mentioned, wastewater lagoon systems, secondary digesters, trickling filter beds and septic systems rely on naturally occurring microorganisms to execute the waste degradation process. This works because microorganisms produce and release enzymes that chop up the contaminants around them into smaller pieces. They then consume those pieces as their “food” source to have the energy necessary for metabolism and reproduction.

Like people, microorganisms develop stronger “appetites” for certain contaminants than others. In more technical terms, some microorganisms are better at producing certain enzymes (e.g., lipase for fats, amylase for starch, protease for proteins, etc.) than others. These bacteria can be isolated, cultivated and commercially produced to serve as a natural additive for biodegrading target wastes. Bacteria that are especially good producers of lipase are prime candidates for applications where there will be a lot of FOG—a dairy processing facility or automotive shop, for example. These targeted microorganisms help eat up the contaminants, so they are reduced before the waste is discharged. This helps facilities avoid excess discharge fees, clogging, odors or similar problems.

Reducing Contaminants with Bioaugmentation

Many examples exist of how bioaugmentation has been used to quickly and significantly reduce contaminant levels and bad odors.

In 2017, a shopping center in Moscow, Russia, decided to use bioaugmentation to reduce the amount of pollutants released in its sewage. The mall had exceeded allowed discharge levels for four pollutant indicators during 2016 (see Image 2). Allowable discharge for FOG was 50 milligrams per liter (mg/L), but average discharge was twice as much at 100 mg/L. Allowable discharge for BOD5 was 300 mg/L, but average discharge was 428 mg/L. At 977 mg/L, the average COD discharge was almost double the allowed discharge of 500 mg/L, and average total suspended solids (TSS) discharge exceeded the allowable rate of 300 mg/L by 84 percent.