Microbial Wastewater Treatment Facilities Are Environmentally Beneficial

By Celia Hall


Microbial wastewater treatment is part of a process to treat sewage generated by public and private users. Waterborne diseases can spread without proper cleaning. Clean water is essential for plants and animals who will suffer if unclean wastewater is discharged into waterways.

We have developed a complex system for the conversion of sewage into a safer form before its release into the environment. Modern facilities manage this process. The general method involves a three stage course of action beginning with the preliminary stage and then proceeding with primary and secondary stages. In advanced systems, a tertiary stage is also utilized.

Incoming influent material is first screened to collect collectible pieces of trash. The trash is disposed of in garbage pits or incinerators. The facility then begins treating the influent which contains biological and chemical pollutants.

Primary treatment removes about 60 percent of the suspended solids from the water through settling processes. With secondary stage more than 90 percent of suspended solids are removed. This stage is entirely dependent upon the use of microbes to decompose the material. The most widely used method involves the use of activated sludge. Tertiary treatment removes more of what is left using methods such as passing through wetlands, further filtering or disinfection by treatment with chlorine, ultraviolet light or ozone. This cleansing stage is not always included in such systems.

The aim is to remove or transform pollutants sufficiently prior to the release of the effluent. There has been an improvement in effluent quality since the passage of the Clean Water Act. Hence from the 1970s onwards, regulation under the Clean Water Act has required facility upgrades that have had a beneficial effect. However, there still remains further scope for technological improvements and progress.

Although bacteria are typically used in the secondary stage, uses in other stages can improve efficiency and lower costs. At the primary level they can degrade solid matter. The microbes can also remove excess organic matter to foil algae blooms. Adding these microorganisms helps to reduce sludge volume through decomposition. Sludge is filtered throughout the various processes involved and needs to be ultimately disposed of.

Additional research has unveiled the productive use of microbial fuel cells to create energy. Microbial fuel cells use certain kinds of bacteria that convert waste into energy. An MFC is a kind of battery that is partially an electrochemical cell and partially a biological reactor. It typically has two electrodes that are separated by an ion exchange membrane. On one side bacteria form a dense cell that adheres to the anode of the MFC. In the course of metabolism the bacteria serve as catalysts and convert organic matter into carbon dioxide, protons and electrons. The bacteria oxidize organic pollutants and transfer the electrons to the anode. These electrons flow through an electrical circuit to the cathode and generate electricity.

The electrical-generating potential of microorganisms has been understood for decades. However, it was only recently that efforts have succeeded in producing a commercially viable amount of energy. Microorganisms have demonstrated their usefulness in a growing number of ways. An increasing number of systems have realized the benefits of efficiency, reduced operational costs and improved capacity. Microbial wastewater treatment facilities apply more natural methods which better serve the ultimate purpose of improving influent quality.




About the Author: