Last week was Labor Day and I thought about the organisms that are the "workers" in biological waste treatment. During operations we look at aeration, flows, chemical feeds, effluent residuals, and other parameters; but we rarely consider the "biology" in a biological treatment system.
The biological waste treatment unit is designed to optimize the environment where microbes convert wastes into new cells, carbon dioxide and water. Engineers often refer to Mixed Liquor Suspended Solids (MLSS) as "bugs". Rather than being a homogenous "bug", the MLSS contains a blend of live and dead bacteria, protozoa, particulates, biological polymers, and in "older" sludge we have metazoa ~ more complex organisms such as rotifers, tardigrades and bristle worms. The actual percentage of living bacteria in the floc is between 10 - 15% in most systems. The protoza work by consuming living and dead bacteria which actually helps remove particulates from the water and improves floc formation.
So next time you see biological waste treatment systems in operation, think about the billions of tiny microbes in each liter of water that do the work, 24 hours a day, 7 days a week.
Erik Rumbaugh has been involved in biological waste treatment for over 20 years. He has worked with industrial and municipal wastewater facilities to ensure optimal performance of their treatment systems. He is a founder of Aster Bio (www.asterbio.com) specializing in biological waste treatment.
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