For centuries, managing wastewater was a problem with no discernable solution. Dealing with wastewater usually meant moving it somewhere else, dumping into rivers and streams with virtually no treatment, or other “out-of-sight-out-of-mind” solutions, which in many cases had negative residual effects on people’s health, public infrastructure or the environment.

Even as recently as the 1960s and ‘70s, most “treated” wastewater was simply drained into lagoons or large ponds. Of course, while this may have provided a simple partial treatment solution to the problem of wastewater, this process also had significant negative impacts on local environments and ecosystems. Entire bodies of water became unusable and the land immediately adjacent could experience odor and other aesthetic issues.

The solution to this dilemma was to begin treating the wastewater in much smaller vessels or reactors. While still substantial in size, these reactors had footprints much smaller than the lagoons. Inside these vessels, air was added, and bacteria would grow. This “activated sludge” would then consume large amounts of the waste in the water. These suspended growth systems were marked improvements on past technology, but were not as efficient in certain applications, especially where treating high-strength wastewater was the goal.

As an alternative to this process, rocks and other “media” were placed within these systems, allowing for a percolation effect that cleaned the wastewater by passing it through bacteria that lived on the rocks and media. This additional method aided in the treatment process, but still fell short of producing clean water that could be reused.

In the 1990s, ultrafiltration came into play as engineers sought more effective means of handling ever-growing cities and their booming populations that continued to produce more wastewater than ever. While this ultrafiltration process produced a cleaner effluent than past systems, it still lacked the ability to remove soluble particles.