In traditional secondary treatment systems utilizing suspended growth, excess biomass is a common issue. However, the Nebula® Multistage Biofilm System from Aquarius Technologies adopts a unique approach by harnessing controlled biological succession within the biofilm, which significantly reduces sludge production.
The Science Behind the Nebula System
As wastewater progresses through the various stages of the Nebula system, the complexity and size of the biofilm communities evolve.
Here’s a simplified overview of the microbial succession involved, which is an example taken from an active installation:
1. Stage 2 – Filamentous bacteria (floc): These fast-growing, simple heterotrophs quickly consume soluble organic materials, laying the groundwork for the formation of a biofilm.
2. Stage 4 – Stalked Ciliates: Typically, the first protozoa identified in wastewater treatment, they anchor to floc and filter free bacteria into their mouth.
3. Stage 6 – Flagellates: Mobile protozoa that graze on smaller organisms and suspended solids; these flagellates further decrease particulate matter.
4. Stage 8 – Rotifers: Voracious feeders, consuming particles up to 10 micrometers in size, recycling nutrients, and controlling algae by grazing on planktonic food sources in addition to free-floating bacteria and particulate matter.
5. Stage 10 – Gastrotrichs: These small metazoans feed on bacteria and organic particulates, effectively reducing biomass and compacting the sludge.
6. Stage 12 – Vorticella: Highly evolved ciliates that thrive in stable, low-load biofilms, enhancing effluent quality by consuming lower trophic levels.
Each organism in this succession is larger and more efficient, preying on the biomass from previous stages and any residual organics in the wastewater. This self-sustaining food chain within the biofilm structure allows for a remarkable reduction of up to 70% in excess sludge, providing substantial operational and economic benefits for wastewater treatment facilities.
By embracing biological processes rather than resisting them, the Nebula system effectively transforms what has traditionally been considered waste into an integral part of the treatment process.
