Monitoring the Nutrient Removal and Algal Community Structure of a Novel Wastewater Treatment System

Algae have great potential for wastewater treatment as they can remove excess nutrients and other pollutants from wastewater. The types of algae that can grow in wastewater treatment systems have not been thoroughly studied. It is also unclear how different algal communities influence the amount of nutrients that are ultimately removed by these systems. In collaboration with the Metropolitan Water Reclamation District of Greater Chicago, we characterized the algal communities of a Revolving Algal Biofilm system (RAB), a wastewater treatment system that allows algae to grow on a vertical substrate that revolves through a wastewater tank. The aim of this study was to determine if the nutrient removal efficiency of the RAB is affected by the algal community or its production of biomass. Additionally, we aimed to determine if wastewater chemistry influences the presence of certain algal taxa. Algal samples were collected biweekly from the O’Brien Water Reclamation Plant in Skokie, Illinois, from 01/13/2021-07/21/2021 and examined with light microscopy at 1000x magnification. We studied two RAB systems: a single 10-ft substrate and a series with four separate substrates each in its own wastewater tank. Multivariate analyses revealed that algal community composition was driven by a seasonal influence with the dominance of Navicula and Sellaphora in the winter and Gomphonema and Cocconeis in the summer. Regression analyses with measures of algal abundance indicated biomass does not affect the removal of total nitrogen, total phosphorus, and other wastewater nutrients. Future studies should consider additional variables, both abiotic and biotic, to understand how community structure is determined