Microbial community development in an ecological wastewater treatment system
Open Access
- Author:
- Hartleb, Marissa Elizabeth
- Graduate Program:
- Environmental Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- November 10, 2016
- Committee Members:
- Rachel Alice Brennan, Thesis Advisor/Co-Advisor
- Keywords:
- ecological engineering
wastewater treatment
Eco-Machine
microbial community - Abstract:
- Ecological approaches to wastewater treatment may offer many advantages over conventional methods by virtue of their low energy and chemical usage as well as their potential to generate significant quantities of beneficial biomass byproducts; however, relatively little is known about the development of the microbial and chemical conditions that lead to high treatment efficiencies. Analysis of their development is necessary to enable broader and more consistent application. The purpose of this study was to examine microbial community development during the start-up and stabilization of a pilot-scale ecological wastewater treatment plant (Eco-Machine™), as well as to analyze potential relationships between various water quality indicators and the microbial communities. This study is the first to analyze the spatial and temporal development of microbial communities in an Eco-Machine™. Both location within the system and total run/development time substantially affected the clustering/ordination of the microbial communities present. Note that the true time factor has not been separated from seasonal effects or changes in the influent itself; all these factors are components of “time” in this study. Location had a linear effect, while time had a unimodal effect. The location effect suggests that analyzing multiple tanks at a treatment plant may give a much more complete view rather than selecting a single oxic tank as has often been done. While some community members are likely prevalent or at least present in the different tanks due to hydraulic connectivity, variations in nutrient levels and other biochemical factors may cause substantial differences throughout the system. There may have been disturbance between 2013 and 2015 which caused the unimodal effect, making continued monitoring ideal to determine if it is truly inherently unimodal. Additionally, lower fungal diversity corresponded to higher prokaryotic (refered to largely at the OTU, operational taxonomic unit, similar to species in macroecology) diversity. Both OTU and SH (species hypothesis, fungi specific) diversity was greatest early in the system, suggesting a iv smaller subset of taxa dominate the rest of the system due to competitive advantage. General water quality appeared to be most improved in the least OTU-diverse year (2015), suggesting that diversity and performance are not directly related, but instead have a unimodal relationship. The performance of the Eco-Machine™ compared well to conventional systems, but as such a study does not appear to have been done on conventional plants, a direct comparison of community spatial and temporal performance is unavailable.