Effect of earthworms and plants on the efficiency of vertical flow systems treating university wastewater
One of the possible ways to improve the operation efficiency of constructed wetlands and to prevent their clogging is the application of earthworms. They have already been successfully applied for vermicomposting and for sludge dewatering and treatment. A few studies have already examined the effect of earthworms on the treatment of wastewater by vertical flow constructed wetlands (VFCWs), but none of them have provided a yearlong research result from an open-air system or compared the effect that different seasons in a temperate climate area can have on these invertebrates. The goal of this research was to estimate the effect that earthworms and plants have on VFCW’s operation. Four mesocosms (a filter, a filter with earthworms, a VFCW and a VFCW with earthworms) were built and their influent and effluent water quality was monitored for a period of 1 year. They were fed with wastewater coming from a building of the University of Bologna (Italy). The results have shown that the presence of earthworms in this specific system did not reduce the organic matter content of the substrate, but it has positively influenced plants’ growth. However, since neither earthworms nor plants had a statistically significant effect on the effluent quality, it can be concluded that the integration of these invertebrates cannot improve wastewater treatment of vertical flow filters or constructed wetlands.
KeywordsConstructed wetlands Earthworms Filters Plants Seasonal effect Wastewater treatment
The first author’s PhD scholarship was financed by the European Commission through Erasmus Mundus PhD in Marine and Coastal Management programme. The authors would like to thank Prof. Elena Fabbri from the University of Bologna for her help during the development of this project, and Dr. Marco Maglionico and Dr. Sara Simona Cipolla from CIRI (University of Bologna) for their contribution to the research.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
- APHA (American Public Health Association) (2005) Standard methods for the examination of water and wastewater, 21st edn. American Public Health Association, Washington, D.C.Google Scholar
- EN ISO 7899-2:2000: Water quality - Detection and enumeration of intestinal enterococci - Part 2: Membrane #ltration method (ISO 7899-2:2000). Available online: https://onlinelibrary.wiley.com/doi/full/10.1111/wej.12088. Accessed on 4th Nov 2018
- Le Bayon RC, Milleret R (2009) Effects of earthworms on phosphorus dynamics—a review. Dyn Soil Dyn Plant 3(2):21–27Google Scholar
- Mancini B (2017) Application of sequence based typing (SBT) technique to typing strains of legionella spp.: development of an environmental risk map. PhD thesis. University of Bologna. Bologna, ItalyGoogle Scholar
- Nuengjamnong C (2010) Implementation of earthworm-assisted constructed wetlands to treat wastewater and possibility of using alternative plants in constructed wetlands. PhD thesis. Hamburg University of technology. Hamburg, GermanyGoogle Scholar
- UNI EN ISO 9308-1:2014/A1:2017 Water quality — Enumeration of Escherichia coli and coliform bacteria — Part 1: Membrane #ltration method for waters with low bacterial background 5ora (ISO 9308-1:2014/Amd1:2016). Available online: http://store.uni.com/catalogo/index.php/uni-en-iso-9308-1-2017.html. Accessed on 7 Nov 2018