Project Number
US GMW

Project title
Microbial controls on winery or distillation effluent treatment in artificial wetlands

Project leader
Wolfaardt, G M

Institution
University of Stellenbosch. Department of Microbiology

Team members
Du Plessis, K R

Project description
This project focuses on defining the dominant microbial populations involved in COD removal in wetland systems, their contribution to some physical parameters of the wetland, and their growth requirements. Optimisation of techniques to study the behaviour of these populations in the wetlands has been completed (T-RFLP technique and FISH). It was anticipated to start in January 2003 with applying these techniques at the pilot scale wetlands at Goudini (Winetech-funded project (WW 19-01) at Nietvoorbij), however, these wetlands only became ready for our part of the work in June 2003. Subsequently, the first samplings were done in the latter parts of June and July, respectively. Samples were collected from the aqueous phase, gravel/soil, and plant roots and are currently analysed for community composition and cell numbers. Laboratory-scale systems were designed and built from perspex to simulate a typical wetland, with and without plants (0.5 m [length] × 0.3 m [width] × 0.4 m [height]) and fed with diluted distillery effluent (COD ~ 6000) to evaluate plant-microbe interactions. Although the system without plants initially showed similar COD removal efficiency, much more slime accumulation occurred and suggested that anaerobic conditions developed. Mini-scale laboratory columns were subsequently constructed to be used in addition to the pilot and laboratory scale wetlands. The primary goal with these columns is to assess the role of microbial slime in the functioning of wetland systems. Firstly in restricting water flow through the porous gravel/soil (potentially negative impact) and secondly in acting as an intermediate form of carbon that facilitates the flow of carbon through the food chain, and thus increased COD removal (positive impact).

Presentation(s)
Du Plessis, K R, Wolfaardt, G M, Botha, A and Gardner, M N. 2005. Evaluation of microbial population stability and COD removal efficiency in an experimental wetland used to treat distillery effluent. Paper presented at the Canadian Society of Microbiologists Conference. Dalhousie University. 12-15 June, Halifax, Canada.

FinalReport.pdf