Project title
Biodegradation of organic components in winery effluents by naturally occurring or other selected yeasts including optimisation of a rotating biological contractor for winery wastewater

Project leader
Bloom, M

Institution
University of Stellenbosch. Department of Microbiology

Team members
Malandra, L
Volschenk, H

Project description
Winery effluents usually have a pH of 4 to 5, as well as a very high chemical oxygen demand (COD) that falls outside the limits set by local authorities. The low pH of winery effluents can partially be ascribed to the presence of organic acids in the effluents, whereas ethanol and sugars contribute to a high COD. Winery effluents are normally discarded untreated and can result in environmental pollution and the contamination of water resources.

Microorganisms that are able to survive the unfavourable conditions associated with winery effluents may provide an efficient and cost-effective biological treatment of winery effluents. Bacterial and fungal isolates from winery effluents were evaluated for their ability to decrease the acidity and COD of winery and distillery effluents. Promising results were obtained with a few yeast isolates that were able to decrease the COD by approximately 50% within 48 h. Due to large variations in the nature of the effluent from day to day, a ?synthetic effluent? was developed based on chemical analyses of winery effluents. One of the yeast isolates was able to decrease the COD of this synthetic effluent by 95% (from 5120 mg/l to 240 mg/l) within 24 h under aerobic conditions.

The efficacy of micro-organisms to survive the harsh conditions associated with winery effluents largely depends on their ability to form biofilms. The development of biofilms was investigated at different stages of treatment in fresh winery effluents at a local winery. Biofilms rapidly formed and included several bacterial and yeast species that colonised a glass surface. A laboratory-scale Rotating Biological Contractor (RBC) was designed and evaluated using diluted grape juice as effluent. A healthy biofilm formed on the discs and a 44% decrease in COD was observed with a retention time of only 7 h. The RBC was subsequently tested on-site at a winery during the 2001 harvest. Winery effluent was pumped into the RBC after excess grape skins and seeds had been removed from the effluent and pumped into a second settling tank. The retention time depended on the flow speed of the effluent into the system and varied from 0.35 to 1.4 hours. The system was continually seeded with micro-organisms from the fresh winery effluent and a thick healthy biofilm was formed that sloughed off when it became too thick. There was an average decrease of 41% in the COD with a retention time of approximately 1 h and the pH was raised by an average of 0.74. Freeze cultures of the biofilm that developed on the rotating discs were made over a period of time. Pure cultures were isolated from the biofilms and further identification is currently being done.

Presentation(s)
1. Viljoen, M, Stassen, L and Zietsman, J J. 1999. Biological treatment of winery effluents. 24th National Congress of the South African Society of Enology and Viticulture, November, Cape Town, South Africa.
2. Stassen, L, Zietsman, J J and Viljoen, M. 2000. Biological treatment of winery effluents. BIOY2K - Combined Millennium Meeting, Grahamstown, South Africa.
3. Viljoen-Bloom, M , Malandra, L and Wolfaardt, G M. 2000. Biological treatment of winery effluents. 2nd International Congress of the South African Society of Enology and Viticulture, 8-10 November, Cape Town, South Africa.
4.  Malandra, M, Wolfaardt, G M and Viljoen-Bloom, M. 2001. Biological treatment of winery effluent. 9th International Symposium on Microbial Ecology, Amsterdam.
5.  Malandra, M, Wolfaardt, G M and Viljoen-Bloom, M. 2001. Biodegradation of winery effluents. 25th National Congress of the South African Society of Enology and Viticulture, 15-17 November, Somerset West, South Africa.
6.  Malandra, M, Wolfaardt, G M, and Viljoen-Bloom M. 2002. Yeast biofilms in winery effluent treatment. The South African Society of Microbiology 11th Biennial Congress, Bloemfontein, South Africa.
7. Coetzee, G, Malandra, M, Wolfaardt G, M and Viljoen-Bloom, M. 2004. Evaluation of a rotating biological contractor for winery effluent treatment. 28th National Congress of the South African Society of Enology and Viticulture, Cape Town, South Africa.

Final report
http://www.sawislibrary.co.za/dbtextimages/finalreport34.pdf

Malandra, L, Wolfaardt, G M, Zietsman, J J, Viljoen-Bloom, M. 2003. Microbiology of a rotating biological contactor for winery wastewater treatment. Water. v. 37 p. 4125-4134

Article

Coetzee, G, Malandra, L, Wolfaardt, G M, Viljoen-Bloom, M. 2004. Dynamics of a microbial bioflim in a rotating biological contactor for the treatment of winery effluent. Water SA. v. 30 n. 3 p. 407-412

Malandra, L, Lovis, K, Coetzee, G, Wolfaardt, G M, Viljoen-Bloom, M. 2004. Evaluation of a rotating biological contractor for biological treatment of winery effluent. WineLand. Mnth Feb p. 68-71

Lovis, K. 2003. Biodegradability of wine distillery wastewater and biofilm development in a rotating biological contractor. M.Sc.

Thesis

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