A little microbiology goes a long way

Can wineries improve the performance of their wastewater treatment plants if they know more about the microbiology that makes it all happen?

The short answer is yes, which means it will be well worth their while taking note of the longer answers and recommendations that will be released over the next few months.

Researchers are completing the final report of a three-year Wine Australia research project that provided a much clearer picture of the diverse microbial populations that exist in treatment plants, and threw up several specific issues to be addressed – or in some cases further studied. A series of sector updates and scientific papers is planned.

Thirty wineries were surveyed over three successive vintages – and four wineries studied in depth – by a team from the University of Adelaide working in partnership with CSIRO Land and Water and JJC Engineering.

‘It’s an area that’s been poorly understood until now but it’s important financially as well as environmentally’, said project co-leader Associate Professor Paul Grbin. ‘There is significant capital expenditure in setting up treatment systems, plus running costs, especially for aerobic systems, which are the most common; you are using pumps and blowers and electricity to drive them.

‘If they work more efficiently you are going to save money, and if you are producing better quality water then that water can be reused quite comfortably for irrigation. There are lots of good reasons to make sure your system is effective.’

A key finding is that, as in industrial and domestic settings, a diversity of bacteria is important in a winery wastewater treatment plant to cope with (i.e. consume) the broad range of substrates that find their way into a plant. When the researchers noted a lack of diversity in one of the four winery systems they studied in depth, they were able to suggest specific actions to address this.

One concern is an apparent link between the heavy use of activated carbon and poor treatment plant performance. Experiments showed that if carbon finds its way into the waste stream after being used to treat wine or juice it can manipulate the chemistry of the water to make it more difficult for the bacteria to function. ‘This is an important finding that we will actively promote to the sector’, A/Prof Grbin said. 

Also surprising was the discovery in many systems of the so-called G-bacteria that stays in suspension rather than settling out of the water like a solid should, producing lower quality water from the treatment process. A PhD project has been established to pursue this further.

More broadly, the researchers noted a higher than expected level of yeasts and bacteria finding their way into the treatment system, suggesting upstream solid separation is not always as good as it should be. 

‘Wineries need to adopt cleaner production techniques to reduce that load’, A/Prof Grbin said. ‘If you put yeast and bacteria into the system they have to be degraded by the waste water bacteria that are present. You are adding more work for the plant to do, which makes it more expensive.’

^{Image: Gram stain of G-bacteria Nostocoida limicola}