Trade “Waste Of Time” – Craft Brewery Wwtp Simplification And Improvement

The worlds’ tastes are becoming more refined. With this development of palette, discerning drinkers are turning increasingly towards microbreweries and craft beer. Malt Shovel Brewery (MSB), Sydney, NSW, is one of Lion Co.’s craft breweries where it tests new products and produces small batch beer volumes. With the importance of this Craft Beer stream of sales the focus on treating the wastes produced increases in kind.

The waste water treatment plant (WWTP) at MSB was over-complicated, prone to blockage and failure, incited multiple manual handling risks and consumed large amounts of caustic soda for pH correction while still exceeding license discharge limits on occasion. This paper describes the steps taken to develop, simplify and improve the WWTP. It also discusses the importance of developing simple, robust WWTPs to apply across the wider Craft/Microbrewery industry as more home-brewers graduate into the Microbrewery scene and major breweries look to scale-down their brewing and treatment processes.

The old MSB WWTP consisted of a large mesh bag filter, followed by tri-filtration, gravity settling, ultra-filtration and pH correction. During times of full production, the bag filter would block 20-30 times a day from spent grain, hop trub, yeast, and diatomaceous earth, requiring the operators to lift a large, heavy bag out of the filter and transfer waste into a local bin. Regardless of this upfront filtration step, the ultra-filtration unit would constantly block and require back-flushing, leading to the statement that it was never “fit for purpose”. Caustic soda was dosed into the inlet tank which would be subjected to wide fluctuations of pH, occasionally not meeting the discharge pH specifications.

This project improved and simplified the WWTP process in the following ways:

• Removal of the bag filtration step.
• Removal of the inline self-cleaning filter and ultra-filtration processes.
• Conversion of the previous neutralisation tank and settling tank to inlet buffer tanks.
• Installation of a rotating filter-mesh Salsnes™ unit as one process to remove all solids.
• pH correction in a small tank immediately prior to discharge to sewer.
• Utilisation of as much of the existing equipment as possible.

In completing the above, the project achieved the following benefits/outcomes:

• Removal of the manual handling risk and down time required to remove fouled bag filters.
• Process simplification by replacing three filtration steps for one.
• The additional inlet buffering volume provided by combining existing tanks lead to improved pH buffering and correction with mixed inlet streams.
• Minimising solids waste and manual handling by screw-compressing spent grain and solids prior to discharge.
• Significantly reduced caustic usage, and manual chemical handling.
• Delivery of the project, under budget, that achieved all client requirements and discharged trade waste to council specifications.