Another by-product of beer production is trub and excess yeast, which is the layer of sediment that resides at the bottom of the fermenter after the yeast has completed fermentation (Briggs, Boulton, Brookes, & Stevens, 2004). If not removed properly, the trub can create off-flavours in the beer. Due to the high yeast content of the trub, disposing of this waste down the drain heightens the water’s level of biochemical oxygen demand (BOD) as yeast requires oxygen for decomposition. This creates an oxygen shortage for other organisms in the water, disrupting the balance of associated ecosystems. Because of this, most trub is collected and stored on-site until a sufficient amount is produced and can then be given to farmers as a high protein food additive for livestock. The excess yeast can also be used in other food products such as bread, or yeast based spreads for human consumption (Youngblood, 2014).