Disclosed herein are methods and systems for treating greywater from a microbial food decomposition process. A method includes flowing, into a mixing chamber of a water treatment tank, a first volume of untreated greywater. A second volume of recirculated greywater mixed with ozone gas is flowed into the mixing chamber, and mixes with the first volume of untreated greywater to produce a third volume. The third volume of greywater is flowed into a storage tank. The method further includes diverting a first portion of the third volume out of the water treatment tank, and diverting a second portion of the third volume into a recirculation line that flows the second portion back to the mixing chamber.