7.1.6. Winery Wastewater

Field site experiments were carried out at the Napa Wine Co. (NWC), which is located in Oakville, California, USA. NWC crushes and decants an annual total of 7000 tons of grapes and creates an annual total of 5.1 × 10<sup>4</sup> m<sup>3</sup> of wastewater. The treatment of on-site wastewater (through aerobic biological oxidation) consumes roughly 654,000 kWh of power per year. A continuous-flow MEC on a scale of 1000 L was built and analyzed for current production and COD removal using winery waste matter, with positive results. The reactor was divided into 24 modules, each containing 144 electrode pairs. The development of an exoelectrogenic biofilm took around 60 days, which is significantly lengthier than the time typically necessary for laboratory reactors. By the time the experiment was scheduled to be completed, current production attained a maximum of 7.4 A·m<sup>−</sup><sup>3</sup> (after 100 days). Despite the fact that the majority of the product gas was transformed to methane (86% ± 6%), the cathodic approach produced a peak of 0.19 ± 0.04 <sup>L</sup>·L−1·day−1. Higher techniques for isolating H2 gas generated at the cathode will be necessary in future testing in order to increase the amount of hydrogen recovered. The current generation was adjusted by guaranteeing a sufficient volatile fatty acid content (VFA/SCOD ≥ 0.5) and by increasing the temperature of the waste materials (to 31 ± 1 ◦C) in the waste stream. In addition, the usage of MECs remains a potential technology for the integration of energy recovery and wastewater treatment [101].

Various substrates have been utilized in MEC as illustrated in Table 2.


**Table 2.** Performance of MEC configurations using different substrates.
