Sustainable practice for the food industry: assessment of selected treatment options for reclamation of washwater from vegetable processing

Water reclamation has become a feasible option due to water scarcity in many regions of the USA. Industrial fresh produce processing wastewater streams usually do not actively employ water recycling despite the large quantities of water being consumed. Further, there is a paucity of information on water reuse options for this sector. Therefore, this study assessed selected treatment processes for washwater from vegetable processing. The work focused on turbidity, chemical oxygen demand, dissolved organic carbon at ambient and low-temperature vegetable processing environments (4 °C). Microfiltration, ultrafiltration, reverse osmosis, and novel biocatalyst composites were evaluated using both synthetic washwater and composite washwater samples collected from a commercial produce processing plant. Results showed that ultrafiltration and microfiltration were able to substantially reduce turbidity, but achieved only minimal chemical oxygen demand and dissolved organic carbon reduction. A majority of the constituents contributing to these two parameters were dissolved compounds, causing challenges for physical separation treatment techniques. The biocatalyst system demonstrated good efficiency at both 22 and 4 °C, with respect to the removal of chemical oxygen demand (72 and 66%, respectively), and dissolved organic carbon (74 and 70%, respectively). Reverse osmosis generated high-quality water that could be employed in vegetable production line; however, extensive pretreatment processes were required. This study demonstrated the potential to recover washwater in produce processing industry. Moreover, the results showed that the biocatalyst treatment could be applied at low temperature and potentially applied to water recycling schemes for wastewater streams from food industries that operate under low operating temperatures.