Hybrid treatment system to remove micromolecular SMPs from fruit wastewater treated with an MBR

Fruit processors want to reduce their environmental footprint by implementing the recycling of treated wastewater. Observations of a membrane bioreactor (MBR) and reverse osmosis (RO) system showed that the RO quickly fouled due to elevated levels of soluble microbial products (SMPs), an inert micromolecular composition in the form of dissolved organic matter (DOM} in the MBR effluent. Bench-scale experiments were performed using enhanced coagulation and granular activated (CAC) carbon sorption. Results showed that enhanced coagulation removed only 20% of the DOM, which was insufficient to protect the RO membrane. However, sorption studies with GAC showed that 98% of the dissolved SMP-DOM could be removed, the fraction of DOM from microbial activities. Results also showed that when enhanced coagulation preceded the sorption stage, GAC column run time could be extended by approximately 15%. The resulting best management practice (BMP) minimizes RO membrane fouling in the agri-food sector and opens further water recycling opportunities.