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 completed using enhanced coagulation and granular activated 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 about 15%. The resulting BMP minimizes RO membrane fouling in the agri-food sector and opens further water recycling opportunities.

Application of PAFC/CPAM for the removal of ZnO nanoparticles by enhanced coagulation

To cope with the increasingly severe challenges of zinc oxide nanoparticles (ZnO-NPs) in the field of the aquatic environment, this paper uses poly-aluminum ferric chloride (PAFC) and cationic polyacrylamide (CPAM) as coagulants to enhance the removal of ZnO-NPs from water. In two environments (pure-water environment and kaolin environment) that simulate suspended solids, we studied the dosage, pH, precipitation time, and hydraulic power of ZnO-NPs at three different initial concentrations (1, 2, and 30 mg/L). The effects of various conditions on the performance of PAFC, CPAM, and PAFC/CPAM to remove ZnO-NPs were examined. Results showed that the overall removal rate of ZnO-NPs in the kaolin environment was slightly higher than that in the pure-water environment. In contrast the removal rate of ZnO-NPs in the PAFC/CPAM was significantly higher than that of PAFC or CPAM alone. The coagulation removal conditions of ZnO-NPs were optimized using a response-surface model. Under the best conditions, the removal rate of ZnO-NPs with an initial mass concentration of 30 mg/L in the PAFC/CPAM combination in pure-water and kaolin environments was 98.54% and 99.17%, respectively. Finally, by studying the changes in floc size during coagulation, enhanced coagulation was an efficient method of removing ZnO-NPs from water.