Assessment of natural tannin-based coagulant for effective ultrafiltration (UF) of UASB effluent: Fouling mechanisms, pollutant removal and water reclamation feasibility

Author(s)

Ragio, Rodrigo Almeria ; Arantes, Camila Clementina ; Garcia, Joan ; Subtil, Eduardo Lucas

• Document type: Journal article
• Source: JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING; v. 11, n. 3, p. 13-pg., 2023-06-01.

Abstract

In this work, tannin coagulant (TANm) was applied at different dosages and compared with a PACl for UASB effluent filterability enhancement during membrane ultrafiltration. The results showed that TANm exhibited the greatest potential to improve UASB effluent filterability. Flux decay, total fouling resistance, and specific cake layer resistance were all reduced by both coagulants. However, the highest flux (55%) and fouling resistance reduction (70%) were obtained with 40 mg.L-1 of TANm, which was caused by an increase in particles larger than 200 & mu;m, facilitating its removal by cross-flow filtration. Protein and carbohydrate reduction in the membrane was only observed at 25 mg.L-1 for both coagulants, with a higher influence of proteins in strongly/very strongly bound for all samples. In addition, fouling irreversibility increases, with a strong correlation between TANm dosage and Rirr and complete and intermediate pore blocking pointed as the main mechanisms responsible for irreversibility for both coagulants. Based on these and other findings, the mechanisms of the fouling layer adhered to the membrane with coagulants included the formation of complexes with proteins that were more strongly adhered (related to UASB effluent zeta potential increase), the density of the cake layer due to the presence of compact aggregates, and action of the coagulants themselves as foulants. Lastly, the economic evaluation revealed that the system without coagulant would have a lower total cost, but payback showed that the application of TANm has a lower investment time of return due to a lesser CAPEX. (AU)

• FAPESP's process: 20/11059-0 - Development of ultrafiltration modules of hollow fiber mixed matrix membranes, polyethersulfone and inorganic nanoparticles, for water and wastewater treatment
• Grantee: José Carlos Mierzwa
• Support Opportunities: Research Grants - Research Partnership for Technological Innovation - PITE
• FAPESP's process: 16/23684-0 - A new approach to wastewater treatment and water and energy recovery: development of an electrochemical conductive membrane bioreactor (EcMBR) operated under Simultaneous Nitrification and Denitrification (SND) condition
• Grantee: Eduardo Lucas Subtil
• Support Opportunities: Regular Research Grants