Optimization of RDM-UF for alfalfa wastewater treatment using RSM.

Rotating disk membrane (RDM) module with ultrafiltration (UF) was an effective alternative method to treat alfalfa wastewater and realize protein recovery and agricultural irrigation water production. A scientific investigation has been conducted to comprehend the effect of operation conditions (feed flow rate, shear rate, transmembrane pressure (TMP), and temperature) on alfalfa wastewater treatment with RDM-UF by central composite response surface methodology (CCRSM). First, the filtration behaviors of three types of UF membranes (PES20, UH030P, and PES50) were studied to select the optimized membrane (UH030P). Then, the effects and interactions of four operation conditions were studied and fitting models were established, while data on pollution reduction and protein recovery, membrane fouling behavior, and energy cost evaluation were collected. Furthermore, the optimized operation conditions calculated by CCRSM were Q = 60 L h, γ = 220 × 10 s, TMP = 5.61 bar, and T = 25 °C. In addition, the concentration test was conducted with these parameters. This work may contribute to the potential application of RDM for membrane wastewater treatment. Graphical abstract Schematic diagram of UF process for alfalfa wastewater treatment and resource recovery.