a b s t r a c tl-Threonine (THR) is widely used in the areas of pharmaceutical industry, medicine and food, which can be extracted from THR fermentation broth. The fermentation broth is pretreated by microfiltration and active carbon for decolorization, and then desalted by electrodialysis (ED) to remove salt ions such as Cl − , NH 4 + , Mg 2+ and Fe x+ . The ED performances are adjusted by the operation voltage, membrane type and initial feed pH, which are optimized to be 30 V, polyvinyl alcohol-based hybrid membranes and isoelectric point of 6.16, respectively. The end of desalination can be reached in the shortest time (106 min) when initial feed pH is at the isoelectric point. The highest THR recovery ratio is 86.1% with desalination ratio of 96.9%. The process energy consumption is 4.36 kW h/kg. Hence, the ED process is effective for desalination and recovery of THR. Removal of Cl − and NH 4 + (up to 99%) is the most effective, while Mg 2+ (87.3%) and Fe x+ (72.4%) are removed in lesser amount. Membrane fouling occurs after the ED process, which enhances the membrane area resistance from 1.8-2.1 to 2.5-2.7 Ω . cm 2 .

Kitchen waste has been confirmed as an appropriate substrate for anaerobic digestion, although means of alleviating the difficulties and time-consuming nature of the start-up phase need to be further explored. Based on the mechanism of anaerobic digestion, we discuss the factors influencing the anaerobic start-up phase of kitchen waste. By controlling the temperature, pH, organic loading rate, inoculation ratio and other parameters, the high activity of methane-producing archaea and other bacteria can be intensified, thereby increasing the biogas yield. Furthermore, we introduce the methods of substrate pretreatment, operating condition optimization and conductive material addition. Finally, we put forward future perspectives and research gaps related to accelerating the start-up phase of anaerobic bioreactors utilized for kitchen waste biodegradation.