Applying membrane technology to water purification has been done for several decades now and is widespread. However, membrane fouling is a serious problem and continues to limit the success of membrane processes. In this study, magnetic biochar (Fe-BC) was prepared using easily available spent coffee grounds to activate peroxymonosulfate (PMS) as a UF membrane pretreatment strategy. Results showed that the average removal rates of humic acid (HA, 10 mg/L) were 55.23 % and 73.55 %, at the Fe-BC dosage of 300 mg/L and PMS dosage of 300 mg/L and 900 mg/L, respectively. The Fe-BC/PMS pretreatment significantly reduced the total (44 %) and reversible (61 %) UF membrane fouling after five filtration cycles at a relatively high flux of 200 L/m2·h, and the Fe-BC and PMS dosage of 100 mg/L. Modeling fit results indicated that pretreatment shifted complete blocking to standard blocking. Therefore, stopping HA-induced membrane fouling could be possible if the load is reduced and complete blocking alleviated.