Magnetic spent coffee biochar (Fe-BC) activated peroxymonosulfate system for humic acid removal from water and membrane fouling mitigation

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.