Quantitative temporal-based contribution of key foulants to fouling proceeding in direct membrane filtration for sewage pre-concentration
摘要
Direct membrane filtration (DMF) is a popular option for raw sewage pre-concentration for the subsequent organic resource recovery. It undergoes rapid and severe fouling. To achieve a fundamental understanding of the contributions of key foulants to DMF, principal component analysis (PCA) using Fourier transform infrared spectroscopy (FTIR) was applied to identify three stages of DMF. Variance partitioning analysis (VPA) and partial least squares (PLS) were used to quantitatively determine the contributions of key foulants. Humic acid (HA) achieved the highest intersection contribution (40.5%) to the total variance of the increase in resistance. Meanwhile, HA and protein (PN) explained 20.1% in the middle stage of DMF. The overall marginal effect of HA accounted for 42.5% of the variance, in conjunction with an overall individual effect of 11.0% (which was the highest in the initial stage: 15.1%). The variable importance in projection (VIP) of impact on the resistance increase of DMF were 1.16 (PN), 0.99 (HA), and 0.82 (polysaccharides, PS). HA&PN with a VIP value approaching or larger than one significantly influenced the resistance increase in DMF. Meanwhile, the VIP of impact on blocking model alteration were 1.03 (PS), 1.01 (PN), and 0.96 (HA). HA, PS, and PN were regarded as vital factors in the fouling mode alteration. PS drives the fouling mode in the initial stage, whereas HA&PN and PN play dominant roles in the middle and final stages. Measures targeting HA and PN removal can be adapted for the efficient and cost-effective fouling control of raw sewage DMF.