Ultrafiltration of separated digestate by tubular membranes: Influence of feed pretreatment on hydraulic performance and heavy metals removal

JOURNAL OF ENVIRONMENTAL MANAGEMENT

卷:250

Article

Camilleri-Rumbau, Maria Salud¹  Popovic, Olga²  Briceno, Kelly¹  Errico, Massimiliano¹  Sotoft, Lene Fjerbwk¹  Christensen, Knud Villy¹  Norddahl, Birgir¹ 

[1] Univ Southern Denmark, Dept Chem Engn Biotechnol & Environm Technol, DK-5230 Odense M, Denmark

[2] Univ Torino, Dept Agr Forest & Food Sci, I-10095 Grugliasco, Italy

关键词: Ultrafiltration;    Digestate pretreatment;    Flocculation-coagulation;    Heavy metals removal;    Membrane fouling;   

DOI  :  10.1016/j.jenvman.2019.109404

来源: Elsevier

【 摘 要 】

The present study investigates the influence of the solid-liquid pretreatment of anaerobically digested slurry on the subsequent ultrafiltration of the obtained liquid fractions in a semi-commercial ultrafiltration pilot plant. The first pretreatment considered is based on centrifugation alone, the second one, is based on a combined flocculation-coagulation and centrifugation step. It was found that during ultrafiltration of the liquid fractions from both pretreatments, the cross-flow velocity had a larger influence on permeate flux than the applied pressure, suggesting the predominance of a gel-like fouling layer. Chemical rejections during ultrafiltration of the liquid fractions were higher than 96.9% for Cu, Zn, Fe, Ca, Mg and Al, without significant differences between the pretreatments. Finally, membrane inspection using SEM showed that the membrane fouling morphology was closely related to the feed pretreatment. Additionally, elemental membrane surface analysis with EDX revealed that alkaline and acidic cleaning was effective in removing most of the inorganic foulants accumulated on the membrane surfaces. However, after chemical cleaning, ultrafiltration membranes processing liquid fractions from centrifugation assisted with flocculation-coagulation restored the membrane pristine surface characteristics to a higher extend. This suggests that obtaining digestate liquid fractions by centrifugation assisted with flocculation-coagulation could have a positive impact on the long-term stability of the subsequent ultrafiltration step.

【 授权许可】

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