Fouling control in membrane bioreactors with sewage-sludge based adsorbents

WATER RESEARCH

卷:105

Article

Villamil, J. A.¹  Monsalvo, V. M.¹  Lopez, J.¹  Mohedano, A. F.¹  Rodriguez, J. J.¹ 

[1] Univ Autonoma Madrid, Fac Ciencias, Secc Ingn Quim, C Francisco Tomas & Valiente 7, Madrid 28924, Spain

关键词: Membrane bioreactor;    Fouling control;    Activated carbon;    Adsorption of SMP;    Sewage sludge;    Inexpensive adsorbent;   

DOI  :  10.1016/j.watres.2016.08.059

来源: Elsevier

【 摘 要 】

The potential application of powdered activated carbon (PAC) to mitigate membrane fouling has been tested in membrane bioreactors (MBRs) fed with cosmetic wastewater. Inexpensive powder activated carbon was prepared from sewage sludge biosolids (B-PAC) by pyrolysis (750 degrees C; 0.5 h) and air-activation (400 degrees C; 2 h). Adsorption capacities of 143 and 570 mg g(-1) were reached for carbohydrates and proteins, respectively,. quite similar to those of a commercial activated carbon (C-PAC). To check the effect of PAC addition on membrane fouling, three MBRs were simultaneously operated without (control-MBR) and with PAC (B-MBR and C-MBR) for 150 days in continuous mode at 8 L m(-2) h(-1) flux. Similar COD removal efficiencies were achieved in these three MBR systems. After 100 days of operation, the effect of the PACs on the sludge filterability was studied in the MBRs for 10 days. B-MBR showed stable transmembrane pressure (TMP) after 9 days of operation, unlike of control-MBR and C-MBR, where the TMP increased after the 2nd and 5th days, respectively. Therefore, operational cost saving can be achieved in the membrane cleaning due to decrease of fouling rate. Operating at stable state condition the addition of PAC gave rise to an increase of the critical flux of 25%. In an extra shear test, carried out at the end of the continuous experiment, a clear reduction in mean size of the flocs from 45 to 28 mu m was observed in control-MBR. However, the extra shear led to a slight reduction of the mean size of flocs (less than 5%) in MBRs with PAC, with average sizes of 62 and 71 mu m in C-MBR and B-MBR, respectively. The molecular weight fractionation of the MBR demonstrated a higher selectivity of B-PAC toward the adsorption of proteins smaller than 1 mu m which prevents the irreversible fouling of the membranes. The membranes lifetime was increased because the B-PAC extended the filtration for a longer period than C-PAC, probably due to its easier in-situ regeneration. (C) 2016 Elsevier Ltd. All rights reserved.

【 授权许可】

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