Combining submerged membrane technology with anaerobic and ...
Combining submerged membrane technology with anaerobic and ...
Combining submerged membrane technology with anaerobic and ...
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Chapter 7GAC did not adsorb VFA, whereas PAC did (Barker <strong>and</strong> Stuckey, 1999; Akram <strong>and</strong>Stuckey, 2008).7.2. ObjectivesIn this study, an AnMBR was operated to treat industrial herbal extraction wastewaterat high MLTS concentration. The aims of this study were to evaluate <strong>membrane</strong> fouling inAnMBR through typical fouling indicators used in aerobic MBR <strong>and</strong> to assess the additionof PAC to an AnMBR treating wastewater from an herbal extraction industry at high MLTSconcentration in order to increase permeate flux. PAC addition was also tested as a usefultool during shock loading.7.3. Materials <strong>and</strong> methods7.3.1. Experimental setupThe continous stirred tank reactor (CSTR) (figure 7.1) had a volume of 23 L <strong>and</strong> wasoperated under <strong>anaerobic</strong> mesophilic conditions (36 °C) during 198 days <strong>with</strong> an organicloading rate (OLR) ranging between 2 <strong>and</strong> 4 kgCOD·m - ³·d -1 . At a feed COD concentrationof 8000 mg·L -1 this resulted in a HRT between 2 <strong>and</strong> 4 d. The separation of the biomasswas assured by a flat sheet ultrafiltration <strong>membrane</strong>, manufactured by A3 water solutionsGmbH (Germany), <strong>with</strong> a pore size of 0.1 µm made of polyethersulfone. The total<strong>membrane</strong> area of the used immersed <strong>membrane</strong> was 0.27 m². The <strong>membrane</strong> wasoperated in cycles of 10 min, <strong>with</strong> 8 min of filtration <strong>and</strong> 2 min of relaxation. Moreover,<strong>membrane</strong> fouling was minimized by sparging the <strong>membrane</strong> <strong>with</strong> biogas.The averagespecific gas dem<strong>and</strong> per <strong>membrane</strong> area (SGD m) was 0.41 Nm 3·h −1·m −2 , which is around60% of the recommended value of the full scale module. The biogas is taken from thehead space of the reactor <strong>and</strong> is recycled to the reactor by a compressor. Furthermore agas-lift loop mixing is achieved. Membrane module was replaced by a new one on day 76due to the high fouling observed.Prior to this operation, the reactor was operated during 125 days at an OLR of 2kgCOD·m - ³·d -1. The reactor was inoculated <strong>with</strong> <strong>anaerobic</strong> digestion sludge of a municipalwastewater treatment plant <strong>with</strong> a concentration of approximately 20 g·L -1 .176
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