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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Tertiary <strong>membrane</strong> filtration of industrial wastewater using granular or flocculent biomass SBRs<strong>membrane</strong> filters. The objective of this period was to investigate the effect of suspendedsolids on TMF in both systems.Period V (from day 325 until day 349). The feeding of diluted wastewater <strong>with</strong>suspended solids was restarted on day 325 <strong>and</strong> continued till the end of operation.3.3.2. Analytical methodsSamples of the influents <strong>and</strong> effluents from both SBRs <strong>and</strong> the permeates from thefiltration chambers were taken. COD, ammonia, nitrite, nitrate, phosphate, mixed liquortotal <strong>and</strong> volatile suspended solids (MLTSS <strong>and</strong> MLVSS) concentrations <strong>and</strong> sludgevolume index (SVI) were analysed according to St<strong>and</strong>ard Methods for the Examination ofWater <strong>and</strong> Wastewater (APHA-AWWA-WPCF, 1998). Dissolved organic carbon (DOC)<strong>and</strong> dissolved total nitrogen (DTN) were determined <strong>with</strong> a Shimadzu TOC-500 analyser,<strong>and</strong> a DN 1900 analyser (Rosemount-Dohrmann).Samples were taken at the end of the <strong>with</strong>drawal period, when the filtration chambershad achieved their maximum operating volumes, a result of the entrance of secondarytreated effluent from the SBRs.Dissolved oxygen concentrations in the reactors <strong>and</strong> filtration chambers weredetermined <strong>with</strong> an Oxi 340 WTW oxygen selective electrode, <strong>and</strong> pH was determined <strong>with</strong>a U-455 Ingold electrode connected to a Crison 506 pH-meter. Conductivity <strong>and</strong>temperature were monitored <strong>with</strong> a CM 35 conductivimeter.Soluble microbial products (SMP) were extracted by centrifuging the biomass for 5min at 5000 rpm (Heraeus, Labofuge 200) <strong>and</strong> filtering the supernatant through 0.2-mmglass fibre filters (GF 52, Schleicher <strong>and</strong> Schuell). Extracellular polymeric substances(EPS) were extracted according to the heating procedure (Zhang et al., 1999). Protein <strong>and</strong>carbohydrate concentrations were determined by visible absorbance on aspectrophotometer (Cecil CE 7200), using bovine serum albumin (Sigma) <strong>and</strong> glucosest<strong>and</strong>ards (Merck), respectively. Carbohydrate <strong>and</strong> protein concentrations weredetermined according to the methods of Dubois et al. (1956) <strong>and</strong> Lowry et al. (1951),respectively. The difference in DOC concentration between the sludge mixture afterfiltration through a 0.45 µm nitrocellulose <strong>membrane</strong> filters (HA, Millipore) <strong>and</strong> thepermeate was assigned to the colloidal fraction of biopolymer clusters (cBPC) in the liquidphase of the sludge mixture suspension (Sun et al., 2008). The critical flux was determinedaccording to the modified flux-step method proposed by van der Marel et al. (2009). Thecriterion employed was that the increment of trans<strong>membrane</strong> pressure (TMP) <strong>with</strong> respect91
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