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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Materials <strong>and</strong> methodsoperation because it offers a rough approximation of the amount of organic matter presentin the solid fraction of wastewater, activated sludge or industrial wastes. MLTS <strong>and</strong> MLTSSare determined following the methods 2540B <strong>and</strong> 2540D described in St<strong>and</strong>ard Methodsfor the Examination of Water <strong>and</strong> Wastewater (APHA-AWWA-WPCF, 1998), whereasMLVS <strong>and</strong> MLVSS are determined following the method 2540E.Determination procedureMLTS are determined weighing a selected (in order to yield a residue between 2.5<strong>and</strong> 200 mg) well-mixed sample volume in a previously clean (heated to 103-105ºC for 2h) porcelain dish after being evaporated at 103-105ºC until constant weight. The increasein weight over that of the empty dish represents the total solids in the initial volume ofsample.For the determination of MLTSS, a selected (in order to yield a residue between 2.5<strong>and</strong> 200 mg) well-mixed sample volume is filtered through a weighed glassfiber filter(Whatman, GF/C, 4.7 cm of diameter, 1.2 μm of pore size) <strong>and</strong> the residue retained on thefilter is dried to a constant weight (2h) at 103-105ºC. The increase in weight of the filterrepresents the total suspended solids.To determine the volatile solids (MLVS or MLVSS), the residue from method 2540B<strong>and</strong> 2540D, respectively, is burnt to constant weight at 550ºC during half an hour. Theweight lost during ignition corresponds to the volatile solids.InterferencesHighly mineralized water <strong>with</strong> a significant concentration of calcium, magnesium,chloride <strong>and</strong>/or sulphate may be hygroscopic <strong>and</strong> requires prolonged drying, properdesiccation <strong>and</strong> rapid weighing. Some inorganic salts such as hydroxides, carbonates orammonium salts are decomposed <strong>and</strong> volatilised at 550 ºC <strong>and</strong> therefore can give a highervalue for the volatile content in the sample.2.2.2. Biofilm concentrationBiomass concentration in the biofilm attached to the plastic support was alsodetermined. Ten plastic supports were sonicated for 10 min in 100 mL of permeate at 65%of amplitude using a probe sonicator (UP200s, Dr. Hielscher). MLTSS <strong>and</strong> MLVSS weredetermined in the resulting mixed liquor according to the methodology previously detailed,<strong>and</strong> this concentration was referred to the surface of the plastic support.75
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