Reading Assignment

There is no reading assignment for this lab.

Introduction Mixed liquor is a combination of sludge và removedfrom the clarifier in the treatment process and reintroduced intoan earlier phase of the treatment process. The mixed liquor containsmicroorganisms which digest the wastes in the raw This lab willshow you how khổng lồ kiểm tra for MLSS và MLVSS in the mixed liquor. Mixed Liquor Suspended Solids(MLSS) is a test for the total suspendedsolids in a sample of mixed liquor. This kiểm tra is essentially the sameas the kiểm tra you performed for TSS in the last lab, except for the use ofmixed liquor as the sample. In addition, the concentration ofsuspended solids found in the mixed liquor is typically much greater thanthat found in the raw or treated MLSS concentrations are oftengreater than 1,000 mg/L, but should not exceed 4,000 mg/L. MLVSS, or Mixed Liquor Volatile Suspended Solids,is a kiểm tra for the amount of volatile suspended solids found in a sample ofmixed liquor. Volatile solidsare those solids which are burnt up when a sample is heated lớn 550°C.Most of the volatile solids in a sample of mixed liquor will consist of microorganisms& organic matter. As a result, the volatile solids concentrationof mixed liquor is approximately equal khổng lồ the amount of microorganisms inthe and can be used lớn determine whether there are enough microorganismspresent lớn digest the sludge. In a treatment plant, operators should chạy thử forMLSS three times per week and for MLVSS once per week. Both tests shoulduse grab samples taken from the same location in the treatment plant.

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Dessicator Drying oven, for operation at 103 khổng lồ 105°C Analytical balance, capable of weighing to 0.1 mg Magnetic stirrer with TFE stirring bar Wide-bore pipets Graduated cylinder Low-khung beaker Glass-fiber filter disks with organic binder Filtration apparatus, which can be any one of thefollowing: Membrane filter funnel Gooch crucible, 25 mL lớn 40 mL capathành phố, with Goochcrucible adapter Filtration apparatus with reservoir và coarse fritteddisk (40 to 60 um) as filter support Filter flasks, of sufficient capađô thị for sample sizeselected Vacuum pump Tubing Stop watch Aluminum weighing dishes Muffle furnace

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Collect a grab sample of mixed liquor. Measure the total suspended solids in your sample using the procedure outlined in Lab 11. You will probably need lớn use a smaller sample volume, such as 5 mL. Record the sample volume và the combined sample and filter weight in the Data section. At least 10% of all samples should be analyzed in duplicate. Ignite the filter & the total suspended solids residue from step 1 in a muffle furnace at 550°C. An ignition time of 15 lớn đôi mươi minutes is usually sufficient for 200 mg residue. However, when igniting more than one sample or when igniting heavier samples, the ignition time may need to lớn be increased. Let the filter cool partially in the air until most of the heat has dissipated. Then transfer the filter to lớn a dessicator lớn cool the rest of the way khổng lồ air temperature. Weigh the filter & record the weight in the Data section. Repeat the cycle of igniting, cooling, desiccating, và weighing until a constant weight is obtained or until the weight change is less than 4% or 0.5 mg, whichever is less. Calculate the volatile solids in the sample, as follows: