Tuesday, July 14, 2009

TSS ,VSS, MLSS and MLVSS Exeperiment

Exeperiment According to AFHA
http://norweco.com/html/lab/WhatTests.htm

Apparatus:

*Dessicator
*Drying oven, for operation at 103 to 105°C
*Analytical balance, capable of weighing to 0.1 mg
*Magnetic stirrer with TFE stirring bar
*Wide-bore pipets
*Graduated cylinder
*Low-form beaker
*Glass-fiber filter disks with organic binder
*Filtration apparatus, which can be any one of the following:
*Membrane filter funnel
*Gooch crucible, 25 mL to 40 mL capacity, with Gooch crucible adapter
*Filtration apparatus with reservoir and coarse fritted disk (40 to 60 um) as filter support
*Filter flasks, of sufficient capacity for sample size selected
*Vacuum pump
*Tubing
*Stop watch
*Aluminum weighing dishes
*Muffle furnace

A. TSS (Total Suspended solid)

Procedure of TSS (Total Suspended solid)

1. Preparation of glass fiber filter disks:

a. Insert the filter disk in filtration apparatus. Apply vacuum and wash disk with three successive 20-mL portions of reagent-grade water.

b. Continue suction to remove all traces of water, turn vacuum off, and discard washings.

c. Remove filter from filtration apparatus and transfer to an inert aluminum weighing dish.

d. Dry in an oven at 103 to 105°C for 1 h.

e. Repeat cycle of drying or igniting, cooling, desiccating, and weighing until a constant weight is obtained or until weight change is less than 4% of the previous weighing or 0.5 mg, whichever is less. Store in desiccator until needed.

2.Selection of sample size : Choose sample volume to yield between 2.5 to 200mg dried residue.

3.Sample analysis: setup the filtration unit with the dried glass fiber filter disk. Apply the well stirred sample volume in the center of the filter. wash the filter with 10 ml of reagent grade water and continue suction for about 3 min after filtration is complete.

4.Carefully remove filter from filtration apparatus and transfer to an aluminum weighing dish as a support.

5.Dry for at least 1 h at 103 to 105°C in an oven, cool in a desiccator to balance temperature, and weigh. Repeat the cycle of drying, cooling, desiccating, and weighing until a constant weight is obtained or until the weight change is less than 4% of the previous weight or 0.5 mg, whichever is less. Analyze at least 10% of all samples in duplicate. Duplicate determinations should agree within 5% of their average weight.

6. Calculation

mg total suspended solids/L =(A-B) X 1000/sample volume, mL

where:
A = weight of filter + dried residue, mg, and
B = weight of filter, mg.

7.Precision

The standard deviation was 5.2 mg/L (coefficient of variation 33%) at 15 mg/L, 24 mg/L (10%) at 242 mg/L, and 13 mg/L (0.76%) at 1707 mg/L in studies by two analysts of four sets of 10 determinations each.
Single-laboratory duplicate analyses of 50 samples of water and wastewater were made with a standard deviation of differences of 2.8 mg/L.


B. VSS (volatile suspended solid)

Procedure of VSS (volatile suspended solid)

1.All the above process is same accept ignition process. Here the the glass filter paper is ignited at 550 degree.

2.Precision
The standard deviation was 11 mg/L at 170 mg/L volatile total solids in studies by three laboratories on four samples and 10 replicates. Bias data on actual samples cannot be obtained.


C. MLSS (Mixed Liquor Suspended Solids) & MLVSS(Mixed Liquor Volatile Suspended Solids)

Mixed liquor is a combination of sludge and water removed from the clarifier in the wastewater treatment process and reintroduced into an earlier phase of the treatment process.The mixed liquor contains microorganisms which digest the wastes in the raw water.

Mixed Liquor Suspended Solids (MLSS) is a test for the total suspended solids in a sample of mixed liquor. This test is essentially the same as the test you performed for TSS in the last lab, except for the use of mixed liquor as the water sample.In addition, the concentration of suspended solids found in the mixed liquor is typically much greater than that found in the raw or treated water.MLSS concentrations are often greater than 1,000 mg/L, but should not exceed 4,000 mg/L.

MLVSS, or Mixed Liquor Volatile Suspended Solids, is a test for the amount of volatile suspended solids found in a sample of mixed liquor.Volatile solids are those solids which are burnt up when a sample is heated to 550°C.Most of the volatile solids in a sample of mixed liquor will consist of microorganisms and organic matter.As a result, the volatile solids concentration of mixed liquor is approximately equal to the amount of microorganisms in the water and can be used to determine whether there are enough microorganisms present to digest the sludge.

Procedure:

1.Collect a grab sample of mixed liquor.

2.Measure the total suspended solids (TSS). Record the sample volume and the combined sample and filter weight .At least 10% of all samples should be analyzed in duplicate.

3.Ignite the filter and the total suspended solids residue from step 1 in a muffle furnace at 550°C. An ignition time of 15 to 20 minutes is usually sufficient for 200 mg residue.

4.Let the filter cool partially in the air until most of the heat has dissipated.Then transfer the filter to a dessicator to cool the rest of the way to air temperature.

5.Weigh the filter and record the weight.

6.Repeat the cycle of igniting, cooling, desiccating, and weighing until a constant weight is obtained or until the weight change is less than 4% or 0.5 mg, whichever is less.

7. Calculate the volatile solids in the sample, as follows:

mg total suspended solids/L = (A-B) X 1000/sample volume, mL

where:
A = weight of filter + dried residue, mg, and
B = weight of filter, mg.

[Simplification of experiment may contain certain error and it is my personal view]


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