How to determine Total Suspended Solids in a Sample

Definition:

 

Total Suspended Solids (TSS) or Mixed Liquor Suspended Solids (MLSS) is the part of the Total Solids present in the sample under investigation, which is removed by filtration. The result is given in mg/L.

APPARATUS:

            Vacuum pump

            Suction flask, 250 or 500 ml

            Hartley funnel

            Measuring cylinder, 250ml

            Watch glass, 15 cm dia

            Glass filter fibre paper, 125 mm dia Whatman Cat. No. 1822 125

            Oven, Set at 110 ^oC

            Dessicator

            Furnace, Set at 500 ^oC

            Furnace tongs

 

PROCEDURE:

1.             Number the glass fibre filter, bring it on a watch glass and put it into the furnace at 500 ^oC for 30 min to ensure that any organic material in the paper is removed. The paper should be kept flat and not folded, as it may become brittle if creased.

2.             Remove the filter paper and watch from the furnace, cool in a Dessicator for 15 minutes and weigh (M₁).

3.             Place the filter paper in the Hartley funnel. Take care not to crease.

4.             Place the Hartley funnel on the top of the suction flask.

5.             Connect the flask to the vacuum pump, and apply vacuum.

6.             Measure 100 ml mixed effluent sample into a measuring cylinder and pour it through the glass fibre paper.

7.             When all the liquid has passed through the filter paper rinse the measuring cylinder with 10 ml distilled water and pour this through the glass fibre paper.

8.             Repeat the rinsing twice more and then place the paper on the watch glass and dry it in an oven at 110 ^oC for 1 hour.

9.             Remove the filter paper and watch glass from the oven, cool in a dessicator for 15 min and record the final mass (M₂).

10.          Place further filter paper and watch glass in a furnace at 500 ^oC for 30 min. (The ignition time should be taken from when the furnace actually reaches the required temperature at 500 ^oC).

11.          Remove the filter paper and watch glass from the furnace and allow to cool in a dessicator for 15 min.

12.          Reweigh the filter paper and watch glass and record the final mass (M₃). (The weight loss will due to organic material burning off (VSS) and the solid left behind on the paper will be the inorganic material (FSS).

CALCULATION:

                                                                      (M₂ - M₁) x 10⁶

Total Suspended Solids (mg/l)   =          --------------------

                                                                                     V

                                                                      (M₃ - M₁) x 10⁶

Fixed Suspended Solids (mg/l)  =          --------------------

                                                                                     V

                                                                         (M₂ - M₃) x 10⁶

Volatile Suspended Solids (mg/l)=         --------------------

                                                                                       V

                                                                   M₃ - M₁

% Fixed Suspended Solids       =          ---------- x 100

                                                                    M₂ - M₁

% Volatile Suspended Solids     =          100 - % Fixed Suspended Solids