Group 1: Solid analysis

The date was friday 01/11/24 and our task was the solid analysis in Savonias labratory. The participants are Kerkko Kivistö, Svenja Köhler, Antti Alatalo, Juliette Jouve, Chloé Fribourg and Thomas Humbert.

Solids analysis

After many courses at the Lake Pieni-Valkoinen and Iso-Valkoinen, we finally went to the laboratory to analyze the water samples we took the weeks before. Each group had a different experiment, where they analysed the water samples and collected information on the quality of the water.

Our experiment consist in measuring the suspended solid content of the samples using vacuum filtration. The quantity of suspended solids describes the amount of organic and inorganic solids in the sample, which leads to further information about the quality.

To measure the quantity of solids that is contained in the water, we use 12 dissimilar water samples, which are previously taken from the lake. For each of the samples, we will repeat the following steps:

We take a glass microfiber filter with the pore size 1.6 μm and weigh it to determine its exact weight. Then we fill in a measuring cylinder glass an appropriate filtration volume, that is between 450 ml and 500 ml of the lake water. Afterwards place the filter above the suction bottle in the Bühner funnel with the help of a tweezers, and wet it with deionized water. We use a pump to create a vacuum within the suction bottle, allowing for faster filtration of the solution. Then we pour the sample water into the flask. After waiting a few seconds, we retrieve the filter. Once these steps are completed for all samples, we place the filters in the oven at 105°C for one hour to ensure they are completely dry. After the hour has passed, we allow the filters to cool to room temperature. After that, each filter is individually weighted, to compare this weight with their initial weight.

Experimental setup shown in figure 1 and 2:

  

Figure 1: Vacuum pump (left), suction bottel with the bühner funnel (right)

Figure 2: Deionised water bottle (left), meassuring zylinder (middle) and pre-treated filter (right)

We record all the quantity we noticed on a sheet, which includes weigh of filters before experiments, weigh of filters after experiments and also the quantity of water used for each samples (captured in table 1).

Figure 3: Filters bevor experiment

Figure 4: Dryed filters with solid content on them

In order to analyze the data, we used an excel table to calculate the result. First, we enter the value of the volume in ml we measured for each sample, then the weight of the empty filter which was written on the filters cups. Finally, after weighting the filters at the end of the experiment, we entered the weight that we measure thanks to a balance, that represents the weight of the filter with sample after dying. These values allow us to calculate the final result which is dimensionally consistent with a mass density in mg/l thanks to the following formula : 

Suspended solids concentration (mg/l) = (final filter weight – initial filter weight) / sample volume

This calculation yielded the suspended solid concentration for each sample, which we expressed in mg/l to maintain consistency in reporting water quality data.

Table 1: Meassurements solids analysis

We can see that the concentration of suspended solids varies among the samples collected, ranging from 0.4 mg/l to 30.0 mg/l. Higher concentrations, for example water sample 11 with the highest concentration of suspended solids, indicate a higher presence of particulate matter, which could be due to natural causes like sediment erosion, or human-related factors such as runoff containing pollutants. Comparatively low levels of suspended solids like water sample 2,3 and 6 might indicate areas with better water quality, often suggesting less environmental impact from surrounding activities or minimal disturbance in those parts of the lake.

The varied results indicate that sampling locations play a significant role in the concentration of suspended solids. These differences can ocure due to variations in water flow, sediment, or nearby land use. It is important to analyse the water samples for further information, to make fact-based statements about the over all quality of the water.