Will you swim in troubled waters? How about drinking it from a well? Surely, you will prefer clean, clear water, in which it is pleasant to soak and which is not dangerous to drink. Today we will talk about what is turbidity of water. Is it suitable for use, and what danger lies in the impurities? How to study quality? And how to get rid of negative phenomena?
What is haze?
Under water pollution it is customary to understand the change in its properties when exposed to chemical or organic substances. If any are found, the use of the life-giving liquid should be suspended, as this can be dangerous for the human body.
In the laboratories at the treatment plants they analyze for:
- turbidity and color of water;
- smell and acidity;
- organic content;
- presence of heavy metals;
- chemical oxygen demand, etc.
Contaminated liquid contains inorganic and organic fine suspensions. The turbidity of water is an indicator that characterizes the degree of transparency.
Causes of haze
Turbidity is spoken of when solid particles of sand, pebbles, and silt most often appear in water. They are washed away by precipitation, melt water into the river, and they can also result from the destruction of the well.
Least impurities in winter. Most of all - in spring and summer, when floods often occur and a seasonal increase in plankton and algae is observed.
State Standards
In our country, the turbidity of water is determined by comparing two samples: standard and taken directly from the reservoir. The photometric method is used. The result is expressed in two forms:
- when using a suspension of coalin - in mg/dm3;
- when using formazin - IU/dm3.
Last adopted by ISO. Referred to as FMU (Formazin Turbidity Unit).
In Russia, such norms of water turbidity are adopted. GOST for drinking - 2, 6 EMF, for disinfecting - 1, 5 EMF.
How to determine water quality
In any water utility there is a laboratory that studies the quality of water supplied to the pipes. Measurements are taken several times a day so as not to miss a single change. Consider the main methods for determining the turbidity of water.
The essence of any method is to pass a beam of light through the liquid. It remains in a completely transparent flaskunchanged, only slightly scattered and has a slight angle deviation. If there are suspended particles in the water, they will interfere with the passage of the light beam in different ways. This fact will fix the reflective device.
Today, the turbidity of drinking water can be determined by the following methods:
- Photometrically. There are two research options: turbidimetric, which captures attenuated rays, and nephelometric, which results in the reflection of scattered light.
- Visually. The degree of contamination is assessed on a scale, 10-12 cm high, in a special turbidity test tube.
Types of suspended particles
Any impurities found in drinking water have their own properties. They are characterized by such a parameter as hydraulic fineness, which is expressed in the rate of settling to the bottom in still water at a temperature of 10 °C. Here are examples of suspended particles in the table.
Suspended particles and their characteristics
| Suspended solids | Size, mm | Hydraulic size, mm/s | Settling time to a depth of 1 m |
| Colloid particles | 2×10-4 | 7×10-6 | 4 years |
| Fine clay | 1×10-3 | 7×10-4 | 0, 5-2 months |
| Clay | 27×10-4 | 5×10-3 | 2 nights |
| Il | 5×10-2 | 1.7-0.5 | 10-30 minutes |
| Fine sand | 0, 1 | 7 | 2, 5 minutes |
| Medium sand | 0, 5 | 50 | 20 seconds |
| Coarse sand | 1, 0 | 100 | 10 seconds |
From the history of turbidity measurements
Obviously, the turbidity of water is one of the most important factors affecting the quality of the fluid consumed. Even small changes in the standards indicate the presence of pathogenic flora, which can lead to various diseases in humans. And as soon as humanity realized that cleanliness is the key to he alth, it immediately became necessary to check the water.
The first people who came up with a special technology to study liquid in the laboratory were Whipple and Jackson, and their device was called the "Jackson candle turbidimeter". It was a flask held over a candle. Water for research was placed inside, into which the world's first suspension based on diatomaceous earth was poured. The liquid was poured slowly until the light from the candle was completely dissipated. Then they looked at the scale and converted the data into Jacksonian units of turbidity.
Despite the fact that there were no polymers in those days and materials from natural resources were prepared for suspensions, although this method gave errors, it was used for a very long time.
It wasn't until 1926 that scientists from Kingsbury and Clark chemically created formazin. It's the perfect stuff to exploreturbidity of the water. To prepare the suspension, you need to take a liter of distilled water, 5.00 g of hydrazine sulfate and 50.00 g of hexamethylenetetramine.
Qualitative turbidity determination method
You will need a test tube 10-12 cm high, a sheet of black cardboard.
Sequence of actions:
- Pull water into a test tube.
- Place the flask so that it stands on a black background, and there is a light source on the side: the sun or an incandescent lamp.
- Visually determine the degree of turbidity: clear water, slightly polluted, slightly cloudy, cloudy, very cloudy.
Method for quantifying turbidity
You will need: analysis flask (height 6 cm, diameter 2.5 cm), screen for tube, syringe, pipette, sample font (height 3.5 mm, line width 0.35 mm)
Sequence of actions:
- Fill water into the flask. Mount it on a tripod.
- Down under the flask, put a sample of the font. It could just be a letter.
- You need to create a screen around the tube to reflect light.
- Place the light source on top directly above the tube.
- Take water with a pipette until you see the letter.
- Measure the height of the water column. Data must be accurate to within 10 mm.
Conclusions
The turbidity of the water is an important factor in determining the degree of contamination of the liquid. In the modern world, at all treatment plants, this indicator is closely monitored in order to choose the right method for further water filtration. You can check the turbidity at home usingmethods of qualitative and quantitative research.
