废水浊度的测定(英文版)

ExperimentⅢthe determination of wastewater turbidity------spectrophotometry

The purpose and requirements of the experiment

1.Know the influence of turbidity to light transmittance;

2.Know the relative between turbidity and SS is exist in certain

condition;

3.Learn the method to determine water turbidity. Experimental program

1.Experimental instruments and drugs

10 clear 50ml colorimetric tubes

Pipette，spectrophotometer

About 50mL 400 degree turbidity standard solution

2.Experimental steps

Preparation standard solution: take 0 mL, 1mL, 2.5mL, 5mL, 10mL, 12.5mL solution from 400 degree turbidity standard solution into 6 clear 50ml colorimetric tubesdilute to 50mL standard line, shake up.

Determining Abs: set the wavelength ofSpectrophotometer in 540nm. The first determine 4 dishes difference and mark which tube is put into which dish to determine, then shake up tubes and wash dishes before determining each tubes, including wastewater without dilution. And writ every data down table. Let the Abs be the ordinate and the turbidity of standard solution be the abscissa and draw up the graph. Through the graph, calculate the turbidity ofwastewater. Experimental result and data handling

The Abs of each turbidity standard solution

Fig. 1 Abs-eachturbiditystandard solution

According to fig. 1 and the following formula we can calculate turbidity of wastewater.

Notes: y refers to the Abs of each turbidity standard solution

x refers to the turbidity of wastewater

The turbidity of wastewater

Conclusion

1.Data reliability analysis

The average of the concentration

The standard deviation of the concentration

The relative standard deviation of data

From the table and formula, we can see the first data is the smaller than others.Review our experiment, I found that we determined 3 solutions each time and the NO.1 wastewater is line in the fourth in second time determination. So the SS in wastewater was precipitating when we determined it. Thereby Abs of NO.1 wastewater is smaller than others. Hence we must determine each wastewaterevery time after shaking up when we determine Abs of wastewater.

Only by that we can reduce error.

2.Standard of turbidity in drinking water

According to < The sanitary norm of drinking water quality >, the turbidity in drinking water can’t exceed 1 NTU. The sample waster have exceeded standard more than 30 times. But in source of water and water purification, its upper limit can reach 3 NTU. And the harm of turbidity in water is small, so there is not any special regulation in the integrated wastewater discharge standard (GB 8978—1996).

3.Treatment technologies

What we treat mainly about turbidity in wastewater is SS, so the method of treatment is the same as treatment of SS. We can also treat low concentration and high color wastewater by activated carbon. Due to activated carbon is expensive, it just suit a few water treatment. In wastewater treatment, we usually treat turbidity in settling tank.

Questions and discussion

1.Explain the difference and relative between SS and turbidity by looking for

material

Answer: turbidity is representative of how much SS is in waster. When it’s low concentration and low color, it is direct proportion between turbidity and the concentration of SS. But if it is low concentration and high color or high concentration of SS, they aren’t any relative. And turbidity is an optical unit, SS is

a mass unit. There aren’t strict conversion relations between them. So SS is just a

reference value for turbidity.

2.Explain the structure and principle of the spectrophotometer and state its

application in the field of environmental monitor by looking for material

Answer: it is mainly two partsin spectrophotometer, a spectrometer for producing light of any selected color (wavelength), and a photometer for measuring the intensity of light. When a light shoot from spectrometer and pass through dish with solution to photometer. By measuring the intensity of light, we can calculate transmittance and Abs.spectrophotometer can be used for the determination of Na, K, Ca in water, ash, biological materials.The concentration of Na and K in cement samples can be found out. It can be also used for the measurement of turbidity, nucleic acid and protein in cells in environmental applications of spectrophotometer.

Advises and opinions

Many students violate operating rules when they do experiment, it leads to experiment apparatus broken and reagent is polluted. The incorrectoperation will make the result of next team be higher than others. So even if we have correct operation and steps, but we still have a result with high error. If teacher make students observeoperating rules that would reduce the influence for the next experiment. And the experiment will become easier.