2. Monitoring indicators of operation parameters
The Operation Department arranges the categories and frequencies of test indicators in the form of business contact sheets according to production needs. The laboratory shall test and analyze the operation parameters. Through the analysis of operation parameters, it can be judged whether the operation of the sewage treatment plant is normal or not, and it will be fed back to the central control room of the sewage treatment plant in time, and the central control room will make necessary adjustments to the operation of the sewage treatment plant.
The project and cycle of sludge normal operation detection in urban sewage treatment plants should be implemented according to the national Ministry of Construction standard CJJ60-94. Please refer to Table 6- 1 and Table 6-2. The test data of routine test items should be fed back in the form of written reports and electronic statements before 9:00 am every day. The data of temporarily added laboratory items shall be reported to the production and operation department in written form in time to analyze the process operation status and take preventive measures for possible problems.
3. Sampling container
The sampling container shall be composed of inert substances, crack resistant, easy to clean, well sealed and easy to open and close. The sampling container must ensure that the sample is free from adsorption, evaporation and foreign body pollution.
The sample bottle can be a hard (boric acid) glass bottle or a high-pressure polyethylene bottle. When selecting sample bottles, possible problems of water samples and containers should be considered, and the types of containers and washing methods should be determined.
4. Sample collection
Immerse the container (barrel or bottle) in the waste water to be sampled at the sampling point, fill it with water or mud-water mixture, take it out and pour it into a suitable sample container prepared in advance. Sometimes, the sample container can be directly immersed in water for sampling. When sampling, be careful not to mix with substances floating on the water. Before formal sampling, wash the container with water samples for 2~3 times. The washed wastewater shall not be poured into the ditch again, so as to avoid stirring the suspended solids in the water. The collected samples should be labeled in time. Fill in the sampling site record form. If it is a user's export sampling, it should be signed by the relevant personnel of the sampled unit.
Matters needing attention in the process of sample collection: For pollutants with stable properties, the samples collected separately can be mixed and determined once. For unstable pollutants, the pollutant concentration can be expressed by the average value after sampling and determination respectively. Some components in wastewater are unevenly distributed, such as oil and suspended solids, and some components are easy to change in analysis, such as dissolved oxygen and sulfide.
If a waste water sub-sample is taken from the total analysis sampling bottle to analyze these items, it will definitely produce wrong results. Therefore, the water samples of this kind of monitoring project should be collected separately, and some of them should be fixed at the scene and analyzed separately. After the sampling is completed, fill in the sampling site data sheet and sample preservation registration card as required, and the water sample label should be consistent with the above two tables.
5. Sample preservation
Fill the container with water sample until it overflows, and then seal it.
In order to avoid the oscillation of the sample during transportation and the interference of oxygen and carbon dioxide in the air on the sample composition and the items to be measured in the container, and affect pH, BOD, DO, etc. , the water sample should be put into the container until it overflows and sealed. However, the container cannot be filled with samples to be frozen, otherwise the container will burst due to volume expansion after water freezes.
Refrigeration: the temperature of water samples during refrigeration should be lower than that during sampling. After water samples are collected, they should be stored in refrigerator or ice water bath, and protected from light, generally at 2 ~ 5℃. Refrigeration is not suitable for long-term storage, and the storage time of wastewater is shorter.
Freezing (-20℃): Generally, the shelf life can be extended, but the techniques of melting and freezing should be mastered so that the sample can be restored to its original state quickly and evenly after melting. Water samples expand in volume when they freeze, and plastic containers are generally used.
Adding protective agent (fixative or preservative): Some chemical reagents can be added to fix some components to be detected in the water sample. Protective agents should be added to empty bottles in advance, and some can also be added to water samples immediately after sampling.
Commonly used protective agents include various acids, bases and biological inhibitors, and the addition amount depends on needs.
The added protective agent will not interfere with the determination of the components to be detected. If in doubt, you should do the necessary experiments first.
Because the volume of the added protective agent will affect the initial concentration of the component to be detected, it should be taken into account when calculating the result, but if the added protective agent has sufficient concentration; The dilution effect can be ignored because the added volume is very small.
The added protective agent may change the chemical or physical properties of components in water, so the influence on determination items must be considered when selecting protective agent. If acidification can dissolve colloidal components and solids suspended on particles, if the items to be detected are dissolved substances, they must be acidified, filtered and preserved.
Blank test must be done to determine the fixative added in some projects. For example, when determining trace elements, it is necessary to determine the amount of elements to be detected that can be introduced by fixative. (For example, acids can introduce a lot of arsenic, lead and mercury. )
It must be noted that some protective agents are toxic and harmful, such as mercury chloride, chloroform and acid. Safety protection must be paid attention to when using and keeping.
6. Laboratory safety
There are some dangerous factors in the laboratory itself, but as long as the analysts strictly abide by the operating rules and regulations, no matter what experiments they do, they should keep in mind that safety is the first and always be vigilant, and accidents can be avoided. If the preventive measures are reliable and the accidents are handled properly, the losses can be minimized. For the safety knowledge of the water quality monitoring laboratory, please refer to the relevant contents in the Quality Assurance Manual for Environmental Water Quality Monitoring. The following are the safety rules that should be observed in daily laboratory work:
When heating volatile or flammable organic solvents, direct heating by flame or circuit is prohibited, and it must be done slowly in a water bath pot or electric heating plate; Combustible substances such as gasoline, alcohol and kerosene. Should not be placed near gas lamps, electric furnaces or other fire sources; At least one person should be on duty to manage heating distillation and related naked flame or electric heating operations, and gloves should be worn when operating high-temperature electric furnaces;
The wires used in the electric heating equipment should be checked regularly for completeness, and the electric heating equipment should be properly padded; The main switch of power supply shall be fitted with a solid cover. Don't get your hands wet when switching. Pay attention. Toxic drugs must be kept and used in a systematic way, and special counters should be set up to be kept by two people and two locks;
Strong acid and ammonia water are stored separately; When diluting sulfuric acid, you must carefully and slowly pour sulfuric acid into water instead of pouring water into sulfuric acid; When you suck acid, alkali and harmful substances with a straw, you can't suck them with your mouth, but you must use an ear-sucking ball. Gloves must be worn when dumping nitric acid, ammonia water and hydrofluoric acid. When opening volatile reagent bottle such as ethanol and ammonia, never point the bottle mouth at yourself or others, especially in summer, when opening it, it is easy to rush out. If you are not careful, you will cause a serious accident.
Operations that produce harmful gases such as digestion must be carried out in a fume hood; When operating the centrifuge, it must be completely stopped before it can be started; Pressure vessels, such as hydrogen cylinders, must be kept away from fire sources and safely parked; Pay attention to washing hands after touching sewage and medicines. Don't touch sewage and drugs when you have a wound on your hand. The laboratory should be equipped with fire-fighting equipment, such as yellow sand barrels and carbon tetrachloride fire extinguishers. The yellow sand in the yellow sand bucket should be kept dry and not soaked in water. The laboratory should maintain good ventilation, good lighting and clean environment. Personal items and items unrelated to the laboratory should not be stored in the laboratory. Every day after work, water, electricity and other safety checks should be carried out. Check the anti-freezing measures before coming off work in winter.
7. Check the calibration curve
Linearity test: that is, test the accuracy of the curve. For the calibration curve drawn with measured signal values of 4~6 concentration units, the correlation coefficient is generally required to be | r |⊙0.9990, otherwise, the reason should be found out and corrected, and the qualified test curve should be redrawn.
Intercept test: that is, test the precision of calibration curve. Linear regression * is carried out on the basis of linear test, and the regression equation y=a+bx is obtained. Then t is used to test intercepts A and 0. When the confidence level is 95% and there is no significant difference after the test, A can be regarded as 0, and the equation is simplified as y=bx, and x=y/b for the shift term. In the linear range, the sample concentration can be calculated by directly correcting the sample measurement signal with blank without referring to the calibration curve.
When a is significantly different from, it means that the calculation result of the regression equation representing the calibration curve is inaccurate. After finding out the reason and correcting it, redraw the calibration curve and pass the linear test, then calculate the regression equation and put it into use after passing the intercept test.
If the regression equation is put into use directly without the above test and treatment, it will inevitably introduce a systematic error with a difference equal to the intercept A to the determination results.
Slope test: that is, to test the sensitivity of analytical methods. The sensitivity of this method varies with the experimental conditions. Under exactly the same analysis conditions, the slope change caused only by random errors in operation should not exceed a certain allowable range, which varies with the accuracy of analysis methods. For example, in general, molecular absorption spectrophotometry requires its relative error to be less than 5%; However, atomic spectrophotometry requires its relative error value to be less than 10% and so on.
8. Comparative analysis of reference materials
Transmission of measurement value: compare the sample or control sample prepared in the laboratory with the standard reference material, check the error of its concentration value and correct it.
Instrument calibration: For instruments using direct quantitative method, the instrument is calibrated with standard reference materials.
Comparative analysis: At the same time of sample analysis, use standard reference materials with similar concentrations or their dilutions for analysis, and judge whether the accuracy of sample analysis results is acceptable according to the coincidence degree between the measured values of standard reference materials and the guaranteed values.
Quality evaluation: taking standard reference materials as unknown samples, the technical level of analysts in laboratories or the consistency of analysis results between laboratories are evaluated, thus helping analysts find problems and ensuring the comparability of data between laboratories.
9. Accident plan
It should include: accident alarm, emergency treatment, accident investigation, responsibility treatment, accident prevention (engineering and technical measures, educational measures and management measures), accident report and accident information transmission (report within a certain range to learn lessons and prevent accidents). Participants in each step of the accident plan should have clear provisions in the accident plan (and should include emergency contact information, etc.). ). For example, accident investigation should be completed by technical director and department head.