Purpose of industrial water quality testing

Guidelines for the entire process of industrial water quality testing

Step 1: Clarify goals and develop plans

Before starting the testing, it is necessary to clarify the purpose and basis of the testing, which is the foundation of all subsequent work.

Determine the purpose of testing: Different purposes determine different testing priorities. For example, daily monitoring focuses on routine indicators; When investigating the cause of equipment corrosion, the content of heavy metals and chloride ions is crucial; To evaluate the biodegradability of wastewater, attention should be paid to indicators such as COD (Chemical Oxygen Demand) and BOD (Biochemical Oxygen Demand).

Identify key indicators: Determine the items that must be tested based on the type of water used, referring to national standards or industry norms. For example, boiler water needs to focus on hardness and silicon content to prevent scaling, while cooling water needs to pay attention to residual chlorine content and microbial indicators to control corrosion and biofouling.

Develop a sampling plan: The plan should specify the specific location of the sampling points (such as inlet, return pipeline, discharge outlet), sampling time and frequency, and plan the sample flow path from sampling to laboratory analysis to ensure the representativeness of the samples.

Step 2: Sample collection, storage, and transportation

The goal of this stage is to obtain samples that can truly reflect the condition of the water body and ensure that their properties do not change before arriving at the laboratory.

Sampling operation: Before sampling, it is necessary to rinse the sampling container with the water sample to be collected two to three times. When collecting water samples from the water surface, the container should be submerged to a certain depth and the bottle mouth should be aligned with the upstream direction of the water flow. If it is necessary to collect water samples at different depths, a professional deep water sampler should be used. After sampling, the sampling location, time, and appearance of the water body should be clearly recorded on the sample label immediately.

Sample preservation and transportation: To prevent changes in water quality during transportation, appropriate preservation measures must be taken. For example, water samples for detecting heavy metals usually require the addition of nitric acid for acidification; The water sample for detecting ammonia nitrogen needs to be refrigerated with sulfuric acid at low temperature. All samples should be transported back to the laboratory as soon as possible in a low-temperature environment (usually 4 ℃), with a maximum storage time generally not exceeding 24 hours.

Step 3: Laboratory Analysis and Data Processing

After the sample arrives at the laboratory, precise analysis will be carried out according to the preset plan.

Conventional physical and chemical index analysis: These indicators can quickly reflect the basic condition of water quality. The pH value is commonly measured using a glass electrode method, conductivity is measured using a conductivity meter, and turbidity is detected using a turbidity meter.

Specific pollutant analysis: high-precision instruments are used to analyze different types of pollutants. Heavy metal elements such as lead, mercury, and cadmium are usually determined using atomic absorption spectroscopy or inductively coupled plasma mass spectrometry (ICP-MS), and their concentrations are extremely low and can be accurately detected. Organic pollutants, such as pesticide residues and volatile phenols, are commonly separated and identified using gas chromatography or liquid chromatography.

Microbial index analysis: By using microbial cultivation method, water samples are inoculated on specific culture media and cultured at a certain temperature for 24 to 48 hours. Then, the total number of bacterial colonies and coliforms are counted to evaluate the hygiene and safety of the water.

Data validation: After obtaining the detection data, rigorous validation is required. This includes checking the accuracy of the data and using statistical methods such as Grubbs' test to identify and handle potential outliers, ensuring the validity and reliability of the data.

Step 4: Report preparation and application of results

After the data analysis is completed, a professional report needs to be generated and the results applied to actual production.

Report preparation: A standardized testing report not only includes sample information, testing items, and results, but also clearly lists the testing methods and judgment criteria used (such as national standards and industry standards). The report should provide a clear interpretation of the results, clearly indicating whether there are any exceedances and their potential risks.

Result application and action: The ultimate value of detection lies in guiding practice. If the result is qualified, the report can serve as proof of compliance with production requirements. If abnormal indicators are found, it is necessary to immediately trace the source, investigate pollution points or process defects, and adjust the water treatment plan (such as increasing filtration accuracy and adjusting the dosage of chemicals). All testing reports and related records should be properly archived as an important basis for production quality management and response to environmental inspections.

Flexible application of detection process

In practical operation, the detection process is not fixed.

Routine testing and emergency testing: Routine monitoring can execute the complete process according to the predetermined plan. When dealing with sudden pollution incidents, it is necessary to activate emergency detection procedures, which may simplify the process and prioritize the use of portable devices to quickly measure key indicators on site, in order to buy time for decision-making.

Key detection points for different water bodies:

Process water: Directly involved in product manufacturing, its purity is crucial, and it is necessary to focus on monitoring conductivity, heavy metal and particle content.

Boiler water: The key indicators are hardness, silicon content, and dissolved oxygen, aimed at preventing scaling, corrosion, and steam water co distillation.

Cooling water: Focus on residual chlorine content, total microbial count, and pH value to control microbial growth and system corrosion.

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