The quality control of the sampling process runs through the entire sampling process, covering aspects such as the sampling personnel, sampling methods, sampling points, sampling containers, sample preservation and transportation, full-process blanks and transportation blanks, on-site parallel samples, the surrounding conditions of the sampling points, and the original sampling records.
First, the sampling personnel should pass the assessment and hold the corresponding certificates before they can start their work.
Second, the setting of sampling sections and points, as well as the use of sampling containers, must comply with environmental monitoring technical specifications; the frequency, time and methods of sampling should be carried out in accordance with the requirements of the monitoring objects and analytical methods, and in accordance with the corresponding technical specifications.
Thirdly, during the sampling process, it is necessary to thoroughly understand the production conditions of the polluting entity, including water consumption, process flow, source of wastewater, treatment capacity and operation status of wastewater treatment facilities, etc. Special attention should be paid to whether there are any abnormal situations.
Fourth, during each monitoring process, at least 10% of on-site replicate samples need to be collected.
The fixed monitoring items on-site should be standardized in accordance with the environmental monitoring technical specifications. They should be sent to the laboratory as soon as possible within the valid storage period. When submitting water samples to the laboratory, the sample handover should be carried out promptly, and both the sender and the receiver should sign the documents.
Fifth, for the determination of suspended solids (SS), pH, BOD, oil, sulfides, radioactivity, residual chlorine, microorganisms, etc., separate sampling is required; for the determination of BOD5, sulfides and organic pollutants, the water samples must fill the containers completely; for the determination of pH, water temperature, conductivity, DO and ORP, it is advisable to conduct the tests on-site. During sampling, except for the items with special requirements such as total bacterial count, coliform bacteria, oil, BOD, organic matter, and residual chlorine, the sampling equipment and water sample containers should be washed with the sampling water 2-3 times first, then the water samples should be collected into the containers, and the corresponding fixatives should be added immediately as required, and labels should be affixed. Regular self-adhesive labels should be used.
Sixth, carefully fill in the sampling record. The main contents include: name of the polluting unit, sample type, sampling purpose, sampling date, sample number, sampling location, sampling time, monitoring items and the name of the preservative added, appearance characteristics description of the wastewater, flow rate, flow volume, and sampling personnel. Ensure that the sampling is carried out on time, accurately and safely. Before the sampling is completed, carefully check the sampling record and the water sample. If there are any missed samples or non-compliant samples, they should be re-sampled immediately.