Microbial Index Testing Methods and Qualification Determination in Water Hygiene Standards

In modern society, the hygiene and safety issue of water resources is receiving increasing attention, especially the detection of microbiological indicators in drinking water, which directly concerns people's health. This article will discuss the detection methods and qualified judgment of microbiological indicators.

Firstly, microbiological indicator detection methods

Microbiological indicator detection is an important means to ensure the safety of drinking water. The main microbiological indicators detected include total bacterial count, total coliforms, thermotolerant coliforms, Escherichia coli, and other microorganisms. The detection methods mainly include cultivation method, rapid detection method, and molecular biological detection method, etc.

Cultivation method: This is a traditional detection method, mainly through inoculating the water sample into culture media, then cultivating under appropriate temperature and humidity conditions, observing and counting the growth of bacteria. Although this method is simple to operate, it takes a long time and has high requirements for environmental conditions.

Rapid detection method: This detection method mainly includes chromogenic method and immunological method. The chromogenic method determines the presence of bacteria by reacting the water sample with chromogenic reagents based on the degree of chromogenic; the immunological method determines the presence of specific bacteria by detecting antigens in the water sample. The advantage of this method is its rapid detection speed, but its accuracy and sensitivity may be affected by reagents and operation.

Molecular biological detection method: This method mainly uses PCR (polymerase chain reaction) technology to amplify specific DNA sequences in water samples to determine the presence of specific microorganisms. The advantage of this method is its high detection sensitivity, but its operation is complex and requires professional equipment and technology.

Secondly, qualified judgment of microbiological indicators

After detecting the microbiological indicators in the water sample, it is necessary to make a qualified judgment according to the national or local water hygiene standards. Generally, the qualified judgment criteria mainly include the limit values of total bacterial count, total coliforms, thermotolerant coliforms, and Escherichia coli and other microbiological indicators.

Total bacterial count: It is usually expressed as the logarithm of bacteria in 100ml of water sample. The national standard stipulates that the limit value is 100 cfu/ml. If the limit value is exceeded, the water sample is considered unqualified.

Total coliforms: The logarithm of total coliforms in 100ml of water sample is used to express. The national standard stipulates that the limit value is 3 per 100ml. If the limit value is exceeded, the water sample is considered unqualified.

Thermotolerant coliforms: The logarithm of thermotolerant coliforms in 100ml of water sample is used to express. The national standard stipulates that the limit value is 3 per 100ml. If the limit value is exceeded, the water sample is considered unqualified.

Escherichia coli: The logarithm of Escherichia coli in 100ml of water sample is used to express. The national standard stipulates that the limit value is 3 per 100ml. If the limit value is exceeded, the water sample is considered unqualified.

In summary, the detection methods and qualified judgment criteria for microbiological indicators are important bases for ensuring the safety of drinking water. With the development of science and technology, detection methods and judgment criteria are constantly being updated and improved. We should always pay attention to the changes in these standards to ensure the safety of drinking water. At the same time, we should also strengthen the protection of water sources, reduce pollution from the source, improve water quality, and safeguard people's health.