Drinking water refers to water that is directly supplied to the human body for drinking without treatment. Water is the main component of body fluid, and it is an important substance that constitutes cells, tissue fluid, plasma and so on. As the medium of all chemical reactions in the body, water is a platform for transporting various nutrients and substances.
The national drinking water standard stipulates that the tds value is ≤≤1000 mg/l/L. The national standard GB5749-2006 Hygienic Standard for Drinking Water requires the limit of dissolved total solids (TDS) for drinking tap water: TDS ≤1000 mg/l.tds (total dissolved solids). TDS meter is designed for this purpose, which can see the ppm value of inorganic or organic matter in water.
Drinking water is from human birth to the end of 18.
1, original drink
/kloc-before the 0/9th century, human society was in the farming era, and there was no industrial pollution, only some microbial pollution. The water in rivers and lakes can meet people's drinking water demand after heating. Therefore, the earliest humans directly took water from mountain springs, rivers and other water sources for drinking.
Later, human beings discovered fire and gradually developed to use fire to boil water and drink boiled water. This can kill harmful microorganisms in water by heating. This is the most primitive and effective method for human beings to deal with microbial pollution in water.
2. Simple precipitation
After agricultural civilization, people gradually found in their life and work that when water is poured into a water tank and left standing for a period of time, the sediment, particles and suspended matter in the water will gradually settle down, and the clear water on it can be used for drinking.
Later, it was found that adding some substances (alum) to water can make it dissolve in water and produce flocculation, thus further precipitating fine suspended solids and colloids in water, thus making the upper water clearer and then taking it for drinking.
Principle of alum water purification
Alum is dissolved in water to generate Al3+, and Al3+ combines with OH generated by water to generate aluminum hydroxide. The colloidal particles of aluminum hydroxide are positively charged, and their charges are neutralized when they meet negatively charged sediment colloidal particles. The charged colloidal particles will soon get together, and the particles will get bigger and bigger, and finally sink to the bottom of the water. In this way, the water becomes clear and clean.
Later, it was found that aluminum contained in alum was harmful to human body. Drinking alum purified water for a long time may lead to Alzheimer's disease. Therefore, alum is no longer advocated as a water purifier.