Up to now, although the water pollution incident of Song Da Water Plant has passed, the Hanoi People's Committee as well as the functional agencies have proposed many measures to ensure the security and safety of water sources, ensuring the safety of water sources. water quality before reaching users such as establishing an important department, installing a camera system to monitor, monitor, detect and promptly handle impacts affecting water sources, upgrading the quality of water quality testing equipment... However, the above measures have not mentioned an equally important stage in the production of domestic water, which is the use of alum as a coagulant. so that the right type ensures absolute safety for people's health.
In Vietnam, there are more than 300 production and domestic water supply plants distributed across 64 cities, large domestic production plants are concentrated mainly in big cities such as Hanoi, Ho Chi Minh City, Da Nang, Hai Room, Binh Duong, Dong Nai, Can Tho... In which most of the factories are applying water treatment technology including steps of alum, sedimentation, disinfection, etc. to produce domestic water, as shown in the diagram. down here:
In the process of treating raw water into domestic water, it is indispensable to make domestic water, ie reduce turbidity, separate suspended residues before disinfection and supply to consumers. This process in scientific language is called coagulation. Coagulation is the process of removing extremely small insoluble lice that are suspended in water. It is thanks to the coagulant that is single alum, alum PAC (Poly Aluminum Chloride) will bind these impurities together into larger and heavier flocs, which will then settle into slurry and be decanted. out of the water. Acacia cotton will pull a lot of other organic impurities, including heavy metals, so this chemical is considered an indispensable ingredient in the water treatment process to purify water as well as reduce its content. impurities harmful to the user.
Figure 1: Sedimentation tank system of Thu Duc - HCM water treatment plant
With the preeminent characteristics of Alum PAC, most domestic water production plants in Vietnam have used Alum PAC in the water purification stage to turn cloudy water into clear water. Most of the Alum PAC used at the factories is imported from China due to its low price. However, the quality of Alum PAC imported from China is a matter of great concern, especially since many factories are using low quality Alum PAC (standard GB-T 22627-2008 issued by China) used for waste water treatment instead of using high quality Alum PAC (standard GB 15892-2009 issued by China) for domestic wastewater treatment.
