Basic concepts of water treatment
Water treatment includes sewage treatment and drinking water treatment. In some places, sewage treatment is subdivided into two types, namely sewage treatment and reclaimed water reuse. Commonly used water treatment chemicals are: polyaluminum chloride, polyaluminum ferric chloride, basic aluminum chloride, polyacrylamide, activated carbon and various filter materials.
The effect of water treatment can be measured by water quality standards.
The process of processing raw water (raw water) in order to meet the water quality requirements of finished water (domestic water, production water or dischargeable wastewater).
When processing raw water for domestic or industrial use, it is called water supply treatment;
When processing wastewater, it is called wastewater treatment. The purpose of wastewater treatment is to discharge (discharge into water bodies or land) or reuse (see wastewater treatment, wastewater reuse).
In the recycling water system and water regeneration treatment, the raw water is wastewater, and the finished water is water. The processing process has the properties of both water supply and wastewater treatment. Water treatment also includes the treatment and final disposal of wastewater and sludge generated during the treatment process (see sludge treatment and disposal), and sometimes the treatment and discharge of waste gas. Water treatment methods can be summarized in three ways: ①The most commonly used is to obtain the required water quality by removing some or all of the impurities in the raw water; ②The required water quality is obtained by adding new components to the raw water through physical or chemical reactions. Water quality; ③The processing of raw water does not involve the problem of removing impurities or adding new ingredients.
Impurities in water and treatment methods Impurities in water include entrained coarse substances, suspended matter, colloids and dissolved matter. Coarse materials such as floating plants in the river, garbage, large aquatic organisms, gravel in wastewater, and large dirt. In the water supply project, the coarse impurities are removed by the facilities of the water intake structure and are not included in the scope of water treatment.
In wastewater treatment, the removal of coarse impurities generally belongs to the pretreatment part of water. Suspended substances and colloids include sediment, algae, bacteria, viruses, and insoluble substances that are originally in the water and produced during the water treatment process. Dissolved substances include inorganic salts, organic compounds and gases. There are many treatment methods to remove impurities in the water, and the scope of application of the main methods can be roughly divided according to the particle size of the impurities (Figure 1). Since the impurities contained in the raw water and the permissible impurities in the finished water are very different in type and concentration, the water treatment process is also very different.
As far as domestic water (or urban public water supply) is concerned, raw water taken from high-quality water sources (well water or well-protected water supply reservoirs) can be treated as finished water as long as it is disinfected; raw water taken from general rivers or lakes, first Removal of muddy impurities such as sediment and then disinfection; more polluted raw water requires removal of organic matter and other pollutants; raw water containing iron and manganese (such as some well water) requires removal of iron and manganese. Domestic water can meet the water quality requirements of general industrial water, but industrial water sometimes requires further processing, such as softening and desalination.
When the wastewater discharge or reuse water quality requirements are low, only need to use screening and sedimentation methods to remove coarse impurities and suspended solids (often called primary treatment); when the removal of organic matter is required, it is generally used after the primary treatment Biological treatment method (often referred to as secondary treatment) and disinfection; the treatment process for wastewater after biological treatment is collectively referred to as tertiary treatment or advanced treatment, such as removal when the wastewater is discharged into the water body to prevent eutrophication The process of nitrogen and phosphorus belongs to the tertiary treatment (see the physical and chemical treatment of water). When wastewater is used as a water source, the quality of the finished water and the corresponding processing flow depend on its use. In theory, modern water treatment technology can produce any high-quality finished water from any poor-quality water.
与此原文有关的更多信息要查看其他翻译信息，您必须输入相应原文
Article Keywords: