Reclaimed water reuse system

DAWT·2022-05-09

System Introduction

The term "reclaimed water" is relative to the upper water [water supply] and the lower water [drainage]. Reclaimed water reuse technology refers to the centralized treatment of residential waste (sewage) water (bathing, toilet, laundry, kitchen, toilet), and reuse it to a certain standard for greening, vehicle washing, road washing, family Toilet flushing, etc., so as to achieve the purpose of saving water. Wastewater reuse is usually confused with reclaimed water reuse, but it is different. Wastewater reuse refers to the recycling of industrial wastewater to the production line through the UF+RO process. If it is recycled, the recovery rate is relatively lower than 75%, and it is not used for greening and irrigation. , vehicle flushing, road flushing, household toilet flushing, etc.

Solution

1. Classification by use

There are three treatment methods for reclaimed water due to different uses

1. One is to treat it to the standard of drinking water and reuse it directly in daily life, that is, to realize the direct recycling of water resources. This treatment method is suitable for areas where water resources are extremely scarce, but the investment is high and the process is complicated;

2. The other is to treat it to the standard of non-drinking water, which is mainly used for water that is not in direct contact with the human body, such as toilet flushing, floor, car cleaning, greening, firefighting, industrial ordinary water, etc. The usual way of water treatment.

3. In industry, the reclaimed water reuse technology can be used to reprocess the industrial sewage that meets the discharge standard. Generally, equipment such as softener, RO, EDI/mixed bed and so on will be added to make it reach softened water, purified water, and ultrapure water. At the same time, industrial recycling can be carried out to achieve the purpose of saving capital and protecting the environment.

2. Classification by processing method

According to the treatment method, the reclaimed water treatment process is generally divided into 3 types:

1. Physical treatment:

Membrane filtration is suitable for situations where the water quality changes greatly.

The characteristics of using this process are: the device is compact, easy to operate, and less affected by load fluctuations.

The membrane filtration method is that under the action of external force, the separated solution flows along the surface of the filter membrane at a certain flow rate, and the solvent, low molecular weight substances and inorganic ions in the solution pass through the filter membrane from the high pressure side and enter the low pressure side, and are discharged as filtrate. ; And the macromolecular substances, colloidal particles and microorganisms in the solution are intercepted by the ultrafiltration membrane, and the solution is concentrated and discharged in a concentrated form.

Evaporative heat method: applicable to any water quality.

The characteristics of using this process are: high stability, easy maintenance, long service life, simple operation, and will not affect equipment operation due to water quality fluctuations.

The evaporative heat method is to separate pure water and salt solids when the solution reaches the boiling point in the evaporating body by heating and evaporating. Pure water quality can be reused through a series of filtration and other measures.

2. Physical Chemistry:

3. Biological treatment

It is suitable for sewage with high organic content. Generally, biological treatment methods such as activated sludge method, contact oxidation method, and biological turntable are used. Either used alone or in combination of several biological treatment methods, such as contact oxidation + biological filter; biological filter + activated carbon adsorption; rotary disc ten sand filtration and other processes. This process has the advantages of strong adaptability to hydraulic load changes, less sludge production, and easy maintenance and management.

At present, due to the excessive and uncontrolled development of water resources in some countries and regions, while the awareness of environmental protection is relatively poor, both surface water and groundwater have been polluted to varying degrees, and the supply of fresh water with good water quality has been affected. Second, the fresh water source to be developed is far away from the centralized water supply point, and the one-time investment cost is high, so some water-scarce areas cannot expand the water supply capacity. To the extent of non-drinking, the concept of reclaimed water is introduced here. Reclaimed water is the reuse of high-quality miscellaneous drainage (excluding feces and kitchen drainage), miscellaneous drainage (excluding fecal sewage) and domestic sewage (waste) water used by people in life and production after collecting and recycling. It can be used as miscellaneous water that is not in direct contact with the human body, such as floor cleaning, watering flowers, car washing, air conditioning cooling, toilet flushing, fire fighting, etc. Because its water quality index is lower than the drinking water quality standard of urban water supply, but higher than the discharge standard of sewage that is allowed to be discharged into surface water bodies, that is, its water quality is between the water quality of domestic drinking water and the water quality standard of allowable discharge of sewage, so it is named &ldquo ; reclaimed water”.

Reclaimed water development and reuse technology has developed rapidly and has been widely used in the United States, Japan, India, the United Kingdom and other countries (especially Japan). These countries have determined the reclaimed water reuse technology suitable for their national conditions and national strength according to their national and regional characteristics, making the reclaimed water reuse technology more and more perfect. In China, this technology has been valued by governments at all levels and relevant departments, and a lot of theoretical research and practical work have been done on the reuse of reclaimed water in buildings. The operation of the project has achieved remarkable results. my country's state-owned industrial enterprises and some private enterprises, such as enterprises with serious pollution and more water resources, have built reclaimed water reuse projects, which have contributed to the national call for low-carbon production and energy conservation and emission reduction.