The term "reclaimed water" is relative to that of water supply and drainagedrainage].Reclaimed water reuse technology refers to the centralized treatment of domestic waste water (bath, toilet, laundry, kitchen, toilet) of residents in the community, and the reuse of it to a certain standard for greening irrigation, vehicle washing, road washing, householdpedestal panFlushing, etc. to achievewater savingThe purpose of.
Reclaimed water reuse isSewage recyclingAnd can effectively solve the problem of water shortage.[1]
Wastewater reuseIt 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,rate of recoveryRelatively less than 75%, not used for greening irrigation, vehicle washing, road washing, familypedestal panFlushing, etc.
Reuse water: both of the above can be called reuse water, but generally, manufacturers will combine them to improve the recovery rate.
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 directly reuse it in daily life, that is, to realize direct recycling of water resources. This treatment method is suitable for areas where water resources are extremely scarce, but with high investment and complex process;
2. The other is to treat it to the standard of non drinking water, which is mainly used to prevent human bodydirect contact Water, such as toilet flushing, groundCar cleaning, green sprinkling, fire fighting, industrial common water, etcReclaimed water treatmentMode.
3. In industry, the reclaimed water reuse technology can be used to treat industrial sewage that meets the discharge standardReprocessing, usually addSoftener, RO, EDI/mixed bed and other equipmentWater softening，Purified water, ultra pure water level, which can be recycled in industry to save capital,protect the environmentThe purpose of.
According to treatment methods, reclaimed water treatment processes are generally divided into three types:
1. Physical treatment:
Membrane filtration, applicable to the situation where the water quality changes greatly.
The characteristics of this process are: compact device, easy operation, and little influence by load change.
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 rateInorganic ionPenetrate from high-pressure sideFilter membraneEnter the low-pressure side and discharge it as filtrate;In the solutionHigh molecular substances, colloidal particles and microorganismsultrafiltration membraneInterception, the solution is concentrated and discharged in the form of concentration.
This process is characterized by high stability, easy maintenance, long service life, simple operation, and no impact on equipment operation due to water quality fluctuations.
The evaporation heat method is to separate pure water andsaltSolids and pure water are condensed into pure water in the form of steam, and the concentrated solution forms salt solids through continuous circulating evaporation.Pure water quality can be reused through a series of filtration and other measures.
It is applicable to sewage with high organic content.Generally adoptedActivated sludge process、Contact oxidation、Biological turntableAnd other biological treatment methods.It can be used alone or combined with several biological treatment methods, such as contact oxidation+Biological filter；Biological filter+activated carbon adsorption;Rotary table ten sand filtration and other processes.This process is adaptableHydraulic loadIt has the advantages of strong changeability, less sludge production, easy maintenance and management, etc.
Currently, due to somecountries and regions At the same time of excessive and uncontrolled development of water resources, the awareness of environmental protection is relatively poor, causing surface water and groundwater to be polluted to varying degrees, limiting the supply of fresh water with good quality;Secondly, the fresh water source to be developedCentralized water supplyThe distance between the points is far, and the one-time investment cost is high, so some water shortage areas are unable to expand their water supply capacity.To the extent of non drinking, the concept of reclaimed water is introduced here.Reclaimed water refers to high-quality miscellaneous drainage (excrement and kitchen drainage excluded) and miscellaneous drainage (exclFecal sewage）And domestic sewage (waste)Water channelAfter the collection and regeneration treatment, it can be reused to serve as miscellaneous water for ground cleaning, flower watering, car washing, air conditioning cooling, toilet flushing, fire fighting and other purposes that are not in direct contact with the human body.Because ofWater quality indexlower thanUrban water supplyinDrinking water quality standard, but it is higher than sewage and is allowed to be discharged into surface water bodyemission standard, that is, its water quality isDrinking WaterIt is between the water quality standard and the allowable sewage quality standard, so it is called "reclaimed water".
Reclaimed water development and reuse technology has developed rapidly, and has been widely used in the United States, Japan, India, Britain and other countries (especially Japan).These countries have determined the reclaimed water reuse technology suitable for their national conditions and strength based on the characteristics of their own countries and regions, making the reclaimed water reuse technology more and more perfect.In China, this technology has attracted the attention of governments at all levels and relevant departments, and has done a lot of theoretical research and practical work on building reclaimed water reuseQingdaoTianjinTaiyuanAnd so onReclaimed water engineeringIt has achieved remarkable results.China's state-owned industrial enterprises and some private enterprises, such as enterprises with serious pollution and more water resources utilization, have built reclaimed water reuse projectsLow carbon productionandconserve energy ,reduce emissionsAnd made contributions.
In the field of membrane science and technologyOrganic membraneThis kind of membrane is easy to prepare, easy to form, good in performance and cheap in price, and has become the most widely usedMicrofiltration membraneType.But withMembrane separation technologyThe development of its application puts forward higher and higher requirements for the use conditions of membranes. It is necessary to develop a membrane solid-liquid separation system under extreme conditions. Compared with organic membranes, inorganic ceramic membranes have high temperature resistancechemical stabilityGood, acid resistant, alkali resistant, and resistantOrganic solventHigh mechanical strength, reverse flushing, strong anti microbial ability, strong cleanabilityPore size distributionNarrow, high permeability,Membrane fluxHigh separation performance and long service life.
There are two main obstacles to the application of inorganic ceramic membrane in water treatment. One is that the manufacturing process is complex, the cost is high, and the price is expensive;The second is membranefluxProblems can only be overcomemembrane foulingOnly by improving the filtration flux of membrane can it be truly popularized and applied to all fields of water treatment.
The polyester bait DEAR inorganic ceramic membrane system developed by Seattle Environmental Science and Technology Co., Ltd. is based on the research of ordinary ceramic membrane. Through high-tech transformation, it reduces membrane pollution, greatly improves membrane flux, effectively overcomes the main problems of the application of inorganic ceramic membrane in water treatment, and makes the application of inorganic ceramic membrane in water treatment possible.
2、 Features
(1) Unique double-layer membrane structure: polyester bait DEAR inorganic ceramic membrane systemMembrane filtrationLayer surface, throughSoloneGel methodpreparationTiO2Sol, coated on ceramic membrane by dip coatingnanometerTiO2Photocatalytic materialsTo make the ceramic membrane surface have the function of "self-cleaning", slow down the accumulation and blockage of organic on the membrane surface, on the one hand, reduce membrane pollution, on the other hand, improve the strength of ceramic membrane tubes and membrane filtration flux, and improve the stability of membrane flux;Al2O3—ZrO2composite membraneStructure: make membrane tubeMechanical propertiesMore excellent. Due to the performance defects of the material itself or some practical problems in the preparation process, a single inorganic membrane material generally cannot meet the actual needs, so inorganic loading compositeSeparation membraneThe development of polyester bait DEAR inorganic ceramic membrane has developed rapidlySol gel methodAl2O3-ZrO2 composite films are prepared. Because the materials containing ZrO2 have bettermechanical strength, ChemistryDurabilityAnd alkali resistance, polyester bait DEAR®;Inorganic ceramic membrane has stronger mechanical strength andthermal stabilityAnd the pore size distribution of the composite membrane is narrow, showing a single peak.
(2) Online backwash and stable membrane flux can be realized: due to the unique structure and mechanical properties of the composite ceramic membrane, it can effectively withstand the backwash pressure below 0.4mp, which can realize online backwash, thus obtaining stable membrane flux and overcoming inorganicMembrane systemThe problems of high price, easy pollution, small membrane flux and huge equipment in water treatment applications make the application of inorganic ceramic membrane system in water treatment possible.The polyester bait DEAR inorganic ceramic membrane is specially designed for sewage treatment. Its biggest feature is that the membrane flux is large, and its running membrane flux is 10-100 times, 50-10 times of ordinary porous ceramic membrane, high mechanical strength, pollution resistance, and online backwash.
3、 Main technical parameters
film Thickness: 50-60 μ m, membrane aperture 0.01-0.5 μ m;
2. Satisfy people's sense requirements, that is, feel happy.Its measurement indicators mainly include turbiditychroma, odor, etc.
3. Meet the requirements of equipment structure, that is, the water quality is not easy to cause serious corrosion and scaling of equipment and pipelines.Its measurement indicators include pH value, hardness, evaporation residueSolubilitySubstance, etc.
China's research on reclaimed water is more and more in-depth, to ensure reclaimed water as a lifeMiscellaneous waterIn 1989, the Water Quality Standard for Miscellaneous Domestic Water (CJ25.1-89) was officially promulgated.
System classification
Announce
edit
Reclaimed water treatmentRecycling systems generally fall into the following four categories according to the scope and scale of their supply:
The reclaimed water source of the system is taken from miscellaneous water andHigh quality miscellaneous drainage。The drainage will be used for flushing toilets, washing vehicles, greening, etc. in the building after being collected and treated.The treatment facilities can be located inside or near the outside of the building according to conditions.Such as Beijing NewWanshou HotelReclaimed water treatment equipmentIt is located in the basement.
2、 Incomplete drainage facilities
Urban drainageWater treatment facilities in areas with imperfect systems cannot reachSecondary treatmentStandard, reuse of reclaimed water can reduce the re pollution of sewage to local rivers.The water source of the system is taken from the flexible drainage purification pool of the building (such asSedimentation tank, septic tankOil removal tankEtc.), the water in the pool is totaldomestic sewage。The system processing facilities can be set indoors or outdoors according to conditions.
3、 Small area buildings
The reclaimed water source of the system is from theMiscellaneous drainage。This system can be used in buildingsResidential quarters, schools and government organizations.Its processing facilities are located in the community.
Brief Introduction of Reclaimed Water Reuse Technology
It is characterized by the use of various physical, chemical, biological and other means to treat industrial wastewater in different depths to achievetechnological requirementsAnd then used in the process to save water resources and reduce environmental pollution.Here are two main recycling technologies:
During cooling, especially duringchemical industryMedium, if usedDirect coolingThe method of indirect cooling can overcome this shortcoming.
2. Reduce cooling requirements and cooling water consumption.
3. Non water cooling is adopted.
For example, in certain process productionAir coolingOr oil cooling to achieve the purpose of cooling.
4. Using laborCold sourceOr seawater can be used as cooling water to reduce the use of groundwater or fresh water.
5. Make rational use of cooling water.
The used cooling water can be repeatedly used after certain cooling measures are taken, or it can be used for other occasions with low requirements for water quality and temperature after being used as cooling water for the first time.
When adopting this method, attention should be paid to each workshopWater supply systemTo strengthen the management of cooling water and avoid affecting the water supply of other workshops due to problems in one link.
6. Recycling of cooling water
This cooling water utilization technology is mainlycoolerThe transformed hot water is cooled down to the temperature of recycled water through the cooling structure for recycling.
When the cooling water is recycled, attention should be paid to the propagation of bacteria in the water, the formation of scale, equipment corrosion, water pressure, water volume changes and other issues.
（2） One water for multiple purposes Sewage purification
becauseProduction processThe water quality standards of each link in are different, so the water in some links will be treated appropriatelyreuseOr used in other links that do not require high water quality.So as to achieve the purpose of water saving.For example, clean water can be used as cooling water first, and then sent to the water treatment station for softeningboiler water supplyUse.cityCentralized sewage treatmentIt can be used in production and life.
Examples of reclaimed water reuse technology
Here is a brief introduction to water in life.
The domestic water mainly refers to the domestic sewage, after being treated and reaching the use standard, used for toilet flushing, greening, landscape, road spraying, cooling water supplement and other miscellaneous purposes.The quality of reclaimed water shall meet the Water Quality Standard for Miscellaneous Domestic Water.
1. Reclaimed water source
When selecting reclaimed water, high-quality miscellaneous drainage shall be selected first, which can be generally selected in the following order:
A、Cooling water B, shower drainage C, toilet drainage D, laundry drainage E, kitchen drainage F, toilet drainage
2. Treatment process
When high-quality miscellaneous drainage and miscellaneous drainage are used as the source of reclaimed water, physical and chemical treatment can be adoptedtechnological process, or adoptbiological treatmentAnd the process flow of physical and chemical treatment.
When domestic sewage is used as the source of reclaimed water, the second stage can be usedbiological treatmentOr biological treatment combined with physical and chemical treatment.
3. Regulations on Reclaimed Water Design and Construction
allConstruction ProjectShould be designed as requiredReclaimed water facilitiesThe following construction projects must be designed and constructed with supporting reclaimed water facilities:
A、Guest (tourist) hall, hotel, shop, apartment, comprehensiveService buildingandHigh-rise residentialThe construction area of such buildings is more than 20000 square meters.B. Institutions, scientific research institutions, colleges and universities and large-scale comprehensive cultureSports facilitiesThe building area is more than 30000 square meters.
C、The planned population of the residential quarter is more than 30000 (or the reclaimed water reuse amount is more than 750 m3/day).
For unificationurban sewage The reclaimed water can be reused as the quality of miscellaneous domestic water, so as to make use of sewage resources and ensure the safety and applicability of miscellaneous domestic waterReclaimed water reuse standard。
This standard is applicable to toilet flushingThe greening of the city, car washing, sweeping and other domestic miscellaneous water is also applicable to water for other purposes with the same water quality requirements.
This standard is implemented by urban planning, design, operation management of domestic miscellaneous water supply and other relevant units.The competent department of the domestic miscellaneous water supply unit shall be responsible for supervising and inspecting the implementation.
This standard is formulated for the regeneration and reuse of local urban sewage as domestic miscellaneous waterWater quality standardsBased on this standard, local governments can formulate local water quality standards for municipal wastewater reclamation and reuse as domestic miscellaneous water according to local characteristics.Local standardsIt shall not be wider than or in conflict with this Standard;In case of special circumstances, it is more lenient than thisStandard timeReportableMinistry of Constructionapproval.The project indicators included in the local standards shall be implemented;The project indicators not listed in the local standards are still subject to this standard.
Water quality standards and requirements
Domestic miscellaneous water pipes, water tanks and other equipment shall not be directly connected with tap water pipes and water tanks.The external surface of domestic miscellaneous water pipes, water tanks and other equipment shall be painted lightlyGreen signTo avoid accidental drinking and misuse.
The domestic miscellaneous water supply unit shall continuously strengthen the management of miscellaneous water treatment, water collection, water supply, metering, testing and other facilities, establish effective drainage, cleaning, disinfection and maintenance systemsOperating ProceduresTo ensure the quality of water supply.
GB/T18920-2002
project
Flushing the toilet
Road cleaning and fire fighting
The greening of the city
Vehicle washing
Building construction
PH
6.0~9.0
Color/degree ≤
thirty
Smell
No unpleasant feeling
Turbidity/NTU ≤
five
ten
ten
five
twenty
Total soluble solids (mg/L) ≤
one thousand and five hundred
one thousand and five hundred
one thousand
one thousand
-
Five day biochemical oxygen demand (BOD5)/(mg/L) ≤
ten
ten
twenty
ten
fifteen
Ammonia nitrogen (mg/L) ≤
ten
ten
twenty
ten
twenty
Anionic surfactant (mg/L) ≤
one
one
one
zero point five
one
Iron (mg/L) ≤
zero point three
-
-
zero point three
-
Manganese (mg/L) ≤
zero point one
-
-
zero point one
-
Dissolved oxygen (mg/L) ≤
one
Total residual chlorine (mg/L)
≥ 1.0 after 30min contact, ≥ 0.2 at the end of pipe network
The inspection method of water quality shall be in accordance with the Standard Inspection Method for Domestic Miscellaneous Water.
Domestic miscellaneous waterCentralized water supply The unit must establish a water quality inspection room, which is responsible for inspecting the water quality of the inlet and outlet of the sewage regeneration facilities, as well as the outlet water and pipe network water.
