how to treat domestic sewage scientifically
sewage treatment catalogue [hidden ]
introduction to sewage treatment
classification of treatment degree
common treatment methods
sewage treatment facilities
sewage treatment in China
development of sewage treatment industry
sewage treatment technology
A company is carrying out sewage treatment (sewage treatment, was.
[Edit this paragraph] Introduction to sewage treatment
According to the classification of sewage sources, sewage treatment is generally divided into production sewage treatment and domestic sewage treatment. Production sewage includes industrial sewage, agricultural sewage and medical sewage, and domestic sewage is the sewage produced in daily life. Sewage treatment is widely used in construction, transportation, energy, petrochemicals, environmental protection, urban landscape, medical care, catering and other fields, and it has also entered the daily life of ordinary people more and more.
[Edit this paragraph] Classification of treatment degree
According to the classification of treatment degree, modern sewage treatment technology can be divided into primary, secondary and tertiary treatment.
primary treatment,
mainly removes suspended solid pollutants from sewage, and most physical treatment methods can only meet the requirements of primary treatment. After primary treatment, BOD can generally be removed by about 31%, which can not meet the discharge standard. Primary treatment belongs to the pretreatment of secondary treatment.
secondary treatment,
mainly removes colloidal and dissolved organic pollutants (BOD, COD) in sewage, and the removal rate can reach more than 91%, so that the organic pollutants can meet the discharge standards.
tertiary treatment,
further treatment of refractory organic matter, soluble inorganic matter such as nitrogen and phosphorus which can lead to eutrophication of water body. The main methods include biological nitrogen and phosphorus removal, coagulation and precipitation, sand ratio, activated carbon adsorption, ion exchange and electroosmosis analysis.
The whole process is that the raw sewage passing through the coarse grid is lifted by the sewage lifting pump, passes through the grid or the sieve separator, and then enters the grit chamber, and the sewage separated by sand and water enters the primary sedimentation tank, which is the primary treatment (i.e. physical treatment), and the effluent from the primary sedimentation tank enters the biological treatment device, including the activated sludge method and the biofilm method. Biofilm method includes biological filter, biological rotary table, biological contact oxidation method and biological fluidized bed). The effluent from the biological treatment device enters the secondary sedimentation tank, and the effluent from the secondary sedimentation tank is disinfected and discharged or enters the tertiary treatment. The primary treatment ends here as secondary treatment, and the tertiary treatment includes biological nitrogen and phosphorus removal, coagulation sedimentation, sand filtration, activated carbon adsorption, ion exchange and electrodialysis. Part of the sludge in the secondary sedimentation tank flows back to the primary sedimentation tank or biological treatment device, and part of it enters the sludge concentration tank, and then enters the sludge digestion tank. After the dehydration and drying device, the sludge is finally utilized.
[Edit this paragraph] Common treatment methods
1. Production wastewater
1. Treatment method of industrial sewage
A method for treating industrial sewage belongs to the technical field of sewage treatment. The method comprises the following steps of: leading sewage to a water collecting tank, adjusting the pH value of a grid at the end of the water collecting tank, lifting the sewage to a first-class pressure dissolved air tank by a first-class dissolved air pump, and simultaneously sucking air and a coagulation decoloring agent, so that the first-class saturated dissolved air water in the first-class pressure dissolved air tank is suddenly released to a first-class air flotation tank to form first-class treated water; The primary treated water overflows into the buffer pool, and then the primary treated water is lifted into the secondary pressure dissolved air tank by using a secondary dissolved air pump to control the pH, and air and coagulation decolorant are sucked in at the same time, so that the secondary saturated dissolved air water in the secondary pressure dissolved air tank is suddenly released into the secondary air flotation pool to form secondary treated water, which overflows to the sedimentation tank and is discharged after sedimentation; The floating mud in the primary and secondary air flotation tanks enters the floating mud tank, and is pressure-filtered into a filter cake, and the filtrate is led back to the water collection tank. The removal rates of CODcr, decolorization rate, SS and BOD5 of industrial sewage treated by this method are 81-91%, 95%, over 91% and 75-81% respectively, which meet the first-class water discharge standard of GB8978－1996.
2. Treatment methods of agricultural sewage
Because agricultural sewage is widely distributed and scattered, it is difficult to collect and treat, so pollutants can only be removed by biological action, such as directly throwing high-density efficient decontamination bacteria into polluted water bodies to achieve the purpose of purifying water.
3. Treatment methods of medical sewage
Hospital sewage treatment usually includes primary treatment and secondary treatment. Generally speaking, if the treated effluent is discharged into municipal sewers, only primary treatment is usually carried out; If the treated effluent is directly discharged into the river, it needs primary treatment and secondary treatment; How to deal with sewage in places with strict discharge standards?
?
The city where we live generally has two sets of pipe networks, namely rainwater and sewage, and some for fire fighting. Drinking water is separated from these. Sewage and rainwater are directly discharged into rivers or oceans after being purified by urban sewage treatment plants, or in some developed areas, the sewage from the treatment country can be reused, but it is only used for flushing toilets and washing cars.
What we drink or take a bath comes from the standard water source above Grade 2, and we won't let you drink it again.
how to treat domestic sewage
some measures or methods taken to make sewage reach certain standards after being treated by certain methods, such as being discharged into a water body, discharged into a water body or reused.
according to the treatment degree, modern sewage treatment technology can be divided into primary, secondary and tertiary treatment.
Primary treatment mainly removes suspended solid pollutants from sewage, and most physical treatment methods can only meet the requirements of primary treatment. After primary treatment, BOD can generally be removed by about 31%, which can not meet the discharge standard. Primary treatment belongs to the pretreatment of secondary treatment.
secondary treatment mainly removes colloidal and dissolved organic pollutants (BOD, COD) in sewage, and the removal rate can reach over 91%, so that the organic pollutants can meet the discharge standards.
Three-stage treatment, further treatment of refractory organic matter, soluble inorganic matter such as nitrogen and phosphorus, which can lead to water eutrophication. The main methods include biological nitrogen and phosphorus removal, coagulation and precipitation, sand ratio, activated carbon adsorption, ion exchange and electroosmosis analysis.
The whole process is that the raw sewage after coarse grid removal is lifted by the sewage lifting pump, passes through the grid removal or sieving device, and then enters the grit chamber, and the sewage after sand-water separation enters the primary sedimentation tank, which is the primary treatment (i.e. physical treatment). The effluent from the primary sedimentation tank enters the biological treatment device, including the activated sludge method and the biofilm method. Biofilm method includes biological filter, biological rotary table, biological contact oxidation method and biological fluidized bed). The effluent from the biological treatment device enters the secondary sedimentation tank, and the effluent from the secondary sedimentation tank is disinfected and discharged or enters the tertiary treatment. The primary treatment ends here as secondary treatment, and the tertiary treatment includes biological nitrogen and phosphorus removal, coagulation sedimentation, sand filtration, activated carbon adsorption, ion exchange and electrodialysis. Part of the sludge in the secondary sedimentation tank flows back to the primary sedimentation tank or biological treatment device, and part of it enters the sludge concentration tank, and then enters the sludge digestion tank. After the dehydration and drying device, the sludge is finally utilized.
energy consumption analysis of various treatment structures
1. Sewage lifting pump house
Sewage entering the sewage treatment plant enters the sewage lifting pump house through coarse grid deletion, and then is lifted to the forecourt of the grit chamber by the sewage pump. The implementation of water pump consumes a lot of energy, which accounts for a considerable proportion of the total energy consumption of sewage plant, which is related to the sewage flow and the lift to be improved.
2. grit chamber
the function of grit chamber is to remove inorganic particles with high specific gravity. The grit chamber is generally located in front of the pumping station and inverted siphon to reduce the abrasion of inorganic particles to the pumps and pipelines. It can also be installed in front of the primary sedimentation tank to reduce the load of sedimentation tank and improve the treatment conditions of sludge treatment structures. Commonly used grit chambers are advection grit chamber, aeration grit chamber, Dole grit chamber and bell grit chamber.
The sand-water separator and sand suction machine, as well as the aeration system of aerated grit chamber, the power system of Dole grit chamber and bell grit chamber are the main energy supplies in grit chamber.
3. Primary sedimentation tank
The primary sedimentation tank is the theme treatment structure of the first-level sewage treatment plant, or it is set in front of the biological treatment structure as the pretreatment structure of the second-level sewage treatment plant. The treated objects are SS and part of BOD5, which can improve the execution conditions of biological treatment structures and reduce their BOD5 load. The primary sedimentation tank includes advection sedimentation tank, radial sedimentation tank and vertical sedimentation tank.
The main energy consumption devices of the primary sedimentation tank are sludge discharge devices, such as chain belt sludge scraper, sludge scraper and sludge suction pump, etc. However, due to the influence of sludge discharge cycle, the energy consumption of the primary sedimentation tank is relatively low.
4. Biological treatment structures
The energy consumption of the sewage biological treatment unit process accounts for a considerable proportion of the direct energy consumption of the sewage plant, and the sum of the energy consumption of the sewage biological treatment unit process and the sludge treatment unit process accounts for more than 61% of the direct energy consumption of the sewage plant. The aeration of the aeration system of activated sludge process consumes a lot of electric energy, which is basically carried out in conjunction with high power, otherwise it will not achieve good aeration effect and poor treatment effect. The aerator installed in oxidation ditch treatment process is also a device with high energy consumption. Compared with activated sludge process, biofilm process has lower energy consumption, but it is seldom used at present, so it needs to be popularized in the future.
5. Secondary sedimentation tank
The capacity consumption of the secondary sedimentation tank is mainly in the pumping of sludge and the removal of floating objects indicated by sewage, and the energy consumption is relatively low.
6. Sludge treatment
In the sludge treatment process, the concentration tank, sludge dehydration and drying all consume a lot of electric energy, and the energy consumption of sludge treatment units is quite large, and the power consumption of these devices is very large.
Energy-saving approaches for various treatment structures
1. Sewage lifting pump house
Sewage lifting pump house should save energy mainly by considering sewage ...
How to treat daily sewage and where to discharge it?
Daily domestic sewage can be reused after being treated and processed by a sewage plant, which can be used as make-up water for water bodies, irrigating fields or discharging water for reuse.
1. Definition of domestic sewage:
It refers to the wastewater generated by urban institutions, schools and residents in their daily lives, including toilet manure, washing and bathing water, household drainage such as kitchens, and drainage from businesses, hospitals and amusement places.
2. Harmful substances in domestic sewage:
Domestic sewage contains a lot of organic substances, such as cellulose, starch, sugar and fat protein; It also often contains pathogenic bacteria, viruses and parasite eggs; Inorganic salts such as chloride, sulfate, phosphate, bicarbonate and sodium, potassium, calcium, magnesium, etc. The general feature is that it contains nitrogen, sulfur and phosphorus, and it is easy to produce malodorous substances under the action of anaerobic bacteria.
3. The activated sludge process for domestic sewage treatment includes:
(1) ordinary activated sludge process
(2) stage aeration activated sludge process
(3) extended aeration activated sludge process
(4) adsorption-regeneration activated sludge process
(5) completely mixed activated sludge process
(6) adsorption. Downstream rivers, lakes, beaches, etc. Discharging and receiving water is the most commonly used way after urban sewage treatment, but the discharged and treated water should meet the relevant national or local discharge standards, which may cause pollution to the receiving water body early.
(2) irrigate the fields. Irrigation of farmland can make full use of the treated water, but it must conform to GB5184-1992 "Water Quality Standard for Irrigation of Farmland" to avoid pollution of soil and crops.
(3) Reuse of discharged water. Reuse of discharged water is the most reasonable way out, which can not only effectively save and utilize limited precious fresh water resources, but also reduce the discharge of sewage and its pollution to the water environment. After secondary treatment and advanced treatment, urban sewage can be reused in a wide range, which can be provided to enterprises and factories for cooling water, and can also be reused for domestic miscellaneous purposes, such as landscape water, landscaping water, watering roads, flushing toilets and so on.
what are the main methods for treating domestic sewage?
Because the core of domestic sewage treatment is the biochemical part, we call the sewage treatment process specifically this part, such as contact oxidation method, SBR method and A/O method. At present, biochemical treatment of domestic sewage (including anaerobic and aerobic treatment) is the most economical and applicable sewage treatment process. Choosing different domestic sewage treatment methods according to the quantity, quality and site conditions of sewage has a decisive impact on investment and implementation cost.
for a long time, the secondary biological treatment of municipal domestic sewage mostly adopts activated sludge process, which is the most widely used secondary biological treatment process in the world at present, and has the advantages of high treatment capacity and good effluent quality. However, there are many problems, such as high capital construction cost, high implementation cost, high energy consumption, complicated management, easy sludge bulking and sludge floating, and the inorganic nutrients such as nitrogen and phosphorus cannot be removed.
natural biological purification treatment
natural biological purification treatment mainly utilizes the action of microorganisms in soil and plant roots or ponds to reduce the concentration of pollutants in water. The main advantages are: low investment (in the case of land acquisition fee of 11,111 yuan/hm), low implementation cost, simple management and few operators needed. Can be used alone, but also can form a combined processing system. Disadvantages: large floor space. The main treatment processes are as follows: domestic sewage-sedimentation-oxidation pond (land treatment)-rapid infiltration (full-speed infiltration, surface overflow)
artificial biological purification and natural biological purification
In towns with abundant land resources and relatively cheap land price, Runde suggests the combination of artificial biological purification and natural biological purification, which has practical significance in economically underdeveloped areas.
The main treatment processes are: domestic sewage-sedimentation-aeration oxidation pond-land treatment (agricultural irrigation). Both aeration oxidation pond and land treatment have the advantages of low execution cost, low energy consumption and simple management. Aerated oxidation pond can remove some N, P, bacteria and parasites.
in most small and medium-sized towns in northwest China, there are available land resources, and natural biological purification process should be strongly advocated to treat domestic sewage.
what are the treatment methods for domestic sewage?
Because the core of domestic sewage treatment is the biochemical part, we refer to the sewage treatment process as this part, such as contact oxidation method, SBR method, A/O method and so on. At present, biochemical treatment of domestic sewage (including anaerobic and aerobic treatment) is the most economical and applicable sewage treatment process. Choosing different domestic sewage treatment methods according to the quantity, quality and site conditions of sewage has a decisive impact on investment and implementation cost.
for a long time, the secondary biological treatment of municipal domestic sewage mostly adopts activated sludge process, which is the most widely used secondary biological treatment process in the world at present, and has the advantages of high treatment capacity and good effluent quality. However, it is common that the capital construction cost and implementation cost are high, and it can