CN109455886B - Municipal road sewage treatment method and system - Google Patents

Abstract

The invention relates to a municipal road sewage treatment method and a municipal road sewage treatment system. The sewage is filtered by a grating machine, primary precipitation is carried out in a primary sedimentation tank, hydrolysis reaction is carried out in an alkali liquor tank, the pH adjusting tank is adjusted to be neutral, biodegradation is carried out in an oxidation ditch, secondary precipitation is carried out in a secondary sedimentation tank, and disinfection and sterilization are carried out in a contact disinfection tank, so that the sewage is finally changed into the purified water which can be directly discharged. The invention has the effect of effectively removing oil stains, tire dust and other organic pollutants in road sewage.

Description

Municipal road sewage treatment method and system

Technical Field

The invention relates to the technical field of municipal sewage treatment, in particular to a municipal road sewage treatment method and system.

Background

A municipal rainwater trunk pipe is arranged below the municipal road, and sewage in fine days along the road and rainwater in rainfall can enter the rainwater trunk pipe below the municipal pipeline from a rainwater inlet beside the municipal road and then are directly discharged to a natural water body.

Generally, due to the frequent running of vehicles on roads, the roads usually accumulate oil stains, tire dust and other organic dirt. When raining, the pollutants enter the rainwater inlet along with rainwater and reach the rainwater main pipe, and finally enter the natural water body through the rainwater main pipe, so that the natural water body is seriously polluted. Moreover, as the range of human activities is getting larger and larger, organic pollutants such as nitrogen and phosphorus generated in the production process of human beings are easy to accumulate on the road surface, and the organic pollutants enter the rainwater trunk pipe below the municipal road along with rainwater and finally enter the natural water body to eutrophicate the water body, so that the normal growth of animals and plants in the water body is not facilitated.

A patent with publication number CN106927586A discloses an urban rainwater sewage purification system and a method for purifying water by the same. This urban rainwater sewage treatment system sets up in urban green belt's rainwater sewer, and this urban rainwater sewage treatment system includes: ecological filter layer, purifying well, sewer; ecological filter layer and purification well are located the top of sewer, and ecological filtering ponds set up in around the purification well outside, the purification well with the sewer intercommunication, just the pipeline of sewer stretches into the bottom center of purification well, the pipeline mouth of sewer is higher than the rest of purification well bottom, forms the recessed groove between the inner wall of purification well and closing of sewer.

Urban rainwater sewage among the above-mentioned prior art scheme is through on the lawn, the road collects the back and flows into the metalling, get into the metalling prefiltering back and flow into and purify the well the inside, purify the well and filter the filtration back inflow purification well of prefiltering the sewage of handling through the filtration pore of crossing of water purification case, through the absorption and the filtration of purifying well inside active carbon (or gravel), flow into the water storage district after the secondary filtration, the water in water storage district flows into outlet conduit after deposiing and discharges into river aquatic, realizes sewage purification and utilizes.

The above prior art solutions have the following drawbacks: urban rainwater sewage is only filtered twice, liquid pollutants and dust particles in the urban rainwater sewage cannot be removed through filtering, and oil stains, tire dust and other organic dirt in the urban rainwater sewage are finally discharged into river water directly to cause water pollution.

Disclosure of Invention

The invention aims to provide a municipal road sewage treatment method and a municipal road sewage treatment system, which have the effect of effectively removing oil stains, tire dust and other organic pollutants in road sewage.

The technical purpose of the invention is realized by the following technical scheme:

a municipal road sewage treatment method comprises the following steps:

step 1, filtering by using a grating, namely conveying municipal road sewage through a grating machine to filter the municipal road sewage; step 2, primary precipitation, namely discharging the municipal road sewage filtered by the grating machine into a primary precipitation tank, and performing precipitation treatment for 3-6 hours; step 3, alkaline hydrolysis, namely conveying the municipal road sewage on the upper layer of the primary sedimentation tank into an alkaline liquid tank, and hydrolyzing the municipal road sewage for 2-3 hours under an alkaline condition; step 4, pH adjustment, namely conveying the municipal road sewage in the alkali liquor tank to a pH adjusting tank, and adjusting the pH range to 7-8; and 5: biodegradation, namely conveying municipal road sewage in the pH adjusting tank into an oxidation ditch for reaction for 2-4 hours; step 6: secondary sedimentation, namely conveying the municipal road sewage which is completely reacted in the oxidation ditch to a secondary sedimentation tank, and standing and settling for 2-4 hours; and 7, sterilizing, namely conveying the municipal road sewage on the upper layer of the secondary sedimentation tank into a contact sterilization tank, and sterilizing for 2 hours. And 8: and (4) discharging purified water, wherein the municipal road sewage subjected to the disinfection and sterilization treatment in the contact disinfection tank is changed into purified water, and the purified water is directly discharged into a natural water body.

By adopting the technical scheme, municipal road sewage enters the sewer line through the rainwater openings at two sides of the road, and the sewage in the sewer line is primarily filtered by the grating machine to remove large-size solid impurities in the sewage; conveying the sewage filtered by the grating machine to a primary sedimentation tank for primary sedimentation, so that solid impurities in the sewage with smaller size are settled through the grating machine, and further removing the solid impurities in the sewage;

the sewage on the upper layer of the primary sedimentation tank is conveyed into the alkali liquor tank, and under the alkaline environment in the alkali liquor tank, ester organic matters, organic acid, ester auxiliaries in rubber dust and other components in the sewage are subjected to hydrolysis reaction or neutralization reaction, so that macromolecular polyester substances can be decomposed into fatty acid salts and alcohols with smaller molecular weight and more quantity, and the degradation efficiency of microorganisms in an oxidation ditch on the organic matters is improved;

in addition, micropores can be formed on the rubber dust after the ester auxiliary agent in the rubber dust undergoes hydrolysis reaction, so that the rubber dust is changed into microporous granular dust, and when the microporous granular dust is subjected to oxidative decomposition in an oxidation ditch, microorganisms and remaining organic pollutants are more favorably adsorbed on the rubber dust, so that the degradation efficiency in the oxidation ditch is improved;

the oxidation ditch is an activated sludge treatment system, an aeration tank of the oxidation ditch is in a closed ditch shape, so the system is different from the traditional activated sludge method in the hydraulic flow state, the oxidation ditch is a circulating aeration ditch which is connected end to end, the oxidation ditch not only applies a biological treatment method to oxidize and degrade various complex organic matters in sewage into simple substances, but also has high-efficiency dephosphorization and denitrification capability, thereby being capable of efficiently degrading complex organic matters and nitrogen and phosphorus compounds in the sewage, and the sewage treatment is more thorough.

After the sewage is subjected to the microbial oxidation degradation in the oxidation ditch, the sewage is subjected to secondary sedimentation and disinfection and sterilization treatment, so that residual solid impurities and bacteria toxic substances in the sewage can be removed more thoroughly, and the obtained purified water is better in purity and more environment-friendly.

More preferably: the step 1 of filtering the grids comprises coarse grid filtering and fine grid filtering, and municipal road sewage is firstly subjected to coarse filtering through the coarse grids and then is conveyed to the fine grids for fine filtering.

Through adopting above-mentioned technical scheme, the town road sewage that is carried from sewer line filters through thick grid earlier, gets rid of in the sewage by the solid-state rubbish that is washed into in the sewer line, then carries sewage to thin grid and carries out the fine filtration, further gets rid of the great graininess solid-state impurity of size in the sewage, and the two-stage of grid machine is filtered can get rid of the great solid-state impurity of size more thoroughly, conveniently carries out subsequent pollutant removal to sewage and handles.

More preferably: and 3, adopting a mixed solution of calcium hydroxide and sodium hydroxide as the alkali liquor in the alkali liquor tank in the step 3, wherein the molar fraction ratio of the calcium hydroxide to the sodium hydroxide is 1: 1.5.

By adopting the technical scheme, the alkali liquor in the alkali liquor pool is formed by mixing and dissolving sodium hydroxide and calcium hydroxide, the sodium hydroxide and the strong calcium oxide can provide strong alkaline conditions, the raw materials are easy to obtain, and the cost is low. The fatty acid radicals in the oil stain or the fatty acid radicals obtained by hydrolyzing the ester auxiliary agent in the rubber dust are usually polymers and have longer carbon chains, and the fatty acid radicals with the long carbon chains are combined with calcium ions to form fatty acid calcium precipitates which are insoluble in water, so that organic pollutants in the sewage can be further removed, the degradation load of organic matters in an oxidation ditch is reduced, and the effect of removing the organic pollutants in the sewage is good.

More preferably: the disinfectant put into the contact disinfection tank in the step 7 is chlorine dioxide aqueous solution.

By adopting the technical scheme, the chlorine dioxide has strong sterilizing capability, does not harm human bodies and animals and does not cause secondary pollution to the environment, is a broad-spectrum environment-friendly sterilizing disinfectant which does not generate carcinogens, and can avoid secondary pollution when sewage is sterilized.

The utility model provides a town road sewage treatment system, includes grid machine, primary sedimentation tank, lye pond, pH equalizing basin, oxidation ditch, secondary sedimentation tank and the contact disinfection pond that connects gradually through the pipeline.

More preferably: and the primary sedimentation tank in the step 2 is a rotational flow grit chamber.

By adopting the technical scheme, the rotational flow grit chamber is a grit device which controls the flow state and the flow speed of water flow by using mechanical force, accelerates the precipitation of sand particles and brings away organic matters along with the water flow. The cyclone grit chamber can enable solid particle impurities passing through the fine grating to be rapidly precipitated, and further remove the solid impurities with smaller sizes in the sewage.

More preferably: and a filter screen is arranged at the liquid outlet of the alkali liquor pool in the step 3.

By adopting the technical scheme, the filter screen is arranged at the liquid outlet of the alkali liquor pool, and can intercept the water-insoluble calcium fatty acid generated in the alkali liquor pool, so that the water-insoluble calcium fatty acid is prevented from entering the oxidation pool to hinder the oxidative degradation of microorganisms.

More preferably: the mesh number of the filter screen is not less than 2500 meshes.

By adopting the technical scheme, because fatty acid radicals in the sewage are basically polymers with large molecular weight, the average particle size of the generated fatty acid calcium is larger than that of light calcium carbonate (precipitated calcium carbonate), the maximum average particle size of the light calcium carbonate is 5 mu m, and the corresponding mesh number is 2500 meshes when the particle size is 5 mu m according to a comparison table of the mesh number of the screen and the particle size (mu m) commonly used in China at present. Therefore, when the mesh number of the filter screen is not less than 2500 meshes, the filtering aperture of the filter screen can be ensured to be less than 5 μm, so that the fatty acid calcium can be more thoroughly intercepted.

More preferably: the oxidation ditch in the step 5 is an improved oxidation ditch, the oxidation ditch is in a closed circular aeration ditch shape, a water inlet and a water outlet are respectively arranged at two ends of the oxidation ditch, a first aerobic zone, a first anoxic zone, a first anaerobic zone, a second aerobic zone, a second anoxic zone and a second anaerobic zone are sequentially arranged in the oxidation ditch from the water inlet along the water flowing direction, wherein the first aerobic zone and the second anaerobic zone are connected end to end; the first aerobic zone and the second aerobic zone are both provided with aeration machines, and the first anoxic zone and the second anoxic zone are provided with mechanical flow-assisting devices.

By adopting the technical scheme, the improved oxidation ditch carries out the biological treatment process of aerobic-anoxic-anaerobic-aerobic-anoxic-anaerobic on the sewage in sequence. The process has good denitrification and dephosphorization effects, and can crack the organic matters with large molecular weight into the organic matters with low molecular weight which are easy to aerobically biodegrade under the anaerobic and anoxic conditions.

In conclusion, the beneficial effects of the invention are as follows:

1. the urban road sewage entering the sewer line is filtered twice by a grating machine, then conveyed into a primary sedimentation tank for sedimentation, and then conveyed into an alkali liquor tank for hydrolysis reaction, so that solid impurities in the sewage are removed more thoroughly, and partial ester organic matters in the sewage are subjected to hydrolysis reaction in an alkaline environment to generate fatty acid salt and alcohol with smaller molecular weight and more quantity, and rubber dust particles form a porous structure, so that the degradation efficiency of microorganisms in an oxidation ditch on the organic matters is improved;

2. the alkali liquor in the alkali liquor pool is formed by mixing and dissolving sodium hydroxide and calcium hydroxide, fatty acid radicals with long carbon chains in oil stains are combined with calcium ions to form fatty acid calcium precipitates which are difficult to dissolve in water, so that organic pollutants in the sewage can be further removed, and the organic matter degradation load of an oxidation ditch is reduced;

3. the oxidation ditch is an improved oxidation ditch, and the oxidation ditch carries out aerobic-anoxic-anaerobic-aerobic-anoxic-anaerobic biological treatment process on the sewage in sequence, so that the sewage treatment device not only has good denitrification and dephosphorization effects, but also can crack organic matters with large molecular weight into organic matters with low molecular weight which are easy to aerobically biodegrade under the anaerobic and anoxic conditions, and the removal capability of the organic matters is stronger.

Drawings

FIG. 1 is a process flow diagram of a municipal road wastewater treatment system according to the invention;

FIG. 2 is a schematic view of the municipal road wastewater treatment system according to the invention; (ii) a

FIG. 3 is a schematic view of the structure of the oxidation ditch in FIG. 2.

In the figure, 1, a grating machine; 11. coarse grating; 12. fine grids; 13. a conveyor belt; 2. a primary sedimentation tank; 3. an alkaline solution pool; 31. filtering with a screen; 4. a pH adjusting tank; 5. an oxidation ditch; 51. a first aerobic zone; 52. a first anoxic zone; 53. a first anaerobic zone; 54. a second aerobic zone; 55. a second anoxic zone; 56. a second anaerobic zone; 57. an aerator; 58. a mechanical flow aid; 59. a partition wall; 6. a secondary sedimentation tank; 7. a contact disinfection tank; 71. a motor; 72. a stirring shaft; 73. stirring blades; 8. a water inlet; 9. and (7) a water outlet.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

Referring to fig. 2, the municipal road sewage treatment system disclosed by the invention comprises a grating machine 1, a primary sedimentation tank 2, an alkali liquor tank 3, a pH adjusting tank 4, an oxidation ditch 5, a secondary sedimentation tank 6 and a contact disinfection tank 7 which are sequentially connected through pipelines.

Install thick grid 11 and thin grid 12 in the grid machine 1, thick grid 11 and thin grid 12 all install in grid machine 1 in the slope, and the conveyer belt 13 that is used for carrying the residue is all installed to the top department of thick grid 11 and thin grid 12, and the sewage that gets into in grid machine 1 passes thick grid 11 and thin grid 12 successively and then carries to first sedimentation tank 2 in through pipeline, and first sedimentation tank 2 is the whirl grit chamber. The alkali liquor tank 3 is filled with alkali liquor, the liquid outlet of the alkali liquor tank 3 is provided with a filter screen 31, and the mesh number of the filter screen 31 is not less than 2500 meshes.

Referring to fig. 3, the oxidation ditch 5 is an improved oxidation ditch, the oxidation ditch 5 is in a closed circular aeration ditch shape, a partition wall 59 is fixed at the center of the oxidation ditch 5, and the partition wall 59 divides the oxidation ditch 5 into a sewage channel which is communicated end to end. The two ends of the oxidation ditch 5 are respectively provided with a water inlet 8 and a water outlet 9, and the oxidation ditch 5 sequentially comprises a first aerobic zone 51, a first anoxic zone 52, a first anaerobic zone 53, a second aerobic zone 54, a second anoxic zone 55 and a second anaerobic zone 56 from the water inlet 8 along the water flowing direction. Wherein the first aerobic zone 51 is communicated with the second anaerobic zone 56 end to end, the water inlet 8 is positioned at one end of the first aerobic zone 51 close to the second anaerobic zone 56, and the water outlet 9 is positioned at the middle position of the first anaerobic zone 53. An aerator 57 is arranged in each of the first aerobic zone 51 and the second aerobic zone 54, and a mechanical flow aid 58 is arranged in each of the first anoxic zone 52 and the second anoxic zone 55.

The contact disinfection tank 7 is filled with disinfectant which is chlorine dioxide water solution, and in order to ensure that the disinfection is more thorough, a stirring shaft 72 and a stirring blade 73 which are driven by a motor 71 are arranged in the contact disinfection tank 7.

Referring to fig. 1, the invention discloses a municipal road sewage treatment method, which comprises the following steps:

step 1: the method comprises the steps of grid filtration, wherein sewage conveyed from a sewer line is introduced into the bottom of a grid machine 1, the sewage sequentially passes through a coarse grid 11 and a fine grid 12 to be subjected to coarse filtration and fine filtration respectively, residue waste decibels accumulated on the coarse grid 11 and the fine grid 12 are conveyed to a conveyor belt 13 at the tops of the coarse grid 11 and the fine grid 12 respectively, and the residue waste is conveyed to a centralized garbage treatment center through the conveyor belt 13 to be treated;

step 2: primary precipitation, wherein sewage filtered by a grating machine 1 is conveyed into a primary precipitation tank 2, precipitation treatment is carried out for 3-6 hours, solid impurities are precipitated at the bottom of the primary precipitation tank 2, and upper-layer sewage is arranged above the solid impurities;

and step 3: carrying out alkaline hydrolysis, conveying the upper-layer sewage in the primary sedimentation tank 2 into an alkaline liquid tank 3, wherein the alkaline liquid tank 3 is filled with alkaline liquid which is a mixed solution of calcium hydroxide and sodium hydroxide with the molar fraction ratio of 1:1.5, the volume ratio of the alkaline liquid to the sewage introduced into the alkaline liquid tank 3 is 1:2, and the sewage reacts in the alkaline liquid tank 3 for 2-3 hours;

and 4, step 4: pH adjustment, namely conveying the sewage completely hydrolyzed in the alkali liquor tank 3 into a pH adjusting tank 4, and adding hydrochloric acid into the pH adjusting tank 4 to adjust the pH to 7-8;

and 5: and (4) biodegradation, namely conveying the sewage with the adjusted pH value in the pH adjusting tank 4 into an oxidation ditch 5, and reacting for 2-4 hours in the oxidation ditch 5. The design parameters of the oxidation ditch 5 are as follows: the sludge age is 11-14 days, and the sludge concentration is 4000-;

step 6: secondary sedimentation, wherein the sewage flowing out of the water outlet 9 of the oxidation ditch 5 is conveyed into a secondary sedimentation tank 6 for secondary sedimentation, and the sedimentation time is 2-4 hours;

and 7: disinfecting and sterilizing, namely conveying the sewage on the upper layer of the secondary sedimentation tank 6 into a contact disinfection tank 7, and carrying out disinfecting and sterilizing treatment on the sewage by using a chlorine dioxide aqueous solution as a disinfectant for 2 hours;

and 8: and (4) discharging the purified water, wherein the sewage which is disinfected and sterilized in the contact disinfection tank 7 is changed into the purified water meeting the discharge standard, and the purified water is directly discharged into the natural water body.

The implementation principle of the embodiment is as follows: filtering urban road sewage twice by a grating machine 1, and then conveying the urban road sewage into a primary sedimentation tank 2 to remove solid impurities with larger particles; then, conveying the sewage into an alkali liquor pool 3 for hydrolysis reaction, wherein partial ester organic matters in the sewage are subjected to hydrolysis reaction under an alkaline environment to generate sodium fatty acid and calcium fatty acid with smaller molecular weight and more quantity, and the long-carbon-chain calcium fatty acid is insoluble in water and can be removed through a filter screen 31 at a liquid outlet of the alkali liquor pool 3; and a porous structure is formed in the rubber dust particles, so that the degradation efficiency of microorganisms in the oxidation ditch 5 on organic matters can be improved, and the effect of removing organic pollutants is better.

The present embodiment is only for explaining the present invention, and it is not limited to the present invention, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present invention.

Claims (4)

1. A municipal road sewage treatment method is characterized by comprising the following steps:

step 1, filtering through a grating, namely conveying municipal road sewage through a grating machine (1) to filter the municipal road sewage;

step 2, primary precipitation, namely discharging the municipal road sewage filtered by the grating machine (1) into a primary precipitation tank (2), and performing precipitation treatment for 3-6 hours;

step 3, alkaline hydrolysis, namely conveying the municipal road sewage on the upper layer of the primary sedimentation tank (2) into an alkaline solution tank (3) to hydrolyze the municipal road sewage for 2-3 hours under alkaline conditions;

step 4, pH adjustment, namely conveying the municipal road sewage in the lye tank (3) into a pH adjusting tank (4), and adjusting the pH range to 7-8;

and 5: biodegradation, namely conveying the municipal road sewage in the pH adjusting tank (4) into an oxidation ditch (5) for reaction for 2-4 hours;

step 6: secondary sedimentation, namely conveying the municipal road sewage which is completely reacted in the oxidation ditch (5) to a secondary sedimentation tank (6), standing and settling for 2-4 hours;

step 7, sterilizing, namely conveying the municipal road sewage on the upper layer of the secondary sedimentation tank (6) into the contact sterilization tank (7), and sterilizing for 2 hours;

and 8: purified water is discharged, the municipal road sewage after being disinfected and sterilized by the contact disinfection tank (7) is changed into purified water, and the purified water is directly discharged into natural water;

the alkali liquor in the alkali liquor pool (3) in the step 3 is a mixed solution of calcium hydroxide and sodium hydroxide, and the molar fraction ratio of the calcium hydroxide to the sodium hydroxide is 1: 1.5;

a filter screen (31) is arranged at the liquid outlet of the alkali liquor pool (3) in the step (3), and the mesh number of the filter screen (31) is not less than 2500 meshes;

the oxidation ditch (5) in the step 5 is an improved oxidation ditch, the oxidation ditch (5) is in a closed circular aeration ditch shape, a water inlet (8) and a water outlet (9) are respectively arranged at two ends of the oxidation ditch (5), the oxidation ditch (5) sequentially comprises a first aerobic zone (51), a first anoxic zone (52), a first anaerobic zone (53), a second aerobic zone (54), a second anoxic zone (55) and a second anaerobic zone (56) from the water inlet (8) along the water flowing direction, and the first aerobic zone (51) is connected with the second anaerobic zone (56) end to end; aeration machines (57) are arranged in the first aerobic zone (51) and the second aerobic zone (54), and mechanical flow-assisting devices (58) are arranged in the first anoxic zone (52) and the second anoxic zone (55).

2. The municipal road sewage treatment method according to claim 1, wherein: the step 1 of grid filtering comprises coarse grid (11) filtering and fine grid (12) filtering, and municipal road sewage is firstly subjected to coarse filtering through the coarse grid (11) and then is conveyed to the fine grid (12) for fine filtering.

3. The municipal road sewage treatment method according to claim 1, wherein: and the primary sedimentation tank (2) in the step 2 is a rotational flow grit chamber.

4. The municipal road sewage treatment method according to claim 1, wherein: the disinfectant put into the contact disinfection tank (7) in the step (7) is chlorine dioxide aqueous solution.

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