CN111573995A - Papermaking sewage recycling process - Google Patents

Abstract

The invention discloses a process for recycling papermaking sewage, which comprises the steps of conveying water flow discharged from a pulping and papermaking trench to a middle section for collecting water, conveying redundant wastewater flow to a comprehensive water collecting tank, pumping the water in the water collecting tank to an inclined screen for recovering slurry, mixing and automatically pressing the slurry to a first sedimentation tank of a concrete structure for sedimentation, pumping the middle-upper water after sedimentation to a transition tank by the first sedimentation tank, pumping a dosing tank in the middle of the first sedimentation tank to a second sedimentation tank, automatically pressing the sludge in the lower part of the first sedimentation tank to a square pool from the middle of the first sedimentation tank, pumping the sludge to a paper machine, drying the sludge into paper, forming a precipitate by the second sedimentation tank by using a layered sedimentation and compression sedimentation principle, forming flocculated suspended matters in the sedimentation process, and automatically flowing the water after sedimentation into a subsequent anaerobic tank. The pulping and papermaking wastewater is recycled, the wastewater treatment reaches the standard and is discharged, the sludge is recycled in a hundred percent, the environmental pollution is avoided, the sludge and biochemical sludge are changed into valuable, the production cost is reduced, and considerable economic benefits are created.

Description

Papermaking sewage recycling process

Technical Field

The invention relates to the field of sewage recycling processes, in particular to a papermaking sewage recycling process.

Background

With the increase of environmental protection pressure, the environmental protection improvement of pulping and papermaking enterprises in China is further enhanced, and sewage treatment becomes a problem concerned by each pulping and papermaking enterprise. The primary, secondary and tertiary sewage treatment modes, the large amount of reuse of wastewater in production and the standard-reaching discharge of tertiary treatment are adopted by more and more pulping and papermaking enterprises, the processes of wastewater reuse circulation and sewage grade treatment processes in production are continuously improved, and the processes of wastewater reuse and sewage treatment standard-reaching discharge are widely applied to the pulping and papermaking industry.

The sewage and sludge reusing process includes feeding the pulping and papermaking sewage into water collecting tank, water separating in 120 mesh nylon inclined sieve and pumping the returned pulp to No. 1 tank for removing core pulp. Polyaluminium chloride (the dilution concentration of the polyaluminium chloride cement pool is 1.5 percent) is added into an inlet of a mixing pool pump, the dosage of each ton of paper is 15kg, and polyacrylamide (the dilution concentration of the polyacrylamide cement pool is 0.15 percent) is added into an outlet of the mixing pool pump, and the dosage of each ton of paper is 0.2 kg. Through the sediment water tower of 13 meters height sediment, can slowly separate at chemical reaction sewer water and mud, 3 ponds in the pond of saving 200m are overflowed to the water of purifying, with pump pumping to go waste paper pulping, paper machine dense adjustment supplementary water, vacuum pump sealing water, white water bucket make-up water, wash the meshwork blanket. Separating and precipitating the sludge, delivering the sludge to a sludge tank under self-pressure, pumping and screening by using a slurry pump, adding the sludge into a paper machine online slurry mixing and delivering system, diluting the sludge to a certain online concentration by using water, performing preliminary dehydration and molding at a wire part of a paper machine to form wet paper sheets, performing squeezing dehydration, and drying to form paper.

The existing technology has the defects that the waste water in production is continuously recycled, no sewage treatment facility process flow exists, only a simple precipitation flow exists, COD in the recycled waste water is higher and higher, the corrosion to pulping, paper machine equipment, steel structures and roof color steel tiles is very severe, a phi 18 screw of a square taper pipe of a head box of a paper machine corrodes for 5 years and then falls off, the roof color steel tile needs to be replaced after being corroded for 3 years, the peculiar smell of staff going to work after work is unpleasant, the body health of the staff is also influenced, and the produced finished base paper has a little sour smell.

Disclosure of Invention

The invention aims to provide a process for recycling papermaking sewage, which aims to solve the problems in the background technology.

In order to achieve the purpose, the invention provides the following technical scheme: a papermaking sewage recycling process comprises the following steps:

s1, delivering water flow discharged from the pulping and papermaking trench to the middle section for water collection, salvaging waste residues and crushed pulp in the waste water by using a slag conveyor, and delivering the redundant waste water flow to a comprehensive water collecting pool;

s2: pumping sewage in a water collecting tank to an inclined screen for recycling slurry, automatically flowing water under a net to 4 square tanks, and automatically pressing the mixture to a first sedimentation tank with a concrete structure for sedimentation;

s3: pumping the precipitated middle-upper water to a transition tank by a first sedimentation tank, pumping a dosing tank of a second sedimentation tank by the middle part of the first sedimentation tank, self-pressing the precipitated sludge at the lower part of the first sedimentation tank to a square tank from the middle of the tank, pumping to a paper machine, and drying into paper;

s4: the second sedimentation tank utilizes the principles of stratified sedimentation and compression sedimentation, flocculated suspended matters form a sediment in the sedimentation process, the sediment is in an integral sedimentation state and forms a relatively obvious solid interface, and the water after sedimentation automatically flows into a subsequent anaerobic tank;

s5: removing organic matters in the sewage in the anaerobic tank, and then automatically pressing the sewage to the subsequent 2 aerobic tanks through holes at the bottom of the anaerobic tank;

s6: the aerobic tank utilizes aerobic microorganisms in the sewage to digest and degrade organic matters in the sewage in the presence of free oxygen, so that the dropped biological membrane enters a subsequent third sedimentation tank along with effluent;

s7: after the third sedimentation tank is settled in the long tank, the third sedimentation tank is collected by a water collecting tank at the top of the tank and enters a subsequent dosing reaction tank, and the third sedimentation tank is mixed and enters a drainage tank under self pressure by utilizing the principles of layered settlement and compression settlement;

s8: sewage after biological treatment enters a sedimentation tank, inflow enters from the middle and flows out by radiation to the periphery, along with more water flow, the liquid level is higher and higher, supernatant water flowing to the edge flows out from a water outlet, in the process of water radiation flowing, the weight of mud is heavier and has been settled on the conical surface of the bottom, all mud is collected into a mud discharge pipe at the center by a mud suction pipe and a mud scraper of the conical surface of the bottom, the mud is in a concrete structure of a water discharge tank, a mud pump at the bottom pumps the mud in a transition tank back to a dosing tank of a second sedimentation tank for circulation, and the COD of the clear water at the tank surface controls the flow of 90mg/L to the edge, and the flow of the effluent flows to a water outlet for discharge.

Preferably, there are air blower pipeline arrangement on the pond face of catch basin in step S2, and pond face pipeline distribution is 3 rows, and every pipeline evenly distributed 12 galvanized pipe, galvanized pipe mouth below is from the bottom of the pool 30cm, and the air-blower operation air blast air feed 24 hours makes the aeration in the catch basin, and sewage is stirring constantly, and two sewage elevator pumps are retrieved catch basin sewage pumping inclined screen department thick liquids, and the net is rivers automatically to 4 square ponds:

a1: adding polyaluminium chloride into the first square pool, performing thin film distillation in each tank (phi 1.3 x 1.4=1.8m and 75kg of polyaluminium chloride is added), diluting the mixture to 4.1% concentration in the stirring tank for thin film distillation at 1.8m, controlling 800L/h and 3 meters by using a medicine feeding pump buoy flow meter 1000L/h, pumping the mixture into the second sedimentation tank and a drainage tank for adding, and adding the polyaluminium chloride into each tank for 30 min, wherein 1.2kg of the polyaluminium chloride is added into each ton of sewage;

a2: adding an anion retention aid on the second square pool, carrying out dry distillation on each tank (phi 1.7 x 1.8=4m and adding 4kg of the retention aid), diluting the solution with the concentration of 0.1% in a 4m agitating tank, controlling the solution to 400L/h by using a chemical feeding pump buoy flow meter 1000L/h, adding 3 solutions, pumping the other two solutions to be added at the inlets of the second sedimentation tank and the drainage tank, carrying out dry distillation on each tank for 4 hours, adding 8g of the retention aid to each ton of sewage, and carrying out mixed autogenous pressure on the solution to the first sedimentation tank with a concrete structure through the third square pool and the fourth square pool to carry out sedimentation.

Preferably, the specific operation steps of step S3 are as follows:

b1: the first sedimentation tank is provided with a mud scraping device, a mud scraper is used for running at a low speed, so that water in the sedimentation tank has moderate turbulence, inorganic impurities still keep a good sedimentation and separation effect, the mud scraper is provided with a submersible pump, and the settled water at the middle upper part is pumped to a transition tank;

b2: two sewage reuse lifting pumps in the middle of the first sedimentation tank pump the wood powder stirrer, the batten and the core pulp pulper to pulp, and one emergency pump is arranged at the position 2m higher than the middle of the sedimentation tank to pump a dosing tank of the second sedimentation tank;

b3: the sludge deposited at the lower part of the first sedimentation tank is self-pressed to a square tank from the middle of the tank, a sludge recycling pump pumps the sludge in the tank to a pulping workshop for jumping and a pulping tank after vibrating frame and screen jumping, the sludge is pumped to a paper machine sizing system by a sludge pump, the sludge is added into the paper machine sizing system after jumping and screen jumping and mixed with pulp on the paper to enter a flow system, the mixture is diluted to certain net-feeding concentration by water, the mixture is preliminarily dehydrated and formed at a net part of a paper machine to form wet paper sheets, and the wet paper sheets are pressed, dehydrated and dried to form paper.

Preferably, the specific operation steps of step S4 are as follows:

c1: in the transition pool behind the first sedimentation tank, pumping into an iron box by a centrifugal pump, wherein the iron box has two grids, a polyaluminium chloride buoy flowmeter is added at the inlet of the pump, the volume is controlled to be 800L/h at 1000L/h, a retention aid is added in the first grid of the iron box, and the buoy flowmeter is uniformly distributed and flows into 2 second sedimentation tanks with a concrete structure after being mixed at the volume is controlled to be 400L/h at 1000L/h;

c2: the second sedimentation tank is provided with a mud scraping device, the mud is scraped at a low speed continuously by using a mud scraper, meanwhile, the water in the sedimentation tank has moderate turbulence, inorganic impurities still keep good sedimentation and separation, the mud is concentrated, the settled mud is pumped back to the water collecting tank by using a mud pump for circulation, and the water settled in the long tank automatically flows into a subsequent anaerobic tank;

preferably, step S5 anaerobic treatment utilizes the effect of anaerobism fungus, get rid of the organic matter in the waste water, the water evenly distributed on second sedimentation tank surface flows into two follow-up anaerobism ponds, 2 dive stirs are installed in the design of anaerobism pond bottom of the pool, the anaerobism pond retrieval and utilization are gone into to the pump by the third sedimentation tank sedimentation mud, the sewage of aerobic pond waste water collection department is gone into the anaerobism pond circulation and is replenished with the pump, anaerobism pond per ton sewage evenly adds 11.5g with the metering pump, anaerobism pond sewage is from pressing to 2 follow-up aerobic ponds through the hole autogenous pressure of bottom of the pool.

Preferably, in step S6, the aerobic microorganisms in the wastewater are used to digest and degrade the organic matters in the wastewater in the presence of free oxygen, so as to stabilize and make harmless the organic matters, the aerobic tank is in the form of a contact oxidation tank, the filler is arranged in the tank, the oxygenated wastewater immerses all the filler and flows through the filler at a uniform flow rate, the oxygen required by the microorganisms in the contact oxidation tank is usually supplied by artificial aeration, after the biofilm grows to a standard thickness, the microorganisms entering the wall of the filler perform anaerobic metabolism due to oxygen deficiency, the generated gas and the flushing action formed by aeration cause part of the biofilm to fall off, the growth of a new biofilm is promoted, the metabolism of the biofilm is formed, the fallen biofilm enters a subsequent third sedimentation tank along with the effluent, the dissolved oxygen in the aerobic tank is stabilized at 2.0-2.5/gm/L per day, the wastewater is collected by a tank at the top of the tank and pumped into the anaerobic tank for circulation, and the redundant sewage of the water collecting tank overflows into a third sedimentation tank.

Preferably, in the step S7, sewage in the aerobic tank overflows and flows into 2 third sedimentation tanks with a concrete structure uniformly, the third sedimentation tank is provided with a mud scraper, the mud scraper operates at a low speed to enable water in the sedimentation tanks to be in order, inorganic impurities still keep a good sedimentation separation effect, suspended particles are gathered at the bottom of the water in the sedimentation process, support and extrude each other to further settle, the settled sludge is pumped back to the anaerobic tank by a slurry pump, the slurry pump pumps the water in the paper machine damageable tank, and the water is collected by a tank top water collection tank and enters a subsequent dosing reaction tank after being settled in the long tank;

the dosing pool is divided into 3 grids, 1000L/h of a buoy flowmeter for adding polyaluminium chloride is added in the first grid and is controlled to be 800L/h, 1000L/h of a buoy flowmeter for adding a cationic retention aid is added in the second grid and is controlled to be 400L/h, and the mixed materials enter the drainage pool under self pressure.

The invention has the technical effects and advantages that:

(1) the first sedimentation tank is used for removing settleable matters and floating matters, reducing the load of subsequent treatment facilities, flocculating fine solids into larger particles, strengthening the solid-liquid separation effect, having a certain adsorption removal effect on colloidal substances, playing a certain homogenizing effect on water quality, slowing down the impact of water quality change on a subsequent biochemical system, mainly clarifying the second sedimentation tank to ensure the water quality of effluent and sludge concentration, reducing the water content of recycled sludge and ensuring the concentration of return sludge, and the third sedimentation tank is mainly used for separating sludge and clarifying mixed liquid, so that the sludge-water separation is carried out to ensure tail water discharge and recycle activated sludge;

(2) the anaerobic tank is used for removing organic matters in the wastewater by using the action of anaerobic bacteria, the design is usually longer, and the aerobic tank is used for carrying out aerobic respiration on the activated sludge to further decompose the organic matters into inorganic matters and remove pollutants;

(3) the process flow combines the sewage treatment and the biochemical activated sludge recycling of the first sedimentation tank, the second sedimentation tank, the anaerobic tank, the aerobic tank, the third sedimentation tank and the drainage tank, has good treatment effect, changes the sludge and the biochemical sludge into valuable, and reduces the production cost.

Drawings

FIG. 1 is a flow chart of the wastewater treatment and activated sludge recycling process of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention provides a process for recycling papermaking sewage, which comprises the following steps:

s1: water flow discharged from the pulping and papermaking trench is sent to the middle section for water collection, wherein one sewage lifting pump is used for pumping inclined screen slurry for recycling, the inclined screen is 100 meshes, the returned slurry is pumped to the core slurry pool, one sewage lifting pump (model 150HW 8) is used for watering on bulk material waste paper piles and battens without rubber plates, the other sewage lifting pump is used for pumping the broken slurry of a batten pulper (pump model ls 125-100) and 200 j), and the redundant wastewater flows to the comprehensive water collection pool;

s2: the surface of the water collecting tank is provided with air blower pipelines which are distributed in 3 rows, each pipeline is evenly distributed with 12 galvanized pipes, the lower part of a galvanized pipe opening is 30cm away from the bottom of the tank, the air blower operates for blowing air and supplying air for 24 hours, so that the water collecting tank is aerated, sewage is ceaselessly stirred, two sewage lifting pumps (model ls 150-125) pump 250B pump the sewage in the water collecting tank to the inclined screen for recycling slurry, and the water under the screen automatically flows to 4 square tanks:

a1, adding polyaluminium chloride into the first square pool, performing 75kg of polyaluminium chloride in each tank (phi 1.3 x 1.4=1.8 m), diluting the mixture with the concentration of 4.1% in the stirring tank with the length of 1.8m, controlling 800L/h and 3 containers by using a chemical feeding pump (the model is 25 FZS-10) and a buoy flow meter 1000L/h, pumping the mixture into the second sedimentation pool and a drainage pool by using another two flow meters, performing 30 minutes in each tank, and adding 1.2kg of polyaluminium chloride into each ton of sewage;

a2, adding the anionic retention aid to the second square pool, carrying out full-automatic plantation at phi 1.7 x 1.8=4m and adding 4kg of the retention aid to each tank (phi 1.7 x 1.8=4 m), diluting the mixture to 0.1% concentration in the stirring tank for 4m, controlling 400L/h and 3 containers by using a buoy flow meter of a dosing pump 1000L/h, pumping the other two containers to the second sedimentation pool and the drainage pool for adding, carrying out full-automatic sedimentation in the third square pool and the fourth square pool, adding 8g of the retention aid to each ton of sewage, and mixing the sewage by the third square pool and the fourth square pool and automatically pressing the mixture to the first sedimentation pool with a concrete structure for sedimentation.

S3: the first sedimentation tank is used for settling suspended substances in the wastewater, and the suspended substances sink under the action of gravity, so that the suspended substances are separated from the wastewater, and the water quality is clarified, and the specific implementation steps are as follows:

b1, arranging a mud scraper on the first sedimentation tank, operating at low speed by using a mud scraper to make the water in the sedimentation tank have moderate turbulence but not form too much stirring, and keeping better sedimentation and separation effects of inorganic impurities, arranging a submersible pump on the mud scraper, and pumping the settled water at the middle and upper parts to a transition tank;

b2, pumping the wood powder stirrer, the batten and the core pulp pulper to pulp by two sewage recycling lifting pumps (the model is ls 125-100-;

b3, pressing the sludge deposited on the lower part of the first sedimentation tank into a square tank from the middle of the tank, pumping the sludge in the tank to a pulping workshop for jumping and a vibrating frame screen for jumping and then to a pulp discharging tank by a sludge recycling pump, pumping the sludge to a paper machine sizing system by a sludge pump, adding paper machine sizing agent for jumping and then mixing with the pulp on the net, entering a flow system, diluting the mixture to a certain net density by water, preliminarily dehydrating and forming at the net part of a paper machine to form wet paper sheets, squeezing and dehydrating the wet paper sheets, and drying the wet paper sheets to form paper;

s4: the second sedimentation tank utilizes the principles of layering sedimentation and compression sedimentation for sedimentation, and flocculated suspended matters in the sedimentation process form a sediment which is in an integral sedimentation state and forms a more obvious solid interface, and the specific implementation steps are as follows:

c1, pumping the transition pool after the first sedimentation pool into an iron box (2 m 4m 1.5m =12m two-stage cultivation lattice) by using a centrifugal pump (model is lS 200-150-250), adding a polyaluminium chloride float flowmeter at the inlet of the pump, controlling the 1000L/h to be 800L/h, adding a retention aid in the first lattice of the iron box, controlling the 1000L/h to be 400L/h to be mixed, and uniformly distributing and flowing the mixed liquid into 2 (33 m 6m 4m =792 m-shaped) second sedimentation pools with concrete structures;

c2, arranging a mud scraping device in the second sedimentation tank, scraping the mud at a low speed by using a mud scraper, simultaneously leading the water in the sedimentation tank to have moderate turbulence, keeping better sedimentation and separation of inorganic impurities, concentrating the mud, pumping the precipitated mud back to the water collecting tank for circulation by using a mud pump (the model is 100XJ 50-15A), and automatically flowing the water which is precipitated in a 33m long tank into a subsequent anaerobic tank;

s5: anaerobic treatment is the effect that utilizes anaerobe, get rid of the organic matter in the waste water, the water evenly distributed on second sedimentation tank surface flows in two follow-up anaerobism ponds, 2 dive stirring (regularly opening and shutting) are installed to the anaerobism bottom of the pool design, the anaerobism pond retrieval and utilization is gone into with the pump to third sedimentation tank sedimentation mud, the sewage of aerobic pond waste water collection department is gone into the anaerobism pond circulation with the pump and is replenished, anaerobism pond per ton sewage evenly adds liquid phosphoric acid 11.5g with the measuring pump, anaerobism pond sewage is through the hole autogenous pressure of bottom of the pool to follow-up 2 good oxygen ponds, anaerobic reaction divide into four stages:

d 1: a hydrolysis stage: the macromolecular organic substance can not directly pass through the cell wall of anaerobic bacteria due to the large molecular volume thereof, and needs to be decomposed into small molecules by extracellular enzyme in vitro, typical organic substances in wastewater, such as cellulose, are decomposed into cellobiose and glucose by cellulase, starch is decomposed into maltose and glucose, protein is decomposed into short peptide and amino acid, and the decomposed small molecules can enter the cell body through the cell wall to be decomposed in the next step.

d 2: and (3) acidification stage: the small molecule organic matter enters into the cell body to be converted into simpler compounds and is distributed outside the cell, and the main products of the stage are Volatile Fatty Acid (VFA), lactic acid, carbon dioxide, hydrogen, ammonia, hydrogen sulfide and the like.

d 3: an acetic acid production stage: at this stage, the product of the last step is further converted into acetic acid, carbonic acid, hydrogen and new cellular material.

d 4: a methanogenesis stage, in which acetic acid, carbonic acid, hydrogen, formic acid and methanol are all converted into methane, carbon dioxide and new cell substances, which is also the most important stage of the whole anaerobic process and the rate-limiting stage of the whole anaerobic reaction process;

s6: an aerobic tank which is a contact oxidation tank, is provided with a filler, and the oxygenated sewage is immersed in all the filler, and flows through the filler at a uniform flow rate, part of the microorganisms are fixed on the surface of the filler in the form of a biofilm, and part of the microorganisms are suspended in the water in the form of floccules, oxygen required by microorganisms in the contact oxidation pond is usually supplied by artificial aeration, after the biological membrane grows to a standard thickness, microorganisms entering the filler wall carry out anaerobic metabolism due to oxygen deficiency, part of the biological membrane falls off due to scouring action formed by generated gas and aeration, the growth of a new biological membrane is promoted, the biological metabolism is formed, and the fallen biological membrane enters a subsequent third sedimentation tank along with effluent;

2 concrete structures of the aerobic tanks are arranged, pipelines on the surface of the aerobic tanks are distributed, 26 pipelines with the diameter of phi 108mm are distributed on the surface of the aerobic tanks, 11 zinc pipes with the diameter of phi 25 are uniformly distributed on each pipeline with the diameter of phi 108mm, the lower part of the zinc pipe orifice with the diameter of phi 25 is 50cm away from the bottom of the aerobic tanks, and 2 blowers operate to blow air and supply air (the three-blade Roots blower is 200HB in model, the air quantity 5033m for carrying out cultivation/min, and the air pressure 68.6Kpa for power 90 kw-4J) for 24 hours;

the dissolved oxygen in the aerobic tank is stabilized by 2.0-2.5/gm/L every day, the sewage is collected by a water collecting tank at the top of the tank and pumped into an anaerobic tank for circulation (the flow rate of a HW type mixed flow water pump is 360 m/h, the lift is 8m, and the power is 11 kw), and the redundant sewage in the water collecting tank overflows into a third sedimentation tank;

the aerobic tank has the function of enabling the activated sludge to perform aerobic respiration to further decompose organic matters into inorganic matters and remove pollutants, and the aerobic tank is operated well by controlling oxygen content and other requirements of microorganisms, so that the microorganisms can perform aerobic respiration with maximum benefit.

Aeration principle: aeration is a means for making air and water strongly contact, and aims to dissolve oxygen in the air into the water and release unnecessary gas and volatile substances in the water into the air, and is a means for promoting substance exchange between gas and liquid, and the important functions of the means can play a role of mixing and stirring, wherein the oxygen in the air is transferred into the water through aeration, the oxygen is subjected to mass transfer from a gas phase to a liquid phase, the aeration is carried out, the sewage is continuously stirred, the dissolved oxygen content in the sewage is stabilized, the number of anaerobic bacteria in the sewage is reduced, the sedimentation rate of a third sedimentation tank is improved, and the load of a subsequent section of sewage treatment is reduced.

S7: the third sedimentation tank utilizes the principles of stratified sedimentation and compression sedimentation, flocculated suspended matters in the sedimentation process form a sediment which is in an integral sedimentation state and forms a relatively obvious solid interface, the function is mainly to separate sludge and clarify mixed liquid, and the sludge-water separation is carried out to ensure tail water discharge and reuse activated sludge;

sewage overflows from the aerobic tank and uniformly flows into a third sedimentation tank with 2 concrete structures, a mud scraping device is designed in the third sedimentation tank, a mud scraper is utilized to operate at a low speed, so that water in the sedimentation tank has moderate turbulence, excessive stirring cannot be formed, inorganic impurities still keep a good sedimentation separation effect, suspended particles are finally gathered at the bottom of the water in the sedimentation process, mutually supported and mutually extruded to generate further sedimentation, the sedimentated sludge is pumped back to the anaerobic tank by using a pulp pump (the model is Ls150-125 sand-slurry 250B, the flow is 150m, the lift is 17m, and the power is 11 kw), and a pulp pump (the model is Ls125-100 sand-slurry 250A, the flow is 90m, the lift is 18m, and the power is 7.5 kw) is used for pumping the water in the sedimentation tank of the anaerobic tank, and the water is collected by a tank top collecting tank and enters a subsequent chemical feeding reaction tank after being sedimentated by using a long tank;

dividing the dosing pool (2.95 m 1.5m 3.5m =15 m) into 3 grids, adding 1000L/h of a buoy flow meter for adding polyaluminium chloride in the first grid, controlling 800L/h, adding 1000L/h of a buoy flow meter for adding the cationic retention aid in the second grid, controlling 400L/h, mixing, and allowing the mixture to enter a drainage pool under self pressure;

s8: the principle of a drainage pool is as follows: the sewage after biological treatment enters a sedimentation tank, the inlet water enters from the middle and flows out in a radiation mode towards the periphery, the liquid level is higher and higher along with more water flow, the supernatant water flowing to the edge flows out from a water outlet, in the water radiation flowing process, the weight of mud is heavier and is already settled on the conical surface of the bottom, all the mud is collected into a central mud discharge pipe by a mud suction pipe and a mud scraper of the conical surface of the bottom, the mud in the transition tank is pumped back to a dosing tank of a second sedimentation tank for circulation by a mud pump (model 100-65-250A) at the bottom, and the clear water on the tank surface controls the flow of 90mg/L to the edge to flow to a water outlet and is discharged to the water outlet.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments or portions thereof without departing from the spirit and scope of the invention.

Claims (7)

1. A papermaking sewage recycling process comprises the following steps:

s1, delivering water flow discharged from the pulping and papermaking trench to the middle section for water collection, salvaging waste residues and crushed pulp in the waste water by using a slag conveyor, and delivering the redundant waste water flow to a comprehensive water collecting pool;

s2: pumping sewage in a water collecting tank to an inclined screen for recycling slurry, automatically flowing water under a net to 4 square tanks, and automatically pressing the mixture to a first sedimentation tank with a concrete structure for sedimentation;

s3: pumping the precipitated middle-upper water to a transition tank by a first sedimentation tank, pumping a dosing tank of a second sedimentation tank by the middle part of the first sedimentation tank, self-pressing the precipitated sludge at the lower part of the first sedimentation tank to a square tank from the middle of the tank, pumping to a paper machine, and drying into paper;

s4: the second sedimentation tank utilizes the principles of stratified sedimentation and compression sedimentation, flocculated suspended matters form a sediment in the sedimentation process, the sediment is in an integral sedimentation state and forms a relatively obvious solid interface, and the water after sedimentation automatically flows into a subsequent anaerobic tank;

s5: removing organic matters in the sewage in the anaerobic tank, and then automatically pressing the sewage to the subsequent 2 aerobic tanks through holes at the bottom of the anaerobic tank;

s6: the aerobic tank utilizes aerobic microorganisms in the sewage to digest and degrade organic matters in the sewage in the presence of free oxygen, so that the dropped biological membrane enters a subsequent third sedimentation tank along with effluent;

s7: after the third sedimentation tank is settled in the long tank, the third sedimentation tank is collected by a water collecting tank at the top of the tank and enters a subsequent dosing reaction tank, and the third sedimentation tank is mixed and enters a drainage tank under self pressure by utilizing the principles of layered settlement and compression settlement;

s8: sewage after biological treatment enters a sedimentation tank, inflow enters from the middle and flows out by radiation to the periphery, along with more water flow, the liquid level is higher and higher, supernatant water flowing to the edge flows out from a water outlet, in the process of water radiation flowing, the weight of mud is heavier and has been settled on the conical surface of the bottom, all mud is collected into a mud discharge pipe at the center by a mud suction pipe and a mud scraper of the conical surface of the bottom, the mud is in a concrete structure of a water discharge tank, a mud pump at the bottom pumps the mud in a transition tank back to a dosing tank of a second sedimentation tank for circulation, and the COD of the clear water at the tank surface controls the flow of 90mg/L to the edge, and the flow of the effluent flows to a water outlet for discharge.

2. The recycling process of sewage from paper making as claimed in claim 1, wherein in step S2, there are air blower pipes on the surface of the collecting tank, there are 3 rows of pipes on the surface of the collecting tank, there are 12 galvanized pipes evenly distributed on each pipe, the bottom of the galvanized pipe is 30cm away from the bottom of the tank, the air blower operates for 24 hours to blow air, so as to aerate the collecting tank, the sewage is continuously turned over, two sewage lift pumps pump the collecting tank sewage to pump slurry at the inclined screen for recovery, the water under the screen automatically flows to 4 square pools:

a1: adding polyaluminium chloride into the first square pool, performing thin film distillation in each tank (phi 1.3 x 1.4=1.8m and 75kg of polyaluminium chloride is added), diluting the mixture to 4.1% concentration in the stirring tank for thin film distillation at 1.8m, controlling 800L/h and 3 meters by using a medicine feeding pump buoy flow meter 1000L/h, pumping the mixture into the second sedimentation tank and a drainage tank for adding, and adding the polyaluminium chloride into each tank for 30 min, wherein 1.2kg of the polyaluminium chloride is added into each ton of sewage;

a2: adding an anion retention aid on the second square pool, carrying out dry distillation on each tank (phi 1.7 x 1.8=4m and adding 4kg of the retention aid), diluting the solution with the concentration of 0.1% in a 4m agitating tank, controlling the solution to 400L/h by using a chemical feeding pump buoy flow meter 1000L/h, adding 3 solutions, pumping the other two solutions to be added at the inlets of the second sedimentation tank and the drainage tank, carrying out dry distillation on each tank for 4 hours, adding 8g of the retention aid to each ton of sewage, and carrying out mixed autogenous pressure on the solution to the first sedimentation tank with a concrete structure through the third square pool and the fourth square pool to carry out sedimentation.

3. The recycling process of papermaking wastewater according to claim 1, wherein the step S3 specifically comprises the following steps:

b1: the first sedimentation tank is provided with a mud scraping device, a mud scraper is used for running at a low speed, so that the water in the sedimentation tank is uniform in turbulent flow, inorganic impurities still keep a good sedimentation separation effect, the mud scraper is provided with a submersible pump, and the settled middle upper water is pumped to a transition tank;

b2: two sewage reuse lifting pumps in the middle of the first sedimentation tank pump the wood powder stirrer, the batten and the core pulp pulper to pulp, and one emergency pump is arranged at the position 2m higher than the middle of the sedimentation tank to pump a dosing tank of the second sedimentation tank;

b3: the sludge deposited at the lower part of the first sedimentation tank is self-pressed to a square tank from the middle of the tank, a sludge recycling pump pumps the sludge in the tank to a pulping workshop for jumping and a pulping tank after vibrating frame and screen jumping, the sludge is pumped to a paper machine sizing system by a sludge pump, the sludge is added into the paper machine sizing system after jumping and screen jumping and mixed with pulp on the paper to enter a flow system, the mixture is diluted to certain net-feeding concentration by water, the mixture is preliminarily dehydrated and formed at a net part of a paper machine to form wet paper sheets, and the wet paper sheets are pressed, dehydrated and dried to form paper.

4. The recycling process of papermaking wastewater according to claim 1, wherein the step S4 specifically comprises the following steps:

c1: in the transition pool behind the first sedimentation tank, pumping into an iron box by a centrifugal pump, wherein the iron box has two grids, a polyaluminium chloride buoy flowmeter is added at the inlet of the pump, the volume is controlled to be 800L/h at 1000L/h, a retention aid is added in the first grid of the iron box, and the buoy flowmeter is uniformly distributed and flows into 2 second sedimentation tanks with a concrete structure after being mixed at the volume is controlled to be 400L/h at 1000L/h;

c2: the second sedimentation tank is provided with a mud scraping device, when the mud is continuously scraped at a low speed by using a mud scraper, the water in the sedimentation tank has moderate turbulence, inorganic impurities still keep better sedimentation separation, the sludge is concentrated, the precipitated sludge is pumped back to the water collecting tank for circulation by using a slurry pump, and the water after being precipitated in the long tank automatically flows into a subsequent anaerobic tank.

5. The recycling process of papermaking wastewater as claimed in claim 1, wherein the anaerobic treatment in step S5 is to remove organic matters in wastewater by using the action of anaerobic bacteria, the water on the surface of the second sedimentation tank is uniformly distributed to flow into the two subsequent anaerobic tanks, 2 submersible stirrers are installed on the bottom of the anaerobic tank, the sludge settled in the third sedimentation tank is pumped into the anaerobic tank for recycling, the wastewater collected in the aerobic tank is pumped into the anaerobic tank for cyclic replenishment, 11.5g of liquid phosphoric acid is uniformly added to each ton of wastewater in the anaerobic tank by using a metering pump, and the wastewater in the anaerobic tank is self-pressurized to the 2 subsequent aerobic tanks through the holes on the bottom of the tank.

6. The recycling process of sewage water for papermaking as claimed in claim 1, wherein step S6 is a treatment apparatus for digesting and degrading organic matters in sewage water by using aerobic microorganisms in sewage water in the presence of free oxygen to stabilize and make harmless the organic matters, the aerobic tank is in the form of a contact oxidation tank, the filler is disposed in the tank, the oxygenated sewage water is immersed in the entire filler and flows through the filler at a uniform flow rate, oxygen required by the microorganisms in the contact oxidation tank is usually supplied by artificial aeration, after the biofilm grows to a standard thickness, the microorganisms entering the wall of the filler undergo anaerobic metabolism due to oxygen deficiency, the generated gas and the scouring action formed by aeration cause part of the biofilm to fall off, the growth of new biofilm is promoted, the biological metabolism is formed, the fallen biofilm enters a subsequent third sedimentation tank along with the effluent water, the dissolved oxygen in the aerobic tank stabilizes 2.0-2.5/gm/L/day, and sewage is collected by a water collecting tank at the top of the tank and is pumped into an anaerobic tank for circulation, and redundant sewage in the water collecting tank overflows into a third sedimentation tank.

7. The recycling process of papermaking wastewater as claimed in claim 1, wherein the step S7 is to overflow the aerobic tank wastewater and flow into 2 third sedimentation tanks with concrete structure, the third sedimentation tank is designed with a mud scraper, the mud scraper is used to operate at low speed to make the water in the sedimentation tank turbulent and orderly, the inorganic impurities still keep better sedimentation and separation, the suspended particles are gathered at the bottom of the water during sedimentation, support each other and extrude each other, further sedimentation occurs, the sedimented sludge is pumped back to the anaerobic tank by a slurry pump, the slurry pump pumps the paper machine to damage the tank for replenishing water, and the water is collected into the subsequent chemical reaction tank through a tank top water collection tank after sedimentation in the long tank;

the dosing pool is divided into 3 grids, 1000L/h of a buoy flowmeter for adding polyaluminium chloride is added in the first grid and is controlled to be 800L/h, 1000L/h of a buoy flowmeter for adding a cationic retention aid is added in the second grid and is controlled to be 400L/h, and the mixed materials enter the drainage pool under self pressure.

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