The dirty oil collected in sewage treatment is dehydrated in the dehydration tank and sent to the storage and transportation tank farm; The separated sludge and scum are sent to the coking unit after concentration and dehydration; The remaining activated sludge is concentrated and dehydrated by centrifuge, and then transported abroad for treatment; The waste gas generated in the operation is sealed and collected, and then discharged into the atmosphere after biological treatment.
The rainwater in the whole plant is divided into three independent systems (rainwater in front of the plant, rainwater possibly containing oil and rainwater in storage and transportation area), which are collected to rainwater monitoring facilities respectively. If the rainwater is qualified, it will be pumped to the external drainage system, and if it is unqualified, it will be upgraded to oily sewage series for treatment.
The designed treatment capacity of oily sewage treatment series is 400 m3/h;
The designed treatment capacity of saline sewage treatment series is 200m3/h;
The design capacity of the three sludge concentration and dehydration facilities is12m3/h;
The effective volume of the rainwater monitoring pool is about 45000m3；;
The designed treatment capacity of waste gas treatment system is16000m3/h.
1.2 process principle
1.2. 1 regulating tank
The regulating tank uses its own volume to temporarily store part of the sewage that exceeds the treatment capacity of the subsequent process, or uses the spare volume in the tank to dilute the high-concentration sewage, so as to regulate the water quality and quantity of the subsequent treatment process and ensure the smooth operation.
There is a floating circulating oil receiver in the tank, and the pressure flow sewage enters the tank and is sent to the ring pipe of the floating oil receiver through the hose. The loop pipe is equipped with a water distribution system, which discharges water at a certain angle. After the water is sprayed, it flows to the center of the tank to form a circulating flow, and the oil and water enter the central oil receiver to complete the first separation. After the oil layer in the middle and upper part of the receiving tank reaches a certain thickness, the oil layer overflows to the central funnel, and then is discharged to the oil pipeline of the regulating tank through the hose to complete the secondary separation. The central funnel uses the density difference of oil and water with the same quality to ensure that only oil is discharged without drainage, and the water at the lower part of the oil tank flows back to the regulating pool. The oil receiver floats along the guide rail around the tank through the buoy with the liquid level. When the water level is low, the oil receiver is placed on the tank bottom support frame. Make full use of the large surface area of the regulating tank to collect oil, at the same time, it has no great influence on the volume of the regulating tank, and realizes the first oil removal of sewage.
1.2.2 oil-water separator
The oil-water separator consists of the following working areas: water inlet buffer area, coarse granulation area, oil-water separation and oil discharge area, and water outlet stability area.
Inlet buffer zone: sewage is lifted to the buffer zone, and through the sudden expansion of the water flow section, the impact of the inflow velocity on the water body in the coarse granulation zone is reduced, and oil and water can be pre-separated.
Coarse-grained area: The collision probability and collision time of tiny oil droplets in sewage are increased and the particle size of oil droplets in sewage is increased by using the different adsorption forces of fillers on oil and water. After coarse granulation, the sewage will enter the oil-water separation and oil discharge area evenly through the water distribution device.
Oil-water separation and oil discharge area: this area is divided into two stages. The separation zone is provided with an inclined tube through which oil and water and suspended matter are separated. The separated dirty oil enters the oil collection bag at the top of the container to control the oil level and discharge oil. When the oil-water interface instrument in the oil discharge area detects the set oil level, the oil discharge valve automatically opens to discharge the dirty oil to the dirty oil pool; A small amount of precipitated sludge is discharged manually and regularly through the drain valve.
Effluent stability zone: sewage enters the effluent stability zone after oil-water separation to ensure uniform effluent of the device and relatively constant water flow in the device.
1.2.3 Vortex concave air flotation
Vortex-concave air flotation is mainly composed of aeration zone, air flotation zone, reflux system, slag scraping system and drainage system. Its working principle is: after coagulation, the sewage containing coagulant and coagulant AIDS first enters the aeration area of the vortex-concave aerator, and a negative pressure area is formed in the water through the rapid rotation of the hollow impeller at the bottom. At this time, the air on the water surface is pumped into the water through the hollow pipe, and is pressed into microbubbles under the action of three shear forces generated by the rapid rotation of the bottom impeller. After reaching the liquid level, the solid pollutants float on the water surface with the support of these microbubbles, and the scum is scraped into the scum collection pool by the scum scraper, and the purified water overflows from the overflow pool to complete the treatment process.
The return pipeline extends from the bottom of the aeration zone along the bottom of the air flotation zone. There is a negative pressure zone at the bottom of the aeration zone due to the action of the vortex concave aeration head, which will make the wastewater flow back to the aeration zone from the bottom of the air flotation zone, and then return to the air flotation zone under the action of microbubbles to realize the backflow. At the same time, oxygen in the air also enters the water, which can oxidize harmful substances in the water and achieve the purpose of purifying sewage.
1.2.4 dissolved air flotation
Dissolved air flotation adopts partial reflux pressure dissolved air flotation process. The sewage containing coagulant and coagulant aid is fully stirred and mixed in the reaction chamber, then enters the contact chamber, descends to the separation chamber under the action of dissolved air water, completes the stratification of water and scum, and then enters the water outlet chamber. Part of the water in the water outlet chamber is pumped up, pressurized compressed air is sent to the air dissolving tank, and the air in the air dissolving tank is dissolved in water under the pressure of 0.3-0.5 MPa to reach a saturated state, and then the saturated dissolved gas is instantly decompressed to a normal pressure state by a dissolved gas releaser, and the released dissolved gas forms bubbles with the diameter of 10-30 μm, and the bubbles can be attached to the surfaces of oil particles, hydrophobic suspensions or colloids in the floating process.
1.2.5 homogenizing tank
The function of the homogenization tank is to homogenize the water quality, that is, to mix the sewage with different time, different components and different concentrations, so as to obtain more uniform water quality and constant flow, and at the same time, to consume the dissolved oxygen content in the air flotation water to meet the requirements of A-level dissolved oxygen. There are generally two ways of homogeneous mixing: one is to mix the wastewater by external power (mechanical mixing, air mixing and forced circulation by water pump). The other uses differential flow to make wastewater mix by itself. The homogenization tank of this device adopts differential flow mode.
1.2.6 A/O biological treatment of oily sewage
The biochemical treatment of oily sewage adopts anaerobic-aerobic biochemical treatment process. By creating an aerobic and anoxic environment in the aeration tank and utilizing the interaction between autotrophic nitrifying bacteria and heterotrophic denitrifying bacteria in activated sludge, the form transformation of nitrogen can be realized. The main function of O section of biochemical tank is to complete carbonation and nitrification. Most organic matter is decomposed into CO2 and H2O under the action of aerobic bacteria, and NH3-N is oxidized into NO3-N and NO2-N. In order to ensure the smooth nitrification, the pH value should be controlled in alkalinity. Because the alkalinity of raw water is insufficient, NaHCO3 or NaOH should be added to the pool to ensure the residual alkalinity of the mixed solution. Biological denitrification generally requires two steps: nitrification and denitrification.
1.2.6. 1 nitration reaction
Nitrification is a two-step process, using two kinds of microorganisms-nitrosobacteria and nitrifying bacteria. These two kinds of bacteria are collectively called nitrifying bacteria. The first step is the process that NH4+ is oxidized to NO2 by nitrifying bacteria, and then NO2 is oxidized to NO3ˉ by nitrifying bacteria in the second step. Both of these reactions will release energy, and nitrifying bacteria will use this energy to synthesize new cell bodies and maintain normal life activities. Nitrification degree is the key to biological nitrogen removal.
2NH4++3O2 2NO2ˉ+4H++2H2O+ Q
2NO2ˉ+O2 2NO3ˉ+ Q
NH4++2O2 NO3ˉ+2H++H2O+ Q
It can be seen from the reaction formula that the whole nitrification process consumes a lot of oxygen. 1g ammonia nitrogen requires 4.75g oxygen for each nitrification. In addition, the nitration reaction will produce strong acid (HNO3), which will increase the acidity of the operating environment. Because the alkalinity of raw water is insufficient, it is necessary to add NaHCO3 or NaOH to the tank to ensure the residual alkalinity of the mixed solution and control the pH value to be alkaline, so it should be adjusted during operation. In order to make nitrification proceed smoothly, low organic load should be adopted to prolong aeration time, and the key is sludge retention time, that is, sludge age. 2/3 aeration tank volume is used as aerobic zone to meet the retention time of sludge.
1.2.6.2 Denitrification reaction
Denitrification is a process in which denitrifying bacteria dissimilate nitrate, that is, nitrate and nitrite produced by denitrifying bacteria are reduced to nitrogen under the action of denitrifying bacteria, and then overflow from water. Most denitrifying bacteria are heterotrophic and facultative bacteria, so the denitrification process should be carried out in an anoxic state. The concentration of dissolved oxygen should be controlled at 0.2 ~ 0.5 mg/L, otherwise the denitrification process will slow down. Control the dissolved oxygen concentration in the aeration tank to obtain an environment suitable for the growth of denitrifying bacteria. It can use various organic substrates as electrons in the denitrification process. Denitrification reaction includes assimilation denitrification and alienation denitrification, and the reaction process is as follows:
Assimilation and denitrification are completed according to the following steps
NO3ˉ NO2 X NH2OH Organic Nitrogen (Battery Composition)
Alienation denitrification is completed in the following two steps: the first step is to convert nitrate into nitrite, and the second step is to convert nitrite into carbon dioxide, nitrogen and inorganic salts.
6 NO3ˉ+2ch2 oh 6 NO2ˉ+2co 2+4H2O
6NO2ˉ + 3CH3OH3N2 + 3CO2 + 3H2O + 6OHˉ
Namely: 6NO3ˉ+5CH3OH 5CO2+3N2+7H2O+6OHˉ.
The oxygen consumed in the nitrification process can be recovered and reused in the denitrification process, and each reduction of 1g NO3ˉ can provide 2.86g of oxygen to oxidize the organic matrix. Denitrification process can also produce alkalinity, which can make up for the alkalinity consumed by nitrification reaction. In the denitrification stage, not only nitrogen compounds can be reduced, but also organic carbides can be oxidized and decomposed. So denitrification will remove both carbon and nitrogen.
1.2.7 biochemical treatment of salty sewage
Activated sludge process is used for saline wastewater, which utilizes the metabolism of various microorganisms (mainly bacteria) in aerobic environment, oxidizes and decomposes various organic substances in wastewater through the process of breathing and reproduction, and can also remove colloidal particles in wastewater through flocculation. The removal of pollutants by activated sludge method is completed through the following processes:
Primary adsorption and hydrolysis 1. 2. 7 1
Because the activated sludge has a large surface area (2000- 10000m2/m3) and a polysaccharide adhesion layer, the suspended solids and colloids in sewage are flocculated and adsorbed within a few minutes after contacting with sewage, which is called the first stage-adsorption stage. At this time, organic matter (COD, more precisely BOD) is only stored on the surface of microbial cells as a backup food source. Then carbohydrates, protein, fat and other macromolecules are hydrolyzed and converted into simple compounds with small molecules, which are further absorbed and decomposed by microorganisms. Some of them are converted into inorganic substances, such as CO2, H2O and NH3. Part of it is transformed into microbial matrix, so that microorganisms can reproduce and enter the second stage-oxidative decomposition stage.
1.2.7.2 decomposition and oxidation of organic matter
At this stage, the activated sludge continues to decompose and oxidize the organic matter absorbed and adsorbed in the first stage, and at the same time continues to adsorb the residual substances that were not absorbed and adsorbed in the first stage, mainly dissolved substances. This stage is quite slow, much longer than the first stage. Most of the volume of aeration tank is used for the oxidation of organic matter and the synthesis of microbial cytoplasm.
The biochemical reaction process of 1 aerobic microorganisms can be briefly described as follows:
Oxidation of (1) organic carbon
[C] (organic carbon) +O2+ microorganism (enzyme) → CO2+H2O+Q.
(2) Oxidation of organic amines
[N] (organic amine) +O2+ microorganism (enzyme) → CO2+NH3+H2O+Q.
(3) Oxidation of organic sulfur or inorganic sulfur
[S] (organic sulfur or inorganic sulfur) +O2+ microorganism (enzyme) → CO2+SO2+H2O+Q.
Through the above three processes, organic matter, organic amine, organic sulfur and inorganic sulfur in sewage are treated, so that sewage is treated.
Purification.
2 Assimilation and synthesis (cell proliferation)
[C] (organic matter) ++ O2 ++ microorganism (enzyme) →[C] (proliferating microorganism)
This process allows microorganisms to multiply, even if activated sludge increases.
3 Endogenous respiration
When microbial cells lack nutrition, some cytokines need to be consumed in order to obtain the energy needed for survival.
Biomass is oxidized, that is, endogenous respiration:
[c] (microorganism) +O2+ microorganism (enzyme) → CO2+NH3+H2O+Q.
This process reduces the total amount of microorganisms, that is, the amount of activated sludge.
1.2.8 secondary sedimentation tank
The secondary sedimentation tank adopts radial sedimentation tank, with water inlet from the central pipe and water outlet from the periphery. Mud-water mixture from the aeration tank enters the central pipe from the bottom of the secondary sedimentation tank, and flows around the central pipe evenly after being rectified by the rectifying plate around the central pipe. Due to the density difference between sludge and water, a density flow is formed, and the supernatant with low density overflows through the outlet weir arranged around the secondary sedimentation tank. Activated sludge settles to the bottom of the tank, and is scraped into the sludge collecting hopper in the center of the tank bottom by the slowly rotating scraper, and then flows into the sludge return tank by gravity, and then is lifted by the pump and returned to the aeration tank. The scum on the water surface is scraped into the slag discharge bucket by the slag scraper and flows to the scum pool by itself.
1.2.9 Coagulation reaction tank and sedimentation tank
1.2.9. 1 coagulation reaction tank
The reaction tank is divided into a mixing section and a three-stage reaction section. Flocculants added to the mixing section quickly diffuse under the action of the agitator and are evenly mixed with sewage. The mechanism of double-layer compression and electric neutralization of flocculant makes the suspended particles in water lose stability and combine with each other to form tiny flocs. After further stirring in the third-stage reaction section, the tiny flocs gradually grow into large flocs under the action of flocculant adsorption bridging and precipitation net capture mechanism, and flow into the sedimentation tank for separation.
1.2.9.2 sedimentation tank (same as the second sedimentation tank)
1.2. 10 quicksand filter
The quicksand filter is based on the principle of countercurrent. The water to be filtered flows to the bottom of the equipment through the water inlet pipe and the central pipe at the upper part of the equipment, enters the bottom of the sand bed through the water inlet distributor, flows upward to the filter layer for purification, and the filtered water is discharged from the water outlet at the upper part of the equipment; The air lift pump lifts the filtered sand particles from the conical bottom of the equipment to the sand washer at the top of the equipment; During the lifting process of the air lift pump, the cleaning of sand particles has begun; Turbulent mixing makes the trapped dirt peel off from the sand; The sand particles entering the sand washer automatically return downward to the sand bed due to gravity, and at the same time, a small amount of filtered water is introduced into the sand washer to form cross flow with the downward moving sand particles, which plays a cleaning role; The washing water is also discharged through the washing water outlet arranged at the upper part of the equipment; The washed sand particles return to the sand bed, forming a slow downward movement of the whole sand bed, thus forming the principle of quicksand filter.
Quicksand filter is a kind of contact deep filter with uniform medium. Moreover, because the quicksand filter has no moving parts, there is no need to stop backwashing for 24 hours, and the filtering quality can be effectively and stably guaranteed.
1.2. 1 1 sludge concentration and dehydration
1.2. 1. 1 sludge concentration
The relationship between sludge water content and sludge volume can be expressed by the following formula:
v = v 0×{[ 100 SW+P(SS-SW)×( 100-P0)]}/{[ 100 SW+P0(SS-SW)]×( 100-P)}
Among them:
V0-the volume of sludge when its water content is P0;
V-volume of sludge with water content of p;
SS-specific gravity of wet sludge;
SW-specific gravity of water;
P-water content of sludge after sludge concentration;
P0-water content of sludge before sludge concentration.
As can be seen from the above formula, the higher the water content of sewage, the greater the sludge volume.
The purpose of sludge concentration is to concentrate and reduce the volume of sludge and do pretreatment for further treatment and utilization.
Sludge concentration mainly includes gravity concentration and air flotation concentration, and gravity concentration can be divided into intermittent and continuous. The intermittent concentration tank is a circular tank with a sludge hopper at the bottom. The sludge is put into a concentration tank, concentrated by gravity sedimentation, and the supernatant is removed by layers at regular intervals, and the sludge is discharged from the bottom hopper. Generally, there are at least two intermittent sludge concentration tanks, one for operation, the other for sludge, and the two tanks are used alternately. The continuous sludge concentration tank enables the sludge before concentration to continuously enter the concentration tank. Under the action of gravity, solid sludge particles naturally sink, and under dynamic conditions, upper clarification zone, middle retardation zone and lower compression zone are formed. The supernatant in the upper clarification area can be discharged through the multistage dewatering valve, and the concentrated sludge in the lower compression area can be continuously discharged through the bottom sludge discharge valve, and sludge concentration can be continuously carried out. Qingdao Refinery adopts continuous sludge concentration tank.
1.2. 1 1.2 Sludge dewatering
(1) Sludge dewatering method
There are mainly natural drying, mechanical dehydration and thermal pretreatment.
⑵ Mechanical dehydration pretreatment
The purpose is to improve the dewatering performance of sludge and increase the production capacity of dewatering equipment. These methods include chemical conditioning, elutriation, heat treatment and freezing.
Chemical conditioning method mainly includes adding coagulant and coagulant aid. To coagulate sludge and improve dewatering performance. Coagulants include inorganic coagulants and polymer polyelectrolyte. The former includes aluminum salt and iron salt. The latter includes organic synthetic polymer polyelectrolyte (such as polyacrylamide PAM) and inorganic polymer coagulant (such as polyaluminum chloride PAC).
⑶ Mechanical dehydration
Mechanical dehydration methods include vacuum filtration, pressure filtration and centrifugation, and the main equipment includes vacuum filter, plate and frame filter, belt filter and centrifuge.
The dehydrator used by Qingdao Refining and Chemical Company is a centrifugal dehydrator, and its basic principle is as follows:
After the sludge after precipitation and concentration is mixed with the polymer flocculant diluted to a certain concentration in the pipeline mixer, the suspended solid particles in the sludge are flocculated into flocs, and the free water is separated. The suspension enters the drum through the feed pipe in the center of the hollow screw. Due to the centrifugal force, the sludge is thrown to the inner wall of the drum immediately after leaving the feed pipe. The sludge particles with higher density are deposited on the inner wall of the drum to form a sludge layer, while the liquid phase with lower density forms a liquid ring layer on the sludge layer, thus realizing the separation of mud and water. The deposited sludge is pushed to the slag discharge port by the screw and thrown out. The liquid phase overflows through the overflow weir.
1.2. 12 waste gas treatment
Waste gas treatment adopts biofilm method. The waste gas from the collection system first enters the pretreatment section for humidification, temperature adjustment and dust removal through the air duct, and then enters the sulfur biological and hydrocarbon biological treatment section. In the process of contact with water (liquid phase), pollutants enter the liquid phase (or liquid film) from the gas phase due to the concentration difference between the gas phase and the liquid phase and the solubility of pollutants in the liquid phase. Pollutants entering the biological layer (or liquid film) on the surface of liquid or solid are absorbed (or adsorbed) by microorganisms, and are decomposed and converted into harmless and simple substances as energy and nutrients during microbial metabolism. It is exhausted by a fan, so as to achieve the purpose of deodorization.
The reaction formula of biodegradation is:
Odor pollutants +O2 cell matter +CO2+H2O
Before using biological filler, a certain number of specific microbial strains should be inoculated and domesticated. After the environmental conditions change, some microorganisms will die and some will continue to live. Surviving microorganisms can develop into dominant bacteria after short-term reproduction. Therefore, it can bear the impact load. When the concentration of pollutants increases, the treatment effect will decrease in a short time, but it will soon return to normal. When the concentration of waste gas is very low, the nutrient solution in the nutrient solution circulation box is evenly sprayed on the biological filler through the circulating pump for microorganisms to absorb nutrients and grow and reproduce.
1.2. 13 rainwater monitoring pool
Rainwater from clean rainwater system, possibly oily rainwater system, storage and transportation area and Qirun oil depot flows into the grid lifting pool in the rainwater monitoring area. The grille adopts mechanical grille, which is obliquely placed on the channel of the grille lifting pool to intercept larger suspended substances or floating objects in the wastewater, such as fibers, broken skins, trees, sawdust, rags, plastic products, household garbage, etc. Otherwise, after these sundries enter the system, they will block the process pipelines, pumps and other equipment, resulting in the system can not operate normally. In addition, it also increases the load of subsequent facilities and structures. Under normal circumstances, the rainwater passing through the grid pool is directly boosted and then discharged into the municipal flood drainage ditch for discharge into the sea. Under special circumstances, such as fire accident or leakage accident in the tank farm, this part of rainwater can be lifted to the rainwater monitoring pool, monitored after receiving oil through the floating oil tank, and then directly discharged or sent back to the sewage treatment plant for treatment according to the water quality.
1.2. 14 Principles and functions of main chemicals
Commonly used chemicals in sewage field mainly include coagulant, coagulant aid, pH regulator, nutrient, disinfectant, sludge conditioner and so on.
1.2. 14. 1 coagulant
In water treatment, this kind of substance that can make colloidal particles in water adhere to each other and coalesce is called coagulant. Coagulants are generally divided into inorganic coagulants and organic coagulants. Polyaluminum (PAC) is an inorganic coagulant used in the field of sewage treatment, which is added to the primary and secondary flotation equipment as a flotation agent. Organic coagulant polyacrylamide (PAM) was added to the coagulation sedimentation tank as flocculant.
(1) polyaluminum (PAC), also known as basic aluminum chloride, has the molecular formula AlN (oh) MC13n-m. ..
Mechanism of action: When polyaluminum is put into wastewater, it is hydrolyzed to produce positive ion Al3+ and negative ion cl-.
AlC 13Al3+ +CI-
Al3+ is a high valence ion, which increases the ion concentration in water. Under the attraction of charged colloidal particles, the electric double layer is compressed, which makes charged colloidal particles tend to be electrically neutral, eliminates electrostatic repulsion, reduces the stability of suspended solids, and combines into larger particles after colliding with each other. Al3+ is hydrolyzed to produce colloidal Al(OH)3.
Al3++3H2O Al(OH)3 +3H+
Colloidal Al(OH)3 has a long strip structure, large surface area and high activity, and can adsorb suspended particles in water. Through adsorption bridging, the dispersed particles form a network structure and become coarse flocs (alum flowers), so that the suspended particles precipitate or float on the water surface.
⑵ Polyacrylamide (PAM) is an organic polymer polymerized from acrylamide. Colorless and tasteless, soluble in water, non-corrosive. Its molecular formula is (-CH2-CH-) n.
CONH2
Mechanism of action: molecular chain length of polyacrylamide. Under the action of alkali, polyacrylamide is hydrolyzed. After hydrolysis of polyacrylamide, the curly molecular chain expands and elongates, and the long chain forms a huge adsorption surface area in water, which improves the bridging ability. In addition, polyacrylamide has polar genes, and its amide genes are easily adsorbed on the surface of colloidal particles through hydrogen bonds; Achieve adsorption bridging effect, form large particle condensate, and separate it from water.
1.2. 14.2 coagulant aid
In the coagulation treatment of wastewater, sometimes a single flocculant can not achieve good coagulation effect, and some additives need to be added to improve the coagulation effect. Some coagulant AIDS themselves do not have coagulation effect, but improve and improve coagulation effect; Others participate in the formation of flocs and improve the structure of flocs.
Polyacrylamide was added as coagulant aid in the primary and secondary flotation of sewage field. Through the adsorption surface area and bridging formed by long chains of polyacrylamide molecules, the coagulation is accelerated, the density and quality of flocculated particles are increased, and the bonding and bridging are strengthened, so that the flocculated particles are large and the surface area is large, the function of adsorption zone can be fully exerted, and the flotation separation effect is improved.
1.2. 14.3 pH regulator
There are generally two ways to adjust the pH value of wastewater: one is to neutralize each other with acid-base wastewater, which is a simple and economical method; The other is neutralization by adding chemicals, and the pH value is adjusted by adding acid-base solution to wastewater. According to the nature of the wastewater to be treated and the requirements of A/O biochemical treatment process for wastewater alkalinity, NaOH or NaHCO3 is added to the wastewater field to adjust the pH value, and acidic substances in the wastewater are used to neutralize and reduce the acidity of the wastewater. The reaction formula is as follows:
Sodium hydroxide+sodium chloride hydrochloride +H2O
NaOH+HNO3 NaNO3 +H2O
NaOH+H2SO4 Na2SO4 +H2O
1.2. 14.4 nutrients
The proportion of elements in microbial cells is c: n: p = 100: 5: 1. Because the treated refinery wastewater contains high content of other elements, and the nutrient element P of microbial cells is very low, almost close to zero, in order to successfully treat these wastewater by biological methods, it is necessary to make the microorganisms involved in decomposing oxidized organic matter obtain the necessary nutrients and supplement the nutrients they lack to meet the needs of microbial growth. The nutrient used in sewage field is disodium hydrogen phosphate? 12H2O .
1.2. 14.5 disinfectant
In order to ensure the quality requirements of reclaimed water and control the number of fecal coliforms, Youchlorojing was used as disinfectant. Disinfectants are usually oxidizing biocides, which are strong oxidants and can oxidize enzymes that play a metabolic role in microorganisms, thus killing microorganisms, killing microorganisms and playing a role in disinfection. The selection of Youchlorine as bactericide in sewage field is mainly based on the selection of the same agent as that in circulating water field, which is convenient for future operation and management. The general structural formula is as follows:
1.2. 14.6 sludge conditioner
Sludge conditioner, also known as dehydrating agent, can be divided into inorganic conditioner and organic conditioner. Inorganic conditioner is suitable for sludge vacuum filtration and plate-frame filtration; Organic conditioner is suitable for centrifugal dehydrator and belt filter press dehydration. The dosage of conditioner (dehydrating agent), coagulant and coagulant aid can be called dosage. The same agent can be used as coagulant in sewage treatment and conditioner or dehydrating agent in excess sludge treatment.
An organic regulator polyacrylamide (PAM) is used in the field of sewage treatment. By neutralizing the surface charges of sludge particles, the bridging effect between particles is generated, so that sludge particles are dense and coarse, and mud-water separation is realized.
Technical characteristics of 1.3
1.3. 1 Sewage is divided into saline sewage series and oily sewage series for treatment according to the principle of sewage diversion;
1.3.2 oily sewage series can be reused after advanced treatment;
1.3.3 Water quality indicators of inlet and outlet water can be monitored and adjusted online;
1.3.4 The water quality and quantity adjustment of the regulating tank are integrated with oil removal, and the oil removal process is not affected by the change of the tank position, so that only oil is collected without water, and the occupied area is saved;
1.3.5 vortex-concave air flotation has the characteristics of high inflation, automatic internal reflux, land saving and low energy consumption;
1.3.6 A/O biochemical tank is equipped with aerator, which can operate in anoxic-aerobic mode or aerobic mode, and the ratio of anoxic-aerobic volume can be adjusted. The process of combining contact oxidation method and activated sludge method is adopted, and K-3 spherical filler is added to Grade A, which is directly added, without fixation, easy to film and block, and prolongs the sludge retention time;
1.3.7 The running of quicksand filter is carried out at the same time of sand washing, and it can automatically run continuously for 24 hours without stopping backwashing. The traditional high-power backwashing system is replaced by the structure of loose blowing sand after being filtered by air pump, and the sand running amount is extremely low.
1.3.8 sludge scum is concentrated and dehydrated, and then sent to coking for treatment, saving treatment cost.
1.3.9 The primary and secondary air flotation and biological aeration tanks are sealed, and the odor is collected through the waste gas pipe network for biological treatment, thus improving the air environment of the sewage treatment plant.
2 process description and flow chart
2. 1 process description
2. 1. 1 oily sewage series
Pressurized oily sewage from the factory system enters the oily sewage regulating tank, which is equipped with a floating circulating oil receiver to remove oil from oily sewage. The effluent from the regulating tank is pumped to the oil-water separator on the third floor of the frame. After oil-water separation, it flows into the concave air flotation on the second floor of the frame to remove some emulsified oil, and then flows into the dissolved air flotation on the first floor of the frame to further remove oil. The effluent is lifted to the homogenization tank by the pump. The flow rate at the outlet of the homogenization tank is regulated by the regulating valve to ensure a relatively constant flow rate to automatically enter the A/O biochemical tank; after biological treatment, it automatically enters the secondary sedimentation tank for mud-water separation; the precipitated sludge is lifted by the sludge reflux pump and refluxed to the aeration tank; the supernatant of the secondary sedimentation tank enters the coagulation sedimentation tank, and the suspended solids which are not easy to settle are further removed by adding chemicals; then the gravity flows into the continuous backwashing sand filter; and the effluent enters the recycling tank after disinfection and monitoring. The sewage that meets the reuse standard is pumped into the reuse system pipe network of the whole plant by the reuse pump, and the sewage that does not meet the reuse standard is pumped into or discharged into the saline sewage monitoring pool by the reuse pump, and can also be lifted and returned to the homogenization pool or coagulation reaction pool by the reuse pump for further treatment.
The foreign self-flowing oily sewage enters the self-flowing oily tank and is lifted to the regulating tank by the self-flowing oily sewage pump.
The foreign domestic sewage enters the domestic sewage pool and enters the homogenization pool or biochemical pool after being lifted by the domestic sewage pump.
2. 1.2 series salty sewage
The pressure of that salty sewage from the system enter the salty sewage regulating tank, and a floating circulate oil receiver is arranged in the regulating tank to collect the oil in the salty sewage. The sewage from the regulating tank is pumped to the oil-water separator on the third floor of the frame. After oil-water separation, it flows into the concave air flotation of the second layer of the frame to remove part of emulsified oil, and then flows into the dissolved air flotation of the first layer of the frame to further remove oil. The wastewater is pumped into the plug-flow blast aeration tank for treatment. The treated sewage mixture flows into the secondary sedimentation tank for mud-water separation, and the settled sludge is lifted by the sludge reflux pump and returned to the aeration tank. The effluent from the supernatant of the secondary sedimentation tank flows into the discharge monitoring tank for monitoring, and the qualified sewage is lifted by the discharge pump and then discharged to the municipal pipe network.
Pressure production wastewater directly enters the saline wastewater monitoring pool and is discharged after monitoring.
Pressure production wastewater directly enters the saline wastewater monitoring pool.
2. 1.3 tertiary sludge treatment
Sludge discharged from the bottom of the regulating tank, sludge discharged from the bottom of the oil-water separator, scum discharged from the vortex cavity and scum discharged from dissolved gas all flow into the sludge scum tank by themselves and are lifted to the sludge scum concentration and dehydration tank by the pump. After gravity concentration and dehydration, sludge scum is sent to coking unit by sludge scum pump for treatment. The concentration and dehydration tank is removed by the five-stage dehydration valve, and the removed water is discharged into the sewage collection tank and enters the saline sewage regulating tank through the lift pump.
The oily and salty sewage secondary sedimentation tank sinks into the activated sludge at the bottom of the tank, flows into the sludge return tank by gravity, and is lifted and returned to the aeration tank by the sludge return pump. The residual activated sludge can be transported to the sludge concentration and dehydration tank through the residual activated sludge discharge valve on the outlet pipeline of the sludge reflux pump. The sedimentation tank for advanced treatment of oily sewage sinks into the low sludge tank, flows into the sludge suction tank by gravity, and is pumped into the sludge concentration and dehydration tank by the sludge lifting pump. The sludge concentration and dehydration tank is discharged through the five-stage dehydration valve, and the discharged water is discharged into the sewage collection tank and enters the saline sewage regulating tank through the lift pump.
After gravity concentration and dehydration, the sludge in the concentration and dehydration tank is lifted to the centrifugal dehydration machine by the feed pump of the dehydration machine through the sludge discharge valve at the bottom of the tank for dehydration, and the dehydrated sludge is sent out and transported by the pump. The drainage water is discharged into the water collection tank, and then pumped up and then enters the saline sewage regulating tank for treatment.
2. 1.4 Treatment of dirty oil and waste gas
The dirty oil collected by the regulating tank and the oil-water separator flows into the dirty oil tank and is lifted by the dirty oil pump to the dirty oil dehydration tank for dehydration. The dewatered dirty oil is sent to the dirty oil tank in the oil tank area by the delivery pump.
The waste gas generated by vortex-concave air flotation, dissolved air flotation and biological aeration tank is covered and collected, then sent to the waste gas treatment system, and discharged from the exhaust pipe after biological treatment.