China is a leather manufacturing country and consumption country, the output and demand are very huge. The leather industry has caused great pollution to the environment. With the concept of environmental protection deeply rooted in the people, whether the pollution discharge of leather wastewater can be effectively solved directly affects whether the leather industry can continue to survive, develop healthily and steadily.

Leather production is mainly wet operation, through physical, chemical and mechanical processes of various raw materials into finished leather. Because most of the work has water as the medium, the preliminary statistics of each production of 1 ton of raw material skin to discharge 60~120 tons of wastewater. In the process of leather production, there is a huge amount of water consumption and sewage discharge demand. Leather wastewater is a kind of industrial wastewater which is difficult to treat. The application of decanter centrifuge to the treatment of tannery wastewater is a technological progress.

Analysis of tannery wastewater, sewage mainly comes from the wet operation preparation section and tanning section of tannery production, including soaking wastewater in leather soaking section, degreasing section wastewater, soaking and removing ash and washing section wastewater, acid leaching wastewater, chrome tanning process wastewater and dyeing grease wastewater, which makes the converging wastewater contain a large amount of organic matter (protein, dye, grease), inorganic matter (sulphide chromium salt, etc.) and sediment harmful substances such as wool residue oil sludge. The practice shows that good economic and environmental benefits can be obtained by using decanter centrifuge to participate in the treatment of tannery wastewater. It can not only change the working environment of leather processing place, but also make the pollutants stable Standard, and the cost of wastewater treatment per ton can be reduced by nearly half, realizing the win-win of environmental and economic benefits.　

The idea of decanter centrifuge participating in tannery wastewater treatment:

Leather wastewater-coarse filtration pretreatment-dosing precipitation-lying decanter centrifuge solid-liquid separation-material recycling.

Horizontal centrifuge involved in tannery wastewater treatment process:

According to different tannery processes, the general components of sewage were analyzed. Through biochemical method, the organic components were decomposed and transferred, and the inorganic components were flocculated and precipitated by horizontal screw centrifuge. After purification, the water quality is up to standard and the organic compost is used as fertilizer.

decanter centrifuge to participate in tannery wastewater treatment station setup:

The main facilities are grille, pre-regulating tank, primary settling tank, oxidation ditch, secondary settling tank, air floatation tank, sludge thickening tank, sludge scum recovery facility and medicament dosing facility;

Pretreatment: waste water through fine grille can intercept a large number of floating matter, iron oxide and suspended matter, it can achieve the purpose of continuous removal of various shapes of small debris, verify the normal operation of subsequent treatment process equipment, in order to reduce the load of subsequent treatment structures;

Precipitation regulation: the waste water is treated by the grille machine and enters the regulating tank. It adjusts the water quantity and water quality while removing the oil slick in the water through the oil collecting pipe;

Flocculation and precipitation: germicidal disinfection of hypochloric acid, precipitation of metal alkali lime, regulation ph sulfuric acid, flocculant.

Filter press and decanter centrifuge are common solid-liquid separation equipment, the quantity is very large, GN discusses with you the technical advantages of solid-liquid separation production line machine from filter press to decanter centrifuge:

1. Decanter centrifuge without filtering medium

Filter press pressure filtration of filter medium (filter) to separate solid and liquid, need to use high pressure water to avoid filter belt obstruction; decanter centrifuge high speed rotation to produce centrifugal position to separate solid-liquid centrifugal settlement, It is not suitable for filter medium because of filter screen, which bypasses the common filter clogging problem in filter operation.

• Decanter centrifuge is widely applicable

Filter press can also most of the solid-liquid separation, but the oil, viscosity and other strong adhesion of solid-liquid separation needs pre-treatment and incomplete separation; decanter centrifuge separation adaptability, can achieve solid-liquid two-phase separation and solid-liquid three-phase separation, better adaptability to solid-liquid separation.

• Automation of production line of decanter centrifuge 

Filter press is intermittent operation of manual cutting slag, loading and unloading belong to intermittent operation most or need manual coordination is not conducive to the formation of automatic production line to improve production efficiency; decanter centrifuge can realize automatic loading and unloading continuous production automatic loading and unloading can form automatic production line production efficiency.

• Decanter centrifuge parameters adaptive adjustment ability

In the process of solid-liquid separation and dehydration, the belt filter is adjusted according to the working conditions, and the parameters such as speed, tension, dosage and flushing pressure often depend on the experience of the operator, which requires high operation technology.

• Low consumption of pre-treatment material for screw centrifuge

Because the filter filter media (mainly filter) mesh will not be very small, so the particle size should not be too small, small particle size should be added a lot of flocculant complex to synthesize large groups to facilitate filtration, which results in the consumption of additional pretreatment materials In decanter centrifuge, fine sludge can also be separated from water, so the dosage of flocculant is less, saving material input and reducing production cost；

• Decanter centrifuge production line environment is good

In addition to the main filter press, the filter press also needs to add medicine and feed conveyor to flush pump air compressor and other ancillary equipment, covering a large area, the whole machine is difficult to airtight, high pressure cleaning water mist and odor pollution environment, poor production line environment; decanter centrifuge covers a small area of high efficiency, supporting equipment simple complete machine seal operation, workshop environment is good

• Low maintenance requirements for decanter centrifuge

The number of easily damaged parts in the fuselage accessories of filter press is many times that of centrifuge. Maintenance is not only labor intensity but also high cost.

It can be seen from the above comparison that the comparison of decanter centrifuge with filter press under the same processing conditions has great technical advantages, and solid-liquid separation from filter press to decanter centrifuge is the trend of development.

The distillery directly sells / sends the distiller’s grains wastewater produced in the production process directly to the local pig farm, fish farm, shrimp farm, or earthworm farm as the direct feeding fertilizer is the simplest, most direct and economical treatment method. As a result, distiller’s grains wastewater can be digested on the spot without destroying the local ecological environment. It is also a very economical feed source for local third parties such as pig farms and fish farmers and shrimp farmers. Winery can also do not need to invest more cost to consider sewage discharge and a series of environmental issues. This treatment is the mainstream treatment of small and medium-sized distilleries for many years. With the outbreak of African swine fever in our country, the number of pigs in pig farms With the waterfall-style collapse, the demand for distillers’ grains in pig farms, one of the main places to go, has also plummeted, with the result that distilleries in many places have chosen to store the excess grains temporarily after simple solid-liquid separation, waiting for the swine fever epidemic to pass before shipping them to pig farms. But with the outbreak of swine fever, regulatory requirements for the source and quality of feed have increased, and swine fever has continued longer than expected, making it impossible for more and more distilleries to hoard distillers. Other treatments must be considered.

If distiller’s grains can not be sold to local third parties for local digestion, the simplest and most traditional method is biochemical treatment. The so-called biochemical treatment is that after the solid-liquid separation of distiller’s grains wastewater by centrifuge, the wastewater is discharged into a biochemical tank. After a series of steps, such as anaerobic, aerobic, sludge reduction and so on, the BOD and COD content in the wastewater are reduced to meet the national discharge standard. The solid slag (distiller’s grains) separated by centrifuge is dried and treated as solid waste. Using this way to deal with is actually helpless. This treatment is direct and simple, but the time, site requirements, and distiller’s grains are uncertain Processing methods can not become mainstream for a long time. Different distiller’s grains wastewater, in different climates, the time required to treat a batch of distiller’s grains wastewater varies from 10 to 20 days, which requires high land cost and time cost for enterprises. Because it is treated by biochemical method, in different environments, the effect of treatment will not remain the same, so enterprises are required to have strict requirements for the closing of the discharge of sewage. Put an end to the discharge of substandard sewage to the national sewage station into the river to cause second pollution. This is also a drawback and uncontrollable aspect of this treatment.

At present, there are some small wineries in China to “upgrade” the biochemical treatment. After simple solid-liquid separation of distiller’s grains wastewater by centrifuge, the effective substances in the wastewater were enzymatically hydrolyzed (released) by adding bacteria microorganism, and then collected and sold as animal feed nutrition additives by concentration, drying and other treatment methods. Although this method still needs to discharge the remaining sewage after biochemical treatment, it can bring certain economic effect to the enterprise after all. In the long run, this method is more favored by the enterprise. But also because of the complexity of enzymatic hydrolysis, as well as the singularity of bacteria, is doomed to use this “upgraded” biochemical treatment method can not maximize the value of distiller’s grains wastewater, and still need to biochemical treatment of the remaining wastewater, can not achieve 0 discharge. Whether from the management of enterprises or the monitoring of relevant state departments have higher requirements.

The above is small for everyone to bring the current domestic distiller’s grains wastewater treatment status. I hope it will help you. In the next issue, we will explain in detail the treatment methods of distiller’s grains wastewater in foreign countries, and will also share with you the treatment methods of distiller’s grains wastewater which can be discharged 0 in China at present.

When it comes to distiller’s grains, first understand what distiller’s grains are. distiller’s grains are the residue of rice, wheat, sorghum, corn and other grains after fermentation. Wine has always been an indispensable member at the table of our country, so there are many kinds of wine in our country, which corresponds to all kinds of distiller’s grains. The distiller’s grains in our country are generally divided into liquor grains, beer grains and alcohol grains.

The distiller’s distiller’s distiller’s distiller’s distiller’s distiller’s distiller’s distiller’s liquid “. The rice wine we often use in our lives (sometimes called sweet wine) is a kind of distiller’s grains. In addition to rich starch and a small amount of alcohol, wine contains a large number of proteins, amino acids, vitamins, nucleic acids, ribose and other trace elements. So distiller’s grains can be treated as feed or waste sources for animals and plants.

There are now three ways to treat distiller’s grains:

The first is the traditional wastewater biochemical treatment, using anaerobic and aerobic treatment of wastewater to the national discharge standards.

Because it is rich in protein and ribose, wine water becomes super high concentration organic wastewater. The BOD and COD concentration of the existing distiller’s grains wastewater in China is more than 1000 times higher than the discharge standard of our sewage. The BOD concentration of domestic sewage for an average of 100000 people a year is equivalent to the 7 day BOD value of a brewery with 500 m3/d of distiller’s grains wastewater per day. And the scale of 500 m3/d of distiller’s grains wastewater production in China can only be counted as a small brewery, such enterprises are numerous. Such a large amount of high-concentration wastewater can be discharged through a series of biochemical treatments Put standard, brought huge pressure and economic burden to enterprise. At present, anaerobic and aerobic traditional methods are widely used in domestic distilleries to treat distiller’s grains wastewater. The effect of this method is good, and it can generally meet the national secondary discharge standard after treatment, but because this method covers a large area, has more sludge, high operating cost and takes a long time (more than 14 days of single batch), it has been puzzling many small and medium-sized wineries.

The second is direct treatment, which sells distiller’s grains wastewater directly to local farmers or farms for livestock or fish and shrimp, or combines the feces of other animals to cultivate fly maggots and earthworms.

This method may seem very reasonable and environmentally friendly, but it has two disadvantages: one is that fresh wine dregs are fed directly to livestock, poor digestion and absorption, mildew and rotten wine dregs are easy to produce virus damage; the other is that fresh wine dregs have high water content, are difficult to transport, and are prone to spoilage. Third, farmers’ needs also change according to market changes, difficult to stabilize. The fourth is to cultivate fly maggots and earthworms, but because of the long production cycle, it is necessary to build large feeding and processing plants to meet the requirements.

The third is resource reuse, that is, distiller’s grains wastewater is treated by a series of processes (including solid-liquid separation, concentration, biochemistry, drying, fermentation enzymatic hydrolysis, etc.) to achieve zero discharge. The separated and concentrated solids can be processed into feed or fertilizer. The third method is the most environmentally friendly and contributes the most to the society, but at the same time, because of the complexity of the process, the investment cost relative to the technical threshold and equipment is relatively high, which is more suitable for medium and large wineries or centralized processing stations.

The third method can be subdivided into two types: one is physical method, the other is biological method. The physical method is to supply energy to dry the distiller’s grains and distiller’s grains wastewater after solid-liquid separation, to realize zero discharge, to solve the environmental protection problem completely, and then to combine the two after drying into feed or feed additive. The finished product of this method has high yield and good feed value, but the operating cost of equipment investment and energy consumption is very high, so it is difficult to popularize in China. The other is the use of (single / more) microorganisms to ferment or enzymatic hydrolysis of distiller’s grains waste liquid, extract high protein substances, and then make them into feed.

The decanter centrifuge is a kind of spiral discharge settling centrifuge, which is mainly composed of high speed drum, spiral conveyor with hollow rotating shaft and differential device with the same speed and lower speed than drum. The liquid phase overflows through the overflow hole of the large end of the drum. Such continuous circulation to achieve the purpose of continuous separation.

The principle used in the separation of suspension by decanter centrifuge: the principle of centrifugal sedimentation is adopted to push the solid phase to the slag outlet at the small end of the drum through the blade on the screw pusher, while the liquid phase is discharged through the overflow hole at the large end of the drum. In this way, the purpose of continuous separation can be realized.

The differential in decanter centrifuge makes abnormal noise during operation, which can be avoided. If the differential in the decanter centrifuge has abnormal noise in the working process, then there is a problem with the differential, for example, the differential parts have problems, or they are not installed in place, etc., which will lead to the above problems. Therefore, the differential should be checked to avoid the above problems. When the decanter centrifuge needs to be cleaned, the centrifuge should be stopped first; then some corresponding valves should be closed, and at the same time, open the clear water valve and rinse with clear water for 3 to 5 minutes; then, close the clear water valve so that it can be closed The centrifuge runs for a while and then stops, so that the remaining water in the centrifuge will be discharged automatically. If the water is very clear, then, it means clean, if the water is very muddy, it is not clean, should continue until the water is clear.

GN has been in the industry for more than a decade. We are a manufacturer and supplier of decanter centrifuge in different models. We have our own technical team for the design work in a customization way for our customers. If you have any questions, please feel free to contact GN for more information.

Horizontal screw pushing sedimentation centrifuge is referred to as horizontal screw centrifuge, which has been widely used in sludge dewatering treatment of sewage treatment plant. Although different manufacturers of different specifications or models of horizontal screw centrifuges have different equipment structure, equipment material, specifications and operation adjustment mechanism, but

Its basic equipment principle is similar, now carries on the brief introduction to it, in order to facilitate the field user to use and adjust better.

The horizontal screw centrifuge is mainly composed of drum, spiral, differential system, liquid level baffle, drive system and control system.

The horizontal screw centrifuge uses the density difference of solid-liquid two-phase to the settling speed of solid particles under the action of centrifugal force to realize solid-liquid separation. The process of separation is that the sludge and flocculant solution are fed into the mixing chamber through the inlet pipe, where the mixed flocculation is carried out (if the sludge pump is added before or after the pump, the flocculation reaction is advanced). The sludge is accelerated and formed a cylindrical liquid ring layer (liquid ring area) inside the rotor due to the high speed rotation and friction resistance of the rotor (spiral and drum). Under the action of centrifugal force, the specific gravity solid particles settle to the inner wall of the drum to form a mud layer (solid ring layer), and then use the screw and drum to form a mud layer (solid ring layer). The The relative velocity difference of the drum pushes the solid phase to the cone end of the drum. After the liquid level is pushed out (shore area or dry area), the mud slag can be dehydrated and dried, and the supernatant is discharged from the large end of the drum to realize the separation of solid and liquid.

The effect of the mechanical part of the horizontal screw centrifuge is divided into adjustable factors and non-adjustable factors. It can be effectively controlled in use.

Settlement is the centrifuge drum installed at the upper end of the shaft, through the transmission driven by the motor and high-speed rotation. There is a set of disc parts in the drum, the disc. There is a small gap between the disc and the disc. The suspension is attended by a feeding tube located in the center of the drum. When the suspension passes through the gap between the discs, the solid particles sink to the disc by centrifuge to form sediment.

The sediment slips along the surface of the disc and leaves the disc and accumulates in the largest diameter of the drum. The separated liquid is discharged from the outlet. The function of the disc is to shorten the settling interval of solid particles and expand the settling area of the drum, which greatly improves the production capacity of the separator because of the installation of the disc. The solid accumulated in the drum is removed by manual removal after the separator stops, or discharged from the drum without stopping.

There are the following points in the settlement centrifuge, which is different from the filter centrifuge:

The settling centrifuge equipment is turned into a closed barrel. The working principle of the equipment is to separate the solid-liquid two-phase through centrifugal force. The centrifuge of this method is called the settling centrifuge. The sedimentation centrifuge is suitable for a wide range of materials, such as high viscosity of materials and small solid particles, which can meet the requirements of solid-liquid two-phase separation by increasing centrifugal force.

Filter centrifuge equipment drum hole, additional filter media through the method of blocking solid-liquid two-phase separation centrifuge we call filter centrifuge, Filter centrifuge is suitable for small viscosity of materials, solid particles are not easy to deform (such as crystal) solid particles large and small batch production conditions, mostly used for industrial dehydration.

The sedimentation centrifuge can complete two kinds of operations: liquid-solid separation, called clarification operation; liquid-liquid separation, called separation operation. Disc separator is widely used in chemical industry, medicine, light industry, food, bioengineering and transportation because of its compact structure, small area and large producti

What is the price of oily sludge treatment technology equipment? Because the oily sludge composition in each area is different, the solution is different. The price is also different, now our country attaches great importance to environmental protection, decades ago buried oily sludge has also been dug to solve, this kind of oily sludge solution is not the same, the price is not the same. General oily sludge treatment technology equipment manufacturers to solve a ton of oily sludge in 200-300 yuan. In the second half of this year, more and more companies intervene in oily sludge solution, and the price relativity is also reduced.

Technical methods are generally as follows:

1. Automatic feeding: The single bucket sludge bucket lifting machine with unique design scheme is used to consider the transportation of liquid, solid and semi-solid oily sludge, and then the oily sludge is sent immediately from the oily sludge tank to the moving pretreatment equipment to consider continuous feeding. And the bucket lift machine raw material entrance place sets up the junior middle school level pick miscellaneous net slot, can avoid the ribbon, the stick and so on block dirty matter enters the solution system software.
2. Pretreatment: Oily Sludge in Oily Sludge Treatment Technical Equipment According to the interaction between Sludge Sorting Runner and Grate Plate, the sludge of block coalescer is scattered according to the rotation of Sludge Sorting Runner, and more than 20 mm of sludge is pushed into the bulk raw material collection box on one side of the pretreatment equipment by the Sorting Runner. Sludge less than 20 mm is sifted into the sludge pretreatment tank according to the round hole of the Sorting grate plate. According to the mutual effect of oily sludge sorting runner and grate plate, the sludge removal, chemical fiber crushing, symmetrical dispersion, oil slurry storage and transportation are completed.
3. Cleaning: In the oily sludge level II level III cleaning equipment. According to the efficacy of medicine, ultrasonic wave, air floatation machine, mixing and so on, the oily sludge is collected, cleaned and dispersed oil is removed.
4. Solid-liquid separation equipment: high-efficiency environmental protection and energy-saving pig manure dehydrator to complete the separation of solid sludge and liquid.
5. Water and oil solution: oil-bearing sludge treatment technology equipment manufacturers according to the three-level cleaning equipment collected floating oil to the oil storage tank, oil storage tank for precipitation of water can be transported to the storage tank. According to the liquid extracted by high efficiency, environmental protection and energy saving pig manure dehydrator into the water storage tank, the floating oil in the water storage tank can be collected and typed into the oil storage tank, and the boiling water can be reused as a return water.

Scraper centrifuge is a continuous operation, intermittent operation of filter centrifuge, its control mode is automatic control, but also manual control. the feeding, separation, washing, dehydration, unloading and filter cloth regeneration processes during the operation of the centrifuge are generally completed at full speed. the single cycle time is short capacity is large, and the dry filter slag and good washing effect can be obtained.

Is a continuous operation, intermittent operation of the filter centrifuge, its control mode for automatic control, but also manual control. the feeding, separation, washing, dehydration, unloading and filter cloth regeneration processes during the operation of the centrifuge are generally completed at full speed. the single cycle time is short capacity is large, and the dry filter slag and good washing effect can be obtained.

I. Working principles

The main working principle of centrifuge is to produce centrifugal force to realize solid-liquid separation, which is composed of feed, washing, liquid discharge and so on.

II. Preparation before boot

1. Open the door cover and check for screw loosening, especially spindle.

2. hydraulic station oil level should be station should be more than 2/3 of the oil standard thermometer label YB-N46.

The main pressure working pressure of 3. gas control box should be more than 4㎏, the explosion-proof pneumatic valve (feeding valve, cleaning valve) can be opened reliably, and the cylinder pressure of material level detection is 2.5~4㎏.

III. Boot

1. Before boot, make sure the cover is closed and all screws are tightened.

2. first press the feeding speed button, after the speed (speed read from the tachometer) arrived, press the feeding speed on / off, the feeding indicator light.

3. open the feed valve, start feeding at this time, when the material is full, the feeding indicator lights out.

4. if the machine vibration is small, can open separation speed, if the vibration is large, open cleaning speed, and pay attention to observation, if the vibration is serious, please reduce to the feeding speed.

5. according to the properties of the separation material, nitrogen gas should be filled if necessary to prevent the separation and scraping of.

6. depending on the production process, determine the separation time, after the separation, press the scraping speed button.

• After the reaches the scraper, press the discharge button.

8. scraper, scraper rotation > scraper drop > scraper rise, scraper rotation two > scraper drop > scraper rise, scraper reset, scraper end.

9. when feeding and discharging, the operator shall not leave the post. When feeding, mainly observe the vibration of the machine, outlet, discharge, discharge, mainly check whether the outlet is blocked, motor speed is normal. 10. When the machine is running normally, if there are no special circumstances, please do not press the emergency stop button, especially when running at high speed; if pressed, all the work of the equipment will stop.

IV. Automatic operation (selection function)

1. After manual normal, input the relevant data into the man-machine interface (select accessories).

• If an exception occurs during 2. operation, cut back to manual operation until troubleshooting.
• Fault handling method is similar to manual.
• If the vibration is too large in 4. operation, the machine will stop automatically and cut back to manual processing.

V. Shutdown inspection

1. the opening cover must wait for the centrifuge to stop completely, confirm that the screw and hook have been unloaded, the material level detection limit switch indicator light can be opened, can press the open cover button, when the cover and drum 95 degrees, insert the safety pin. If not, check the compressed air pressure to ensure that the level detection plate is not in the position to open the door cover safely. Similarly, the probe board should not be in the probe position when closing the cover.

2. If want to work in the machine, press the emergency stop button after opening the cover.

3. centrifuge running speed is high, rotation inertia is large, operators must always pay attention to safety, to ensure the safety of personnel and equipment.

4. Clean and replace the filter cloth before work or as appropriate, clean up the material above the hopper, material exploration, etc., and remove the material from the liquid outlet.

5. to check the drum weld, fence, shell parts corrosion, timely reporting.

The main function of centrifuge separator equipment is to remove insoluble matter from fluid, whether solid or liquid. This problem comes, a lot of heavy metal pollution ions are soluble, how to do this? GN discusses with you how precipitator flocculant these sewage treatment agents in the horizontal centrifuge solid-liquid separation process how to cooperate and how to choose.

The precipitator reacts to the chemical characteristics of free ions to form insoluble precipitates. The flocculant aggregates the very small solid suspended matter together to form a large particle size polymer. The pretreatment of the fluid facilitates the solid-liquid separation operation of the decanter centrifuge. Combined use of sewage treatment agents such as precipitators and flocculants, the aggregation and deposition of solid particles and the removal of some dissolved organic matter simplify the operation, save the cost, make the removal of pollutants in wastewater treatment more thorough, more efficient, more complete and lower cost.

In order to achieve a good effect of sewage treatment, the selection of chemicals in the treatment of sewage by decanter centrifuge should be specially analyzed for the physical and chemical properties of sewage, and the distribution of sewage ions, the properties of colloid and suspended matter and the concentration of selected agents should be determined. If the pollutants in water are colloidal, inorganic flocculant is the first choice to make the pollutants metastable and condensed. If the floc is small, it is necessary to add polymer flocculant or to use activated silica gel and other coagulants.

Sometimes in-depth analysis of material characteristics will bring unexpected surprises, according to the charge principle of the same sex repulsive phase absorption, The use of negatively charged flocculants to complex positive charge suspended particles with twice the result with half the effort. It is more suitable for positively charged flocculants to capture the particles with very small negative charge in sewage. Of course, to determine whether the charge properties of pollutant particles are the best partners of horizontal centrifuge, sampling and computer experiments are essential.

In the treatment of horizontal centrifuge, the choice of flocculant precipitator is best determined by sampling experiment, and the sewage sample is determined by the test centrifuge equipment, and then the best proportion of the reagent is confirmed by fine adjustment in production.

Treatment processes such as filtration and flotation are often used in wastewater treatment. By using inorganic flocculant and polyelectrolyte coagulant, the treatment capacity is greatly improved by extending the treatment range. Flocculant precipitator and other chemicals combined with the characteristics of wastewater water quality, flocculant can be used alone, or a variety of flocculant compound use or one main and one auxiliary compound use (auxiliary as coagulant aid). In many cases, the combined use of inorganic flocculant and polymer flocculant can obviously improve the coagulation effect and extend the application range of separation and processing of decanter centrifuge.