Monthly Archives: December 2020

Trend of Solid-Liquid Separation from Filter Press to Decanter Centrifuge

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´╝Ť

  • 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.

Wastewater Treatment of Distiller’s Grains(2)

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.

Wastewater Treatment of Distiller’s Grains

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.

Cleaning Procedure of Decanter Centrifuge

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.