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.

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