Food wastewater mainly refers to the wastewater discharged from alcohol, monosodium glutamate, beer, liquor, starch, lactose, xylitol, citric acid, vegetable processing and various beverage processing. The main pollutants in food wastewater are:
1. Solid matter floating in wastewater.
2. Oil, protein, starch, colloids, etc. suspended in wastewater.
3. Sugar, acid, alkali, salt, etc. dissolved in wastewater.
4. Mud, sand and other impurities.
5. Possible pathogenic bacteria, etc.
The main feature of its wastewater quality is that it has a relatively high content of COD, BOD, SS and grease, which is a high-concentration organic wastewater. The main pollution hazard of food industry wastewater is eutrophication of the water body, causing the death of fish and other aquatic animals, and promoting the decomposition of organic matter deposited at the bottom under anaerobic conditions, producing odor, deteriorating the water body and polluting the environment.
The traditional method of treating this organic wastewater is physical sedimentation and biochemical fermentation. In the biochemical treatment process, a polymer flocculant is used for sludge dehydration treatment. The high-molecular flocculants used in this section are generally cationic polyacrylamide products with relatively high ionicity and molecular weight. The flocculant used in the brewery is generally strong cationic polyacrylamide with a molecular weight of 9 million or more, and the effect is relatively good.
Attention should be paid to the selection of polyacrylamide products:
1. Climate change (temperature) affects the selection of polyacrylamide.
2. Select the molecular weight of polyacrylamide according to the size of the floc required by the treatment process.
3. The charge value of polyacrylamide must be screened through experiments.
4. The strength of flocs can be improved by increasing the molecular weight of polyacrylamide.
5. Polyacrylamide must be thoroughly mixed and dissolved with sludge before treatment.
6. The selection of polyacrylamide must fully consider the requirements of process and equipment.