1. Wastewater generated during the wine production process mainly originates from multiple production stages. Rice washing water and soaking water from the brewing stage contain a large amount of organic matter; waste liquid from the fermentation stage is rich in sugars, proteins, and yeast residue; wastewater from the distillation stage and cooling water are at high temperatures; bottle washing water and disinfection water from the bottling stage may contain alkaline substances; in addition, there is auxiliary production wastewater such as site cleaning water and domestic sewage. These wastewater collectively constitute the winery wastewater system, exhibiting distinct industry characteristics.
2. The most significant characteristic of winery wastewater is its high COD concentration, typically between 2000-10000 mg/L, and sometimes even exceeding 20000 mg/L. The BOD5/COD ratio in the wastewater is high, generally above 0.5, indicating good biodegradability. The suspended solids content is high, mainly including grain residues, yeast cells, and other solid matter. The wastewater is acidic or weakly acidic, with a pH value mostly between 4 and 6. High temperatures are also a characteristic of distillery wastewater, especially distillation cooling water. Furthermore, the wastewater quality and quantity fluctuate significantly, with marked seasonal production variations, posing a challenge to the stability of the treatment system.
3. Distillery wastewater contains complex organic components, primarily carbohydrates such as starch, sugars, proteins, and cellulose, which originate from the processing of raw grains. Organic acids, such as lactic acid, acetic acid, and citric acid, fermentation products, are also important components of the wastewater. Alcohols, including ethanol, propanol, and butanol, although most are recovered in the final products, remain in the wastewater. The wastewater also contains nutrients such as nitrogen and phosphorus, mainly from proteins in the raw materials and added nutrients.
4. Inorganic salts such as chlorides, sulfates, and phosphates are also present in the wastewater. In addition, the wastewater contains small amounts of oils, phenols, and esters. Suspended solids mainly include incompletely decomposed raw material particles, yeast cells, and other microbial cells. These components collectively determine the difficulty of treating distillery wastewater and the appropriate treatment process.
