Characteristics and Pollution Challenges of Industrial Alcohol Production Wastewater

Industrial alcohol production is a fundamental sector of the national economy. Alcohol is widely used in the chemical industry, food processing, daily chemicals, pharmaceuticals, and healthcare, and also serves as a base for alcoholic beverages, extractants, solvents, detergents, and surfactants. 

Taking China as an example, the feedstock composition for alcohol production consists of approximately 75% starchy raw materials (such as corn, dried sweet potato, and cassava), 20% waste molasses, and 5% synthetic alcohol. Therefore, alcohol production in China relies mainly on starchy materials such as corn and dried sweet potato. 

Pollution from distillery residues (stillage) generated by alcohol enterprises is one of the most serious sources of pollution in the food and fermentation industries. Due to limitations in investment, production scale, technology, and management, the overall resource utilization rate of alcohol enterprises in many developing countries remains relatively low. 

Alcohol wastewater is a high-strength organic wastewater characterized by high COD, high temperature, and high suspended solids. Treatment technologies for such wastewater were developed early and have progressed rapidly. The solid residues in the effluent include shredded cassava peels, roots, and other coarse fibers, which constitute insoluble COD. Cellulose and hemicellulose in cassava are polysaccharides that cannot be utilized as a carbon source by yeast during fermentation and therefore remain in the wastewater as soluble COD. In addition, inorganic ash, sand, and grit further increase the complexity and difficulty of wastewater treatment.