1. Overview

The food industry has a wide variety of products, including dairy products, beverages, seasonings, and agricultural product processing, with significant differences in raw materials, processes, and scale. The discharged wastewater varies greatly with seasons and production processes. The wastewater contains a large amount of organic matter (protein, starch, fat), which is prone to decay, but does not contain harmful substances. The processing method is mainly based on biological methods, combined with physical and chemical methods. Taking starch wastewater as an example to illustrate its treatment process.

2. Wastewater discharge situation and treatment requirements

The discharge of high concentration organic wastewater from a certain starch factory is 400m3/d; CODcr5500 mg/L, BOD3400 mg/L, ρ (SS) 1-15 g/L, pH 4, water temperature 45-55.C， The discharge volume of low concentration organic wastewater is 100m3/d; CODcr 100 mg/L, BOD450 mg/L, pH 6-7, water temperature 20-22. This process adopts anaerobic (UASB+AF) - contact oxidation - air flotation process for treatment. The COD removal rate of the anaerobic section is 85%, and the BOD removal rate is 90%. The COD removal rate of the contact oxidation process is 76%, and the BOD removal rate is 77%

3. Process flow

High concentration wastewater → regulating tank → UASB+AF → contact oxidation tank → air flotation device → standard discharge

4. Characteristics

1. The use of air flotation method can remove oil and solidified protein and oil from water and high concentration water discharged in accidents.

2. The use of AF can decompose large organic molecules into easily biodegradable small molecules and remove a large amount of organic matter.