With the rapid development of the economy, the improvement of living standards, and the strengthening of industrialization, the environmental pollution caused by the food production process has increased, and the harm to human health has become increasingly common and serious. In particular, the wastewater discharged from the production process has a high concentration of organic pollutants. , High chroma, large water quality and water volume changes, etc., is one of the most difficult industrial wastewater to treat. In particular, chromaticity has always been a difficult and important point in the treatment of wastewater from the food industry.
1 Source of food industry wastewater
The food industry wastewater mainly comes from 3 production sections.
The first is the cleaning of raw materials and production equipment: a large amount of sand, soil, debris, leaves, skins, scales, meat, feathers, hairs, and pigments enter the wastewater, making the wastewater contain a large amount of suspended solids.
The second is the production section: many ingredients in the raw materials cannot be fully utilized during the processing, and the unused part enters the wastewater, which contains a large amount of organic matter.
The third is the forming section: in order to increase the color, aroma and taste of the food, and to extend the shelf life, various additives are used, and part of the loss enters the wastewater, such as various dyes (caramel pigment, lemon yellow, turmeric, fruit green, bright blue, etc.) , Which makes the chemical composition of wastewater complex.
In addition, the production of additives (especially the production of food coloring) removes a large amount of waste and wastewater that also form chemical pollution.
2 Characteristics of food industry wastewater
Due to the wide variety of food and raw materials, the food industry wastewater has suspended solids, high oil content, high color, large COD (chemical oxygen demand) and BOD (biochemical oxygen demand) values, large changes in water quality and volume, and nitrogen , Features such as high phosphorus compound content.
3 The harm of food industry wastewater
Food industry wastewater itself is non-toxic, but contains a large amount of degradable organic matter. If the wastewater is discharged into the water body without treatment, it will consume a large amount of dissolved oxygen in the water, causing the water body to become hypoxic and causing the death of fish and aquatic organisms.
The suspended matter in the wastewater sinks to the bottom of the river and decomposes under anaerobic conditions, producing odorous water that deteriorates water quality and pollutes the environment.
If wastewater is introduced into farmland for irrigation, it will affect the use of agricultural products and pollute groundwater sources. The animal excrement contained in the wastewater contains insect eggs and pathogenic bacteria, which will cause the spread of diseases and directly endanger the health of humans and animals.
4 Current status of high-chroma wastewater treatment in the food industry
The treatment of high-chroma wastewater has always been a difficult point in the treatment of wastewater from the food industry.
The main source of high chroma of food industry wastewater:
First, in the food production process, chemical reactions produce pigments and finally enter the wastewater, such as melanoids produced by glucose oxidation during soy sauce fermentation.
Second, in the production process, in order to achieve a good color and luster of the food, food coloring and dyes are added, such as the caramel color added in the soy sauce preparation and the fruit green added in the production of green beans.