◆Process introduction

Soy product wastewater is characterized by a large amount of wastewater discharge, high concentration of organic matter, and complex composition. Taking tofu production as an example, the COD of yellow swill is as high as 20,000 to 30,000 mg/L, the COD of soaking water is 4,000 to 8,000 mg/L, and the COD of washing and washing tax is 500 to 1,500 mg/L. The main recognition of the soaking tax is water-soluble non-protein nitrogen. , Oligosaccharides such as threose and raffinose, organic acids such as citric acid, water-soluble vitamins, minerals, etc., in addition to pigments such as isoflavones. The composition of yellow swill water is more complicated. In addition to all the ingredients of soaked bean water, it also contains protein, amino acids, lipids, etc. The cleaning water for tofu production contains soy albumin, sugars, bean dregs and detergents.

The aerobic process has the characteristics of stable operation, high removal rate, and good effluent quality. It is suitable for the treatment of low-concentration organic wastewater. For high-concentration wastewater and wastewater containing many complex organic substances, it is not economical to use aerobic process alone, and some organic substances are not economical. Aerobic bacteria are difficult to biodegrade or non-degradable, but these organic matter can often be decomposed into smaller molecular organic matter by anaerobic bacteria, and those smaller molecular organic matter can be further decomposed by aerobic bacteria. The anaerobic process has the characteristics of high load, low energy consumption, low mud production and low investment in civil construction, and is suitable for treating high-concentration wastewater. However, when the anaerobic process is used to treat high-concentration wastewater, aerobic biological treatment is required to ensure the effluent effect. Therefore, the anaerobic + aerobic combined biological process is a suitable combination to treat the wastewater.