Wastewater treatment process of citric acid plant

In the production process of a citric acid plant, many streams of wastewater (concentrated sugar water, sugar washing water, filter cloth washing water, etc.) are discharged, which mainly contains a large number of soluble organic matters (sugar, fatty acid, protein, starch, etc.), with good biodegradability, no toxic and harmful substances and yellow color. The citric acid output of the plant is 6 × 104 T / A, COD (mg / L) is 10000

Citric acid wastewater adopts the process of pretreatment, anaerobic UASB as the main body and three-stage aerobic as the post-treatment

economic analysis

The total operation power of the whole sewage treatment system is about 400 kW, and the operation cost is about 0.8 yuan / m3. In the anaerobic process, the biogas yield is 0.6m3/kgcod, the biogas yield is 29000-34000m3 / D (1m3 waste water 4-5m3 biogas) under full load operation, and the calorific value of biogas is above 35mj / m3. At present, a 4 T / h gas boiler (steam used for heating in production) and a 1.68 × 107 kJ / h direct combustion engine (used for LiBr refrigeration in production) are designed to use biogas specially. The recovery value of biogas can reach more than 2 million yuan per year, which exceeds the power consumption cost of wastewater treatment system. In addition, some biogas is supplied to the canteen instead of coal. When the boiler and LiBr direct fired machine are not in operation (or the gas consumption is less than the gas production), the safety automatic combustion system will start automatically for high altitude incineration