1. Source and characteristics
Juice wastewater mainly comes from processes such as fruit washing, crushing, juicing, bottle washing, sterilization, broken bottle loss, and floor and surface washing in the canning process. The wastewater contains high concentrations of sugars, pectin, pomace, water-soluble substances, cellulose, fruit acid, tannins, mineral salts, etc.
| Organic matter concentration | High concentration of organic matter, generally CODcr>6000mg/L, BOD5>4000mg/L |
| Viscosity | Contains colloids such as pectin, and the wastewater is highly viscous |
| SS | Contains a large amount of pomace, pulp, fruit scraps and other substances. Generally, SS>4000mg/L |
| Water quality, quantity and changes | Due to the frequent changes in processing varieties and output, the discharge is uneven and the water quality and quantity vary greatly. The COD change value can reach 2000-3000mg/L, and the SS change value can reach 1000-2000mg/L. |
| Biodegradability | COD cr/BOD5=0.5～0.6, strong biodegradability. |
| pH | Juice wastewater contains a lot of fruit acid, so the pH is low, the lowest can be around 4.0 |
| Nutritional elements | The nutrient composition is single, the C:N ratio is high, and it lacks nitrogen and phosphorus. |
| Water temperature | 20-25 degrees Celsius |
2. Process selection
UASB process
When actually treating juice wastewater, UASB+ SBR process and UASB-contact oxidation process are often used, which have high removal rates for COD, BOD5, SS, and NH3-N.
Hydrolysis acidification-contact oxidation process
It mainly utilizes the different oxidative metabolism mechanisms of anaerobic and aerobic microorganisms on organic pollutants. The anaerobic microorganisms are first controlled under the conditions of hydrolysis acidification to convert the difficult-to-biodegrade high-molecular complex organic substrates into easily biodegradable low-molecular simple organic matter, thereby improving and enhancing the biodegradability of wastewater. The wastewater is then further treated by aerobic process to achieve the purpose of completely degrading organic wastewater.
Anaerobic baffled reactor - contact oxidation process
The structure of the anaerobic baffled reactor (ABR) is similar to a simple series connection of multiple UASB reactors without a three-phase separator. The sludge in each reaction chamber can exist in a granular or flocculent form. After the wastewater enters the reaction chamber, it flows up and down along the guide plate and passes through the sludge bed of each reaction chamber in turn. The organic matter in the wastewater is removed by full contact with the microorganisms.