The following table shows an example of the analysis and characteristics of dairy wastewater.
As the analysis of effluents shows, the effluents of dairy industries contain a high amount of COD and BOD. In addition, the amount of TSS and fat in this type of wastewater is very high. Therefore, before performing biological treatment, physical and chemical treatment methods are required before using biological treatment. Biological treatment units for dairy wastewater are aerobic or anaerobic. Anaerobic method is more useful due to less produced sludge and less energy required.
But these biological units are not able to remove a high amount of TSS and oil and fat, and the performance of these biological systems is disturbed, and it is necessary to use physical removal methods of fat and TSS.
Physical wastewater treatment units for dairy industries
Garbage collector to remove coarse particles
Simple degreaser and homogenizer unit: due to the use of acidic and alkaline solutions in the production line, wastewater is homogenized in this unit, and its pH and flow rate are uniform. In the simple degreaser unit, the insoluble fat and oil in the effluent, which is in a non-soluble state, comes to the surface due to its lightness and is collected by a paddle.
Advanced units for degreasing and removal of suspended particles: in these units, dissolved fat and suspended solid particles of wastewater are physically or chemically removed, the most important of these methods include DAF degreaser, chemical coagulation and flocculation, electric coagulation or fat and API and CPI are.
Biological treatment of wastewater treatment package
After ensuring the removal of fat, oil and suspended particles, the wastewater enters the biological treatment section, which is performed aerobically and anaerobically. Wastewater with high COD content cannot be directly entered into aerobic treatment because it reduces the efficiency. In the anaerobic method, the wastewater is treated by anaerobic microorganisms without aeration with a long retention time. These methods can be called UASB, UABR, etc. In aerobic treatment, by injecting air into wastewater, organic materials are decomposed by microorganisms. This method includes: extensive aeration, adherent growth such as IFAS, and other methods that are used based on the analysis of incoming wastewater.