Pasteurization or homogenization is the process used in the dairy industry for producing milk, butter, cheese or yogurt. Anaerobic treatment is most widely used for treating dairy wastewaters. The waste water produced has high level of BOD and COD load. This load has to be eradicated with the Dissolved Air flotation equipment before discharge for further treatment of water because it reduces effectively organic loading. The by-products produced during the process of pasteurization include buttermilk, whey and other end product. The volume of water utilized during homogenization process produces effluents that contain- fats, proteins, dissolved sugar and possible residues. DAF units installed for dairy wastewater management plays a vital role as it considerably reduces the level of oil, fat, grease, TSS etc. before discharge to a POTW.
Biochemical oxygen demand (BOD) is present at an average range of 0.8 to 2.5 kg per metric ton of milk in the water which will go to DAF unit for further processing. Chemical oxygen demand (COD) is actually 1.5 times of the BOD level present in the untreated water. Total suspended solids available are about 100-1000 milligrams per liter. Total dissolved solids such as phosphorus ranges from 10-100mg per liter and nitrogen approx. 6% of the BOD level.
The main cause of BOD in waste water is cheese, cream, whey and butter. The waste load present in the milk quantity are-
1kg milk fat = 3 Kg COD
1Kg Protein = 1.37Kg COD
1Kg Lactose = 1.10 Kg COD
In the waste water obtained during the dairy process there are chances of stinking smell. The advantages of the solutions incorporated with DAF technology provided by us so far are:-
The recycle of waste water from dairy industry can be supplied for utilization of adsorption and membrane segregation along with other processes in DAF unit. The odor and color in the waste water can be eradicated with the help of activated carbon treatment. The pre-treated water thus can be distributed through cross flow osmosis membrane system and the pretreated water is available for further usage.