EFFLUENT TREATMENT PLANT

EFFLUENT TREATMENT PLANT

The dairy industry involves processing raw milk into products including milk, butter, cheese, yogurt, using processes such as chilling, pasteurization, and homogenization. Typical by-products include buttermilk, whey, and their derivatives.
Huge amounts of water are used during the process producing effluents containing dissolved sugars and proteins, fats, and possibly residues of additives. These effluents have the following characteristics

· Biochemical oxygen demand (BOD), with an average ranging from 0.8 to 2.5 kilograms per metric ton (kg/t) of milk in the untreated effluent

· Chemical oxygen demand (COD), which is normally about 1.5 times the BOD level

· Total suspended solids (TSS), at 100–1,000 milligrams per liter (mg/l)

· Total dissolved solids (TDS): phosphorus (10–100 mg/l), and nitrogen (about 6% of the BOD level).

Cream, butter, cheese, and whey production are major sources of BOD in wastewater. The waste load equivalents of specific milk constituents are: 1 kg of milk fat = 3 kg COD; 1 kg of lactose = 1.13 kg COD; and 1 kg protein = 1.36 kg COD. The wastewater may contain pathogens from contaminated materials or production processes. A dairy often generates odors and, in some cases, dust, which also need to be controlled.

The effluent treatment plant in MILMA is as shown in the block diagram given above.The reuse of wastewater from the dairy industry can also be provided for by usage of adsorption and membrane separation among other processes. The color and the odor may be removed completely after activated carbon treatment. The pretreated water can be passed through a cross flow reverse osmosis membrane system and the permeate water can then be reused.