**3. Conclusions**

Milk and dairy products are among the sources of industrial wastewater that cause significant pollution of natural aquatic environments. Wastewater generally comes from the dilution of milk or dairy products. In addition, detergents, disinfectant materials, machine oils and cloth fibres used in cleaning take place in wastewater. Dairy effluent nature is slightly alkaline, high temperature, unpleasant rancid odours, bitter or medicinal taste, hard, scaly deposits, and so on when it is disposed without treatments, it may result in adverse effects in fish growth, reproduction and immunity in water bodies, harmful effect on beneficial microorganism's and plant growth due to decrease micronutrients solubility, serious problems of health and hygiene, eutrophication.

In order to treat industrial wastewater of milk and dairy products, quite different systems have been developed in different countries of the world. Factors such as the initial investment and operating costs in the selection of treatment technologies, the presence of appropriate staff for the enterprise and the need for treatment to ensure the regulations are taken into account.

The use of membrane technology in wastewater treatment by biological treatment has a short history covering the last 20–30 years. It is in a rapid development process, since it removes many disadvantages of classical systems. Membrane processes are in their process of being an effective remedy for most wastewater treatment with their unique properties. They can be used alone or together with other wastewater treatment systems. Membrane bioreactors offer effective solid-liquid separation, high yields of effluent, smaller plant sizes and low sludge production.

Treatment methods supported by chemical substances (coagulation-flocculation, oxidationreduction, flotation, etc.) implemented for organic matter in water and wastewater treatment, solid material, turbidity, heavy metal, colour removal purposes. The treatment efficiency is affected by such factors such as the parameter to be eliminated, the chemical substance used, the duration of the detention, the intensity of the mixture; the amount of sludge formed can be more or less than the chemical substance. Compared to biological processes, advantages such as ease of operation, removal of the non-degradable part of the organic material, removal of the treatment efficiency from changes are caused to be particularly preferred.
