**1. Introduction**

The dairy industry is responsible for the consumption of high volume of water, being the natural resource most used in the productive process of the sector. The need for water mainly occurs to maintain the conditions of cleaning, sanitary, and hygiene within the production sectors. With the high consumption of water, the generation of considerable effluent flow occurs, which makes the dairy industry a potential polluter. The effluents of the dairy industry contain organic matter, whey, and other constituents of milk, cleaning products, and soaps.

It is necessary to treat this effluent in order to meet the release standards set forth in the legislation and, consequently, reduce the pollutant loads released into the water environment. In

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

this sense, it becomes important the study for the proposal of methods of treatment of effluents and water reuse in the dairy industry. The possibilities of reuse of the effluent after treatment for industrial processes are restricted to the dairy industry, depending on the country and the legislation applied to the segment, since it is a food production industry. However, even in these industries, there is the possibility of reuse for cleaning floors, garden watering, cooling water, and use water in boilers.

In the dairy industry, water consumption is significant, being the natural resource most used in this sector [3]. The authors, Saraiva et al. [4, 5], investigating the consumption of water in the dairy industry found the coefficients shown in **Table 1**, which refer to the types of products

Membrane Technology and Water Reuse in a Dairy Industry

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The consumption of water is quite variable, related to the size of the dairy, the standardization of activities, reuse practices, the technologies employed, and the type of product produced. The mean intakes reported for different European and Nordic countries are shown in **Table 2**. The high consumption of water in the dairy industry is related to the need to maintain sanitary and hygiene conditions and is mainly due to cleaning operations, milk washing, cooling, and steam generation [3]. According to Vourch et al. [6], the water consumption of the dairy industries will depend on the volume of milk that is processed, the water quality required for the different industrial processes, and the water management practices in the industry.

By analyzing the data presented in **Tables 1** and **2**, it is possible to notice that the highest coefficient of consumption found by Saraiva et al. [4] occurs in the production of yogurt, presenting a consumption of 10 liters of water for each liter of processed milk. This figure was above the other production lines and was well above the figures cited by Maganha [3] for European and Nordic countries. Differently from Saraiva et al. [4, 5] found high consumption for the production of milk candy, but they mentioned the possibility of standardization of processes, reduction of waste by dairy employees, and adoption of reuse practices as ways of reducing consumption of this production line. Looking at the data, it can be observed that consumption can vary widely according to the production lines, as well as the water management practices of the dairy industries, which makes relevant the development of studies referring to better forms of use and reuse of water.

Industrial effluents are liquid streams from processes, operations, and utilities in industries [7]. It is also possible to consider the currents originated from the processes and operations in which water is used, but there is no incorporation of this in the final product, besides the net

**(1) (2)**

**2.1. Liquid effluents from the dairy industry**

Source: (1) adapted from [4] and (2) adapted [5].

**Activity/product Water/consumption (L L−1 of processed milk)**

Yogurt 10 5.15 Butter 1 — Mozzarella cheese 1.55 — Ricotta cheese 0.2 — Curd 1.4 — Creamy cheese 1.39 — Milk candy — 9.14

**Table 1.** Water consumption in the dairy industry in different production lines.

produced.

Membrane separation processes have been prominent in recent years regarding the treatment of effluents for their reuse, since it allows the use of compact treatment systems, generating good-quality reuse water, which makes it possible for industries to save. In membrane separation systems, synthetic membranes are used, which imitate the selectivity characteristics of natural membranes, in order to separate, concentrate, or purify the substances present in the water, making it of better quality. A hydraulic pressure gradient or electric field must be applied in order for the separation to occur [1]. In this way, membrane separation processes have generated interest in the dairy industry, especially for the possibility of generating goodquality reuse water that can help to minimize consumption, as well as reduce the generation of effluents by these industries.

With the objective of elucidating membrane separation processes in the treatment of dairy effluents, research was carried out in the national and international literature, using previously published studies on the subject, verifying results obtained and the importance with regard to the reuse of water and the valorization of products.
