Development of Dairy Wastewater Treatment for Valuable Applications

With the increasing demand for different dairy products, dairy industries have increased their production resulting in the generation of an enlarged volume of waste. Wastewater (WW) is their major waste which contains high concentration of biological and chemical oxygen demand, and different organic and inorganic debris. There is little scope for processing entire WW in terms of overall production cost. Therefore, a major portion of the WW is discarded either after the primary treatment or directly without any treatment in different developing countries. However, different research groups are trying their best to find out a low-cost and eco-friendly solution for developing a suitable treatment process. Current review summarises the recent development in the treatment of dairy WW (DWW) using different techniques. Since the DWW contains a high concentration of organic pollutants, it can be used as a carbon source for the production of bio-energy like methane gas and bioelectricity. For this purpose, microbial fuel cell (MFC) is one of the advanced techniques. Many researchers are working on the development of a suitable MFC for the DWW treatment coupled with bio-energy generation. Further, the MFCs are hybridised to produce high calorific hydrogen gas which will be going to become the common fuel for all types of energy purposes. Direct anaerobic treatment of the WW is another technique used for the production of biogas; however, the longevity of anaerobic reactor has posed many questions. The high organic pollutant containing DWW is used as a substrate for the production of bio-surfactants, bio-plastics and bio-molecules through different biotechnological methods. Although there is potential in the valorisation of DWW streams to produce bio-energy and bio-products while also resolving the waste handling challenges, more work remains to be done to enhance and demonstrate the industrial viability of these technologies.