Treatment of dairy waste by anaerobic digestion to produce methane as green energy

Abstract

Treatment and management of lactoserum from dairy industry has become a global issue. In fact, generated effluents have high organic loads (lactose, protein, vitamin, minerals etc.) constituting a major source of environmental pollution. In a sustainable green approach, anaerobic digestion is considered a promising solution for the treatment of lactoserum or cheese whey. At first, we conducted a biochemical characterization showing a lactose composition of 52 and 46 g/kg, for sweet and acidic cheese whey, respectively, with an average COD of about 70 g/kg. The biodegradability of sweet lactoserum showed an extremely high value of 97% equivalent to 0.34 $\mathrm{N}\mathrm{m}^{3}\mathrm{C}\mathrm{H}_{4}\cdot \mathrm{k}\mathrm{g}\ \mathrm{C}\mathrm{O}\mathrm{D}^{-1}$. However, low biodegradability was noted for acidic lactoserum with a value of17%. This highlights the importance of the use of the sweet one in terms of energy recovery. For the optimization of the process, we also tried an incursion towards little explored tracks by evaluating the intensification of methane production, applying ultrasounds pretreatment on inoculum. The best yield was obtained after sonication with an energy input of 90 kJ/kg.