Wastewater treatment is nowadays moving into resource recovery from wastewaters. Hence, wastewaters should not only be considered as a waste to be treated through an energy-consuming process, but a resource containing energy and nutrients to be recovered. The final aim should be a wastewater treatment process with a positive energy balance. In this frame, industrial wastewaters with high biodegradable organic matter content are a paradigmatic scenario for this novel concept of energy recovery.
Among all industrial wastewaters, the effluents from the dairy industry are a very interesting case of study. These industries process raw milk into products such as commercial milk, cheese, butter, yogurt or ice cream, involving chilling, pasteurization, and homogenization, being buttermilk, whey, and their derivatives are the typical by-products. We are trying to convert these effluents into resources. For instance, we have been recovering the chemical energy cheese whey as hydrogen in bioelectrochemical systems at lab-scale with very satisfactory results. These results are the basis for the scale-up of these systems in a 100-L MEC pilot plant which is, at this moment, under construction. On the other hand, we are using the brine from cheese salting to diminish the energetic requirements of bioelectrochemical systems aiming at microbial electrosynthesis.
We are collaborating with "Centre Especial de Recerca Planta de Tecnologia dels Aliments (www.cerpta.com) in this field