Producció de biogàs a través de la digestió anaeròbica d'aigües residuals concentrades amb canvi de temperatura estacional

Abstract

Nowadays, everybody knows that water is an essential resource for the human life and industrial activity. Water also plays and important role on our ecosystem’s conservation. For this reason, it is essential to treat this water to avoid contamination of rivers, reservoirs or seas. Centralized wastewater management plants have been commonly used since a long time ago. Due to different facts, such as the growth of cities, the high demand of potable water and the security, the use of decentralized wastewater facilities is growing. In recent years new trends are also emerging, such as the Australian sewer mining concept. This strategy purposes the treatment of local wastewater from a collector to meet the local needs of potable water. There are many research projects related with sewer mining, for example Watintech (JPI waterworks 2014). This project purposes the combination of new sewer mining technologies to recover resources from wastewater and rainwater. These resources are water, oxygen, sodium hydroxide and methane. This methane represents an important source of renewable energy. For this reason, the main objective of the work was to study the potential generation of renewable energy from a synthetic concentrate prepared in the lab, which was obtained from a forward osmosis process that treats wastewater. In addition, the quantity and quality of the biogas produced under different temperature conditions (34, 23 and 15ºC) and different wastewater characteristics (50, 80 and 90% recovery from the forward osmosis process) were also observed. To accomplish this study a biochemical methane potential (BMP) test was carried out. A manometric method was followed and the biogas composition was analysed with a gas chromatograph. Based on the results obtained in a period of 35 days, it was observed that using an anaerobic digestion process the different synthetic concentrates effectively generate methane. It was seen that the highest quantity of the biogas was observed under conditions of 34ºC and a recovery percentage of 90%. In these conditions the best biodegradability of the synthetic concentrate was noted too. It was also observed that the quality of the biogas was very high, and this quality was independent for all conditions