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Soil organic carbon (SOC) plays an important role on improving soil conditions and soil functions. Increasing land use changes have induced an important decline of SOC content at global scale. Increasing SOC in agricultural soils has been proposed as a strategy to mitigate climate change. Animal manure has the characteristic of enriching SOC, when applied to crop fields, while, in parallel, it could constitute a natural fertilizer for the crops. In this paper, a simulation is performed using the area of Catalonia, Spain as a case study for the characteristic low SOC in the Mediterranean, to examine whether animal manure can improve substantially the SOC of agricultural fields, when applied as organic fertilizers. Our results show that the policy goals of the 4 × 1000 strategy can be achieved only partially by using manure transported to the fields. This implies that the proposed approach needs to be combined with other strategies.

There is high interest in applying anaerobic digestion to organic wastes for the recovery of biogas as a renewable energy source. In the case of protein-rich residues, the performance of anaerobic digesters might be affected by the accumulation of ammonia and volatile fatty acids. High concentrations of these compounds impact negatively on the activity of the acetotrophic methanogenic archaea (AMA). This limitation can be overcome by promoting the enrichment within digesters of syntrophic acetate-oxidizing bacteria (SAOB) in conjunction with certain groups of hydrogenotrophic methanogenic archaea (HMA). These two microbial populations have a relatively high tolerance towards the aforementioned inhibitory compounds. Hence, when the partial pressure of hydrogen is low enough, SAOB metabolize acetate to carbon dioxide and hydrogen, which are syntrophically consumed by HMA. Once the organic matter has been biodegraded, the remaining nitrogen can be biologically removed from digester supernatants by the anaerobic ammonium oxidation (anammox). This pathway consists of the simultaneous conversion of ammonium and nitrite to (di)nitrogen gas, and, therefore, a previous partial oxidation of ammonium to nitrite under aerobic conditions is required. Interestingly, the whole process constitutes a completely autotrophic nitrogen removal strategy. This chapter compiles the current knowledge on the syntrophic oxidation of acetate and on the anaerobic oxidation of ammonium, mostly focusing on technological aspects in view of a sequential bioreactor implementation.

Background Continuous aspiration of subglottic secretions is effective in preventing ventilator-associated pneumonia, but it involves a risk of mucosal damage. The main objective of our study was to determine the incidence of airway complications related to continuous aspiration of subglottic secretions. Methods In consecutive adult patients with continuous aspiration of subglottic secretions, we prospectively recorded clinical airway complications during the period after extubation. A multidetector computed tomography of the neck was performed during the period of 5 days following extubation to classify subglottic and tracheal lesions as mucosal thickening, cartilage thickening or deep ulceration. Results In the 86 patients included in the study, 6 (6.9%) had transient dyspnea, 7 (8.1%) had upper airway obstruction and 18 (20.9%) had dysphonia at extubation. Univariate analysis identified more attempts required for intubation (2.3 ± 1.1 vs. 1.2 ± 0.5; p = 0.001), difficult intubation (71.4 vs. 10.1%, p = 0.001) and Cormack score III–IV (71.4 vs. 8.8%; p