Inoculum-to-substrate ratio and solid content effects over in natura spent coffee grounds anaerobic digestion.

Coffee is the second most traded commodity worldwide, and its production is associated with the generation of a large number of residues, which are underused and disposed of in landfills. Notably, the coffee industry annually generates approximately 6 million tons of industrial spent coffee ground (ISCG) when extracting coffee flavorings to produce soluble coffee. That resource loss scenario has been highlighted in sustainable waste management contexts as an opportunity to improve the coffee circular economy. Despite ISCG bioconversion to methane potentially meets the waste-to-energy purposes of reducing residues disposal in landfills, decreasing greenhouse gas (GHG) emissions, and increasing renewable energy sources, data about anaerobic digestion (AD) of ISCG remains quite restricted. That limitation becomes more apparent owing to the lack of data focusing on AD key parameters for ISCG as substrate. This study assessed the influence of inoculum-to-substrate ratio (ISR) and the solid content influences on mesophilic (37 °C) ISCG-AD throughout the Response Surface Methodology (RSM) and Central Composite Design (CCD). Results revealed that both factors, ISR and solid content, should be kept above a certain threshold of 0.5 and 6.0 gTVS L-1 to ensure experimental reliability, as well as reproductively and above 1.0 and 8.0 gTVS L-1 to avoid underestimation on the MY potential achieved. Concerning ISCG-AD kinetics, the quadratic model optimum condition was at 1.36 and 14.83 gTVS L-1 for ISR and solid content, respectively. This optimum range for ISR and solid content could guide further development of process configurations for mono- and co-digestion of ISCG, avoiding underestimation of the MY potential and extended incubation periods.

Térmicos cervicais: indicaçöes em funçäo das ligas utilizadas / The cervical terminations: indications in function of the alloys used

Neste trabalho säo comparados tipo de térmicos cervicais em funçäo das ligas utilizadas para a confecçäo de próteses parciais fixas em metalo-cerâmicas, discutindo as vantagens e desvantagens clínicas e laboratoriais entre ligas básicas de níquel-cromo e ligas áureas, além das conveniências financeiras que estas possam acarretar. O tipo de preparo utilizado nos E.U.A. difere dos preparos mais utilizados no Brasil, em funçäo da indicaçäo destas ligas