Spent coffee ground characterization, pelletization test and emissions assessment in the combustion process

Abstract

Industrial development and increased energy requirements have led to high consumption of fossil fuels. Thus, environmental pollution has become a profound problem. Every year, a large amount of agro-industrial, municipal and forest residues are treated as waste, but they can be recovered and used to produce thermal and electrical energy through biological or thermochemical conversion processes. Among the main types of agro-industrial waste, soluble coffee residues represent a significant quantity all over the world. Silver skin and spent coffee grounds (SCG) are the main residues of the coffee industry. The many organic compounds contained in coffee residues suggest that their recovery and use could be very beneficial. Indeed, thanks to their composition, they can be used in the production of biodiesel, as a source of sugar, as a precursor for the creation of active carbon or as a sorbent for the removal of metals. After a careful evaluation of the possible uses of coffee grounds, the aim of this research was to show a broad characterization of coffee waste for energy purposes through physical and chemical analyses that highlight the most significant quality indexes, the interactions between them and the quantification of their importance. Results identify important tools for the qualification and quantification of the effects of coffee waste properties on energy production processes. They show that (SCG) are an excellent raw material as biomass, with excellent values in terms of calorific value and low ash content, allowing the production of 98% coffee pellets that are highly suitable for use in thermal conversion systems. Combustion tests were also carried out in an 80kWth boiler and the resulting emissions without any type of abatement filter were characterized.

Integrating UAVs and Canopy Height Models in Vineyard Management: A Time-Space Approach

“…Table 2 reports the canopy volumes determined for all grape-vine rows through fie measurement and the average percentage of the Green Canopy Cover (GCC) area [47 The measurements were performed using the TRV technique (Equation ( 1)) and automat approaches based on UAV-derived digital models created using ArcGIS and MATLA software. 1 Twelve measurements repeated for nine rows were used to extract the value of TRV; 2 One hundred measurements repeated for four rows were used to extract the value of TRV; 3 One hundred measurements repeated for six rows were used to extract the value of TRV.…”

“…Precision farming techniques assume the optimal use of inputs to improve production efficiency and sustainability [1][2][3][4]. A more efficient use of plant protection products and tools leads to fewer pollution loads to rural environments, higher crop quality, less monetary costs, and increased production rates, impacting the economic and ecological sustainability of farms in a positive manner [5][6][7][8][9][10].…”

“…Twelve measurements repeated for nine rows were used to extract the value of TRV; 2 One hundred measurements repeated for four rows were used to extract the value of TRV;3 One hundred measurements repeated for six rows were used to extract the value of TRV.…”

An Industrial Scale, Mechanical Process for Improving Pellet Quality and Biogas Production from Hazelnut and Olive Pruning

“…The products C and M from both the feedstock showed an improved quality as solid fuel, since they had a highly reduced ash content compared with the raw material. Ash adversely affects the calorific value, the dust emissions and the combustion plant performance because of the formation of unburnt material, accompanied by corrosion, erosion and fouling; they showed a highly reduced nitrogen content compared with the raw pruning, and nitrogen is an undesired element since in the combustion process it generates nitrogen oxides, responsible for irritant effects on humans and the formation of photochemical smog [39]. In small-scale combustion systems in which the flue gas temperature are above 1300 • C nitrogen oxides are assumed to be formed mainly from fuel nitrogen during biomass combustion [40].…”

Qualitative Characterization of the Pellet Obtained from Hazelnut and Olive Tree Pruning

“…Each of the studies highlighted both positive and critical aspects of the pellets themselves. The most critical parameters found in these studies were mainly related to the ash and nitrogen content for the vineyard [49,50], spent coffee [51], hazelnut, and olive tree [52,53]. At the same time, for the 3 and 6-year-old poplar pellets, there were problems with bulk density and ash, but not of nitrogen [54].…”