Direct and efficient liquefaction of potato peel into bio-oil

The world has become dependent on petroleum as a feedstock for most products that we use in our daily lives. As an alternative, bio-refineries that transform biomass into biofuels and primary chemicals are emerging. Actually, many wastes are not fully recycled. For instance, potato peel is a cheap residue available from the potato industry. Up to now, potato peel has been used mostly for livestock feeding. Here, potato peel waste was subjected to direct acid liquefaction at 160 °C in 2-ethylhexanol and diethylene glycol using p-toluene sulfonic acid as catalyst. The product was characterized by infrared spectroscopy, chemical analysis, hydroxyl number and acid value. Results show that liquefaction was achieved in yields higher than 80%. The reactional profile shows two time zones, one comprising the process of liquefaction and one corresponding to the process of decomposition. Kinetics indicate that the liquefaction process occurs 1.9 times faster than the decomposition process. Overall, our findings show for the first time that, despite the water content, potato peel waste can be used to produce bio-oil. The products can be further used as fuels or refined chemicals such as levulinic acid, furfural, 5-hydroxyfurfural, dimethyl furfural and sugars in fermentation processes.     

Evaluation of biotechnological processes to obtain ethanol from recycled paper sludge

Journal of Material Cycles and Waste Management - Finding innovative solutions to manage waste and to expand the production of biofuels are some of the current challenges. Pulp and paper sectors,...     

Agronomic characterisation of different types of sewage sludge: Policy implications

Spain is one of the main municipal sewage sludge producers of Europe. This paper aims to agronomically characterise different types of sewage sludge stabilised by different methods (anaerobically digested, composted, and pelletised) and deliver policy recommendations from the results of this characterisation. Anaerobic sewage sludge quality is found to be better in plants with a lower volume of water processing. Composted sludge shows the best quality from a heavy metal point of view, but its low available nitrogen content increases the input of heavy metals when spread, as compared to digested or pelletised sludge. Pelletised sludge has higher heavy metal content than anaerobically digested sludge. Despite the good quality of the sludges, future regulations, especially with regard to Cd levels, will limit the use of this waste in agriculture.     

Trace metals in river bed sediments: An assessment of their partitioning and bioavailability by using multivariate exploratory analysis

In this study, river bed sediments were submitted to a BCR sequential extraction, together with three bioavailability tests: a weak acid elutriate (HCl), a physiologically based extraction test (PBET) and a toxicity characteristic leaching procedure (TCLP). The most remarkable features of the BCR procedure were: i) Mn and Zn showed the highest proportion of the F1 exchangeable fraction; ii) in addition to Fe, Pb and Zn were the metals with the higher percentages in the F2 reducible fraction; iii) Fe and Cu were the elements with the highest proportion of the F3 oxidizable fraction; iv) the application of Principal Component Analysis to the metals in each of the three fractions did not show clear associations between metals and sediment components considered as metal scavengers, v) considering the sum of the three BCR fractions, the elements showed a decreasing availability of: Fe > Pb > Zn > Cu > Mn > Ni > Cr. The single extractions followed a decreasing extractability order of: HCl > PBET > TCLP and they were far from the extractability deduced from the sum of fractions in the BCR extraction.     

Study of the solubility and stability of polystyrene wastes in a dissolution recycling process

Dissolution with suitable solvents is one of the cheapest and more efficient processes for polystyrene waste management. In this work the solubility of polystyrene foams in several solvents benzene, toluene, xylene, tetrahydrofuran, chloroform, 1,3-butanediol, 2-butanol, linalool, geraniol, d-limonene, p-cymene, terpinene, phellandrene, terpineol, menthol, eucalyptol, cinnamaldheyde, nitrobenzene, N,N-dimethylformamide and water has been determined.Experimental results have shown that to develop a “green process” the constituents of essential oils, d-limonene, p-cymene, terpinene, phellandrene, are the most appropriate solvents. The action of these solvent does not produce any degradation of polymer chains. The solubility of the polymer in the mentioned solvents at different temperatures has been investigated. The solvent can be easily recycled by distillation.     

Production patterns of packaging waste categories generated at typical Mediterranean residential building worksites

The construction sector is responsible for around 28% of the total waste volume generated in Europe, which exceeds the amount of household waste. This has led to an increase of different research studies focusing on construction waste quantification. However, within the research studies made, packaging waste has been analyzed to a limited extent. This article focuses on the packaging waste stream generated in the construction sector. To this purpose current on-site waste packaging management has been assessed by monitoring ten Mediterranean residential building works. The findings of the experimental data collection revealed that the incentive measures implemented by the construction company to improve on-site waste sorting failed to achieve the intended purpose, showing low segregation ratios. Subsequently, through an analytical study the generation patterns for packaging waste are established, leading to the identification of the prevailing kinds of packaging and the products responsible for their generation. Results indicate that plastic waste generation maintains a constant trend throughout the whole construction process, while cardboard becomes predominant towards the end of the construction works with switches and sockets from the electricity stage. Understanding the production patterns of packaging waste will be beneficial for adapting waste management strategies to the identified patterns for the specific nature of packaging waste within the context of construction worksites.     

Aggregate material formulated with MSWI bottom ash and APC fly ash for use as secondary building material

The main goal of this paper is to obtain a granular material formulated with Municipal Solid Waste Incineration (MSWI) bottom ash (BA) and air pollution control (APC) fly ash to be used as secondary building material. Previously, an optimum concrete mixture using both MSWI residues as aggregates was formulated. A compromise between the environmental behavior whilst maximizing the reuse of APC fly ash was considered and assessed. Unconfined compressive strength and abrasion resistance values were measured in order to evaluate the mechanical properties. From these results, the granular mixture was not suited for certain applications owing to the high BA/APC fly ash content and low cement percentages used to reduce the costs of the final product. Nevertheless, the leaching test performed showed that the concentrations of all heavy metals were below the limits established by the current Catalan legislation for their reutilization. Therefore, the material studied might be mainly used in embankments, where high mechanical properties are not needed and environmental safety is assured.     

Analysis of the relation between the cellulose,hemicellulose and lignin content and the thermal behavior of residual biomass from olive trees

The heterogeneity of biomass makes it difficult if not impossible to make sweeping generalizations concerning thermochemical treatment systems and the optimal equipment to be used in them. Chemical differences in the structural components of the biomass (cellulose, hemicellulose, and lignin) have a direct impact on its chemical reactivity. The aim of this research was to study the influence of the organic components of the raw material from olive trees (leaves, pruning residues, and wood) in the combustion behavior of this biomass, as well as to find the component responsible for the higher ash content of olive leaves. Accordingly, the study used a thermogravimetric analyzer to monitor the different states and complex transitions that occurred in the biomass as the temperature varied. The decomposition rates of the different samples were analyzed in order to establish a link between each combustion phase and the composition of the raw materials. Two methods were used to determine the hemicellulose and cellulose contents of biomass from olive trees. Significant differences among the results obtained by the different methods were observed, as well as important variations regarding the chemical composition and consequently the thermal behavior of the raw materials tested.     

Influence of the composition of the initial mixtures on the chemical composition,physicochemical properties and humic-like substances content of composts

The influence of the proportion of C- and N-rich raw materials (initial C/N ratio) and bulking agent on the chemical functional groups composition, humic-like substances (HS-like) content and physicochemical properties of composts was assessed. To achieve these goals, seven initial mixtures (BA1–6 and C1) of dog food (N-rich raw material) were composted with wheat flour (C-rich raw material). Composts were analyzed in terms of chemical functional groups, physicochemical, maturity and stability parameters.The C-rich raw material favored the formation of oxidized organic matter (OM) during the composting process, as suggested by the variation of the ratios of the peaks intensity of FT-IR spectra, corresponding to a decrease of the polysaccharides and an increase of aromatic and carboxyl-containing compounds. However, although with high proportion of C-rich raw material, mixtures with low initial C/N seems to have favored the accumulation of partially oxidized OM, which may have contributed to high electrical conductivity values in the final composts. Therefore, although favoring the partial transformation of OM into stabilized HS-like, initial mixtures with high proportion of C-rich raw material but with low initial C/N led to unstable composts.On the other hand, as long as a high percentage of bulking agent was used to promote the structure of biomass and consequently improve of the aeration conditions, low initial C/N was not a limiting factor of OM oxidation into extractable stabilized humic-like acids.