Sustainable management of peel waste in the small-scale orange juice industries: A Colombian case study

Appropriate waste management in emerging economies like Colombia should be an asset for the overall sustainability. In the Orange Peel Waste case, incineration and Anaerobic Digestion are challenging solutions for the orange juice agro-industrial sector for avoiding the landfill, which is the conventional practice. However, these alternatives should be assessed in order to determine their feasibility. This paper aims to understand if incineration and Anaerobic Digestion are potential alternatives to landfill form a techno-economic and environmentally perspective. To this aim, a comparative Life Cycle Assessment was carried out in four scenarios. In the first scenario coal and landfill are used as source of energy and landfill disposal in the actual orange juice process. In the second scenario, the peels are incinerated to avoid landfill and reduce the need for coal. The third scenario includes the valorization of the peels by means of Anaerobic Digestion which produces biogas for the plant energy requirements. In the fourth scenario, apart from the energy from biogas, the digestate becomes a fertilizer for use in the orange crops. The results revealed that scenario III and IV are environmentally friendly options compared to Scenario I, but they incur higher costs than Scenario II. Carbon footprint found that 1.55 kg of CO2 are saving when coal substitution is reduced from 0.493 kg in SI to 0.279 kg in SII. Therefore, Scenario II is more suitable for the Colombian socioeconomic reality since Scenario II is not only techno-environmentally achievable, but also economically feasible. The methodology used in this case study could be applied to other countries or small and medium scale technologies and could also be useful for the scientific community, enterprises and policy-makers.The authors wish to acknowledge the financial support of the Fondo Regional de Tecnología Agropecuaria FONTAGRO [Contract:ATN/RF 16111RG, 2016] and of the Departamento Administrativo de Ciencia, Tecnología e Innovación, Doctorados Nacionales [Contract:727, 2015]. Also this article is the result of the work developed through the "Programa de investigación reconstrucción del tejido social en zonas de pos-conflicto en Colombia" [SIGP 57579] withthe research project "Competencias empresariales y de innovación para el desarrollo económico y la inclusión productiva de las regiones afectadas por el conflicto colombiano" [SIGP 58907]. Finally, the authors would like to express their appreciation to FLP Procesados Company for providing the data for the case study

Sustainable management of peel waste in the small-scale orange juice industries: A Colombian case study

Appropriate waste management in emerging economies like Colombia should be an asset for the overall sustainability. In the Orange Peel Waste case, incineration and Anaerobic Digestion are challenging solutions for the orange juice agro-industrial sector for avoiding the landfill, which is the conventional practice. However, these alternatives should be assessed in order to determine their feasibility. This paper aims to understand if incineration and Anaerobic Digestion are potential alternatives to landfill form a techno-economic and environmentally perspective. To this aim, a comparative Life Cycle Assessment was carried out in four scenarios. In the first scenario coal and landfill are used as source energy and landfill disposal in the actual orange juice process. In the second scenario, the peels are incinerated to avoid landfill and reduce the need for coal. The third scenario includes the valorization of the peels by means of Anaerobic Digestion which produces biogas for the plant energy requirements. In the fourth scenario, apart from the energy from biogas, the digestate becomes a fertilizer for use in the orange crops. The results revealed that scenario III and IV are environmentally friendly options compared to Scenario I, but they incur higher costs than Scenario II. Carbon footprint found that 1.55 kg of CO2 are saving when coal substitution is reduced from 0.493 kg in SI to 0.279 kg in SII. Therefore, Scenario II is more suitable for the Colombian socioeconomic reality since Scenario II is not only techno-environmentally achievable, but also economically feasible. The methodology used in this case study could be applied to other countries or small and medium scale technologies and could also be useful for the scientific community, enterprises and policy-makers

Mechanisms of interaction among enzymes and supports

Enzymes are outstanding biocatalysts for catalyzing reactions under mild conditions, with versatile substrate specificity and high product selectivity. Despite these desirable properties, the industrial application of soluble enzymes is hindered by their low operational stability and efficiency of use leading to a high incidence of enzyme’s operational cost and complex recovery after use being usually part of the final product. These downsides have been successfully tackled through the years by enzyme immobilization techniques. The present chapter is aimed to explore this field of biocatalysis, with particular emphasis on inorganic porous materials as supports for enzyme immobilization. Its main goal is to provide basic principles of (1) enzyme-support interaction, (2) peculiar features of the most common porous supports and strategies for tuning their synthesis according to the enzyme structural properties, and (3) complementary characterization techniques of immobilized enzymes

Time-based evaluation of bioavailable phosphorus in a calcareous soil after the application of anaerobically digested sewage sludge

AbstractNowadays, phosphorus natural reserves are being depleted, while P fertilizers demand is increasing. Phosphorus is well contained in waste materials such as sewage sludge. Only a small amount (1–3%) of the soil total phosphorus is bioavailable for plant nutrition. More in detail, the present study focuses on the determination of the kinetics of bioavailable phosphorus concentrations in a sandy calcareous soil after the application of sewage sludge. A centrifuged (C) and dried (D) anaerobic digestate from sewage sludges obtained from the same wastewater treatment plan were separately tested to fertilize a calcareous sandy soil. Falcon tubes (50 mL) containing negative control (T) and soil treated with C and D were incubated from 1 to 90 days. Soil phosphorus fractionation was performed with the SMT method and bioavailable-P was extracted through the Olsen method. Phosphorus was spectrophotometrically quantified by the molybdovanadate method. Lastly, kinetics of bioavailable-P on soils were evaluated using four kinetic models. Phosphorus fractions were constant throughout the experiment. Conversely, the bioavailable-P significantly decreased from day 1 to day 90 in C treatment (from 34.9 ± 2.9 to 23.8 ± 1.5 ppm) and T treatment (from 4.2 ± 1.2 to 0.3 ± 0.6 ppm). This decrease might be due to the precipitation of P with calcium; in fact, high concentration of Ca2+ ions and the alkaline soil pH can induce the sequential formation of calcium phosphates, even less soluble over time. Whereas D treatment showed a peak of bioavailable-P concentration on day 14 (26.6 ± 3.0). This trend could be due to organic carbon compounds, competitive sorption and metal bridging. The fitting of experimental data revealed that the Elovich model best described the adsorptive-precipitate process of bioavailable-P in T (r2 = 0.90) and C (r2 = 0.93). Conversely, none of the models satisfactorily described the behavior of bioavailable-P in D samples. This study increases the knowledge on P-related phenomena for designing and optimizing fertilizers and reducing their drawbacks such as eutrophication.</jats:p