Assessing the Circularity of Nutrient Flows Across Nested Scales for Four Food System Scenarios in the Okanagan Bioregion, BC Canada

In light of continued nutrient pollution in water bodies and anticipated insecurities related to future nutrient supplies, there is an increasing awareness of the need to use nutrients in a more circular way. As part of a food system design study in the Okanagan bioregion, BC Canada we set out to evaluate different food system scenarios for the year 2050 in terms of nutrient circularity. In doing so, the objective was to evaluate the circularity of nutrient flows not only in the Okanagan, but also in relation to exogenous regions, insofar as nutrient flows relate to feed and food consumption and production in the Okanagan. This is important because feed and food trade means that nutrient inputs to crop production in the Okanagan may make their way into organic residuals outside the Okanagan, and vice versa. If not accounted for, this may lead to a distorted picture when analyzing nutrient circularity. To this effect, we applied an analytical framework and calculation model that explicitly tracks nutrients from crop production to organic residual generation. The results of the study suggest that assessing nutrient circularity across nested scales was critical for two reasons. First, changes in overall nutrient flows in response to population increase and dietary change were found to be more pronounced outside the Okanagan. Second, our analysis clearly revealed the extent to which feed and food trade boost nutrient self-reliance in the Okanagan at the expense of nutrient self-reliance outside the Okanagan. This kind of analysis should therefore be useful to explore, ideally together with food system and organic residual management actors, how different food system and organic residual management scenarios perform in terms of nutrient circularity, in the geographical area being considered, but also how it impacts nutrient flows and circularity in the places with which feed and food are traded.

Sustainable development of Romanian cities through biogas production from municipal wastes and application in co-combustion processes

Today municipal wastes represent a general problem from multiple points of view: necessary space for depositing, odor, possible soil contamination. In the same time, a large quantity of organic residual material remains unused in terms of energy conversion by potentially producing a biofuel which, in its term, can be used for covering at least partially, the human demand for energy. In this context, the present paper underlines the possible applications of anaerobic fermentation for biogas production by using as main substrate solid municipal waste from city of Timisoara, Romania, inside a pilot installation for determining its potential for further usage at larger scale in firing or co-firing processes; in this context, conclusions will be traced, based on the resulted experiments.

Use of residual powder obtained from organic waste to partially replace cement in concrete

The main objective of this research is to investigate the feasibility of using the residual powder obtained from organic waste to replace a part of Portland cement during concrete production. The chemical and physical properties of the organic residual powder were first investigated using scanning transmission electron microscopy (STEM) and energy dispersive X-ray spectroscopy (EDS). The replacement ratios of cement have also been studied for 0%, 5%, 10%, 15%, and 20% of the residual powder by weight. Moreover, we evaluated the compressive strength, specific gravity, water absorption, and voids content of the concrete specimens that were modified with different concentrations of the residual powder. Results indicate that 5% residual powder concentration resulted in better physical and mechanical properties of the modified concrete when compared with the reference concrete. At this concentration, the addition of residual powder act as fillers in concrete, reducing the amount of voids and causing a higher density in the material.

Fabrication of PANI/C-TiO2Composite Nanotube Arrays Electrode for Supercapacitor

Polyaniline/carbon doped TiO2composite nanotube arrays (PANI/C-TiO2NTAs) have been prepared successfully by electrodepositing PANI in C-TiO2NTAs which were prepared by directly annealing the as-anodized TiO2NTAs under Ar atmosphere. The organic residual in the TiO2NTAs during the process of anodization acts as carbon source and is carbonized in Ar atmosphere to manufacture the C-TiO2NTAs. The specific capacitance of the PANI/C-TiO2electrode is 120.8 mF cm−2at a current density of 0.1 mA cm−2and remains 104.3 mF cm−2at a current density of 2 mA cm−2with the calculated rate performance of 86.3%. After 5000 times of charge-discharge cycling at a current density of 0.2 mA cm−2, the specific capacitance retains 88.7% compared to the first cycle. All these outstanding performances of the as-prepared PANI/C-TiO2NTAs indicate it will be a promising electrode for supercapacitor.