Utilization Of Waste Streams Research Articles

Comparison of the physicochemical properties of microalgae biodiesel with other oilseed feedstocks for sustainable energy production: A meta-analysis

Biodiesel has emerged as an alternative diesel fuel, offering environmental advantages such as biodegradability, non-toxicity, and low emissions. This study conducted a meta-analysis to compare microalgae biodiesel with other oilseed feedstocks for sustainable energy production. The analysis involved compiling a database of published articles on biodiesel derived from microalgae and plant seeds. The results demonstrated that microalgae are one of the most promising feedstocks among various oilseeds. The cetane number and fuel density of biodiesel from microalgae were significantly higher than those from plant seeds (p<0.05). In conclusion, microalgae are a suitable feedstock for biodiesel production, surpassing traditional oil and crop sources, and can potentially mitigate the expansion of conventional agricultural practices. Moreover, microalgae can be cultivated year-round and in various climates, allowing for extended production seasons and site flexibility. Additionally, their utilization of waste streams as nutrient sources and non-requirement of arable land can contribute to reducing the environmental impact on other industries.

Biochemical composition of Hediste diversicolor (OF Müller, 1776) (Annelida: Nereidae) reared on different types of aquaculture sludge

IntroductionSustainable growth of the salmon aquaculture industry is highly dependent on the availability of new feed resources as well as improved management and utilization of waste streams from production. Polychaetes are capable of recapturing and recycling valuable biomolecules contained in aquaculture sludge and at the same time constitute a possible resource for aquafeeds.Material and methodsIn this study, the potential of Hediste diversicolor (OF Müller, 1776) to recover nutrients and energy contained aquaculture sludge was evaluated. Hereby, the effect of two different diets, smolt and post-smolt sludge, and different feed levels on polychaete growth, and biochemical and elemental composition was assessed.Results and discussionSurvival ranged from 80-90%, independent of treatment. Specific growth rates at the highest feed levels were significantly higher than at the lowest feed levels and growth was not affected by the type of diet. Similarly, total lipid and total fatty acid content of polychaetes were positively correlated with feed level while the type of diet had a limited effect. Fatty acid composition of polychaetes reflected feed levels: in both diet groups, polychaetes at lower feed levels showed a higher percentage of saturated fatty acids; monounsaturated fatty acids increased with increased feed supply for smolt sludge-fed group and polychaetes fed post-smolt sludge showed increased polyunsaturated fatty acid content with increasing feed levels. Neither diet nor feed levels affected protein content and amino acid composition of polychaetes. In conclusion, H. diversicolor could be successfully cultivated on both smolt and post-smolt sludge and was rich in proteins and lipids as well as essential amino and fatty acids. The species can be considered a promising candidate for recycling valuable nutrients from different types of side streams salmon aquaculture.

The effect of growth inhibiting compounds of grease trap waste on Candida tropicalis ATCC 20962

The production of chemicals through a circular economy is becoming increasingly important and one way to achieve this is through the utilisation of waste streams. One such waste stream that holds potential for production of chemicals through biochemical methods is grease trap waste (GTW). However, before this waste stream can be used in bioprocesses, it is crucial to understand its effects on the process. This study explores the toxicity of the GTW on the growth of Candida tropicalis ATCC 20962, a yeast that is applied to convert lipids into valuable long-chain dicarboxylic acids (LCDAs). The GTW is characterised and the inhibition of the different components on the growth of C. tropicalis is examined. Results indicate significant inhibition of yeast growth at a concentration of 40 g/L of GTW and higher. Further analysis confirms that the presence of anionic detergents may partially contribute to this inhibition. In contrast, the pesticides, free fatty acids and heavy metals did not appear to significantly affect the growth of C. tropicalis. Although this study suggests that GTW could be a suitable feedstock for Candida tropicalis ATCC 20962, more research is required to identify other potentially toxic components and to determine if pre-treatment is necessary for industrial applications.

Net protein contribution from an intensive Australian pork supply chain

Debate surrounding the adverse consequences of feeding human-edible feedstuffs to livestock can be addressed through calculation of the net protein contribution (NPC) of the production system. If the NPC is greater than 1.0 for the production system, then there are net benefits from the system for human populations with an ever-increasing requirement for protein and amino acids. The aim of this paper was to calculate the NPC for an Australian pork supply chain on the basis of the unique characteristics of Australian ingredients. While calculation of NPC is not complex, intimate knowledge of the source of the nutrients and their quality, and interpretation of their human-edible protein fractions is essential if an accurate estimate is to be achieved. The NPC for an Australian pork supply chain was calculated using (a) actual, published or estimated values for human-edible fractions of feedstuffs, (b) the percentage of protein available within raw materials considered to be human edible, (c) recommended amino acid scoring patterns for infants, adolescents and adults, (d) published, and calculated from standard reference nutrient databases, digestible indispensable amino acid scores, (e) carcase yields and carcase composition from published studies, and (f) actual feed formulations, feed volumes and production data from a large Australian pork supply chain. The NPC for the assessed Australian pork supply chain was 3.26. This means the supply chain generates more than three times the human-edible protein it consumes in the process. This NPC is higher than previously published values, largely because of the composition of Australian pig diets, but demonstrates the positive value that livestock production systems make to human food supply. Livestock systems are often targeted as net consumers of vital nutrients such as protein and amino acids and the diversion of these nutrients from human diets. If production systems focus on the utilisation of waste streams, co-products and human-inedible feedstuffs, then they can make a net contribution to human-edible protein supply.

Rural development opportunities in the bioeconomy

In this paper we discuss the rural development implications of the bioeconomy. We define the bioeconomy broadly but dedicate much of the paper to the implications of bioenergy and how it will transform the economies of rural regions. We then conclude with three different bioenergy related concepts that will provide a broader framework for the development of the rural bioeconomy. These include the costs of bioenergy and especially transportation costs, the regional energy balance and the utilization of waste streams.