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Start date: 2022Subject: search.filters.subject.Recycling

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    Design and trial of a comprehensive home composting evaluation tool
    (OICCC Press, Witney, United Kingdom, 2025-06-01) Mensah S; Hannon J; Hytten KF
    Purpose: In this study, a comprehensive home composting evaluation tool (HCET) was designed and trialled to support the analysis of empirical and quality assurance parameters of home composting systems. Method: The proposed HCET was developed based on a review of relevant scientific literature, a range of ‘how to’/‘good practice’ guidelines for home composting, and guiding principles from the New Zealand Compost Standard. It was then trialled within a research project examining home composting practices in Palmerston North, Aotearoa New Zealand. Results: This research showed that whilst home composting is widely undertaken in Palmerston North and diverts a significant amount of organic waste from landfill, home composters often encounter technical challenges and have variable results. Critical reflection on the practical experience of trialling the draft HCET in the context of the broader findings from the research project enabled the HCET to be refined and finalised. Conclusion: A growing body of literature demonstrates that home composting is a popular and cost-effective opportunity to divert municipal organic waste from landfill, reduce greenhouse gas emissions and enhance local soils and home gardening. As such, effective and systematic evaluation of the various home composting technologies, practices and outputs is a critical opportunity to accelerate the development of a more sustainable, low emission circular bioeconomy. The proposed HCET provides a quick, accurate and effective way to undertake data collection and system analysis, which will support future research further developing and optimising home composting technologies and practices.
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    Optimization of the rearing environment for the black soldier fly, Hermetia illucens L. (Diptera: Stratiomyidae), a promising agent for organic waste bioconversion : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Massey University, Manawatū, New Zealand
    (Massey University, 2022) Liu, Zhongyi
    Bioconversion is an environmentally, socially and economically sound measure for organic waste management. The black soldier fly (BSF), Hermetia illucens L. (Diptera Stratiomyidae), is one of the promising species for organic waste bioconversion. Larvae of BSF (BSFL) can feed on multiple types of organic waste, and the harvested larvae could be processed into valuable products such as animal feed, chitin, and organic fertilizer. To maximize the efficiency of a bioconversion system using BSFL, it is necessary to optimize the rearing environment of the insects, which requires knowledge of the impact of environmental factors on BSF at different life stages. This thesis reports my investigations on (1) the effect of diet on selected BSF larval (BSFL) life history and physiological traits and bioconversion efficiency, (2) the effect of substrate type and moisture content on BSF pupation, and (3) the effect of artificial light type, light regime, and adult density on BSF reproduction. First of all, I tested three types of organic waste (brewer’s waste, pig manure, and semidigested grass) against a standard diet (broll; a mixture of wheat bran and wheat flour). Among the organic wastes tested, brewer’s waste led to the fastest larval growth and highest larval weight gain. However, protein conversion efficiency of BSFL fed on brewer’s waste was lower than the larvae fed on the standard diet, which may be due to the high protein content in brewer’s waste. A meta-analysis revealed that dietary lignocellulosic content has an adverse impact on BSFL weight gain. Second, I investigated the effects of two pupation substrates (vermiculite and wood chips) and nine moisture levels on BSF pupation rate and depth. Using moist pupation substrate could reduce prepupal water loss, improve prepupal survival rate, and move forward the onset of pupation. BSF prepupae were found to stay at shallower depth levels when moisture content exceeded 20% and 70% for vermiculite and wood chips, respectively, which may be due to reduced oxygen availability. Third, I assessed four types of artificial light for their suitability of supporting mating of BSF from two different colonies. The artificial light that matches the spectral sensitivity of photoreceptors of BSF adults led to the highest mating success. Interestingly, artificial light resembling summer sunlight failed to support BSF mating, which may be due to its flickering. Colony effect was also significant on BSF mating success. Moreover, I found an interaction between the light regime and adult density on mean individual female reproductive output and adult survival rate. To optimize the reproductive output of a BSF colony, 8 h of photoperiod would be sufficient for a low adult density (e.g., lower than 800 individuals∙m−3), whereas longer photoperiods may be needed for higher adult densities. Finally, I present the implications that can be drawn from my findings, and my recommendations for future research and the relevant industry.