Recirculating frass from food waste bioconversion using black soldier fly larvae: Impacts on process efficiency and product quality.

Biowaste generation is increasing worldwide and inadequate disposal has strong negative impacts on food systems and ecosystems. Biodigestion of biowaste using black soldier fly (Hermetia illucens) larvae (BSFL) generates valuable by-products such as animal feed (larval biomass) and organic fertiliser (frass). However, the latter is typically unstable immediately after waste conversion and is thus unsafe for use as a fertilizer in terms of maturity. This study evaluated recirculation of frass within bioconversion of post-consumer food waste (FW) as a dietary component for BSFL to improve the quality of the subsequent frass obtained. Frass was introduced at increasing inclusion levels replacing food waste (2.5-100% on wet-weight basis) as part of the larvae's feeding substrate. Bioconversion efficiency and material reduction were significantly reduced by frass inclusion, while larval yield per experimental unit remained unchanged. When considering only the waste component in the larval diet, larval yield (dry-weight basis) ranged between 207 (0% frass inclusion) and 403 (40% frass inclusion) kg tonne FW-1, thus increasing by up to 94% at higher frass inclusion. With increasing dietary inclusion rate of frass from 0% to 100%, crude protein content of larval biomass increased by 41%, while fat content was reduced by 32%. The recirculated frass (obtained after including frass in the larval diet) had elevated concentrations of P, K, S, Na and B and around 6% lower organic matter content, demonstrating a higher degree of decomposition. Frass inclusion in the larval diet generated recirculated frass that were more stable and mature, as indicated by self-heating capacity, CO2 and NH3 volatilisation, seed germination bioassays and other parameters. It was concluded that frass recirculation improves waste bioconversion efficiency in relation to food waste unit, as well as larval biomass and frass quality, ensuring safer use as a fertilizer.

Composting as a strategy to recycle aquatic animal waste: Case study of a research centre in São Paulo State, Brazil.

Aquaculture is a fast-growing activity in Brazil and around the world, which generates large amounts of waste from fingerling production to the final consumer. Among several possibilities for the management of these wastes, windrow composting stands out as a simple and low-cost method. In this study, 16 composting piles were assembled with wood shavings and peanut shells and managed according to two methods; one with carcasses recharges and another without. A description of the daily occurrences and management details were made. Temperature and moisture content were monitored and at the end of the decomposition process, and after 60 and 100 days of curing, physic-chemical analysis was performed to assess composts quality. A germination index test was performed to assess composts phytotoxicity. All piles exceeded 55 °C for more than 15 days (with the aid of turnings) and germination indices were above 50% for both lettuce and cress seeds. Total nitrogen concentration among composts varied from 22.1 to 33.2 g kg-1 and carbon:nitrogen ratios were below 20, while pH values were above 6.0 in all composts. Curing composts for 60 and 100 days did not influence any of the physic-chemical characteristics of all composts, so this practice can be dodged, thus avoiding unnecessary land use and increasing production costs. The type of management adopted for carcasses of aquatic animals influenced total and inorganic nitrogen, C/N ratio, organic matter and pH values of the composts, being recommended the recharge of carcasses to improve composts stability and quality.

Frass derived from black soldier fly larvae treatment of biodegradable wastes. A critical review and future perspectives.

Inadequately treated biodegradable waste is considered an environmental, social and economic threat worldwide, which call for great attention. Waste treatment with larvae of the black soldier fly (BSF, Hermetia illucens) complies with the concepts of circular economy, as it enables the transformation of these wastes into marketable products, closing loops and promoting circularity. The processing residues of the treatment (frass) is constantly generated in waste management facilities in large volumes, and this product can be used as an organic fertilizer in agriculture, stimulating a transition to a circular economy. However, many aspects related to frass are still unknown, such as its varying composition of nutrients, microorganisms and bioactive compounds, its post-processing requirements for improved biological stabilization, its behavior in the soil and action in the plants' metabolism, among other aspects. In this review article, we highlight the potential of frass from BSF larvae treatment of biodegradable waste in the world market regarding its possible use as a fertilizer, summarize recent results with this novel product and point towards future research perspectives.

Reduction of Bacteria in Relation to Feeding Regimes When Treating Aquaculture Waste in Fly Larvae Composting.

This study evaluated the impact of feeding regimes on process performance and inactivation of microorganisms during treatment of aquaculture waste with black soldier fly (BSF) larvae. In three treatments (T1-T3), a blend of reclaimed bread and aquaculture waste was used as substrate for BSF larvae. In T1, the substrate was inoculated with four subtypes of Salmonella spp. and Escherichia coli (both at 1% w/w), and offered only once, at the beginning of the 14-day trial. In T2 and T3, the substrate was supplied on three different days, with contaminated substrate provided only the first event in T2 and in all three events in T3. Provision of a lump sum feeding (T1) proved unfavorable for larval growth and process efficiency, but did not affect the microbial reduction effect. The total reduction in Salmonella spp. was approximately 6 log10 in T1 and T2, and 3.3 log10 in T3, while the total reduction in E. coli was approximately 4 log10 in T1 and T2, and 1.9 log10 in T3. After removing the larvae, the treatment residues were re-inoculated with Salmonella spp. and E. coli. It was found that the inactivation in both organisms continued in all treatments that originally contained BSF larvae (T1-T3), suggesting that antimicrobial substances may have been secreted by BSF larvae or by its associated microbiota.

Predicted 2100 climate scenarios affects growth and skeletal development of tambaqui (Colossoma macropomum) larvae.

Climate changes driven by greenhouse gas emissions have been occurring in an accelerated degree, affecting environmental dynamics and living beings. Among all affected biomes, the Amazon is particularly subjected to adverse impacts, such as temperature rises and water acidification. This study aimed to evaluate the impacts of predicted climate change on initial growth and development of an important Amazonian food fish, the tambaqui. We analyzed growth performance, and monitored the initial osteogenic process and the emergence of skeletal anomalies, when larvae were exposed to three climate change scenarios: mild (B1, increase of 1.8°C, 200 ppm of CO2); moderate (A1B, 2.8°C, 400 ppm of CO2); and drastic (A2, 3.4°C, 850 ppm of CO2), in addition to a control room that simulated the current climatic conditions of a pristine tropical forest. The exposure to climate change scenarios (B1, A1B, and A2) resulted in low survival, especially for the animals exposed to A2, (24.7 ± 1.0%). Zootechnical performance under the B1 and A1B scenarios was higher when compared to current and A2, except for condition factor, which was higher in current (2.64 ± 0.09) and A1B (2.41 ± 0.14) scenarios. However, skeletal analysis revealed higher incidences of abnormalities in larvae exposed to A1B (34.82%) and A2 (39.91%) scenarios when compared to current (15.38%). Furthermore, the bone-staining process revealed that after 16 days posthatch (7.8 ± 0.01 mm total length), skeletal structures were still cartilaginous, showing no mineralization in all scenarios. We concluded that tambaqui larvae are well-adapted to high temperatures and may survive mild climate change. However, facing more severe climate conditions, its initial development may be compromised, resulting in high mortality rates and increased incidence of skeletal anomalies, giving evidence that global climate change will hamper tambaqui larvae growth and skeletal ontogeny.

The influence of midazolam on heart rate arises from cardiac autonomic tones alterations in Burmese pythons, Python molurus.

The GABAA receptor agonist midazolam is a compound widely used as a tranquilizer and sedative in mammals and reptiles. It is already known that this benzodiazepine produces small to intermediate heart rate (HR) alterations in mammals, however, its influence on reptiles' HR remains unexplored. Thus, the present study sought to verify the effects of midazolam on HR and cardiac modulation in the snake Python molurus. To do so, the snakes' HR, cardiac autonomic tones, and HR variability were evaluated during four different experimental stages. The first stage consisted on the data acquisition of animals under untreated conditions, in which were then administered atropine (2.5mgkg-1; intraperitoneal), followed later by propranolol (3.5mgkg-1; intraperitoneal) (cardiac double autonomic blockade). The second stage focused on the data acquisition of animals under midazolam effect (1.0mgkg-1; intramuscular), which passed through the same autonomic blockade protocol of the first stage. The third and fourth stages consisted of the same protocol of stages one and two, respectively, with the exception that atropine and propranolol injections were reversed. By comparing the HR of animals that received midazolam (second and fourth stages) with those that did not (first and third stages), it could be observed that this benzodiazepine reduced the snakes' HR by ~60%. The calculated autonomic tones showed that such cardiac depression was elicited by an ~80% decrease in cardiac adrenergic tone and an ~620% increase in cardiac cholinergic tone - a finding that was further supported by the results of HR variability analysis.