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Environmental concerns, caused by greenhouse gases released to the atmosphere and overrunning of nutrients and pathogens to water bodies, have led to reducing direct spread onto the land of cattle manure. In addition, this practice can be a source of water and air pollution and toxicity to life by the release of undesirable heavy metals. Looking at the current practices, it is evident that most farms separate solids for recycling purposes, store slurries in large lagoons or use anaerobic digestion to produce biogas. The review explores the potential for cattle manure as an energy source due to its relatively large calorific value (HHV of 8.7–18.7 MJ/kg dry basis). This property is beneficial for thermochemical conversion processes, such as gasification and pyrolysis. This study also reviews the potential for upgrading biogas for transportation and heating use. This review discusses current cattle manure management technologies—biological treatment and thermochemical conversion processes—and the diverse physical and chemical properties due to the differences in farm practices.

The increase of annual organic wastes generated worldwide has become a major problem for many countries since the mismanagement could bring about negative effects on the environment besides, being costly for an innocuous disposal. Recently, insect larvae have been investigated to valorize organic wastes. This entomoremediation approach is rising from the ability of the insect larvae to convert organic wastes into its biomass via assimilation process as catapulted by the natural demand to complete its lifecycle. Among the insect species, black soldier fly or Hermetia illucens is widely researched since the larvae can grow in various environments while being saprophagous in nature. Even though black soldier fly larvae (BSFL) can ingest various decay materials, some organic wastes such as sewage sludge or lignocellulosic wastes such as waste coconut endosperm are destitute of decent nutrients that could retard the BSFL growth. Hence, blending with nutrient-rich low-cost substrates such as palm kernel expeller, soybean curd residue, etc. is employed to fortify the nutritional contents of larval feeding substrates prior to administering to the BSFL.Alternatively, microbial fermentation can be adopted to breakdown the lignocellulosic wastes, exuding essential nutrients for growing BSFL. Upon reaching maturity, the BSFL can be harvested to serve as the protein and lipid feedstock. The larval protein can be made into insect meal for farmed animals, whilst the lipid source could be extracted and transesterified into larval biodiesel to cushion the global energy demands. Henceforth, this review presents the influence of various organic wastes introduced to feed BSFL, targeting to reduce wastes and producing biochemicals from mature larvae through entomoremediation. Modification of recalcitrant organic wastes via fermentation processes is also unveiled to ameliorate the BSFL growth. Lastly, the sustainable applications of harvested BSFL biomass are as well covered together with the immediate shortcomings that entail further researches.

Our ever-increasing interest in economic growth is leading the way to the decline of natural resources, the detriment of air quality, and is fostering climate change. One potential solution to reduce carbon dioxide emissions from industrial emitters is the exploitation of carbon capture and storage (CCS). Among the various CO2 separation technologies, cryogenic carbon capture (CCC) could emerge by offering high CO2 recovery rates and purity levels. This review covers the different CCC methods that are being developed, their benefits, and the current challenges deterring their commercialisation. It also offers an appraisal for selected feasible small- and large-scale CCC applications, including blue hydrogen production and direct air capture. This work considers their technological readiness for CCC deployment and acknowledges competing technologies and ends by providing some insights into future directions related to the R&D for CCC systems.

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