In this study, the principle of sustaining circular economy is presented as a way of recovering valuable resources from wastewater and utilizing its energy potential via anaerobic digestion (AD) of municipality wastewater. Biostimulation of the AD process was investigated to improve its treatability efficiency, biogas production, and kinetic stability. Addressing this together with agricultural waste such as eggshells (CE), banana peel (PB), and calcined banana peels (BI) were employed and compared to magnetite (Fe3O4) as biostimulation additives via 1 L biochemical methane potential tests. With a working volume of 0.8 L (charge with inoculum to substrate ratio of 3:5 v/v) and 1.5 g of the additives, each bioreactor was operated at a mesophilic temperature of 40 °C for 30 days while being compared to a control bioreactor. Scanning electron microscopy and energy dispersive X-ray (SEM/EDX) analysis was used to reveal the absorbent’s morphology at high magnification of 10 kx and surface pore size of 20.8 µm. The results showed over 70% biodegradation efficiency in removing the organic contaminants (chemical oxygen demand, color, and turbidity) as well as enhancing the biogas production. Among the setups, the bioreactor with Fe3O4 additives was found to be the most efficient, with an average daily biogas production of 40 mL/day and a cumulative yield of 1117 mL/day. The kinetic dynamics were evaluated with the cumulative biogas produced by each bioreactor via the first order modified Gompertz and Chen and Hashimoto kinetic models. The modified Gompertz model was found to be the most reliable, with good predictability.
Background. Respirable dust, diesel particulate matter, crystalline silica and noise pollution are the most common causes of health issues experienced by underground mine workers. Assessment of exposure levels in relation to standard regulatory body permissible levels is essential for the safety of mine workers. Objectives. The present study compared exposure levels of diesel particulate matter, crystalline silica dust and noise experienced across different underground mine worker job titles. Methods. Subjective sampling was employed using gravimetric air samplers over an 8-hour time weighted average for two periods designated as period 1 (first half of the year) and period 2 (second half of the year). A comparative analysis of exposure levels between job titles and in relation to the National Institute for Occupational Safety and Health (NIOSH) permissible exposure levels (PELs) was performed. Results. In the present study, 90% of the selected job titles were over-exposed to noise and 80% were over-exposed to diesel particulate matter. The highest exposures for crystalline silica dust and diesel particulate matter were found in the 40–49-year-old age group. Conclusions. The present study of exposure levels of diesel particulate matter, respirable dust, crystalline silica, and noise during underground gold mining demonstrates that better control mechanisms are needed to protect workers. Participant Consent. Obtained Ethics Approval. This study was approved by the Ethics Committee of the Kwame Nkrumah University of Science and Technology, Ghana. Competing Interests. The authors declare no competing financial interests.
The demand for technological and industrial change has become heavily dependent on the availability and use of petroleum products as a source of energy for socio-economic development. Notwithstanding, petroleum and petrochemical products are strongly related to global economic activities, and their extensive distribution, refining processes, and final routes into the environment pose a threat to human health and the ecosystem. Additional global environmental challenges related to the toxicological impact of air, soil, and water pollutants from hydrocarbons are carcinogenic to animals and humans. Therefore, it is practical to introduce biodegradation as a biological catalyst to address the remediation of petroleum-contaminated ecosystems, adverse impacts, the complexity of hydrocarbons, and resistance to biodegradation. This review presents the bioremediation of petroleum hydrocarbon contaminants in water and soil, focusing on petroleum biodegradable microorganisms essential for the biodegradation of petroleum contaminants. Moreover, explore the mineralization and transformation of complex organic and inorganic contaminants into other simpler compounds by biological agents. In addition, physicochemical and biological factors affecting biodegradation mechanisms and enzymatic systems are expanded. Finally, recent studies on bioremediation techniques with economic prospects for petroleum spill remediation are highlighted.
Biochar, or carbon obtained from biomass, is a particularly rich source of carbon created by thermal burning of biomass. There is a rise of interest in using biochar made from waste biomass in a variety of disciplines to address the most pressing environmental challenges. This chapter will provide an overview on the methods employed for the production of biochar. Biochar has been considered by a number of analysts as a means of improving their ability to remediate pollutants. Process factors with regards to biochar properties are mostly responsible for determining biomass production which is discussed in this present chapter. Several characterization techniques which have been employed in previous studies have received increasing recognition. These includes the use of the Fourier transform infrared spectroscopy and the Scanning electron microscope which duly presented in this chapter. This chapter also discusses the knowledge gaps and future perspectives in adopting biochar to remediate harmful contaminants, which can inform governmental bodies and law-makers to make informed decisions on adopting this residue.
Lignocellulosic biomass has gained increasing recognition in the past decades for the production of value-added products (VAPs). Biomass feedstocks obtained from various sources, their composition, and pretreatment techniques employed for delignification into bioenergy production are discussed. The conversion processes of biomass into VAPs involve various methods. Notable among them are biochemical conversions; namely, anaerobic digestion and ethanol fermentation, and thermo-chemical conversions; namely, pyrolysis and gasification which are considered in this chapter. Microalgae can adapt to changes in the environment, producing biomass that serves as a precursor for a variety of biomolecules, such as proteins, which find their application in pharmaceutical, cosmetic, and biofuel industries. Suitable strains of freshwater microalgae biomass contain high levels of lipid which can be harnessed for bioenergy production. Hence, the advancement in the conversion of biomass into VAPs could help scientists and environmentalists for sustainable use of biomass in future developments.
The quality of freshwater and its supply, particularly for domestic and industrial purposes are waning due to urbanization and inefficient conventional wastewater treatment (WWT) processes. For decades, conventional WWT processes have succeeded to some extent in treating effluents to meet standard discharge requirements. However, improvements in WWT are necessary to render treated wastewater for re-use in the industrial, agricultural, and domestic sectors. Three emerging technologies including membrane technology, microbial fuel cells and microalgae, as well as WWT strategies are discussed in this chapter. These applications are a promising alternative for manifold WWT processes and distribution systems in mitigating contaminants to meet acceptable limitations. The basic principles, types and applications, merits, and demerits of the aforementioned technologies are addressed in relation to their current limitations and future research needs. The development in WWT blueprints will augment the application of these emerging technologies for sustainable management and water conservation, with re-use strategies.
Biochar is a carbon-rich pyrogenic material that is made from carbon-neutral sources (i.e., biomass). It offers key strategies for carbon capture and storage (CCS) as well as being an environmentally friendly means of soil amendment. The recent recognition of biochar as a versatile media for catalytic applications has prompted preliminary research into biochar’s catalytic capacity and mechanistic practices via various routes. This chapter provides a review of biochar production technologies, biochar’s catalyst development, and its application in various catalytic processes as well as descriptions of the benefits and drawbacks of the various applications currently available. The characteristics of biochar-based catalysts, challenges of effective application of this catalyst system, emerging application, prospects, and future work consideration for effective utilization of biochar-based catalysts were presented.
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