Assessment of pollution levels resulting from biomass gasification

Abstract

Today the large scale introduction of biomass gasification is hampered by health, and environmental issues which present a major barrier in the deployment of this technology. The condensate in particular resulting from producer gas cooling before use in gas engines is highly toxic and carcinogenic which, if not adequately controlled, can lead to detrimental impacts on human health and the environment. The study was therefore aimed at assessment of pollution levels resulting from biomass gasification organic condensates. The study involved assessing the concentration of polycyclic aromatic hydrocarbons (PAHs) and BTEX (i.e. benzene, toluene, ethylbenzene and xylene) in the condensate deemed toxic and carcinogenic, mention their impact on human health and the environment as well as recommend measures aimed at minimizing pollution levels resulting from biomass gasification.The gasifier installation at Makerere University was run in downdraft mode using maize cobs as biomass fuel. The producer gas was cooled using a water cooled condenser connected to the exhaust pipe of the gasifier. The condensate was then transferred into sampling bottles made of opaque glass to minimize photochemical reactions in water samples and preserved in a cooler at 2 o C to 6 o C until the time for analysis to minimize volatilization and bacterial degradation of the hydrocarbons. The capillary gas chromatography with mass spectrometric detector (CGCMSD) was used to analyze the condensate for the selected hydrocarbons.The procedures involved preparation of PAHs and BTEX standard solutions using standard mixtures and internal standards, calibration of the CGCMSD, extraction of the aromatic hydrocarbons using hexane, performing a surrogate analysis to . Acenaphthylene, acenaphthene, fluorene, phenanthrene and anthracene were not detected in the condensate by the CGCMSD due to their concentration levels being below the detection limit of the CGCMSD. The concentrations of naphthalene and xylene were considerably high compared to the recommended permissible exposure limits thus posing risks on both human health and the environment. It is therefore important to treat the condensate before disposal to the environment. On the other hand, the concentrations of benzene, toluene and ethylbenzene were below the permissible exposure limit and therefore for this study, the liquid effluent was considered to meet the regulatory standards. The recommendations aimed at minimizing pollution levels during biomass gasification were also discussed.

Biocompositional and thermodecompositional analysis of South African agro‐waste corncob and husk towards production of biocommodities

“…Cellulose and hemicellulose are the repositories of fermentable sugars; hence, their use as feedstocks in microbial conversion processes for the production of second‐generation bioethanol and several value‐added biocommodities . Similarly, the efficiency of thermo‐conversion of corn waste, a lignocellulosic biomass, into energy carrier gases such as syngas for electricity generation also depends on the quality, physicochemical property, and biocomposition of the waste.…”

Aspen plus simulation of sargassum for quality synthesis gas

“…This is because a higher ER allows more oxygen to react with the volatiles in the pyrolysis zone [ 1 ], the quality of the gas is also reduced with high ER rates because the heating value of the gas is reduced due to the dilution of nitrogen from the air used ( Table 10 ). The high variability in the concentrations of the respective light aromatic tars can be attributed to the volatile nature of the compounds [ 25 ].…”