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A laboratory scale bioreactor has been designed and set up in order to degrade hydrogen sulfide from an air stream. The reactor is a vertical column of 7 litre capacity and 1 meter in height. It is divided into three modules and each module is filled with pellets of agricultural residues as packing bed material. The gas stream fed into the reactor through the upper inlet consists of a mixture of hydrogen sulfide and humidified air. The hydrogen sulfide content in the inlet gas stream was increased in stages until the degradation efficiency was below 90%. The parameters to be controlled in order to reach continuous and stable operation were temperature, moisture content and the percentage of the compound to be degraded at the inlet and outlet gas streams (removal or elimination efficiency). When the H2S mass loading rate was between 10 and 40 g m-3h-1,the removal efficiency was greater than 90%. The support material had a good physical performance throughout operation time, which is evidence that this material is suitable for biofiltration purposes. [ABSTRACT FROM AUTHOR]

In the past, black slag from an Electric Arc Furnace was dumped or stockpiled. Nevertheless, after much controversy, slag can no longer be considered a “waste”, and bearing in mind its positive properties, reuse alternatives are being sought. In this study, a black slag was used as an alternative packing material for toluene, ethylbenzene and p -xylene biofiltration, with these pollutants being fed both individually and jointly. Ethylbenzene recorded the highest elimination capacity when the ternary mixture was fed. The electrical conductivity of the leaching solution showed that the slag did not contribute to ion release or dissolution. The acid neutralizing capacity of the slag played a major role in preventing bed acidification. All the biofilters were invaded by mites, and other meiofauna including nematodes and rotifers also developed in the bed. Under these conditions, CO 2 production was attributed not only to contaminant degradation but also to the metabolic processes of the meiofauna originating from the inoculum. Despite the favourable evolution of the operating parameters and the suitable performance of the slag bed, its high bulk density restricts the size of the bed. Slag is nonetheless recommended for use as a co-packing material. [ABSTRACT FROM AUTHOR]

Black slag from an electric arc furnace (EAF) was used as an innovative inorganic co-packing material in organic biofilters for the biodegradation of CS 2 -polluted gases. The effect on biofilter performance of increasing the inlet concentration ( IC ) and reducing the empty bed residence time (EBRT) was evaluated in three biofilters packed with different bed configurations. Macro-kinetic modelling pointed to a lower CS 2 biodegradation activity related to the presence of the slag. Nevertheless, the presence of black slag improved long-term biofilter performance, and the maximum elimination capacity (43 g m −3 h −1 ) was recorded in the biofilter packed with a mixed support. Molecular profiling of the eubacterial populations demonstrated the ubiquitous presence of the potential CS 2 degrading species Thiomonas intermedia . Co-packing with EAF slag also prompted the development of a more complex microbial community encompassing halophilic species involved in the metabolism of sulphur compounds (i.e. Thiohalophilus spp. and Paracoccus thiocyanatus ). [ABSTRACT FROM AUTHOR]