Comparison between continuous and daytime mixing for the treatment of raw anaerobically digested abattoir effluent (ADAE) and microalgae production in open raceway ponds
The effect of mixing duration on two microalgae grown in abattoir wastewater was studied.
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Biomass productivity was similar for Chlorella sp. under 12 h and 24 h mixing.
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Biomass productivity was higher for 24 h paddle wheel mixed Scenedesmus sp. than 12 h.
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Scenedesmus sp. had higher productivity and nutrient removal rates than Chlorella sp.
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Microalgae growth in abattoir effluent reduced aerobic bacteria and eliminated E. coli.
Abstract
This study investigated the outdoor cultivation of two local microalgae species (Chlorella sp. and Scenedesmus sp.) in raw anaerobically digested abattoir effluent (ADAE) which were subjected to both continuous (24 h) and daytime only (12 h) paddle wheel mixing. The goal of this study was to identify the most efficient microalgae species and mixing condition for raw ADAE bioremediation. No differences in Chlorella sp. biomass productivity were recorded for both mixing conditions while values were higher (14%) for 24 h mixed Scenedesmus sp. Despite the exhaustion of ammoniacal nitrogen (NH3-N) in all treatments, only between 14 and 28% of NH3-N was assimilated for biomass production. Microalgae growth in ADAE significantly reduced the total aerobic bacteria population and eliminated Escherichia coli content in ADAE for all treatments. Overall, Scenedesmus sp. demonstrated higher biomass productivity and nutrient removal efficiency in ADAE when compared to Chlorella sp., with the continuously (24 h) mixed cultures being most efficient.
