Biological nitrate removal from synthetic wastewater using a fungal consortium in one stage bioreactors

Abstract

A series of lignocellulosic fungi, capable of cellulase and/or xylanase production, were isolated from soil to be used for cellulose degradation and nitrate removal from nitrate-rich wastewater in simple one-stage anaerobic bioreactors containing grass cuttings as source of cellulose. The fungal consortium, consisting of six hyphomycetous isolates, some of which belong to the genera Fusarium, Mucor and Penicillium, was able to remove a significant portion of the nitrate from the treated water. The results were obtained for three bioreactors, i.e. FR, FRp and AFRp, differing in volume and mode of grass addition. Bioreactor AFRp received autoclaved grass, instead of non-autoclaved grass containing natural microbial consortia, as supplied to FR and FRp. Nitrate removal in FR amounted to 89% removal efficiency, while this was 65% and 67% in FRp and AFRp, respectively. The residual chemical oxygen demand (COD) concentration in FR was higher than 600 mg/ℓ, while it was 355 and 379 mg/ℓ in FRp and AFRp, respectively.

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