membrane bioreactors enable high rate treatment of slaughterhouse wastewater, Biochemical Engineering Journal http://dx. Highlights-AnMBRs are an effective technology for treatment of slaughterhouse wastewater -COD removal was consistently over 95% and was independent of OLR and HRT -Organic loading limit of 3-3.5 gCOD.L -1 d -1 was imposed by active biomass inventory -Biomass inventory in the AnMBR was limited to 40 g.L -1 (TS) to manage fouling ABSTRACT Anaerobic Membrane Bioreactors (AnMBRs) enable high space loading by retaining solids selectively through microfiltration membranes. For organic industrial wastewaters, this offers an alternative to lagoons and granule based high-rate anaerobic treatment due to excellent effluent quality, high tolerance to load variations, and ability to produce a solids free effluent for the purposes of reuse. While there has been extensive work on low-strength and low solids effluent, there has been limited application in high-solids, high fats systems such as slaughterhouse wastewater, which are a key application. A 200L AnMBR pilot plant operated at 2 Australian cattle slaughterhouses consistently removed over 95% of chemical oxygen demand (COD) from the wastewater. Virtually all degradable COD was converted to biogas, 78-90% of nitrogen and 74% of phosphorus in the wastewater were released to the treated permeate as ammonia and phosphate respectively; which would enable subsequent nutrient capture. The mass loading rate limit of 3-3.5 gCOD.L -1 d -1 is imposed by the active biomass inventory, with this in turn limited to 40 g.L -1 (TS) by the need to manage membrane fouling control.
This study addressed the removal of ammonia from recycled centrate via biological nitrification and denitrification in batch reactors. Nitrification was successful at ammonia feed concentrations up to 400 mg/L and carbon-to-nitrogen (C/N) ratios greater than 1. The use of pre-exposed biomass to ammonia-rich centrate reduced considerably the overall time required for nitrification, which was also reflected on the corresponding specific rates. The denitrification of naturally-generated nitrates proceeded smoothly, with methanol modestly outperforming acetate as external carbon source. Furthermore, simultaneous nitrification and denitrification (SND) was induced in the presence of readily biodegradable organic carbon (i.e., methanol or acetate) under aerobic conditions. Overall, total nitrogen removal from ammonia-rich centrate by biological methods was viable under the conditions investigated.
Anaerobic membrane bioreactors (AnMBRs) offer a suitable alternative to existing lagoon and high-rate granular treatment options for high solids and fatty industrial wastewaters. AnMBR fouling is however, a major limitation to industrial applications, particularly in the treatment of complex, particulate substrate. Model analyses that integrate the multiple controlling factors of fouling offer a better understanding of controlling mechanisms than experimental analysis, however, existing membrane bioreactor (MBR) models are limited to simple hydraulic profiles and do not take into account complex reactor hydrodynamics. In response, this thesis investigated the effect of particulate fouling on AnMBR performance and identified the impact of reactor hydrodynamics on membrane fouling for the development of a holistic MBR optimisation model.Mechanistic fouling analysis identified that protein hydrophobicity and compressibility were key contributors to its high fouling propensity. Protein also showed high reactivity with lipids causing synergistic fouling behaviour in protein-lipid mixtures and a surfactant effect on lipids, changing the fouling mechanism from irreversible pore fouling in pure lipids to cake fouling in protein-lipid mixtures. CFD modelled shear was integrated into a distributed parameter model to simulate membrane fouling profile and flux distribution. Incorporation of a flux-pressure feedback loop allowed for the simulation of flux-step experiments and the prediction of critical flux. This model demonstrated a wide variety of applications including, for the identification of complex hollow fibre shear and the effect of operating conditions, such as total solids, sparge rate and filtration strategy, which can be directly applied to MBR design, optimisation and cost analyses.ii
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