Anaerobic membrane bioreactors enable high rate treatment of slaughterhouse wastewater

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 3–3.5g CODL−1d−1 is imposed by the active biomass inventory, with this in turn limited to 40gL−1 (TS) by the need to manage membrane fouling control.