The operational viability of implementing anaerobic digestion technology to pre-treat craft brewery wastewater in Western Australia

Operational difficulties associated with the rapid build-up of aerobic sludge, has resulted to irreversible damage to a series of ultrafiltration membranes at a local brewery. High chemical oxygen demand (COD) (≈1654.7±588.5mg/L) and total suspended solids (TSS) concentrations (≈235.5±100.3mg/L) of the raw brewery wastewater has been identified as the cause of the excess build-up of sludge in the onsite moving bed biofilm reactor (MBBR). The downstream damage associated with the rapid generation of sludge is in excess of AUD94,600 per year. This thesis project investigates the operational viability of using anaerobic digestion (AD) technology to pre-treat the raw brewery wastewater to determine the resultant downstream effect of AD on the ultrafiltration (UF) membranes. This was achieved by conducting a pilot scale study (investigating the relationship between the hydraulic retention time (HRT) and temperature on COD removal, TSS removal and biogas generation) and a bench top study (investigating the maximum degradability of brewery wastewater via AD was also assessed in this project along with the maximum biogas generation potential of the waste stream). Results from this study suggest that the addition of an AD system would achieve a 75.9% and 89.6% increased reduction of COD and TSS respectively compared to the current MBBR system at a digestion temperature of 20oC and a residence time of 5 days. Reducing the reactor temperature and wastewater residence time would negatively affect the AD process, with COD and TSS removals of 61.2% at 18oC and 66% at 3 days detention times noted respectively. Mathematical modelling of the AD process suggests that UF will no longer be necessary, as the quality of the effluent would meet the wastewater discharge limits set by local authorities (≤30mg/L TSS). The downstream effects of the proposed system suggest that an operational expenditure (OPEX) recovery between AUD37,500 and AUD50,000 per annum can be achieved by reducing the damage to the UF membranes. This research found that, for the AD of brewery wastewater an activation energy (Ea) in the range of 20.41kJ/mol.K to 20.09 kJ/mol.K for an upflow type reactor is required. The Arrhenius constant (θ) for the treatment process ranges between 1.03 and 1.09 at 30oC and 22oC respectively