Abstract

Membrane-based processes are consistently gaining popularity to provide a dependable supply of reusable water from wastewater streams, while simultaneously combatting the water shortage issues and reducing the wastewater load to the environment due to the rising cost of intake water and water shortages experienced around the world. Beer is one of the top five beverages consumed in the world, and brewing industries have high economic value. However, beer production generates a high quantity of wastewater (~3 to 10 L wastewater per 1 L of beer production) containing sugars, ethanol, soluble starch, total suspended solids, volatile fatty acids, and a low concentration of heavy metals. The breweries dispose of 70% of their consumed water to the environment or to the municipal sewage system with or without any treatment. Increasing restrictive environmental regulations and enormous wastewater surcharges related to water consumption and wastewater discharges in the brewery industries have led to the investigation of emerging technologies and their integration with conventional processes for water recovery. The implementation of membrane bioreactor (MBR) technologies has achieved a substantial amount of organic removal for brewery wastewater, as well as showcasing the potential to recover energy through biogas production. The primary goal of this research is to identify suitable membrane-based processes for water reclamation from MBR treated brewery wastewater and to identify the challenges for its implementation. To attain this objective, (i) performance assessment of different effective membrane-based processes for water reclamation were carried out. Here, both the pressure-driven methods (reverse osmosis, RO and nanofiltration, NF), as well as the emerging thermally driven methods (membrane distillation, MD), were explored. Significantly higher water recovery (~ 86%) was obtained with the MD, compared to NF (~16%) and RO (~12%) with a relatively lower water flux drop (~53%) for MD compared to substantial flux drop (~98%) for NF and RO. The physicochemical characterization of the fouled membranes revealed biofouling along with organic and inorganic fouling for both NF and RO membranes whereas the MD membrane was fouled primarily by organic and inorganic species, with no noticeable biofouling. Further research concerning the effect of operating conditions on membrane fouling was carried out to select optimal condition for water reclamation application. The study identified a 0.45 µm PVDF membrane with 55°C hot feed temperature and 10 gCOD/L/d feed load to MBR to be the optimal condition for stable DCMD implementation for water reclamation with low flux drop and moderate recovery with minimal membrane fouling and excellent contaminant rejection. A techno-economic analysis was conducted to provide a basic understanding regarding the energy and cost associated with membrane distillation process implementation on a larger scale. The study observed a $2.34/m3 water price for a 100 m3/day stand-alone DCMD system. Results suggested that the source of energy is a key parameter for optimizing cost in DCMD application, and waste heat incorporation could lead towards a viable, and cost-effective DCMD application. The understanding of water reclamation performance, membrane fouling tendencies, contaminant rejection, optimal operating conditions, and economic perspective of membrane distillation research will provide insight towards sustainable water recovery in brewery industries leading towards the reduction of the water footprint in beer production and a better understanding of the feasibility of adopting membrane distillation for brewery industries.

This research recommends membrane distillation as an efficient and cost-effective method for water reclamation from membrane bioreactor treated brewery wastewater effluent and enhances the knowledge around the optimal conditions for its water recovery application. The study contributes to the application viability of membrane distillation for water reclamation and advances the knowledge on ideal conditions for membrane performance including high recovery, low flux drop, minimal fouling, high rejection, and membrane reuse along with utilizing alternate energy sources to fulfill the energy requirement of the hot feed. This can further expand to the pilot scale and eventually real scale application of membrane distillation for water reclamation from pre-treated brewery wastewater enhancing the future fresh water supply.