Abstract
The low-pressure reverse osmosis (LPRO) process is a recent development of reverse osmosis (RO) technology for the reduction in RO energy consumption and operation cost. The goal of this study was to investigate the performance of LPRO processes for the treatment and reuse of effluent discharged from brewery upflow anaerobic sludge blanket bioreactors (UASB). In this study, three different commercially available LPRO membranes were tested to evaluate the water quality that can be achieved under different operational and pretreatment conditions. It was found that the filtration performance and the effluent quality of the LPRO membranes can be considerably affected by the operation conditions and the selection of the pretreatment processes. The ultrafiltration (UF) pretreatment and the control of the operation pressure were found to be essential for mitigating LPRO membrane fouling, which could be caused by Ca2+ associated precipitates and organic gelation, in the treatment of the brewery UASB effluent. Water quality analyses showed that an integrated process of the UASB + UF + LPRO could achieve an effluent quality characterized by concentrations of 10.4–12.5 mg/L of chemical oxygen demand (COD), 1.8–2.1 mg/L of total nitrogen (TN), 1.3–1.8 mg/L of ammonia nitrogen (NH3-N) and 0.8–1.2 mg/L of total phosphorus (TP). The effluent quality and the LPRO performance could be further improved by adding a granular activated carbon (GAC) adsorption process between the UF and LPRO processes, which reduced the concentration of COD to 7–10 mg/L and those of TN, TP, NH3-N to below 1 mg/L. For the treatment of the UASB effluent tested in this study, the UF, UF + GAC (retention time 4 hrs), UF + LPRO, and UF + GAC + LPRO, respectively, achieved overall COD removal efficiencies of 89.6–93.7%, 94.5–96.7%, 99.3–99.1% and 99.3–99.4%; TN removal efficiencies of 73.0–78.2%, 89.2–97.2%, 97.1–98.2% and 94.3–99.7%; and TP removal efficiencies of 29.3–46.2%, 77.0–95.4%, 95.9–97.6z% and 98.0–98.3%. This study showed that both UASB + UF + LPRO and UASB + UF + GAC + LPRO are effective treatment processes for treating brewery wastewater toward reuse water quality standards set by the United States Environmental Protection Agency (US EPA). Therefore, the results of this study would help to answer whether a LPRO can treat the brewery UASB effluent to meet the requirements of wastewater reuse standards.
Highlights
The increased demand for clean water has led to industrial wastewater being viewed as more of a resource rather than a burden
For the Upflow Anaerobic Sludge Blanket (UASB) effluent tested in this study, the chemical oxygen demand (COD) concentrations of the filtrates obtained from the 1.5 μm filter, 0.45 μm membrane filtration, and 0.04 μm membrane filtration were in the ranges of 271.3 mg/L to 436 mg/L, 206.7 mg/L to 300 mg/L, and 92.2 mg/L
These results indicated the water quality obtained from the filtration of 1.5 μm filter paper, 0.45 μm membrane, and 0.04 μm membrane varied significantly with the UASB effluent characteristics
Summary
The increased demand for clean water has led to industrial wastewater being viewed as more of a resource rather than a burden. While the brewery industry is facing increased pressure to reduce water for cost reduction and production expansion, it is important to look into water reuse through tertiary treatment of the UASB effluent. Werkneh et al [1], who reviewed some of the recent advances in areas of water reuse and energy recovery, highlighted membrane bioreactors (MBR), nanofiltration (NF) and reverse osmosis (RO), and fluidized bed reactors (FBR) as areas of important developments of brewery wastewater treatment and reuse. Han et al [3] reported that an anaerobic membrane bioreactor used in the treatment of brewery wastewater achieved a COD removal higher than 98% at an organic loading rate of 5 g/L/d, where the membrane filtration made a substantial improvement in the removal of COD and total suspended solids. AlvaradoAlssman [4] showed that anaerobic inverse fluidized bed reactor (IFBR) achieved around
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