As the microbrewery industry expands, disposal of brewery wastewater is becoming more of a concern, both for brewery operators and for local municipal wastewater authorities. Brewery wastewater is characterized as containing high strength organics and high variability in both organic and hydraulic loading. This high variability increased the challenge of treating brewery wastewater properly. Therefore, it is significant for optimizing the operation condition for the small-scale wastewater treatment system. This study conducted a batch study and a field study for optimizing a craft brewery on-site wastewater treatment system, which is equipped with two moving bed biofilm reactors (MBBR). In the batch study, a two-factor Box-Wilson central composite design (CCD) was adopted to find optimum biomethane production conditions for the digestion of brewery wastewater with a dairy manure inoculum. The effects of two major influencing factors of temperature (T) (25-49°C) and brewery wastewater concentration (BWC) (2-9 g VS/L) on biochemical methane potential (BMP) (CH₄ yield) and CH₄ maximum production rate (Rmax) were evaluated by applying response surface methodology (RSM). All of the trials presented a high organic removal efficiency with volatile solid (VS) 82-91%, soluble chemical oxygen demand (sCOD) 77-88%, and total chemical oxygen demand (tCOD) between 47% -76%. The experiment result suggested that the first-order kinetic rate constant and biogas content (methane percentage in the biogas) can be affected by the temperature. The mesophilic regime had the highest average rate constant, and the psychrophilic regime rate constant was significantly lower than the mesophilic and thermophile regime. The conditions in the thermophile range present a high variability for the first-order rate constant. The methane ratio in the biogas increased and stabilized by the operation time. Mesophilic and thermophilic regimes obtained a stabile biogas content around 25 days, and the psychrophilic regime spent extra time to stabilized. At the end of the anaerobic digestion, the psychrophilic, mesophilic, and thermophilic regimes had an average methane percentage of 47%,65%, and 67% respectively. Optimum BMP and Rmax were achieved under conditions of 49 °C and BWC of 5g VS/L. Correspondingly, the BMP and Rmax were 141.40 mL CH₄/g VS added and 36.5 mL CH₄/ day, respectively. However, by pursuing stability the preferable operational condition T=35℃ and BWC=5 g/L is recommended, at this condition methane yield is 110.07 CH₄/g VS added and maximum methane daily production is 28.06 CH₄/ day, which is similar to the maximum result. In field study, an on-site brewery wastewater treatment system equipped with two MBBR reactors was evaluated from October 12th, 2018 to February 10th, 2020 in Beau`s All-Natural Brewing Company, Vankleek Hill, Ontario, Canada. The aim of the study was to characterize the wastewater production (flow and organic loading rate), evaluate the operating conditions and performance of the MBBR system, and recommend improvements. Discharge from the brewery is highly variable for both organic and hydraulic loading with flow balancing recommended. The MBBR full-scale reactors operated at relatively stable conditions at a surface area loading rate (SALR) of less than 25 g/m2.d and dissolved oxygen (DO) greater than 2mg/L. Kinetic rate constants for suspended growth and attached growth biomass in the reactors were found to be similar at 0.0764-0.0908 h-1, however, a much larger attached growth mass in the reactors suggests that only a fraction of the attached growth biofilm is active. Effluent recycle was shown to be effective at controlling filamentous bacteria (type-0041) sludge bulking, reducing suspended solid concentration, and sCOD concentration.