Journal of Emerging Trends in Engineering and Applied Sciences: Research Areas

Abstract:
The design and fabrication of a bioreactor (or a vessel) used for treating brewery wastewaters and assessing it performance will rely strongly on biochemical oxygen demand (BOD) database. For this reason an appropriate empirical correlation for predicting BOD data will be desired. Therefore, the focus of this paper is on the empirical modelling of the biochemical oxygen demand (BOD) profile of brewery wastewater. To achieve this objective, wastewater samples were collected at five different discharge points from a local brewery plant: general run-off water discharge, bottle washer discharge, bad and off-specification brew discharge, fermentation/maturation vessels drain and brew-house wash water discharge. The temperature, pH and BOD of the brewery wastewater samples were measured on a daily basis for a 12-day study period. BOD reaction rate expressions were formulated in line with first and second order rate law. Least Square Technique and LINEST function (in ms-excel environment) were used to fit the measured BOD data in order to obtain the kinetic parameters of the rate expressions (i.e. UBOD, k1 and k2). Method of integration was used as solution tool to establish time dependent BOD models for the brewery wastewater samples. Results obtained showed that the brewery wastewater samples are non-acidic and slightly alkaline. The measured BOD data for all samples showed continuous increase within the 12-day study period. The rate (or decay) constants for the BOD reactions showed higher speed of biodegradation in first order reaction, k1 than for second order reaction, k2 for all brewery wastewater samples studied. Also, the exponential model obtained from first order rate law fitted the measured BOD data more accurately than the inverse model from second order rate law. The correlation coefficient, R2 for predicted versus measured BOD plots obtained for this study oscillated between 0.7 and 0.98.

Keywords: brewery wastewater, biochemical oxygen demand, organic pollutant, BOD decays constant, mathematical technique

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