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Cattle Slaughterhouse Wastewater Characterization and Alternative Methods for Treatment and Energy Recovery
Abstract
Processing cattle produces a substantial amount of high strength wastewater that require proper treatment before discharge. The lack of information about wastewater characteristics, the need for baseline data and the interest in alternative treatment and energy recovery methods for slaughterhouse wastewater prompted this research. The main objectives of this research were to characterize the wastewater of two cattle slaughterhouses and investigate two alternative wastewater treatment and energy recovery methods: dark fermentation (hydrolysis and acidogenesis) and microbial fuel cells. Wastewater samples were collected from two cattle slaughterhouses located in the Midwest of the U.S. in three sampling events over six months, focusing on the overall wastewater, antimicrobial interventions, and viscera processing. The wastewater concentrations were impacted by the water use, dilution and wastewater pre-treatment that occurs within the slaughterhouse. Even though wastewater concentrations were different, the overall wastewater loads for both slaughterhouses were similar. Wastewater streams from antimicrobial interventions have low pH and impose potential shock-loading sources to wastewater. Viscera processing is the largest wastewater load and any improvement in this process could enhance impact the sustainability of cattle processing industry. The effects of temperature, initial pH and microbial community on the hydrogen production from slaughterhouse wastewater streams were evaluated. A small volume of hydrogen gas was observed when fermenting the overall slaughterhouse wastewater. When fermenting lactic acid wastewater, the highest hydrogen yield (0.85 mol H2/ mol lactate consumed) was achieved at 45 °C and initial pH 7.5. 16s rRNA sequencing analysis revealed that at 35°C, bacteria from the Clostridium genera were the most abundant by the end of fermentation, while at 45°C, Clostridium and Pseudomonas were the most abundant. Tubular membrane and membrane-less MFCs fed with cattle slaughterhouse wastewater were evaluated in batch mode. Comparable energy recovery and organics removal were achieved by the membrane-less MFC for different wastewater streams, but not membrane MFC. The highest energy recovery was achieved when feeding the overall slaughterhouse wastewater to membrane MFC (0.26 kWh/ kg COD) and carcass wash wastewater membrane-less MFCs (0.36 kWh/ kg COD). Combining dark fermentation with MFC for lactic acid wastewater improved the overall organic removal and energy.
Subject Area
Civil engineering|Environmental engineering|Energy
Recommended Citation
Ziara, Rami M M, "Cattle Slaughterhouse Wastewater Characterization and Alternative Methods for Treatment and Energy Recovery" (2018). ETD collection for University of Nebraska-Lincoln. AAI10844435.
https://digitalcommons.unl.edu/dissertations/AAI10844435