Acid-stressed control of market waste anaerobic digestion using pH adjustment

Authors

  • Panatda Pibul,

    1. The Joint Graduate School of Energy and Environment, King Mongkut's University of Technology Thonburi, Tungkru, Bangkok, Thailand
    2. Center of Excellence on Energy Technology and Environment, Ministry of Education, Bangkok, Thailand
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  • Sirintornthep Towprayoon

    Corresponding author
    1. The Joint Graduate School of Energy and Environment, King Mongkut's University of Technology Thonburi, Tungkru, Bangkok, Thailand
    2. Center of Excellence on Energy Technology and Environment, Ministry of Education, Bangkok, Thailand
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Abstract

This work highlights the influence of pH on the acid stress control of market waste in a single-stage batch reactor for two different pH-controlled regimes (neutral pH and stepwise increasing pH). The stress from the acid was defined using two primary parameters, the total volatile fatty acid (TVFA) and undissociated acid (UA) concentrations, and the ratio of the two parameters (TVFA/UA). The results indicated that stepwise increases in the pH value of the system are much better than maintaining a neutral pH throughout the entire process because the first option sustains an appropriate value for the TVFA, that is, <20 g of acetic acid (HAc) per liter, which allows its gas to reach a methane concentration of 60%. Conversely, the second regime only reached a maximum methane concentration of 9%, which yielded TVFA values between 30 g HAc/L and 40 g HAc/L. These TVFA concentrations inhibit the system. The stepwise control of the pH thus helps to handle market waste in a single stage digester and avoids acid stress between dissociated and undissociated volatile fatty acids (VFAs). © 2014 American Institute of Chemical Engineers Environ Prog, 34: 132–138, 2015

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