Title: Assessing maximum soluble combined heavy metals not causing inhibition to brewery sludge in anaerobic wastewater treatment

Authors: Nusara Sinbuathong; Sutha Khaodhiar

Addresses: Scientific Equipment and Research Division, Kasetsart University Research and Development Institute (KURDI), Kasetsart University, Bangkok 10900, Thailand ' Department of Environmental Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok 10330, Thailand; Center of Excellence on Hazardous Substance Management, Faculty of Engineering, Chulalongkorn University, Bangkok 10330, Thailand

Abstract: The effect of varying the soluble concentration of cadmium (Cd), copper (Cu) and zinc (Zn) on methane production and chemical oxygen demand removal was systematically investigated to reveal the soluble combined heavy metal concentration and the mass of soluble combined heavy metals loading to microorganisms that cause anaerobic system malfunctions. The critical value of soluble combined metal concentration was proposed as a model allowing soluble combined metals to cause 20% inhibition and still provide protection for the process. The proposed equation to protect the anaerobic system was K = (Zn/32.7 + Cd/56.2 + Cu/31.8), where K is the maximum soluble combined metal concentration that cannot exceed 0.0038 mEq/L, and Zn, Cd, and Cu are the soluble combined heavy metal concentrations in wastewater measured in milligrams per litre. The mass of soluble combined metals loading to microorganisms cannot exceed 0.38 mEq/kg of mixed liquor volatile suspended solids (MLVSS). The soluble combined metals caused synergistic inhibition and caused system failure at concentrations exceeding 0.01 mEq/L or 1.0 mEq/kg MLVSS.

Keywords: anaerobic digestion; biogas; brewery sludge; heavy metal; inhibition; synergistic inhibition; wastewater.

DOI: 10.1504/IJGW.2021.118361

International Journal of Global Warming, 2021 Vol.25 No.2, pp.212 - 227

Received: 22 Dec 2020
Accepted: 14 Feb 2021
Published online: 23 Oct 2021 *

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