New Approach for Determination of Volatile Fatty Acid in Anaerobic Digester Sample

Abstract

Abstract

Presence of volatile fatty acids (VFAs) is one of the major indicators of anaerobic digestion of organic matters present in wastewater, activated sludge, organic fractions of municipal solid wastes, and landfill leachates. The present article focused on a modified spectrophotometric method for measuring VFAs, based on the classical Montgomery method, and also compared its performance with other existing techniques of VFA determination such as distillation method, high-performance liquid chromatography (HPLC), and gas chromatography (GC). Comparisons have been made with regard to measured concentration of acetic acid standards and accuracy of the respective method. In addition, comparisons between the proposed method and GC, HPLC, and distillation methods have been made with regard to VFA measurement (as CH₃COOH) from real anaerobic samples. The distillation method showed poor mean accuracy of 74.96% in comparison to that for the HPLC (using Aminex column) (100.00%) and for the GC (99.81%). The modified spectrophotometric method showed a superior accuracy range (95.76–115.35%) over five sets of experimental trials. The precision range (1.66–27.63%) of the proposed methodology was compared to a past case study of a similar spectrophotometric method (1.70–14.00%) along with the GC method (5.70–14.80%) and the distillation method (1.80–4.90%). In addition, limit of quantification and standard deviation were also compared.