A Simple and Accurate Approach for Determining the VFA Concentration in Anaerobic Digestion Liquors, Relying on Two Titration Points and an External Inorganic Carbon Analysis

A new analytic approach is presented for determining the total volatile fatty acids (VFAT) concentration in anaerobic digesters. The relies on external determination of inorganic carbon (CT) analyzed solution, along with two strong-acid titration points. CT can be determined by either a direct analysis (e.g., using TOC device) or estimating it from recorded partial pressure CO2(g) biogas (often routine digesters). carried out to pH 5.25 and then 4.25. results are plugged into an alkalinity-mass-based equation terms subtracted each other yield which VFAT sole unknown (since known effect orthophosphate ammonia concentrations shown small at this range). development algorithm its verification four reactor liquors presented, both raw water acetic acid-spiked samples. show method accurate (up 2.5% expected value VFAT/Alkalinity >0.2) repetitive when known, fairly (±5% >5 mM) these completely neglected. PHREEQC-assisted computation knowledge (and pH, EC temperature liquor) resulted very good estimation (±3%), indicating that technique adequate purpose alarming operators case process deterioration imminent failure.