Volatile fatty acid production from mesophilic acidogenic fermentation of organic fraction of municipal solid waste and food waste under acidic and alkaline pH

• Published in: Environmental science and pollution research international 2019-12, Vol.26 (35), p.35509-35522
• Main Authors: Cheah, Yen-Keong, Vidal-Antich, Carme, Dosta, Joan, Mata-Álvarez, Joan
• Format: Article
• Language: English
• Subjects: Acetic acid; Acid production; Advances & Prospects in the field of Waste Management; Ammonia; Ammonia - chemistry; Anaerobic conditions; Anaerobic digestion; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Biological treatment; Bioreactors; Earth and Environmental Science; Ecotoxicology; Effluents; Environment; Environmental Chemistry; Environmental Health; Environmental science; Fatty acids; Fatty Acids, Volatile - chemistry; Fermentation; Fermenters; Food; Food plants; Food waste; Hydraulic retention time; Hydrogen-Ion Concentration; Municipal solid waste; Municipal waste management; Organic matter; pH effects; Raw materials; Refuse Disposal - methods; Retention time; Solid Waste - analysis; Solid waste management; Solubilization; Volatile fatty acids; Waste Water Technology; Water Management; Water Pollution Control
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-019-05394-6

This study is focused on the effects of pH on the production of volatile fatty acids (VFAs) and their distribution through the acidogenic fermentation of source-sorted organic fraction of municipal solid waste (OFMSW) from a mechanical-biological treatment (MBT) plant, and food waste (FW) from a university canteen. In semi-continuous lab-scale digesters using OFMSW at a hydraulic retention time (HRT) of 3.5 days under acidic conditions (pH 6.0), the VFA concentration in the effluent increased to 9.8–11.5 g L −1 (VS content of the feedstock between 4.2 and 5.2% w / w ), while its individual VFA profiling was similar to the influent which was already pre-fermented (namely, C 2 35–41%, C 3 18–22%, C 4 17–21%, and C 5 9–12%). When working with the same conditions but using FW as feedstock, an effluent with a VFA concentration up to 11.5 g VFA L −1 (FW with a VS content of 5.5% w / w ) and a stable distribution of C 2 and C 4 acids (up to 60.3% and 12.9%, respectively) but with very low quantities of C 3 and C 5 acids (lower than 1.8 and 2.7%, respectively) was obtained. Anaerobic batch tests using FW revealed that alkaline pH near 9 could lead to higher VFA production with high acetic acid content when compared to pH 6. In the semi-continuous fermenters working at alkaline conditions (pH 9.5–10) using OFMSW and FW, an enhanced solubilization of organic matter was registered with respect to the fermenters working under acidic conditions. This fact was not reflected in a higher VFA production when using OFMSW as feedstock, probably due to free ammonia inhibition, since OFMSW was mixed in the MBT plant with supernatant from anaerobic digestion of this biowaste. However, when using FW, alkaline conditions lead to an enhanced VFA production with respect to the reactor working under acidic conditions, being acetic acid the predominant product, which represented up to 91% of the VFA spectrum obtained.