Effect of acid speciation on solid waste liquefaction in an anaerobic acid digester.
Laboratory scale experiments were carried out to evaluate and determine the suitable working conditions for the enhancement of volatile fatty acids (VFAs) production with the stabilization of solid pineapple waste (peel) simultaneously when operating two-phase anaerobic digestion. It was found that acid production, enhanced when the digester was operated at neutral pH. VFAs, could be obtained at about 50 g/kg-waste within 14 days when operating at pH 6.5-7.5 compared to 33 g/kg-waste for digester operated at pH 5.0-6.0 for 32 days. The total volatile solid reduction of 42-48% was obtained with a 51-57% volume reduction at neutral pH. The effect of undissociated acids on the activity of acetogenic bacteria was also studied. The inhibitory level of undissociated acids for acidogenesis was found to be about 2300, 650, and 120 mg/L at pH 5, 6, and 7, respectively. The results revealed that at low pH, undissociated acids are inhibitory. It was found that for efficient operation of two-phase anaerobic digestion, both VFAs concentration and pH should be controlled.
Babel
Sandhya
S
Environmental Technology Program, Sirindhorn International Institute of Technology, Thammasat University, P.O. Box 22, Thammasat Rangsit PO, Pathumthani 12121, Thailand. sandhya@siit.tu.ac.th
Fukushi
Kensuke
K
Sitanrassamee
Bunpot
B
D000143:Acids / Q000737:chemistry; D031230:Ananas; D001421:Bacteria, Anaerobic / Q000378:metabolism*; D019149:Bioreactors; D005232:Fatty Acids, Volatile / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007220:Industrial Waste; D009930:Organic Chemicals / Q000378:metabolism; D012037:Refuse Disposal / Q000379:methods*; D012722:Sewage / Q000737:chemistry / Q000382:microbiology; D013997:Time Factors
D000143:Acids; D005232:Fatty Acids, Volatile; D007220:Industrial Waste; D009930:Organic Chemicals; D012722:Sewage