reduction of alkali supplement in a pilot-scale thermophilic multi-staged uasb reactor treating alcohol distillery wastewater

one of the main disadvantages of anaerobic wastewater treatment at a low ph is the significantoperational cost due to the addition of necessary alkali. to reduce alkali supplement and thus the cost, thisstudy proposes a sequential multi-feed (sqmf) mode (distributed feeding) and effluent recycle (er) mode.experiments were conducted with a pilot-scale (2.5 m3) thermophilic (55°c) multi-staged up-flow anaerobicsludge blanket reactor. alcohol distillery wastewater (shochu), a major source of industrial wastewater injapan, was used for the study. the sqmf mode of operation (influent ph: 5.0; organic loading rate: 45kgcod/m3/day; hrt: 12 hours; influent cod concentration: 20,900 mgcod/l) successfully reduced thealkali supplement (24% naoh solution) requirement by 67.2% compared with the single-feed mode. for theer mode operation (organic loading rate: 35 kgcod/m3/day; hrt: 12 hours; influent cod concentration:17,400 mgcod/l), operation was possible without any alkali supplement since the system uses the alkalinity generated during microbial metabolism.