Anaerobic prefermentation and primary sedimentation of wastewater in a sequencing batch reactor

Abstract

This research was carried out with the aim of evaluating the solubilisation and acidification capacity of fermenting organisms in suspension in a sequencing batch reactor (SBR), which had a volume of 1 800 ℓ. Using 8 h cycles with 340 min of anaerobic reaction time, the wastewater fed to the SBR presented an average of total and dissolved COD of 315 and 230 mg/ℓ. The experiment was divided into three phases: In Phase 1 the organic load was decreased from 1.46 to 0.27 kgCOD/kgTSS·d, as total COD, during a period of 154 d. If the acidification is defined as the fraction of organic substrate that is transformed to volatile fatty acids (VFA) then the highest acidification percentage (80%) of the dissolved COD (COD D) was obtained for the organic load runs of between 0.62 and 0.72 kgCOD/kgTSS·d. Within this range of organic load the 2 nd and 3rd experimental phases were achieved at the same time after 130 d while the pH and temperature were the control parameters: pH from 5.5 to 7.5 and temperature from 22 to 31ºC.

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