Nitrogen removal from piggery waste with anaerobic pretreatment

Abstract

Aerobic degradation of high strength piggery waste elevated the reactor temperature inhibiting nitrification. This study included anaerobic pretreatment with various influent by-pass rates to control the temperature and to minimize the external carbon requirement for denitrification. To find the optimum operating conditions, both lab-scale AnSBR (anaerobic sequencing batch reactor) and Ax/Ox (anoxic/oxic) SBR were operated at 35 degrees C. The heat energy released from Ax/Ox SBR was assumed to be used for heating the AnSBR, with which the Ax/Ox reactor temperature could successfully be controlled below 40 degrees C. The optimum rates of by-pass were 1.0 for winter, 0.4 for spring/fall and 0.2-0.4 for summer, respectively. Applying the correction factors for the measured AUR2 (nitrite nitrification rate) and AUR (nitrate nitrification) at the predicted temperatures, the required oxic HRTs were computed. The required Ax/Ox HRT ratios were respectively 0.5 for COD/TKN>8, 1.0 for COD/TKN ratio of 5.5-8 and 3.5 for below 5.5. The optimum HRTs were 16 days for AnSBR and 17 days for Ax/Ox SBR with the corrected AUR2.

Combined anaerobic and activated sludge anoxic/oxic treatment for piggery wastewater

“…The configuration proposed by Kim et al (2004) and Deng et al (2006) was tested in Phase 1. In this process, the raw slurry was divided into two parts, i.e.…”

“…(i) Optimize the management of the organic matter (OM) between the anaerobic and anoxic/oxic reactors: For that, Kim et al (2004) and Deng et al (2006) proposed a combined process based on an anaerobic digester followed by an anoxic/oxic reactor ensuring nitrogen removal by nitrification/denitrification. To provide enough OM for denitrification in the anoxic/aerobic reactor, a fraction of the raw wastewater was bypassed the digester and fed directly to the anoxic/aerobic reactor.…”

Combined anaerobic digestion and biological nitrogen removal for piggery wastewater treatment: a modelling approach

“…An external addition of carbon in the aerobic/anoxic reactor could be performed using a bypass flow of anaerobic digestion (Kim et al 2004;Deng et al 2006). For this, Deng et al (2006) used a bypass flow rate fixed at 30% of the input influent ( Figure 1).…”

“…Based on the literature results (Bernet et al 2000;Kim et al 2004;Deng et al 2006) and aiming to optimize the organic matter use, a combined anaerobic and aerobic treatment was developed for piggery wastewater treatment ( Figure 3). …”