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Optimization of Operation Conditions for Partial Nitrification of Anaerobic Sludge Digester Supernatant in Sequencing Batch Reactor

Author(s):

C. Lathiga , COIMBATORE INSTITUTE OF TECHNOLOGY; Dr. S. Keerthinarayana, COIMBATORE INSTITUTE OF TECHNOLOGY; Dr. S. V. Srinivasan, CSIR-CENTRAL LEATHER RESEARCH INSTITUTE

Keywords:

Anaerobic Digestion (AD), Partial Nitrification (PN), Anaerobic Ammonium Oxidation (ANAMMOX), Sequencing Batch Reactor (SBR)

Abstract

the supernatant obtained from the anaerobic digestion of excess sludge contains high amount of ammonia (1020 mg/L as NH4-N), which increases the nitrogen load during wastewater treatment. Anaerobic ammonium oxidation (ANAMMOX) process is the most economically viable option for removing nitrogen from wastewater containing high ammonia, however the anammox process required the substrates NO2-N and NH4-N in a ratio of 1:1.This paper deals with the optimization of process parameters for partial nitrification (PN). Initially anaerobic digestion (AD) was carried out for waste sludge taken from a 5L capacity lab scale SBR by using sewage sludge as inoculum which resulted in the specific biogas yield of 20.304 mL/g of VS of the sludge. Then the ammonia rich supernatant was separated and treated using PN to meet the required NO2-N/NH4-N ratio of 1:1. The partial nitrification was carried out in 1L bubble column reactor inoculated with nitrifying seed sludge from the lab scale SBR .Seven operational factors (pH, DO, Temperature, Cycle time, MLSS, C/N and aeration strategy) which significantly affect the NO2-N.NH4-N ratio were taken for the study. Plackett-Burman DOE was used to find out which of these factors have the most significant effect in achieving the required NO2-N: NH4-N ratio. A total of 12 runs based on the design were operated for a minimum of three days per run. Data was collected and the result feed to Minitab software to analyze the effect of the factors affecting the NO2-N/NH4-N ratio. The results showed that it is possible to reach a stable partial nitrification with high pH (7.60), low C/N (0.5), high cycle time (10hrs), low DO concentration (1mg/L), low MLSS/MLVSS (3500) mg/L), high temperature (32ºC) and intermittent aeration. The main effect interaction plots also shows the NO2-N/NH4-N increases with increasing pH, DO, Temperature and cycle time and decreases with the corresponding MLSS and C/N ratio operated. Pareto chart of the factors considered shows that the pH influence the NO2/NH4-N ratio the most and DO influence the least within the range of values taken.

Other Details

Paper ID: IJSRDV5I21248
Published in: Volume : 5, Issue : 2
Publication Date: 01/05/2017
Page(s): 2033-2036

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