Electronic Thesis and Dissertation Repository

Degree

Master of Engineering Science

Program

Chemical and Biochemical Engineering

Supervisor

Dr. Jesse Zhu & Dr. George Nakhla

Abstract

In wastewater treatment field, one of the severe challenges is the handling of ammonia-rich wastewater with a low C/N ratio. The failure of nitrogen treatment can lead to adverse ecological and biological effects including depletion of dissolved oxygen, eutrophication, toxicity to aquatic life, and reduction in the suitability of water for reuse. Conventionally, extra organic carbon dosing is required in treating low C/N wastewater. Alternately, partial nitrification is of interest as an emerging technology for its’ lesser need of organic carbon addition and cost savings in aeration. In this study, a lab-scale partial nitrification fluidized bed bioreactor (PNFBR) and a pilot-scale circulating fluidized bed bioreactor (CFBBR) were investigated for the treatment of ammonia-rich synthetic wastewater and low C/N ratio domestic wastewater, respectively.

The results of the this study demonstrated that the PNFBR is capable of handling synthetic wastewater with exceptionally high ammonia concentrations (up to 400 mg NH4+-N/L) at the maximum nitrogen loading rate (NLR) of 0.8 kg N/(m3·d) without dosing extra carbon source. By controlling dissolved oxygen of 1.31 mg/L in the system, partial nitrification was observed at a hydraulic retention time (HRT) of 18 hours. The effluent of PNFBR achieved a NO2--N /NH4+-N ratio of 1.27, which can be utilized as appropriate influent of anaerobic ammonium oxidation (anammox) process towards complete nitrogen removal.

Additionally, domestic wastewater with Low C/N (2.8) ratio was treated in a pilot-scale CFBBR at various OLRs (organic loading rates) ranging from 0.06 to 0.44 kg COD/m3-d and NLRs (Nitrogen loading rates) ranging from 0.03- 0.07 kgN /(m3·d). Glucose was dosed to provide enough carbon source. The CFBBR was able to achieve a 84% reduction in carbon and a 90.5% reduction in nitrogen, with the effluent TN < 20mg/L, COD < 60mg/L.

The results demonstrated that the PNFBR is capable of handling exceptionally high ammonia concentrations (up to 400 mg NH4+-N/L) of synthetic wastewater with the maximum nitrogen loading rate (NLR) of 0.8 kg N/(m3·d). By means of keeping influent alkalinity/NH4+-N ratio of 5, hydraulic retention time (HRT) of 18 hours and controlling dissolved oxygen of 1.31 mg/L in the system, it is successfully achieved the effluent NO2--N /NH4+-N ratio of 1.27 in the end. This effluent can be appropriate influent of anaerobic ammonium oxidation (anammox) process for complete nitrogen removal.

Domestic wastewater with Low C/N (2.8) ratio was treated in a pilot-scale CFBBR at various organic loading rates (OLRs) and NLRs ranging from 0.06 to 0.44 kg chemical oxygen demand (COD)/m3-d and 0.03- 0.07 kgN /(m3·d), respectively, corresponding to influent flowrate of 275 to 800 L/d, by dosing extra organic matter in the form of glucose. The CFBBR is able to achieve a 84% reduction in carbon and a 90.5% reduction in nitrogen, with the effluent total nitrogen (TN) < 20mg/L, COD < 60mg/L.


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