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| Author(s): |
Cristiane Arruda de Oliveira
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Carlos. |
| Institution: | Universidade de São Paulo (USP). Escola de Engenharia de São Carlos (EESC/SBD) |
| Defense date: | 2023-06-23 |
| Examining board members: |
Marcia Helena Rissato Zamariolli Damianovic;
Ana Claudia Barana;
Paulo Igor Milen Firmino;
Lucas Tadeu Fuess;
Carla Eloisa Diniz dos Santos
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| Advisor: | Marcia Helena Rissato Zamariolli Damianovic |
| Abstract | |
In the present research, the effect of salinity on the performance of anaerobic, aerobic and anoxic structured bed reactors inoculated with non-halophilic sludge was investigated for the treatment of synthetic effluent with salinity, organic matter, ammonia nitrogen (N-NH4+) and sulfate (SO42-) based on water produced in oil and gas extraction platforms. Batch tests evaluated the kinetics for methane production and SO42- reduction in the presence of salinity ranging from 0 to 35 g-NaCl L-1, without gradual adaptation to it. Methane production declined at high salinities, with values ranging from 139 to 29 NmL for 15.6 and 35 g-NaCl L-1, respectively. The reduction of SO42- was affected from 10.4 g-NaCl L-1, where the apparent kinetic constant ranged from 0.06 h-1 - 0 g-NaCl L-1 to 0.014 h-1 - 10.4 g-NaCl L-1. The results allow us to conclude that the sulfate-reducing bacteria (BRS) were the first affected by salinity, unbalancing the system and leading to acid accumulation. In a continuous anaerobic reactor, with COD/SO42- of 1.6, the salinity was increased from 1.7 to 50.0 g-NaCl L-1. The results showed that up to 35 g-NaCl L-1, methanogenic archaea (MA) and BRS equally participated in the COD conversion. In the presence of 50 g-NaCl L-1, COD removal efficiency ranged from 83 to 44% associated with acetate accumulation, with a 62% participation of the sulfidogenesis. Sulfetogenic activity was less sensitive to high salinity levels compared to methanogenesis, contrary to results obtained in batch tests. Next, a simultaneous nitritification and denitrification reactor (NDS) and only nitrifier with salinity from 0 to 35 g-NaCl L-1 were evaluated. The oxidation efficiency of N-NH4+ was 95%. However, for 35 g-NaCl L-1 there was an accumulation of nitrite during the operation of the NDS reactor. The variation of dissolved oxygen from 6 to 3 mg-O2 L-1 and the return to 6 mg-O2 L-1 allowed us to infer that the loss of N-NH4+ efficiency was due to salinity. The residual nitrate, present in the effluent from the aerobic reactor, indicated the possibility of a sequential treatment process using biogas rich in sulphide, generated in the anaerobic reactor at an N/S ratio of 1.6. To the autotrophic denitrifying reactor was added salinity from 0 to 15.6 g-NaCl L-1. The viability of this process was observed for 10.4 g-NaCl L-1, with nitrite accumulation in the order of 30 mg-N-NO2-L-1 being observed at higher concentrations. (AU) | |
| FAPESP's process: | 17/22952-4 - Treatment of oil and gas produced water, with autotrophic denitrification using sulfide, associated with the washing of biogas produced in anaerobic reactor |
| Grantee: | Cristiane Arruda de Oliveira |
| Support Opportunities: | Scholarships in Brazil - Doctorate |