Banca de DEFESA: OUCILANE INGRET MORENO ALVES
Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.STUDENT : OUCILANE INGRET MORENO ALVES
DATE: 16/12/2022
TIME: 08:30
LOCAL: Programa de Pós-Graduação em Engenharia Civil
TITLE:
Domestic Wastewater Treatment with Aerobic Granular Sludge: Influence of the Anaerobic/Anoxic Prolonged Phase and the Mixing Condition
KEY WORDS:
removal of COD, N and P; operational strategy; granules stability; air pulses; SND; PAO; DPAO
PAGES: 109
BIG AREA: Engenharias
AREA: Engenharia Civil
SUMMARY:
Wastewater treatment systems with aerobic granular sludge (AGS) are a promising technology for presenting several advantages in comparison with conventional activated sludge (AS) systems. Among them is the reduction of the area of implementation and the simultaneous removal of organic matter (OM) and nutrients (N and P), one of the attractions for the use of this technology. However, its large-scale application with real wastewater presents some challenges. The main ones are the instability conferred to the granules during their formation and the maintenance of satisfactory nutrient removals over long periods. The first works with AGS were carried out in aerobic-only reactors. This study aimed to evaluate the influence of including a prolonged (60 or 90 min) anoxic/anaerobic phase, with different mixing conditions through the introduction of air pulses, on the: (i) granule formation and stability; (ii) microbial community composition; and (iii) nutrient removal efficiency. Two sequential batch reactors (SBR) were used, each with a working volume of 115 L, a height to diameter ratio (H/D) of 10, a volumetric exchange rate of 71%, and an upflow air superficial velocity rate of 1.0 cm.s-1 . The reactors were fed with low concentration domestic wastewater (OM and P) and started operation without adding inoculum. The operating cycle was 4 h and the application of two mixing conditions during the anoxic/anaerobic phase resulted in 5 operating strategies (OPS), with air pulses every 20 min (OPS I90.20 and II60.20) or 5 min (OPS III90.5, IV60.5 and V90.5). The phases of the operational cycle in each batch consisted of feeding (2 min), anoxic/anaerobic phase (60 min for OPS II60.20 and IV60.5; 90 min for OPS I90.20, III90.5 and V90.5), aeration (124 min for OPS I90.20, III90.5 and V90.5 and 154 min for OPS II60.20 and IV60.5), sedimentation (20 min) and effluent discharge (4 min). Aerobic granules were obtained in the reactor without added inoculum between days 39 and 87 of operation for all five OPS. Only OPS V90.5 reached full granulation (diameter ≥0.2 mm) at 168 days. Organic matter removal efficiencies (in COD) greater than 70% were obtained in all OPS. For nitrogen removal it was observed that the predominance of granules with diameter greater than or equal to 0.6 mm and the higher frequency of air pulses (OPS III90.5 and V90.5) favored the higher occurrence of the simultaneous nitrification and denitrification process (SND), with effluent average concentrations of NO2- -N and NO3- -N of 1.1±2.1 and 1.3±1.4 mg. L-1 , respectively, for OPS III90.5; and of 3.3±2.7 and 4.1±4.6 mg.L-1 for OPS V90.5, respectively. The application of a longer anoxic/anaerobic phase (90 min) and air pulses every 5 minutes provided the system with higher activity of Polyphosphate-accumulating organisms (PAO) and stability in orthophosphate removal. The maximum P removal efficiency for OPS III90.5 was 88% and for OPS V90.5 93%, and for the latter, denitrifying phosphate accumulating organisms (DPAO) were the responsible microorganisms. Regarding the microbial community of OPS V90.5, the main genus active in the treatment was Pseudomonas. These microorganisms acted both in SND and in phosphorus removal, in the latter together with Pseudoxanthomonas. Among the five strategies applied, the ones that presented the best results were OPS III90.5 and V90.5, which operated with the same anoxic/anaerobic phase (90 min) and higher air pulse frequency (5 min). These OPS showed the best results, both for the development of the granular biomass and in reactor performance.
COMMITTEE MEMBERS:
Presidente - 3133998 - BRUNA SCANDOLARA MAGNUS
Externo ao Programa - 3141471 - FABRICIO MOTTERAN - nullExterna ao Programa - 1761999 - KENIA KELLY BARROS DA SILVA - nullExterna à Instituição - NELIA HENRIQUES CALLADO SARMENTO - UFAL
Externa à Instituição - SHYRLANE TORRES SOARES VERAS - UFPE