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Abstract:
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Neste trabalho foi realizado o estudo do comportamento de um reator híbrido operado em bateladas seqüenciais (RHBS), no tratamento de esgoto urbano. O reator piloto RHBS possuía 2,20 m de altura e 0,95 m de diâmetro interno, com um volume útil para tratamento de 1,42 m3. Na parte inferior do reator foram instalados dois difusores de ar do tipo membrana circular, com 20 cm de diâmetro cada, que foram alimentados por um compressor de ar. O funcionamento do reator era automatizado, controlando assim o número e o tempo de cada fase que compõe um ciclo padrão de tratamento (enchimento, reação anóxica e aeróbia, decantação e retirada), por meio de um painel de comandos elétricos. Em cada ciclo padrão, com duração de oito (8) horas, foram realizados três enchimentos e três fases de reação anóxica e aeróbia. O material suporte empregado no sistema híbrido foi a rede de nylon, escolhida entre os materiais testados em estudos anteriores (SOUTO, 2007). Foram realizadas quatro (4) estratégias operacionais, com duração total de 294 dias, testando-se diferentes cargas carbonáceas (0,20 a 1,35 kgDQO/m3.dia); nitrogenadas (42 a 60 gNH4-N/m3.dia); e de fósforo (50 a 70 gPO4-P/m3.dia). Foram avaliados os processos de degradação carbonácea, nitrificaçãodesnitrificação e biodesfosfatação, e também a velocidade de consumo de oxigênio por meio de respirometria, a fim de determinar a composição (heterótrofa e autótrofa) da biomassa bacteriana e sua distribuição no interior do reator (fixa e em suspensão). O reator apresentou eficiências médias de remoção de: ~80% de SST e DQO; 90% a 95% de DBO5; 60% a 87% de Nitrificação; 80% a 90% de Desnitrificação; ~70% de Nitrogênio Total; ~50% de PO4-P. Em condições de funcionamento normal, o lodo do reator apresentou flocos compactos e bem estruturados, com boa sedimentação; por sua vez, o biofilme apresentou-se denso e com presença de muitas Amebas e Rotíferos em sua superfície. A biomassa fixa apresentou maior atividade que a biomassa em suspensão, sendo que a biomassa ativa era composta, predominantemente, por microrganismos heterótrofos (~90%). A biomassa autótrofa estava principalmente fixa no suporte (58%-62%). The intent of this research is to historicize the moment when the issue of trafficking in women for sexual exploitation was raised in media coverage in Brazil and in Spain. The object of the investigation is discourses that constituted human trafficking as a problematic phenomenon around the turn of the twenty first century. The sources are news reports from two widely-read newspapers, Brazil's Folha de São Paulo, and Spain's El País, analysed using a comparative approach. The time outlined is the period in between 1997 and 2007, which is when references to trafficking were made regularly in the media discourse. The most widely-reported modality of trafficking was the trafficking in women for sexual exploitation, and this information does not constitute simple evidence of reality, but rather is the result of a certain way of understanding women, prostitution and ntemporary migration. This work shows the study of the behavior of hybrid sequencing batch reactor (HSBR), in urban wastewater treatment. The pilot HSBR reactor was 2.20 m high and had a diameter of 0.95 m, with a volume of 1.42 m3. In the base of the reactor two air diffusers, membrane type, of the 20 cm, were installed and fed by an air compressor. The operation of the reactor was automated, with time control in each phase of the standard cycles (fill, anoxic, aerobic, settle and drawl) through an electronic command panel. Each standard cycle lasted 8 hours, with three (3) fillings and three (3) phases of anoxic and aerobic reaction. The support material used in the hybrid system was a net of nylon, chosen from materials tested in previous studies of hybrid sequencing batch reactor (SOUTO, 2007). The experiment was carried out in four (4) operational strategies, which lasted 294 days, each one with different operational conditions regarding applied carbonaceous loads (0,20 a 1,35 kgCOD/m3.day); nitrogen (42 a 60 gNH4-N/m3.day); and phosphate (50 a 70 gPO4-P/m3.day). For each strategy, the process of biological carbon, nitrogen and phosphorus removal, and also the oxygen uptake rate (OUR) were evaluated through respirometry, in order to determine composition (heterotrophic and phototrophic) of bacterial biomass and its distribution inside the reactor (fixed and suspended). During the four strategies, the reactor presented average efficiencies: ~80% for total solids and COD; 90% at 95% for BOD5; 60% at 87% for nitrification; 80% at 90% for denitrification; ~70% for total nitrogen; ~50% for PO4-P. In normal operation conditions, the reactor sludge presented compact and well structured granules, and good sedimentation; the biofilm was thick and presented a large amount of amoebae and rotifers in its surface. The fixed biomass demonstrated higher activity when compared to suspended biomass, and the total biomass was composed by heterotrophic microorganisms (~90%). The phototrophic biomass was in fix support mostly (58%-62%). |
