The inhibition effect of limonene on the organisms involved in anaerobic reactors may affect obtaining H2 in this process. Rapid and precise limonene quantification is desirable to characterize wastewaters. The objective of this research was to develop a Gas Chromatography Coupled to Mass Spectrometry (GC-MS) method to determine limonene concentration in liquid samples from batch reactors applied to H2 production at 30 ºC. Method validation was carried out through calibration curves (3 to 20 mg L-1of limonene), in addition to evaluating its precision (CV =0.1%), linearity (R2=0.979), limits of detection (1.7 mg L-1) and quantification (4.2 mg L-1). Its inhibitory effect was evaluated with increasing concentrations of limonene (without addition to 2000 mg L-1). Limonene affected the starting time of H2 production (λ), since λ was 8.7 h in control assays and 15 h with 2000 mg L-1 of limonene. The same was observed for obtaining H2, since 19.5 mmol H2 L-1 was obtained in control assays and 8.7 mmol H2 L-1 was obtained in assays with 2000 mg L-1 of limonene. This method was effective for limonene determination in liquid samples from batch reactors and could be used for characterization and control of anaerobic reactors.

RESUMO O objetivo principal da pesquisa foi avaliar o potencial de tratamento de esgoto sanitário de baixa carga orgânica em reator compartimentado anaeróbio/aeróbio (RCAA) em escala piloto. O reator, mantido em temperatura ambiente (27ºC a 30ºC), foi implantado no campus da Universidade Estadual Paulista "Júlio de Mesquita Filho" (UNESP) (Bauru, SP, Brasil) e tratou esgoto sanitário com carga orgânica entre 0,06 e 0,61 kg DQO.d-1. O RCAA é composto de quatro câmaras fisicamente separadas, sendo as três primeiras anaeróbias e a quarta aeróbia, seguidas por decantador laminar. O monitoramento foi realizado durante o período de 203 dias para tempos de detenção hidráulica total (TDH) de 33, 22, 16,5 e 8,25 horas. Durante o período experimental, verificou-se remoção média de matéria orgânica, em termos de demanda química de oxigênio total (DQOTotal), de 71 a 82% no sistema completo, com valores elevados de remoção na fase anaeróbia entre 62 e 71%. Em termos de sólidos em suspensão totais (SST), o reator apresentou remoções médias em torno de 90%. Os resultados obtidos nesta pesquisa permitiram um avanço no conhecimento operacional de uma alternativa biotecnológica de baixo custo, com o propósito de diminuir o impacto causado pela geração de esgotos de pequenas comunidades urbanas e rurais que ainda não contam com sistema de tratamento, e ainda possibilitar o reúso do efluente tratado.

ABSTRACT The research's main goal was to evaluate the treatment potential of low-strength sanitary sewage in an anaerobic/aerobic baffled reactor (AABR) at pilot-scale. The reactor, maintained at room temperature (27ºC to 30ºC), was deployed at Universidade Estadual Paulista "Júlio de Mesquita Filho" (UNESP), campus Bauru (SP, Brazil), and treated sanitary sewage with organic charge between 0.06 and 0.61 kgCOD.d-1. The AABR was composed by four chambers, physically separated, being the first three chambers anaerobic and the forth chamber aerobic, followed by a settling tank. The monitoration was done during 203 days for the hydraulic retention times (HRT) of 33, 22, 16.5 and 8.25 hours. During the experimental period, it was verified in the whole system a chemical oxygen demand (COD) removal between 71 and 82%, with high removal rates in the anaerobic phase between 62 and 71%. In terms of total suspended solids (TSS), the reactor reached average removal around 90%. The progress reached with this research allowed to present a low cost biotechnological alternative, with the propose of solving the sewage demand derived from small urban and rural communities, and also making possible the reuse of the treated effluent.

The performance of an anaerobic sequencing-batch biofilm reactor (ASBBR- laboratory scale- 14L )containing biomass immobilized on coal was evaluated for the removal of elevated concentrations of sulfate (between 200 and 3,000 mg SO4-2·L-1) from industrial wastewater effluents. The ASBBR was shown to be efficient for removal of organic material (between 90% and 45%) and sulfate (between 95% and 85%). The microbiota adhering to the support medium was analyzed by amplified ribosomal DNA restriction analysis (ARDRA). The ARDRA profiles for the Bacteria and Archaea domains proved to be sensitive for the determination of microbial diversity and were consistent with the physical-chemical monitoring analysis of the reactor. At 3,000 mg SO4-2·L-1, there was a reduction in the microbial diversity of both domains and also in the removal efficiencies of organic material and sulfate.

Avaliou-se o potencial de uso reator anaeróbio operado em bateladas seqüenciais com biomassa imobilizada (ASBBR), em escala piloto, no tratamento de água residuária industrial contendo elevadas concentrações de sulfato. O ASBBR, com volume total de 1.2 m³, foi preenchido com carvão mineral como meio suporte para imobilização da biomassa (leito fixo). Foram aplicadas cargas de 0,15; 0,30; 0,65; 1,30 e 1,90 kg SO4-2/ciclo (ou batelada) com duração de 48 h, correspondendo, respectivamente, às concentrações de sulfato no afluente de 0,25; 0,50; 1,0; 2,0 e 3,0 gSO4-2.l-1. Utilizou-se etanol como doador de elétrons para a redução do sulfato. O reator foi operado à temperatura ambiente (29±8ºC), tendo sido obtidas eficiências médias na redução de sulfato entre 88 e 92% em 92 ciclos (275 dias). Os resultados obtidos permitem concluir que o uso de reatores ASBBR constitui-se em alternativa eficiente para a remoção de sulfatos de águas residuárias com características semelhantes às utilizadas neste trabalho.

The potential use of an anaerobic sequencing batch biofilm reactor (ASBBR) in pilot-scale for the treatment of a sulfate-rich industrial wastewater was evaluated. The pilot 1.2 m³ ASBBR reactor was filled with mineral coal for biomass immobilization (fixed film). The sulfate loading rates applied were 0.15; 0.30; 0.65; 1.30 and 1.90 kg SO4-2/cycle (or batch). Each cycle lasted 48 h. The influent concentrations were, respectively, 0.25; 0.50; 1.0; 2.0 and 3.0 gSO4-2.l-1. Ethanol was used as electron donor for sulfate reduction. The reactor operated at ambient temperature (29±8ºC), and the mean efficiencies of sulfate removal were in the range 88 to 92% in the 92 run cycles. The total operating period comprised 275 days. Based on the results obtained in this research, it could be concluded that the ASBBR can be an efficient alternative for the removal of sulfate from other industrial wastewaters with similar characteristics.

Avaliou-se o desempenho de dois reatores anaeróbios operados em bateladas seqüenciais (1,2 m³) diferenciados pelo tipo de imobilização de biomassa, na forma de suporte inerte e de biomassa granular no tratamento de esgoto sanitário do Campus da USP de São Carlos. O monitoramento ao longo de 70 dias de operação revelou similaridade no comportamento das configurações ensaiadas, que apresentaram eficiências médias de remoção de DQO e sólidos suspensos ao redor de 60% e 75%, respectivamente. Por meio de técnicas de biologia molecular constatou-se diferenças na comunidade bacteriana nos reatores no 35º e 70º dias de operação, indicando que a imobilização de biomassa selecionou populações bacterianas diferentemente. Em relação ao domínio Archaea houve maior similaridade, provavelmente, pelo fato desses microrganismos utilizarem substratos específicos ao final do processo anaeróbio.

The performances of two anaerobic sequencing batch reactors (1.2 m³) containing biomass immobilized in inert support and as granular sludge in the treatment of domestic sewage from the Campus of São Carlos-University of São Paulo were evaluated. The experimental phase lasted seventy days. During this period, the reactors presented quite similar performances in respect to COD and total suspended solids removal, achieving average efficiencies of approximately 60% and 75%, respectively. The analysis using molecular biology techniques on biomass samples taken at 35th and 70th showed differences in the bacterial community in the reactors indicating that the type of biomass immobilization selected the populations differently. A higher similarity was found for the Archaea domain probably because these microorganisms utilize specific substrates formed at the end of the anaerobic process.