Effect of impeller type and stirring frequency on the behavior of an AnSBBR in the treatment of low-strength wastewater

Abstract

The influence of impeller type and stirring frequency on the performance of a mechanically stirred anaerobic sequencing batch reactor containing immobilized biomass on an inert support (AnSBBR--Anaerobic Sequencing Batch Biofilm Reactor) was evaluated. The biomass was immobilized on polyurethane foam cubes placed in a stainless-steel basket inside a glass cylinder. Each 8-h batch run consisted of three stages: feed (10 min), reaction (460 min) and discharge (10 min) at 30 °C. Experiments were performed with four impeller types, i.e., helical, flat-blade, inclined-blade and curved-blade turbines, at stirring frequencies ranging from 100 to 1100 rpm. Synthetic wastewater was used in all experiments with an organic-matter concentration of 530±37 mg/L measured as chemical oxygen demand (COD). The reactor achieved an organic-matter removal efficiency of around 87% under all investigated conditions. Analysis of the four impeller types and the investigated stirring frequencies showed that mass transfer in the liquid phase was affected not only by the applied stirring frequency but also by the agitation mode imposed by each impeller type. The best reactor performance at all stirring frequencies was obtained when agitation was provided by the flat-blade turbine impeller.

Effect of Organic Load and Alkalinity on Dairy Wastewater Biomethanation

“…In doing so, these plastic rings were placed in a tray, submerged in sludge, and then kept static in an incubator at 45°C for seven days. Afterwards, they were randomly placed into the bioreactor and fed with a synthetic sewage effluent -SSE (Cubas et al, 2011), simulating a domestic sewage with a low organic load. It was injected at a flow of 3 mL.min -1 to keep the biosystem active and stabilized.…”

“…Again, biogas production stabilization (±10%) and pH responses (±0.2%) were the criteria for salt concentration changes. *initial situation = the bioreactor was fed with SSE for biofilm maintenance and stabilization of the controlled culture medium (Cubas et al, 2011). ** A 2-day HRT was assumed as sufficient so that all the fermenter fluid is fully replaced with the SIE.…”

Identifying proper agitation interval to prevent floating layers formation of corn stover and improve biogas production in anaerobic digestion

“…Different kinds of agitation intensity (or stirring rate) (Gómez et al, 2006;Hoffmann et al, 2008;Stafford, 1982) and agitation durations (or interval) (Cubas et al, 2011;Kowalczyk et al, 2013;Lindmark et al, 2014a) were applied in anaerobic digestion processes. The effects of different intensities or intervals on biogas production are always different because conditions such as substrate, loading concentration or temperature are not same.…”

Avaliação de desempenho do reator anaeróbio em batelada seqüencial (ASBR), contendo biomassa imobilizada em pedra pome, para tratamento de esgoto sanitário

“…No SHS/EESC/USP diversas pesquisas estão sendo realizadas com esse tipo de reator, na busca de melhor compreensão dos aspectos fundamentais dos processos, com vistas à ampliação de escala para uso em tratamento de despejos industriais e domésticos (CUBAS et al, 2001;PINHO et al, 2002;SARTI et al, 2002;CUBAS et al, 2002).…”

“…Não é possível fazer a comparação dos parâmetros obtidos, pois a literatura apresenta coeficientes decorrentes de outras condições experimentais como substrato, temperatura, agitação e tamanho de partícula ; RATUSZNEI et al, 2001;CUBAS et al, 2001CUBAS et al, e 2002PINHO et al, 2002). No entanto, vários autores obtiveram o mesmo comportamento cinético, ou seja, modelo cinético de primeira ordem para descrever o decaimento da concentração de matéria orgânica no reator anaeróbio em batelada seqüencial CUBAS et al, 2001CUBAS et al, e 2002PINHO et al, 2002;RODRIGUES et al, 2003). Foi elaborada uma tabela qualitativa a fim de resumir todas as morfologias observadas por microscopia ótica de luz comum e contraste de fases e microscopia eletrônica de varredura, do inóculo, da pedra pome aos 62 dias de operação e no final da operação, com 84 dias, que pode ser visualizada na TABELA 5.4.…”