This study proposes a simplified mathematical model to describe the processes occurring in an anaerobic sequencing batch biofilm reactor (ASBBR) treating lipid-rich wastewater. The reactor, subjected to rising organic loading rates, contained biomass immobilized cubic polyurethane foam matrices, and was operated at 32 degrees C +/- 2 degrees C, using 24-h batch cycles. In the adaptation period, the reactor was fed with synthetic substrate for 46 days and was operated without agitation. Whereas agitation was raised to 500 rpm, the organic loading rate (OLR) rose from 0.3 g chemical oxygen demand (COD) . L(-1) . day(-1) to 1.2 g COD . L(-1) . day(-1). The ASBBR was fed fat-rich wastewater (dairy wastewater), in an operation period lasting for 116 days, during which four operational conditions (OCs) were tested: 1.1 +/- 0.2 g COD . L(-1) . day(-1) (OC1), 4.5 +/- 0.4 g COD . L(-1) . day(-1) (OC2), 8.0 +/- 0.8 g COD . L(-1) . day(-1) (OC3), and 12.1 +/- 2.4 g COD . L(-1) . day(-1) (OC4). The bicarbonate alkalinity (BA)/COD supplementation ratio was 1:1 at OC1, 1:2 at OC2, and 1:3 at OC3 and OC4. Total COD removal efficiencies were higher than 90%, with a constant production of bicarbonate alkalinity, in all OCs tested. After the process reached stability...
The effect of a lipase-rich fungal enzymatic preparation, produced by a Penicillium sp. during solid-state fermentation, was evaluated in an anaerobic digester treating dairy wastewater with 1200 mg of oil and grease/L The oil and grease hydrolysis step was carried out with 0.1% (w/v) of solid enzymatic preparation at 30 degrees C for 24 h, and resulted in a final free acid concentration eight times higher than the initial value. The digester operated in sequential batches of 48 h at 30 degrees C for 245 days, and had high chemical oxygen demand (COD) removal efficiencies (around 90%) when fed with pre-hydrolyzed wastewater. However, when the pre-hydrolysis step was removed, the anaerobic digester performed poorly (with an average COD removal of 32%), as the oil and grease accumulated in the biomass and effluent oil and grease concentration increased throughout the operational period. PCR-DGGE analysis of the Bacteria and Archaea domains revealed remarkable differences in the microbial profiles in trials conducted with and without the pre-hydrolysis step, indicating that differences observed in overall parameters were intrinsically related to the microbial diversity of the anaerobic sludge. (C) 2009 Elsevier Ltd. All rights reserved.; Coordenacao de Aperfeicoamento Pessoal de Nivel Superior (CAPES); Conselho Nacional de Pesquisa a Desenvolvimento (CNPq); Fundacao Carlos Chagas Filho de Amparo a Pesquisa no Estado do Rio de Janeiro (FAPERJ); Global Ciencia a Tecnologia Co. (GCT)
This study aimed at evaluating the effect of increasing organic loading rates and of enzyme pretreatment on the stability and efficiency of a hybrid upflow anaerobic sludge blanket reactor (UASBh) treating dairy effluent. The UASBh was submitted to the following average organic loading rates (OLR) 0.98 Kg.m(-3).d(-1), 4.58 Kg.m(-3).d(-1), 8.89 Kg.m(-3).d(-1) and 15.73 Kg.m(-3).d(-1), and with the higher value, the reactor was fed with effluent with and without an enzymatic pretreatment to hydrolyze fats. The hydraulic detention time was 24 h, and the temperature was 30 +/- 2 degrees C. The reactor was equipped with a superior foam bed and showed good efficiency and stability until an OLR of 8.89 Kg.m(-3).d(-1). The foam bed was efficient for solid retention and residual volatile acid concentration consumption. The enzymatic pretreatment did not contribute to the process stability, propitiating loss in both biomass and system efficiency. Specific methanogenic activity tests indicated the presence of inhibition after the sludge had been submitted to the pretreated effluent It was concluded that continuous exposure to the hydrolysis products or to the enzyme caused a dramatic drop in the efficiency and stability of the process, and the single exposure of the biomass to this condition did not inhibit methane formation. (C) 2011 Elsevier B.V. All rights reserved.
Agitation rate is an important parameter in the operation of Anaerobic Sequencing Biofilm Batch Reactors (ASBBRs), and a proper agitation rate guarantees good mixing, improves mass transfer, and enhances the solubility of the particulate organic matter. Dairy effluents have a high amount of particulate organic matter, and their anaerobic digestion presents inhibitory intermediates (e. g., long-chain fatty acids). The importance of studying agitation in such batch systems is clear. The present study aimed to evaluate how agitation frequency influences the anaerobic treatment of dairy effluents. The ASBBR was fed with wastewater from milk pasteurisation process and cheese manufacture with no whey segregation. The organic matter concentration, measured as chemical oxygen demand (COD), was maintained at approximately 8,000 mg/L. The reactor was operated with four agitation frequencies: 500 rpm, 350 rpm, 200 rpm, and no agitation. In terms of COD removal efficiency, similar results were observed for 500 rpm and 350 rpm (around 90%) and for 200 rpm and no agitation (around 80%). Increasing the system`s agitation thus not only improved the global efficiency of organic matter removal but also influenced volatile acid production and consumption and clearly modified this balance in each experimental condition.
O foco deste trabalho foi desenvolver um sistema de tratamento híbrido, constituído por um pré-tratamento fotocatalítico heterogêneo (POA) e posterior tratamento biológico por lodo ativado (SLA), para a redução da carga orgânica de efluentes laticinista oriundos do processamento de lácteos líquidos, como por exemplos, cremes, iogurte e beneficiamento de leite. Para a caracterização analítica do efluente in natura e tratado empregaram-se as metodologias Standard Methods, validadas em função do tipo e da complexidade da amostra (DQO, DBO, Norgânico, N-NH4 +, PTotal, Fe2+, O&G, ST, STF, STV, SS, SD, Al, As, Ca, Fe, Mge Pb). Através de planejamentos fatoriais determinaram-se as melhores condições entre as variáveis estudadas para as etapas de tratamentos com POA e lodo ativado, tendo como fator de resposta a redução da DQO. Para a etapa de POA empregou-se a fotocatálise, utilizando como semicondutor o dióxido de titânio (TiO2) finamente distribuído e fixado com tinta poliuretânica sobre uma chapa metálica plana, onde o efluente foi percolado sobre o respectivo leito catalítico posicionado em um ângulo fixo de 23º, recebendo a radiação solar direta. O dois tipos de estrutura de TiO2 (rutilo ou anatase) foram avaliados morfologicamente (DRX...
O presente trabalho teve como objetivo avaliar a influência da velocidade ascensional de recirculação e da estratégia de alimentação na eficiência de um reator anaeróbio com biomassa imobilizada operado em bateladas seqüenciais tratando efluentes provenientes de um laticínio de pequeno porte. Avaliaram-se três condições operacionais com valores de velocidade de 0,2 m.h-1, 3,8 m.h-1 e 6,4 m.h-1, com tempo de ciclo de 48 horas. Finda esta etapa, avaliou-se a influência do volume tratado na eficiência do sistema. Nesta avaliação, o tempo de ciclo foi de 24 horas e estudaram-se duas condições experimentais, nas quais diariamente o reator era alimentado com 50% e 67% de seu volume. O reator, com volume total de 1000 L, foi instalado em área próxima ao laticínio. O suporte ("biobob") utilizado para imobilização da biomassa foi um enchimento plástico preenchido com espuma de poliuretano. A alimentação foi feita com efluentes oriundos do laticínio escola da Prefeitura do Campus USP Pirassununga - PUSP-P com carga orgânica variável, de acordo com suas atividades. O monitoramento do reator foi realizado através de análises de demanda química de oxigênio (DQO) em amostras filtradas em membrana de poro 1,2 µm e brutas...
Os produtos lácteos são tidos como os alimentos mais perfeitos para o homem devido ao seu alto valor nutritivo. Entretanto, esses produtos vêm refletidos na elevada carga orgânica de efluente gerado. Os Processos Oxidativos Avançados (POA) são métodos químicos baseados na geração de radicais hidroxilas, que promovem a oxidação de compostos orgânicos. O uso de semicondutores no tratamento de efluentes tem sido de grande interesse devido à sua alta eficiência, estabilidade fotoquímica, natureza não-tóxica e baixo custo, especialmente quando a luz do sol é usada como fonte de irradiação. O uso de Óxido de Zinco (ZnO), por exemplo, além de mais econômico, absorve uma fração maior de espectro UV e tem melhor desempenho em pH neutro. Este estudo consistiu em avaliar a aplicação e eficiência da fotocatálise heterogênea (POA) solar com ZnO em termos de percentual de degradação de Carga Orgânica Total (COT) para um posterior tratamento biológico aerado visando melhorar as condições de despejo do efluente de modo a preservar o ecossistema e economia dos recursos naturais. O sistema POA consistiu de um volume fixo de efluente de 3L, de uma chapa metálica 800 x 250 mm revestida com uma formulação de tinta contendo ZnO...
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Processo FAPESP: 2010/11066-4; Spirulina platensis is a filamentous cyanobacterium, photosynthetic tissue that can live in soil, marshes, alkaline lakes and freshwater, brackish and marine. Microalgae cultivation is a beneficial process, not only due to the production of proteins of high biological value for human and animal nutrition, but also for obtaining other products like vitamins, pigments and lipids. The microalgae can be used for biodiesel production in the pharmaceutical industry and also in wastewater treatment because it has the ability to consume organic substances and inorganic nutrients from wastewater. The wastewater from a dairy industry refers to water for washing machines and production equipment. This carries significant quantities of dairy products. Whey is the residue from cheese-making which retains significant part of the nutrients of milk. Both the dairy effluent as cheese whey have high values of Chemical Oxygen Demand (COD) and therefore need appropriate treatment avoiding they become pollutants when reach water bodies. This study aimed to evaluate the potential of Spirulina platensis in COD reducing of two alternative cultivation medium: one containing wastewater from a dairy in three different dilutions (1000...
O presente trabalho teve como objetivo desenvolver e avaliar o desempenho de um flotador utilizando uma pedra porosa inserida na garganta de um Venturi modificado para formação de bolhas de ar, utilizadas para flotar partículas suspensas de leite após ajuste do pH a aproximadamente 4,6, no qual ocorre o ponto isoelétrico das proteínas do leite implicando na precipitação das mesmas. O uso do Venturi dispensa o uso de compressores e válvulas de redução de pressão para formação das bolhas de ar, essenciais na operação de flotação. Foram realizados ensaios em sistema descontínuo e contínuo para diferentes tempos de flotação, diferentes vazões de reciclo de água residuária (QL) e de ar (Qar). A eficiência do sistema foi avaliada através da determinação da concentração de sólidos suspensos de leite floculado no afluente e no efluente do equipamento. Os resultados encontrados demonstraram que o flotador foi eficiente para remoção de partículas sólidas floculadas de água residuária láctea sintética tanto em sistema descontínuo quanto em contínuo, apresentando, respectivamente, eficiências máximas de separação de sólidos em torno de 100% e 70%. Portanto, os experimentos realizados em sistema descontínuo apresentaram melhores eficiências de separação de sólidos; The objective of this work was to develop and evaluate the performance of a flotator with a porous stone inserted in the modified Venturi throat for bubbles air formation...
This work aimed to apply a sequential batch operation mode to promote the biomethanation of a
real dairy wastewater enriched in fat. Three cycles were conducted with biomass previously acclimated to
oleic acid. Soluble COD, VFA and methane content were analyzed in each cycle at different time intervals.
The soluble COD removal efficiency improved slightly in each new feed and the total VFA levels detected
decreased successively. The maximum cumulative methane production also improved from cycle 1 to cycle
3. These results contribute to support the idea that the key for the degradation of effluents with high lipid
content is to sequence adsorption and degradation steps during the treatment process.
Two anaerobic sludges previously loaded with oleate and palmitate accumulated 4570 ± 257 and 5200 ± 9 mgCOD-LCFA gVSS?1, respectively. These sludges were incubated in batch assays and methane production was recorded after addition of 100–900 mg L?1 of oleate and palmitate, respectively. The batch assays were conducted before and after allowing the depletion of the biomass-associated LCFA. The presence of biomass-associated LCFA decreased the capacity of both sludges to convert the added LCFA to methane. After the degradation of biomass-associated LCFA, the lag phases observed before the onset of methane production were significantly reduced, evidencing an increase in the tolerance of the acetotrophic methanogens to the presence of LCFA. In another experiment, three recurrent pulses were performed with a real dairy wastewater containing 3.6 gCOD L?1, from which 53% was fat. Methane yields of 0.45 ± 0.01, 0.88 ± 0.02 and 1.29 ± 0.08 gCOD- CH4 gCODfed-1 were achieved in the first, second and third pulses, respectively, evidencing an increasing capacity of the sludge to convert substrate accumulated in previous additions.; Fundação para a Ciência e a Tecnologia (FCT; Fundo Social Europeu (FSE)
Salvador, A. F.; Cavaleiro, A. J.; Pereira, M. A.; Alves, M. M.
Publicado em /08/2008Português
Relevância na Pesquisa
Background and aims: Anaerobic digestion is an opportunity to generate energy from treatment of
effluents with high lipid content. Nevertheless, long-chain fatty acids (LCFA) usually accumulate within
reactors causing biomass washout and microbial inhibition. Discontinuous operation was suggested as the
optimal strategy to treat LCFA-rich wastewater. In this work, microbial community dynamics was
investigated, during the discontinuous operation of an anaerobic reactor treating a synthetic dairy
Methods: An anaerobic lab scale reactor was operated in cycles, with OLR ranging from 4 to 8
kgCODm-3day-1. Feeding was composed of sodium oleate and skim-milk. Eight biomass samples were
collected during the reactor operation and after DNA extraction, microbial community was studied by
means of PCR-DGGE of the 16S rRNA gene fragments.
Results: DGGE-fingerprints of Archaea and Bacteria showed that bacterial community was more
affected by the operating conditions imposed than the archaeal one. Shifts in microbial community
correlate well with the reactor performance and point out to microbial acclimation, since overall COD
removal efficiency and methane yield increased along time up to 98% and 91%, respectively. Specific
methanogenic acetoclastic and hydrogenotrophic activities increased from 2 and 56 mlCH4(STP)gVS-1d-1 at
the beginning to 246 and 512 mlCH4(STP)gVS-1d-1 at the end of the operation...
This work deals with the performance analysis of a separation set-up characterized by the ejector-hydrocyclone association, applied in the treatment of a synthetic dairy wastewater effluent. The results obtained were compared with the results from a flotation column (cylindrical body of a hydrocyclone) operated both batch and continuously. As far as the experimental set-up studied in this work and the operating conditions imposed to the process, it is possible to reach a 25% decrease in the total effluent chemical oxygen demand (COD). This corresponds approximately to 60% of the COD of the material in suspension. The best results are obtained for ratios air flow rate-feed flow rate (Qair/Q L) greater then 0.15 and for ratios underflow rate-overflow rate (Qu/Qo) lower than 1.0.
An enzymatic extract produced by Penicillium restrictum having a high level of lipase activity (17.2 U.g-1) was obtained by solid-state fermentation using babassu cake as substrate. The enzymatic extract was used in the hydrolysis of a dairy wastewater with high fat contents (180, 450, 900 and 1,200 mg.L-1). Different hydrolysis conditions were tested, and it was determined that it should be carried out at a temperature of 35ºC, without agitation, with 10% v/v enzymatic extract and a hydrolysis time of 12 hours. Both crude and hydrolysed effluents were then submitted to an anaerobic biological treatment. It was observed that for the enzymatically pretreated effluent there was a significant improvement in the efficiency of the anaerobic treatment. For the highest fat content tested (1,200 mg.L-1), removal efficiencies of 19 and 80% were attained for crude and hydrolysed effluents, respectively. In addition, a tenfold increase in the removal rate of COD from the hydrolysed effluent (1.87 kg COD.m-3.d-1) was observed in relation to the crude effluent (0.18 kg COD.m-3.d-1). The results obtained in this study illustrate the viability of using a hybrid treatment (enzymatic-biological) for wastewaters having high fat contents.
The aim of this work was to develop a mathematical model for a continuously operating flotation tank to provide the scale-up and optimization of the separation system. The fluid dynamic of the tank was assumed to be a perfect mixture and the flotation kinetics to be a first-order reaction, as suggested by the batch operation. The experiments were carried out in a continuously operating 60 L tank, used in the treatment of a synthetic dairy waste at its isoelectric point. A mathematical model that describes the behavior of a continuously operating flotation tank used in the treatment of a synthetic dairy waste at its isoelectric point is not only proposed, but also validated with experimental data.
Among the food industries, the dairy industry is considered to be the most polluting one because of the large volume of wastewater generated and its high organic load. In this study, an aerobic membrane bioreactor (MBR) was used for the treatment of wastewater from a large dairy industry and two hydraulic retention times (HRT), 6 and 8 hours, were evaluated. For both HRTs removal efficiencies of organic matter of 99% were obtained. Despite high permeate flux (27.5 L/h.m²), the system operated fairly stablely. The molecular weight distribution of feed, permeate and mixed liquor showed that only the low molecular weight fraction is efficiently degraded by biomass and that the membrane has an essential role in producing a permeate of excellent quality.
The objective of this work was to evaluate the replacement of Gum Arabic for sodium chloride to reduce fat and organic contents in dairy wastewater using two low cost commercially available lipase preparations from animal source (Kin Master - LKM and Nuclear- LNU). The best performance was achieved when lipase Nuclear (LNU) was used as catalyst. In addition, this lipase preparation has also lower cost, which makes its use a quite promising technique for reduction of suspended solids as proteins and lipids contents found in wastewater generated by dairy industries.
Lipids-rich wastewater was partial hydrolyzed with porcine pancreas lipase and the efficiency of the enzymatic pretreatment was verified by the comparative biodegradability tests (crude and treated wastewater). Alternatively, simultaneous run was carried out in which hydrolysis and digestion was performed in the same reactor. Wastewater from dairy industries and low cost lipase preparation at two concentrations (0.05 and 0.5% w.v-1) were used. All the samples pretreated with enzyme showed a positive effect on organic matter removal (Chemical Oxygen Demand-COD) and formation of methane. The best results were obtained when hydrolysis and biodegradation were performed simultaneously, attaining high COD and color removal independent of the lipase concentration. The enzymatic treatment considerably improved the anaerobic operational conditions and the effluent quality (lower content of suspended solids and less turbidity). Thus, the use of enzymes such as lipase seemed to be a very promising alternative for treating the wastewaters having high fat and grease contents, such as those from the dairy industry.
Surface water and groundwater are continuously used as sources of drinking water in many metropolitan areas of the United States. The quality of water from these sources may be reduced due to increases in contaminants such as Escherichia coli from urban and agricultural runoffs. In this study, a multiplex fluorogenic PCR assay was used to quantify E. coli O157:H7 in soil, manure, cow and calf feces, and dairy wastewater in an artificial wetland. Primers and probes were designed to amplify and quantify the Shiga-like toxin 1 (stx1) and 2 (stx2) genes and the intimin (eae) gene of E. coli O157:H7 in a single reaction. Primer specificity was confirmed with DNA from 33 E. coli O157:H7 and related strains with and without the three genes. A direct correlation was determined between the fluorescence threshold cycle (CT) and the starting quantity of E. coli O157:H7 DNA. A similar correlation was observed between the CT and number of CFU per milliliter used in the PCR assay. A detection limit of 7.9 × 10?5 pg of E. coli O157:H7 DNA ml?1 equivalent to approximately 6.4 × 103 CFU of E. coli O157:H7 ml?1 based on plate counts was determined. Quantification of E. coli O157:H7 in soil, manure, feces, and wastewater was possible when cell numbers were ?3.5 × 104 CFU g?1. E. coli O157:H7 levels detected in wetland samples decreased by about 2 logs between wetland influents and effluents. The detection limit of the assay in soil was improved to less than 10 CFU g?1 with a 16-h enrichment. These results indicate that the developed PCR assay is suitable for quantitative determination of E. coli O157:H7 in environmental samples and represents a considerable advancement in pathogen quantification in different ecosystems.