Transformation of lipids in activated sludge

Dueholm, T.D.; Andreasen, Kjær; Nielsen, Per Halkjær

doi:10.2166/wst.2001.0040

Cited by 38 publications

(26 citation statements)

References 18 publications

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“…The overall goal of a treatment plant is to reduce the organic load exiting after treatment. This removal process takes place at several stages throughout the treatment plant, where organisms consume the lipids and other organic matter for energy [16].…”

Section: Lipid Origins In Wastewater Treatment Facilitiesmentioning

confidence: 99%

Mississippi State Biodiesel Production Project

Hernández¹,

French²,

Fernando³

et al. 2008

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Executive SummaryMunicipal wastewater treatment plants in the United States produce over 6.2 million metric tons of dried sewage sludge every year. This microorganism rich sludge is often land filled or used as fertilizer. Recent restrictions on the use of sewage sludge, however, have resulted in increased disposal problems. Extraction of lipids from sludge yields an untapped source of cheap feedstock for biodiesel production. Solvents used for extraction in this study include n-hexane, methanol, acetone, and supercritical CO 2 .Gravimetric yield of oil was low for non-polar solvents but addition of polar solvents gave a considerably increased yield. However, the percent of saponifiable material was less. Extraction of lipids with a mixture of n-hexane, methanol, and acetone gave the largest conversion to biodiesel for a solvent system, 4.41% based on total dry weight of sludge. In Situ transesterification of dried sludge resulted in a yield of 6.23%. Assuming a 10% dry weight yield of FAMEs the amount of biodiesel available for production in the United States is 1.4 million cubic meters per year. Outfitting 50% of municipal wastewater plants for lipid extraction and transesterification could result in enough biodiesel production to replace 0.5% of the national petroleum diesel demand (0.7 million cubic meters).Other sources of lipids investigated were Black mustard, birdseed rape, canola, Camelina, Crambe, flax, and Hesperis. These plants were selected based on their oil content and their capability to grow in the US Southeast. Genetic procedures were developed to increase the oil content of these plants. Of the species investigated, canola, sunflower, and okra have the greatest potential. However, it should be noted that even 4 record yields of all the crops mentioned above will not come close to fully replacing the U.S. need for oil/petroleum. Extraction procedures were developed to recover nutritional components, such as omega-3 fatty acid eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), from oil and biodiesel. Additionally, a method was developed to isolate another value added product, Vitamin E, from oils. The methods developed were based on differences in binding between polyunsaturated fatty acid methyl esters and the transition metal ions.More than 90% EPA was recovered using AgBF4/SiO2•Im+•PF6¯. After a consecutive two-step stripping by ethyl ether and then 1-hexene, the concentration of EPA increased from 7% in the feed stock solution to about 90% in the 1-hexene stripping solvent. After five recycles, the sorbent is still usable.Ordered mesoporous adsorbents were prepared by physically coating functionalized ionic liquids onto mesoporous silica gel. These adsorbents were successfully applied to the selective extraction and separation of vitamin E from a model mixture of soybean oil deodorizer distillate. Five adsorbent recycle tests showed good reusability of this ionic liquid-modified mesoporous adsorbent.Another approach to improve the overall economic feasibility of biodiesel production...

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Section: Lipid Origins In Wastewater Treatment Facilitiesmentioning

confidence: 99%

Mississippi State Biodiesel Production Project

Hernández¹,

French²,

Fernando³

et al. 2008

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“…Os valores de concentração de lipídeos, nesses efluentes, são mostrados na Tabela 3. Nas estações de tratamento desses efluentes, a elevada concentração de triacilgliceróis necessita inicialmente ser hidrolisada para, em seguida, ser transformada em fonte de carbono para as bactérias e, posteriormente, ser convertido em biomassa (lodo ativado) 32 .…”

Section: Lipídeosunclassified

“…A transformação de lipídeos em lodo ativado é necessária por duas razões: os lipídeos contribuem com 30-40% da matéria orgâni-ca, presente nos efluentes e esses compostos estimulam o crescimento de microrganismos filamentosos, importantes na remoção de nutrientes como fósforo e nitrogênio, promovendo a sustentação do lodo formado 32 . Com baixa concentração desses microrganismos, a probabilidade de formação de grânulos maiores de lodo é reduzida, acarretando sua flotação 19 .…”

Section: Lipídeosunclassified

“…A transformação de lipídeos em lodo ativado, empregando a espécie microbiana Microthrix parvicella foi estudada por Dueholm et al 32 , por meio do monitoramento das taxas máximas de consumo de oxigênio e nitrogênio. Esses autores observaram que os AGCL e triacilgliceróis adsorvidos pelo lodo dificultam a quantificação de oxigênio e nitrogênio consumidos para produção de células.…”

Section: Lipídeosunclassified

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Aplicação de lipases no tratamento de águas residuárias com elevados teores de lipídeos

Mendes¹,

Castro²,

Pereira³

et al. 2005

Quím. Nova

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Recebido em 12/12/03; aceito em 14/9/04; publicado na web em 4/2/05 APPLICATION OF LIPASES FOR WASTEWATER TREATMENT CONTAINING HIGH LEVELS OF LIPIDS. The process of anaerobic digestion has been greatly developed during the last decades for the treatment of wastewater from food industries as for example, wastewaters from sugar and starch manufacturing and from breweries. However, for wastewaters which contain high amounts of fats and proteins, such as those from slaughterhouses and dairies, anaerobic digestion was found to be troublesome, due to the potential of sludge flotation, the formation of scum layers of lipids at the surface of the reactor, which are not digested and the toxicity of the intermediate compounds (long chain fatty acids) generated during the anaerobic digestion of the wastewater. The addition of hydrolytic enzymes, such as lipases prior to the anaerobic digestion can minimize these problems. In this work, this strategy is reviewed and the technical issues that must be considered in determining its feasibility are discussed.Keywords: wastewater; lipids; lipase and enzymatic treatment. INTRODUÇÃOA adoção de um maior rigor nos padrões de descarte de águas residuárias tem motivado a realização de pesquisas, cujo objetivo é reduzir o impacto ambiental, especialmente em efluentes contendo elevados teores de lipídeos, como os provenientes de laticínios, matadouros e avícolas, enlatados, extração de óleos, entre outros. A Política Nacional de Recursos Hídricos, instituída pela Lei Federal n° 9.433 de 8 de janeiro de 1997 trata da cobrança pelo uso dos corpos d'água para o lançamento de despejos líquidos.Os lipídeos contidos nesses efluentes, além de representarem uma perda industrial importante, interferem negativamente nos Sistemas de Tratamento de Efluentes. Elevadas concentrações de lipídeos resultam na formação de lodos com diferentes características físicas e reduzida atividade hidrolítica devido à flotação dessa biomassa, aumento do tempo de retenção hidráulica desses efluentes nas lagoas de estabilização, redução da capacidade de aeradores e elevada demanda de produtos floculantes 1 . Dentro deste contexto, processos alternativos vêm sendo utilizados na redução da concentração de lipídeos contidos nesses efluentes por meio de ação de enzimas, particularmente lipases. Essas enzimas apresentam uma importância particular, pelo fato de hidrolisarem especificamente óleos e gorduras, o que pode ser de grande interesse para o tratamento de efluentes com alto teor de gordura. As lipases (triacilglicerol acil hidrolases, E.C.3.1.1.3) compreendem um grupo de enzimas hidrolíticas que atuam na interface orgânica-aquosa, catalisando a hidrólise de ligações éster-carboxílicas, presentes em acilgliceróis 2 . A sua utilização reduz os níveis de sólidos suspensos e lipídeos, o que possibilita melhores condições de operação no tratamento anaeróbio e desobstrui filmes de óleos em tubulações, resultando no aumento da vida útil dos equipamentos.Além disso, esse tratamento apresenta algumas vantagens, tais como a e...

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“…Although it is not common practice to characterize the transformation kinetics of lipids in activated sludge using OUR (Dueholm et al 2001), it serves as a good measure of the metabolic activity and health of the activated sludge process.…”

Section: Introductionmentioning

confidence: 99%

Comparative evaluation of the microbial community in biological processes treating industrial and domestic wastewaters

2007

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Aims: Comparison of the microbial composition and process performance between laboratory scale processes treating domestic and vegetable oil wastewaters. Methods and Results: Two laboratory scale modified Ludzack–Ettinger processes were operated under similar operating conditions. One process was fed domestic wastewater and the other an industrial wastewater, vegetable oil effluent. Nitrogen removal capacities of the processes were similar. The industrial process exhibited a lower COD removal capacity and oxygen utilization rate, although a greater mixed liquor volatile suspended solids concentration was observed in the industrial process. Fluorescent in situ hybridization (FISH) with probes EUBmix, ALF1b, BET42a, GAM42a and HGC69a revealed that 81% and 72% of total cells stained with 4′, 6‐diamidino‐2‐phenylindole (DAPI) within the domestic and industrial processes respectively bound to EUBmix. This indicated a slightly lower Eubacterial population within the industrial process. The alpha‐proteobacteria was the dominant community in the industrial process (31% of EUBmix), while the beta‐proteobacteria dominated the domestic process (33% of EUBmix). Conclusions: The findings served to establish a difference in the microbial population between the processes. Therefore, the class alpha‐proteobacteria could play a primary role in the degradation of vegetable oil effluent. Significance and Impact of the Study: This research will aid in process design and retrofitting of biological processes treating vegetable oil effluent.

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Transformation of lipids in activated sludge

Cited by 38 publications

References 18 publications

Mississippi State Biodiesel Production Project

Mississippi State Biodiesel Production Project

Aplicação de lipases no tratamento de águas residuárias com elevados teores de lipídeos

Comparative evaluation of the microbial community in biological processes treating industrial and domestic wastewaters

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