Paranoá Lake restoration: impact of tertiary treatment of sewage in the watershed

Cavalcanti, Cristine Gobbato Brandão; Pinto, Marcelo Teixeira; Freitas, Hélio José de; Moreira, Ricardo Cosme Arraes

doi:10.1080/03680770.1995.11900803

Cited by 6 publications

(8 citation statements)

References 3 publications

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“…A hipótese mais provável para explicar este fenômeno, é que apesar da diminuição anterior de 70% do aporte de fósforo ao lago (Cavalcanti et al 1997 partir da segunda intervenção (Tabela I), a abundância de fi toplâncton e do fósforo restante no lago era sufi ciente para se retro-alimentar, ou seja, a mortalidade das algas disponibilizava fósforo ao lago, que por sua vez era reabsorvido novamente para o aumento da produtividade primária. O fl ushing terminou com este ciclo fazendo com que o Lago tenha nos dias atuais áreas com transparência (visibilidade) da ordem 6 metros, inclusive recebendo praticantes de pesca subaquática para a captura de carpas com arpão (F. Starling, observação pessoal).…”

Section: Discussionunclassified

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Efeitos De Diferentes Intervenções No Processo De Eutrofização Do Lago Paranoá (Brasília – Df)

Angelini

Bini

Starling³

2008

Oecol. Austr.

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RESUMOO monitoramento temporal das variáveis de um corpo d'água possibilita o conhecimento de sua dinâmica e, por fi m, de seu manejo. O Lago Paranoá em Brasília, formado em 1959, passou por um longo período de eutrofi zação. Neste trabalho, usando dados de monitoramento de longa duração da CAESB, os efeitos da instalação de duas Estações de Tratamento de Esgoto (ETE) e de um evento de fl ushing foram avaliados para as variáveis Clorofi la-a, Fósforo Total e Transparência medidas entre 1976 e 2001. Utilizando-se da Análise de Intervenção foram mensuradas a efetividade de três intervenções: o início das operações das ETE (01/1993); o pleno funcionamento destas ETE (01/1996); e um evento de fl ushing (abertura abrupta das comportas, 11/1999). Os resultados mostram que: i) a 1 a intervenção não surtiu nenhum efeito; ii) a 2ª intervenção fez com que os níveis de Fósforo Total e Clorofi la-a fossem reduzidos signifi cativamente; iii) apenas o fl ushing (3ª intervenção), fez com que a transparência da água aumentasse para mais de um metro na maioria dos pontos, inferindo-se que apesar da redução do aporte de fósforo ao lago com as ETE (1ª e 2ª intervenções), a abundância restante de fi toplâncton na água tenha mantido um mecanismo de feedback com o fósforo que só foi interrompido com a abertura abrupta das comportas que eliminou o fi toplâncton da superfície e conduziu o lago à um novo patamar de produção primária. O programa de monitoramento da CAESB foi fundamental para o entendimento deste processo e o que justi fi ca a manutenção e a ampliação deste programa. Palavras-chave: intervenção, reservatório tropical, CAESB, monitoramento, Paranoá. ABSTRACT EFFECTS OF INTERVENTIONS ON THE EUTROPHICATION PROCESS OF PARANOÁ LAKE RESERVOIR OF BRASILIA, BRAZIL.Long-term environmental monitoring of aquatic ecosystems is essential to understand their dynamics and to the proposition of management practices. Paranoá Reservoir was created in 1959 and was subject to a long period of eutrophication. In this paper, data obtained by the monitoring program carried out by the "Companhia de Abastecimento e Saneamento de Brasília", between 1976 and 2001, were evaluated to measure the effects of three direct interventions on water quality (as measured by water transparency, P-total and chlorophyll-a concentrations): the activation of two water treatment plants (01/1993); the proper operation of these plants (01/1996), and a major fl ushing event (sudden release of water in 11/1999). The following results were obtained: i) the fi rst intervention had no effect on the mean values of the variables analyzed; ii) the chlorophyll-a and total phosphorus concentrations signifi cantly declined after the second intervention; iii) water transparency increased after the third intervention. An apparent mechanism of phosphorus feedback supported by phytoplankton was interrupted by the fl ushing and, after that intervention, the primary production of Paranoá Reservoir declined to a new level. The dataset obtained by the monitoring program was essential to...

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Section: Discussionunclassified

“…Como alternativa, a CAESB implantou duas novas Estações de Tratamento de Esgoto (ETE), a ETE Norte e a ETE Sul, que entraram em operação em 1993, com um avançado sistema de tratamento terciário que reduziu em 70% o aporte de fósforo e nitrogênio ao lago (Cavalcanti et al 1997).…”

Section: Introductionunclassified

Efeitos De Diferentes Intervenções No Processo De Eutrofização Do Lago Paranoá (Brasília – Df)

Angelini

Bini

Starling³

2008

Oecol. Austr.

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“…They dominate the fish community today. Since 1993, the Brazilia Water and Sewage Corporation (CAESB) has reduced the external nutrient loading by 70%, using an advanced tertiary treatment with biological removal of P and N (Cavalcanti et al ., 1997). Nevertheless, over three decades of intensive discharge by the two sewage plants, a layer of organic sediment (sludge) up to 3 m thick has accumulated upstream of the two branches of the reservoir that receive the sewage plant effluents (Fig.…”

Section: Study Sitementioning

confidence: 99%

“…Overall external TP‐loadings were computed as the sum of the loadings from the sewage plant and the tributaries. Diffuse loadings in this urban branch of the reservoir is of limited importance as they contribute <15% to the total external input (Cavalcanti et al ., 1997). Zooplankton densities and TP and chlorophyll a concentrations were determined following APHA's (1998) standard methods.…”

Section: Baci Approachmentioning

confidence: 99%

Contribution of omnivorous tilapia to eutrophication of a shallow tropical reservoir: evidence from a fish kill

et al. 2002

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SUMMARY 1. We examined whether a large stock of tilapia (>750 kg ha−1, in littoral areas >1300 kg ha−1), mostly Oreochromis niloticus (L.) and Tilapia rendalli (Boulenger), could contribute to the eutrophication of a tropical reservoir (Lago Paranoá, Brasília, Brazil) by enhancing P‐loading. 2. We took advantage of an extensive fish kill (>150 tons removed) during May–August 1997 in a hypereutrophic branch of the reservoir to compare water quality characteristics 1 year before and after this event by means of BACI statistics. We also measured P‐excretion rates in laboratory trials to assess the P‐loading of the reservoir by the tilapia relative to tributary inputs and loading from a sewage treatment plant. 3. Concentrations of chlorophyll a (decline from 84 to 56 μg L−1, P=0.018) and total P (decline from 100 to 66 μg L−1, P < 0.001) decreased significantly in the branch of the reservoir affected by the fish kill, compared with a similar but unaffected branch that served as a control. Because P‐loading by both a sewage treatment plant and tributaries remained high after the incidence, the fish kill was likely to contribute to the observed water quality improvement. 4. Removing 150 tons of dead tilapia corresponded to 20 days of external total phosphorus load (TP‐load) to the branch, and resulted in a reduction of 5.1 kg P day−1 in internal recycling via tilapia excretion, which is equivalent to 12% of the external TP‐load. 5. Implementing professional tilapia cast‐net fisheries could be an efficient biomanipulation approach to improve water quality and limit the occurrence of cyanobacteria blooms and fish kills in hypereutrophic branches of Lago Paranoá and similar tropical lakes.

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“…In 1993, a restoration program began focusing on nutrient loading reduction. In 1995, notwithstanding phosphorus reduction (Cavalcanti et al, 1997), no change in zooplankton community structure was recorded (Mattos et al, 1997).…”

Section: Introductionmentioning

confidence: 97%

New cladoceran records from Lake Paranoá, Central Brazil

2004

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The zooplanktonic community of Lake Paranoá has been studied for more than thirty years. Until 1998, when it was considered eutrophic, only three cladoceran species were known from the reservoir. Since 1999, when Lake Paranoá underwent intentional flushing, definite changes in species diversity and composition were identified. At the same time, exploratory studies on littoral cladoceran species were being done. The present study aims to provide additional information on the cladoceran species composition of Lake Paranoá. Seven new species records are presented, four of them also representing the first record from the Federal District (Brasília). The population previously considered as belonging to Bosmina longirostris was reconsidered and re-identified as Bosmina freyi. Figures and comments on species taxonomy and distribution are also provided.

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Paranoá Lake restoration: impact of tertiary treatment of sewage in the watershed

Cited by 6 publications

References 3 publications

Efeitos De Diferentes Intervenções No Processo De Eutrofização Do Lago Paranoá (Brasília – Df)

Efeitos De Diferentes Intervenções No Processo De Eutrofização Do Lago Paranoá (Brasília – Df)

Contribution of omnivorous tilapia to eutrophication of a shallow tropical reservoir: evidence from a fish kill

New cladoceran records from Lake Paranoá, Central Brazil

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