Backwash as a simple operational alternative for small-scale slow sand filters: From conception to the current state of the art

Souza, Fernando Hymnô de; Pizzolatti, Bruno Segalla; Sens, Maurício Luiz

doi:10.1016/j.jwpe.2020.101864

Cited by 10 publications

(4 citation statements)

References 33 publications

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“…As in Phase 1, the low removal of SFs may be associated with the presence of small‐diameter suspended particles, because massive removals of color by these systems are not expected (De Souza et al, 2021; Freitas et al, 2021). When comparing turbidity, apparent color, and true color removals of the slow filtration columns (SF1 and SF2), there is no statistical difference ( α > 0.05).…”

Section: Resultsmentioning

confidence: 99%

Pre‐filtration followed by slow double‐layered filtration: Media clogging effects on hydraulic aspects and water quality

Lunardi

Martins

Pizzolatti

et al. 2022

Water Environment Research

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This study evaluated clogging effects on head loss and water quality in sand prefiltration columns, followed by innovative double-layered slow-filter filtration technology using anthracite coal and sand. The study was divided into two phases. Phase 1 (filtration rate 11 m 3 /m 2 Ád) had a layout of a pre-filter (PF) system followed by a slow filter (SF). In Phase 2 (filtration rates of 5.5 and 11 m 3 /m 2 Ád), two PF systems (PF1 and PF2) followed by SFs (SF1 and SF2) were monitored, be differed only by filtration rate. Phase 1 presents a mean turbidity removal of 45.6% in PF and 23.9% in SF. PF presented a lower head loss in the superficial layers of the filter media, whereas SF presented a more important contribution in the deeper layers of the bed. In Phase 2, the mean results obtained for turbidity removal in PF1 and SF1 were 84.7% and 22.4%, in that order. PF2 and SF2 promoted mean reductions of 84.5% and 22.0%, respectively. Greater clogging is observed in the PF's surface layers, whereas the SFs dissipate greater clogging with depth. Filtration rates and water quality were similar in filter media of different compositions. Practitioner Points• Double-layer filters show better use of the porous media in depth.• Different materials produce different forms of clogging. • Higher filtration rates increase the number of pre-filter and slow filter runs.

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Section: Resultsmentioning

confidence: 99%

Pre‐filtration followed by slow double‐layered filtration: Media clogging effects on hydraulic aspects and water quality

Lunardi

Martins

Pizzolatti

et al. 2022

Water Environment Research

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“…Durante o tratamento, ocorre o acúmulo de impurezas e biomassa no meio filtrante que, com o tempo, reduz a produção de água filtrada (ELLIOTT et al, 2008). Para evitar a colmatação e restaurar a taxa de filtração, a limpeza ou lavagem do filtro lento pode ser realizada por raspagem e/ou substituição do meio filtrante ou por retrolavagem (WANG et al, 2022), que, embora seja mais complexa, promove uma limpeza eficiente (DE SOUZA et al, 2021), prologa a vida útil do meio filtrante e permite o funcionamento do filtro logo após a lavagem, que dura apenas alguns minutos.…”

Section: Introductionunclassified

“…Ambos os filtros foram capazes de reduzir significativamente o número de bactérias identificado na água bruta (teste estatístico Kruskal-Wallis; p < 0,05). Ao passo que, apenas as eficiências de remoções de coliformes totais foram significativamente diferentes entre os filtros lentos (teste estatístico Wilcoxon; p < 0,05).As reduções máximas de coliformes totais e E.coli foram de 2,65 log e 5 log para o FL-D, enquanto que o FL-T apresentou os valores de 2,86 log para coliformes totais e 5 log para E.coli, respectivamente (Figuras 3 e 4).Para ambos os filtros estudados, as remoções medianas de E.coli se enquadraram no intervalo de 1 a 3 log de remoção recomendado pela OMS (2017) e foram superiores as eficiências encontradas em outros estudos que avaliaram filtros lentos de areia(Andreoli e Sabogal-Paz, 2020;De Souza et al, 2021;Terin et al, 2021). As eficiências parecem ter sido afetadas pelo período inicial de operação e após a retrolavagem, momentos que são caracterizados pela ausência ou comprometimento do schmutzdecke.…”

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Economia circular do resíduo de caulim no tratamento de água em filtros lentos

Sousa¹,

G.Sa.²,

Coura³

et al. 2023

CLCS

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Este estudo apresentou a viabilidade do emprego e a valorização do resíduo de caulim como meio filtrante alternativo em filtros lentos. O sistema experimental foi composto por dois filtros lentos operados em paralelo e um sistema de retrolavagem por bombeamento, em escala piloto. Um filtro apresentava leito filtrante de camada dupla (FL-D) e o outro continha leito filtrante de camada tripla (FL-T), empregando resíduos de caulim em diferentes granulometrias em cada camada. Os filtros foram operados por 92 dias e foram alimentados diariamente com água de rio. A eficiência de tratamento foi avaliada a partir da realização diária dos parâmetros pH e turbidez, enquanto o ferro total (Fe-), nitrogênio amoniacal (N-NH3), coliformes totais e E. coli foram analisados semanalmente. As eficiências máximas de remoção de turbidez foram de 97,9% (FL-D) e 98,7% (FL-T). Os filtros atingiram 94,9% (FL-D) e 98,5% (FL-T) na remoção de Fe- e completa remoção de N-NH3 em aproximadamente 50% das amostras. O desempenho de ambos os filtros na remoção de E. coli foi melhorado após um tempo de maturação de 22 dias e a ausência de bactérias foi alcançada em 17% das amostras do FL-D e 25% no FL-T. A retrolavagem foi realizada após 63 dias do início da operação, e no schmutzdecke foram identificados diversos tipos de algas, além de microcrustácios, rotíferos e protozoários. Portanto, o tratamento de água em filtros lentos com resíduo da mineração de caulim apresenta potencial de aplicação, contribuindo, assim, para a sustentabilidade e promovendo a economia circular deste resíduo no tratamento descentralizado de água.

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“…The sand filter efficiency decreases with increasing sand particle diameter (Shortridge & Benham, 2018) and increasing pollutant load of the treated effluent (Nieto et al, 2016; Wen‐Yong et al, 2015). Small particles can pass through the filter and be released during filter and backwashing operations (De Souza et al, 2021; Elbana et al, 2012). Sand particle size also has a key effect on sand filter head loss (Arbat et al, 2011; Mesquita et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Performance of sand filter with disc and screen filters in irrigation with rainbow trout fish effluent

Hasani

Aminpour²,

Nikmehr

et al. 2022

Irrigation and Drainage

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Drip irrigation is the most suitable system for reusing effluents in agriculture, but emitter clogging is still its major drawback. Adequate filtration is needed to prevent emitter clogging, but little information is available about the performance of different filter types when using fish farm effluent. The purpose of this study was to evaluate the performance of three filtration treatments for rainbow trout effluent in drip irrigation systems: (1) sand filter (T1), (2) sand filter followed by a disc filter (T2) and (3) sand filter followed by a screen filter (T3). The treatments were tested with a constant discharge of 14.4 m3 h−1 at two working pressures of 300 and 150 kPa until reaching the backwashing threshold. For each filter, the following were computed: filtered volume per cross‐section until reaching the backwashing threshold (VB), filtered volume per cross‐section unit and head loss (V10), suspended solids removal efficiency (EF) and filter mass retention (q). T2 at 300 kPa had a significantly (p < 0.01) higher VB, whereas T1 and T3 only showed a VB of 53% and 45% at 300 kPa and 48% and 47% at 150 kPa, respectively, higher than that obtained by T2. The results suggest that using a combination of sand and disc filters at an operation pressure of 300 kPa is the best option when using rainbow trout effluent.

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Backwash as a simple operational alternative for small-scale slow sand filters: From conception to the current state of the art

Cited by 10 publications

References 33 publications

Pre‐filtration followed by slow double‐layered filtration: Media clogging effects on hydraulic aspects and water quality

Pre‐filtration followed by slow double‐layered filtration: Media clogging effects on hydraulic aspects and water quality

Economia circular do resíduo de caulim no tratamento de água em filtros lentos

Performance of sand filter with disc and screen filters in irrigation with rainbow trout fish effluent

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