scholarly journals Impact of alum pretreatment on biosand filter performance: reply to Dorea's commentary on Curry et al. (2020) article

2020 ◽  
Vol 10 (4) ◽  
pp. 1036-1036
Author(s):  
Kevin D. Curry ◽  
Christopher P. Bloch
Keyword(s):  
Filter Performance ◽  
Biosand Filter

scholarly journals Impact of alum pretreatment on biosand filter performance: a commentary on Curry et al. (2020)

2020 ◽  
Vol 10 (4) ◽  
pp. 1034-1035
Author(s):  
Caetano C. Dorea
Keyword(s):  
Feed Water ◽  
Recent Contribution ◽  
Flow Rates ◽  
Lower Flow ◽  
Filter Performance ◽  
Biosand Filter

Abstract In a recent contribution by Curry and colleagues, a field-derived assessment of a reportedly common pretreatment technique to reduce turbidities of biosand filter (BSF) feed water was reported. Their results demonstrated that despite alum pretreatment achieving lower settled turbidity values relative to control filters, such intervention led to significantly lower flow rates in the alum-dosed BSFs. However, their study stopped short of providing a more meaningful interpretation to what may initially seem like a counterintuitive finding, which is presented here.

scholarly journals Impact of surface maintenance on BioSand filter performance and flow

2017 ◽  
Vol 15 (2) ◽  
pp. 262-272 ◽  
Author(s):  
Sarah Singer ◽  
Brain Skinner ◽  
Raymond E. Cantwell
Keyword(s):  
Flow Rate ◽  
Recovery Period ◽  
Pause Time ◽  
Effluent Water ◽  
Removal Rates ◽  
Filter Performance ◽  
Biosand Filter ◽  
Slow Sand Filter ◽  
And Performance ◽  
Sr Method

The BioSand filter (BSF) is a household scaled, intermittently operated, slow sand filter. The BSF requires maintenance to remove trapped sediments. This study evaluated the effects of maintenance on the filter's flow rate and performance. Four concrete BSFs received three styles of maintenance: surface agitation (SA), stirring method (SM), and sand removal (SR). Effluent water was collected from the filter between 0–2 L effluent (0–2 L effluent) and between 15–20 L effluent (15 L+ effluent). After maintenance, effluent at 15 L+ (no pause time) showed a significant decrease in thermotolerant coliform removal rates by 0.66–0.91 log (SA), 0.57–0.67 log (SM) and 0.32–0.83 log (RM) (<0.001). Effluent water at 0–2 L (with pause time) did not significantly decrease in thermotolerant coliform removal rates (>0.17) for any maintenance method. The recovery duration after maintenance for all methods at 0–2 L effluent had a median recovery of <1.2 days. The effluent at 15 L+ had a longer recovery period (at least 3.9, 3.0 and 12.75 days for the SA, SM, and SR method, respectively). The flow rate recovery for SA (76%) and SM (82%) was lower compared to SR (138%).

In-home performance and variability of biosand filters treating turbid surface and rain water in rural Kenya

2013 ◽  
Vol 3 (2) ◽  
pp. 189-198 ◽  
Author(s):  
Erica R. McKenzie ◽  
Marion W. Jenkins ◽  
Sangya-Sangam K. Tiwari ◽  
Jeanie Darby ◽  
Wycliffe Saenyi ◽  
...  
Keyword(s):  
River Water ◽  
Low Income ◽  
Rain Water ◽  
Fecal Coliforms ◽  
Performance Study ◽  
Factors Affecting ◽  
Effluent Quality ◽  
Filter Performance ◽  
Biosand Filter ◽  
Households With Children

Thirty low-income Kenyan households using turbid river and relatively cleaner rain water participated in a 6 month in-home Biosand filter (BSF) performance study comprised of surveys and monthly monitoring of BSF influent and effluent water for turbidity and fecal coliforms (FC). River–river (influent–effluent) sample pairs (n = 155; 90% of observations) resulted in average BSF instantaneous FC and turbidity removals of 1.41 log10 (96.1%) and 32.5%, respectively. Cumulative distributions of influent and effluent quality demonstrated unambiguous improvement of river water but rain water improvement was limited and less reliable. Filter performance varied considerably within and across units. A hierarchical set of hypothesized factors affecting filter bacterial performance variability was assessed. BSF effluent FCs were positively correlated with influent (flush water) FCs and influent and effluent turbidity, and negatively correlated with turbidity applied to-date and days since maintenance. Interrupted use and moving the BSF negatively impacted effluent quality. Households with children age 6–10 collecting BSF filtered drinking water, or with more members, had higher effluent FCs. BSFs fed only river water performed better, on average, than mixed-source filters. Implications for BSF implementation in developing countries are discussed, including aqueous chemistry aspects of performance.

Field Evaluation of Long-Term Performance and Use of Biosand Filters in Posoltega, Nicaragua

2009 ◽  
Vol 44 (2) ◽  
pp. 111-121 ◽  
Author(s):  
Jason C. Vanderzwaag ◽  
James W. Atwater ◽  
Karen H. Bartlett ◽  
Derek Baker
Keyword(s):  
Loading Rate ◽  
Field Evaluation ◽  
Hydraulic Loading Rate ◽  
Hydraulic Loading ◽  
User Training ◽  
Filter Performance ◽  
Biosand Filter ◽  
Biosand Filters ◽  
And Performance

Abstract An evaluation was conducted in 2007 on biosand filters that were installed in Posoltega, Nicaragua in 1999 and 2004.The objectives were to characterize the condition and use of filters eight and three years after installation, determine filter performance of those filters still in use, and identify determinants of successful long-term use and performance. Methods consisted of household identification, user questionnaires, and water quality testing. Of the 234 filters installed, only 24 were found to still be in use. Average log reductions were 1.73 (98%) for total coliforms, 1.36 (96%) for Escherichia Coli, and 0.91 (88%) for turbidity. Statistically significant effects were detected for the magnitude of the contamination of source water, the peak hydraulic loading rate, and the standing depth of water over the filter media. Questionnaire results indicated user training on filter maintenance could improve the peak hydraulic loading rate and hence filter performance. The low rate of sustained use (10%) is an indication of failed implementation, and is attributable to structural failure, particularly cracking of the concrete filters from 2004. Nonetheless, this evaluation demonstrated the biosand filter technology to be robust since those filters still in use were performing as expected three and eight years postimplementation.

The impact of loading frequency and copper as a biocide on biosand filter performance

2013 ◽  
Vol 3 (3) ◽  
pp. 355-364 ◽  
Author(s):  
Elizabeth M. Hyde ◽  
Laura W. Lackey
Keyword(s):  
Loading Frequency ◽  
Sand Filters ◽  
Performance Effect ◽  
Filter Performance ◽  
Copper Addition ◽  
Biosand Filter ◽  
Point Of Use ◽  
Significant Difference ◽  
Significant Performance ◽  
The Impact

Biological sand filters (BSFs) can appropriately serve as point-of-use water treatment in developing nations. This study examined the benefit of adding copper to a BSF, and evaluated the impact of its addition in relation to extended pause times. Four 70-L BSFs were created – copper was incorporated in the packing of the two BSFs labeled Filter 1 and Filter 3. Filters 1 and 2 were loaded daily while Filters 3 and 4 were watered every third day. Source water was taken from the Ocmulgee River in Macon, Georgia. To investigate variation due to watering frequency and biocidal addition, BSF performance was quantified using coliforms, turbidity, solids, dissolved oxygen, pH, and copper analyses. E. coli removal efficiencies for Filters 1, 2, 3, and 4 averaged 90, 77, 87, and 80%, respectively. Paired t-tests at α = 0.05 indicate that effluent coliform concentrations from filters watered daily were significantly impacted by the presence of copper. Filters loaded every third day showed no significant performance effect from copper addition on coliform removal efficiency. Similar paired t-tests at α = 0.05 for turbidity, solids, and COD showed no significant difference between filter performance.

Utilizing structural equation modeling to correlate biosand filter performance and occurrence of diarrhea in the village of Enseado do Aritapera in Para, Brazil

2014 ◽  
Vol 15 (1) ◽  
pp. 164-172 ◽  
Author(s):  
L. E. Voth-Gaeddert ◽  
D. W. Divelbiss ◽  
D. B. Oerther
Keyword(s):  
Structural Equation Modeling ◽  
Structural Equation ◽  
Water Source ◽  
Influential Factor ◽  
Equation Modeling ◽  
Filter Performance ◽  
Biosand Filter ◽  
Point Of Use ◽  
The Village ◽  
Proper Operation

Previously, our earlier work demonstrated the use of structural equation modeling to evaluate the effectiveness of point-of-use biosand filters (BSF) to reduce the occurrence of diarrhea in rural Guatemala. While prior research in laboratory and field locations has documented the effectiveness of BSF to remove agents of diarrhea, experience in field sites suggests that multiple local factors greatly influence the occurrence of diarrhea. In addition to the BSF, this study evaluated household education level, socioeconomic status, water source and handling, and sanitation as factors impacting the occurrence of diarrhea for households in the village of Enseado do Aritapera in Para, Brazil. Of the 18 correlations examined, 16 were negatively correlated, and the strongest correlation was between the utilization of an ‘improved’ water source and the reduction of the occurrence of diarrhea within the household. While proper operation and maintenance of the BSF was found to have a negative correlation with the occurrence of diarrhea, it was not the most influential factor. This result supports the prior findings from our earlier work suggesting that more research is needed to evaluate which intervention should be prioritized for maximum return on investment with aid distribution.

scholarly journals Impact of rock alum pretreatment on biosand filter performance in Cambodia

2020 ◽  
Vol 10 (1) ◽  
pp. 166-170 ◽  
Author(s):  
Kevin D. Curry ◽  
Christopher P. Bloch ◽  
Vantha Hem
Keyword(s):  
River Water ◽  
Flow Rate ◽  
Water Source ◽  
Drinking Water Source ◽  
Source Water ◽  
Filter Performance ◽  
Biosand Filter ◽  
Tonle Sap ◽  
Alum Treatment ◽  
Water Filters

Abstract Alum is often recommended by WASH agencies as a pretreatment flocculent to improve filtration in biosand filters (BSFs) for communities using a turbid drinking water source. Floating villages on the Tonle Sap Lake in Cambodia using BSFs encounter severe declines in filtration rates while using alum, resulting in reduced use of the BSF. We tested the effect of rock alum treatment on flow rate and turbidity. The flow rate of all BSFs declined over time, but degradation of flow was more rapid for alum-treated water than untreated water. Rock alum treatments significantly reduced the turbidity of borrow pit source water. Filters switched to untreated river water decreased in turbidity to levels ≤ rock alum-treated river water. Rock alum treatments increased aluminum in source water 4–15 times, but filtration by BSFs decreased levels of aluminum to near 0.05 mg/L. Though rock alum effectively reduces turbidity in source water, we believe it continues its coagulation inside the BSF during pause periods, negatively impacting flow rates.

scholarly journals An assessment of long-term biosand filter use and sustainability in the Artibonite Valley near Deschapelles, Haiti

2013 ◽  
Vol 3 (1) ◽  
pp. 51-60 ◽  
Author(s):  
Andrew J. Sisson ◽  
Peter J. Wampler ◽  
Richard R. Rediske ◽  
Azizur R. Molla
Keyword(s):  
Water Quality ◽  
Field Studies ◽  
Water Quality Monitoring ◽  
Technical Support ◽  
Quality Monitoring ◽  
Culturally Appropriate ◽  
Filter Performance ◽  
Biosand Filter ◽  
Common Problems

A non-randomized assessment of long-term biosand filter (BSF) use and sustainability in the Artibonite Valley near Deschapelles, Haiti was conducted during March, 2011. Of the 55 BSFs visited, 47% were no longer in use. Filter lifespan ranged from <1 year to systems still in use after 12 years. Interviews with BSF owners revealed problems related to intermittent filter use due to travel for employment or personal matters; broken or missing filter parts; and fears that the filter would not be effective against cholera. In addition, 17 BSF field studies were reviewed to identify common issues impacting usage. Culturally appropriate technologies and education materials explaining proper maintenance and operation are essential for improved filter performance and sustainability. For Haiti, education materials should be provided in Creole and French and should include, (1) diagrams and descriptions of how the BSF works, (2) how to troubleshoot common problems, (3) how to properly maintain filters, and (4) a contact in case of questions. Operational problems can be minimized by providing long-term technical support, periodic water quality monitoring, and maintenance assistance for filter users.

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