Treatment of Greywater by Geotextile Filter and Intermittent Sand Filtration

Intermittent sand filtration (ISF) is an efficient system for treatment of greywater; however, the high quality of effluent and the simple set-up contrast with the high failure rate due to clogging of surface layers. The efficacy of several polypropylene non-woven geotextiles (apparent opening size from 0.10 to 0.18 mm) used as primary treatment filters to remove suspended particles from domestic greywater and the effects of this pretreatment in the performance of fine and small media size (0.3 and 0.6 mm) ISFs was examined. Results showed geotextile achieved suspended solids (SS) removal rates from 25 to 85% and chemical oxygen demand (COD) from 3 to 30%; although the portion larger than 75 μm was removed at higher rates (55–90%), particles smaller than the nominal pore size of the filter were also captured. Geotextile used as pretreatment resulted in improvement of lifetime of the ISFs over an experimental run of 60 days. The vertical profile of volatile organic matter in the ISFs was evaluated at the end of the experiment and it showed a clear reduction in the accumulation of organic material on the top layer of the ISFs, effectively avoiding its early failure by accumulation of solids.

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The Purifying Effect of Sand Filtration

Scientific American ◽

10.1038/scientificamerican08151891-13026bsupp ◽

1891 ◽

Vol 32 (815supp) ◽

pp. 13026-13027

Author(s):

B. H. Coffey

Keyword(s):

Sand Filtration

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Giardia and Virus Monitoring of Sewage Effluent in the State of Arizona

Water Science & Technology ◽

10.2166/wst.1989.0076 ◽

1989 ◽

Vol 21 (3) ◽

pp. 43-47 ◽

Cited By ~ 8

Author(s):

Joan B. Rose ◽

Ricardo De Leon ◽

Charles P. Gerba

Keyword(s):

United States ◽

Produced Water ◽

Wastewater Reuse ◽

Limited Resource ◽

The State ◽

Sewage Effluent ◽

Sand Filtration ◽

Southwestern United States ◽

Treatment Facilities ◽

Giardia Cysts

Arizona, located in the arid Southwestern United States, is heavily dependent on groundwater. In order to protect this limited resource, wastewater reuse has been implemented. Virus and Giardia monitoring of wastewater used for irrigation has also been initiated as a means for controlling the public's exposure to these pathogens. Treatment facilities must produce wastewater with no detectable Giardia cysts and one virus plaque forming unit (pfu) per 40 liters (L) for unrestricted reuse. For restricted reuse, 125 pfu/40 L is allowed. Methods based on filtration were used to monitor facilities at monthly, quarterly or biannual frequencies. Results after two years of monitoring are presented. All 11 treatment facilities produced water meeting the virus standard of 125 pfu/40 L. Only plants which used sand filtration and disinfection achieved consistent levels of virus below 1 pfu/40 L. Out of 70 samples, 74% contained no detectable viruses. Giardia was detected in 29 to 50% of the samples. Most plants would need to upgrade their treatment in order to meet standards for unrestricted irrigation.

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