Grain displacement during backwash of drinking water filters

Backwashing rapid sand filters causes inadvertent displacement of filter media grains from their previous depths. This displacement can affect the hydraulic function of filters by mixing or segregating media grains, and the function of biofilters through displacement of active biomass and coatings f...

Descripción completa

Guardado en:

Detalles Bibliográficos
Autores principales:	Loren Ramsay, Feng Du, Majbritt Lund, Haiyan He, Ditte A. Søborg
Formato:	article
Lenguaje:	EN
Publicado:	IWA Publishing 2021
Materias:	backwash biofiltration drinking water grain displacement rapid sand filtration Water supply for domestic and industrial purposes TD201-500 River, lake, and water-supply engineering (General) TC401-506
Acceso en línea:	https://doaj.org/article/568ab13a323c4a02b8acd275a25433c6
Etiquetas:	Agregar Etiqueta Sin Etiquetas, Sea el primero en etiquetar este registro!

id	oai:doaj.org-article:568ab13a323c4a02b8acd275a25433c6
record_format	dspace
spelling	oai:doaj.org-article:568ab13a323c4a02b8acd275a25433c62021-11-06T07:04:48ZGrain displacement during backwash of drinking water filters1606-97491607-079810.2166/ws.2020.300https://doaj.org/article/568ab13a323c4a02b8acd275a25433c62021-02-01T00:00:00Zhttp://ws.iwaponline.com/content/21/1/356https://doaj.org/toc/1606-9749https://doaj.org/toc/1607-0798Backwashing rapid sand filters causes inadvertent displacement of filter media grains from their previous depths. This displacement can affect the hydraulic function of filters by mixing or segregating media grains, and the function of biofilters through displacement of active biomass and coatings from proper depths. This study quantifies grain displacement in a pilot-scale filter using tracer grains of colored sand, glass beads, anthracite and garnet to determine the effect of grain size, density and shape on grain displacement. Statistical moments are used to describe the depth distributions resulting from displacement during backwashing. Results show that significant grain displacement occurs during backwash consisting of air scour, air-and-water wash and sub-fluidization water-only wash. Here, displacement is largely independent of grain size, density and shape. When fluidization backwash is used, greater displacement and more dependence on grain characteristics is seen. A variety of grain movement phenomena can be observed during the backwashing steps, indicating that grain movement and therefore the resulting displacement is highly inhomogeneous in four dimensions. These results have direct practical implications for the design of rapid sand filters and the optimization of backwashing procedures, while suggesting that the current widespread backwashing practice used in the case study country (Denmark) should be abandoned.Loren RamsayFeng DuMajbritt LundHaiyan HeDitte A. SøborgIWA Publishingarticlebackwashbiofiltrationdrinking watergrain displacementrapid sand filtrationWater supply for domestic and industrial purposesTD201-500River, lake, and water-supply engineering (General)TC401-506ENWater Supply, Vol 21, Iss 1, Pp 356-367 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	backwash biofiltration drinking water grain displacement rapid sand filtration Water supply for domestic and industrial purposes TD201-500 River, lake, and water-supply engineering (General) TC401-506
spellingShingle	backwash biofiltration drinking water grain displacement rapid sand filtration Water supply for domestic and industrial purposes TD201-500 River, lake, and water-supply engineering (General) TC401-506 Loren Ramsay Feng Du Majbritt Lund Haiyan He Ditte A. Søborg Grain displacement during backwash of drinking water filters
description	Backwashing rapid sand filters causes inadvertent displacement of filter media grains from their previous depths. This displacement can affect the hydraulic function of filters by mixing or segregating media grains, and the function of biofilters through displacement of active biomass and coatings from proper depths. This study quantifies grain displacement in a pilot-scale filter using tracer grains of colored sand, glass beads, anthracite and garnet to determine the effect of grain size, density and shape on grain displacement. Statistical moments are used to describe the depth distributions resulting from displacement during backwashing. Results show that significant grain displacement occurs during backwash consisting of air scour, air-and-water wash and sub-fluidization water-only wash. Here, displacement is largely independent of grain size, density and shape. When fluidization backwash is used, greater displacement and more dependence on grain characteristics is seen. A variety of grain movement phenomena can be observed during the backwashing steps, indicating that grain movement and therefore the resulting displacement is highly inhomogeneous in four dimensions. These results have direct practical implications for the design of rapid sand filters and the optimization of backwashing procedures, while suggesting that the current widespread backwashing practice used in the case study country (Denmark) should be abandoned.
format	article
author	Loren Ramsay Feng Du Majbritt Lund Haiyan He Ditte A. Søborg
author_facet	Loren Ramsay Feng Du Majbritt Lund Haiyan He Ditte A. Søborg
author_sort	Loren Ramsay
title	Grain displacement during backwash of drinking water filters
title_short	Grain displacement during backwash of drinking water filters
title_full	Grain displacement during backwash of drinking water filters
title_fullStr	Grain displacement during backwash of drinking water filters
title_full_unstemmed	Grain displacement during backwash of drinking water filters
title_sort	grain displacement during backwash of drinking water filters
publisher	IWA Publishing
publishDate	2021
url	https://doaj.org/article/568ab13a323c4a02b8acd275a25433c6
work_keys_str_mv	AT lorenramsay graindisplacementduringbackwashofdrinkingwaterfilters AT fengdu graindisplacementduringbackwashofdrinkingwaterfilters AT majbrittlund graindisplacementduringbackwashofdrinkingwaterfilters AT haiyanhe graindisplacementduringbackwashofdrinkingwaterfilters AT ditteasøborg graindisplacementduringbackwashofdrinkingwaterfilters
_version_	1718443853382418432

Grain displacement during backwash of drinking water filters

Ejemplares similares