[Destabilisation of humus by means of the natural polymere chitosan as coagulant]

agua potable agua superficial arena ceramics chitosan chitosane coagulation colloidal properties cuarzo drinking water eau potable eau superficielle escherichia coli filters filtration filtre filtros granule granules humus indicator organisms noruega norway organisme indicateur organismos indicadores pilot projects porosidad porosity projet pilote propiedades coloidales proyectos pilotos purification de l'eau quartz quitosano sable sand surface water water purification