Biological Layer in Household Slow Sand Filters: Characterization and Evaluation of the Impact on Systems Efficiency

• Published in: Water (Basel) 2022-04, Vol.14 (7), p.1078
• Main Authors: Lubarsky, Helen, Fava, Natália de Melo Nasser, Souza Freitas, Bárbara Luíza, Terin, Ulisses Costa, Oliveira, Milina, Lamon, Atônio Wagner, Pichel, Natalia, Byrne, John Anthony, Sabogal-Paz, Lyda Patricia, Fernandez-Ibañez, Pilar
• Format: Article
• Language: English
• Subjects: Analysis; Bacteria; Biofilms; Carbohydrates; Coliforms; Datasets; Depletion; Dissolved oxygen; Drinking water; E coli; Efficiency; Escherichia coli; Extracellular polymers; Filters; Households; Microorganisms; Oxygen depletion; Pathogens; Proteins; Purification; Rivers; Sand; Sand beds; Sand filters; Scanning electron microscopy; Turbidity; Water; Water purification; Water treatment
• ISSN: 2073-4441; 2073-4441
• DOI: 10.3390/w14071078

Schmutzdecke, the biofilm formed on the top of the sand bed in household slow sand filters (HSSF) is a key factor for the filters’ high efficiency in removing particles and microorganisms from water. This paper aims to investigate the extracellular polymeric substances composition (carbohydrates and proteins), biomass, dissolved oxygen, and microbial community in two types of HSSFs and identify a correlation between them and their efficiency. A continuous- and an intermittent-HSSF (C-HSSF and I-HSSF) were studied to treat river water for 48 days. Their efficiencies for bacteria (E. coli and total coliforms), turbidity, and apparent color removals were analyzed. Results clearly showed an increase of carbohydrates (from 21.4/22.5 to 101.2/93.9 mg·g−1 for C-/I-HSSF) and proteins (from 34.9 to 217/307.8 mg g−1 for C-/I-HSSF), total solids (from 0.03/