Household slow sand filters in intermittent and continuous flows to treat water containing low mineral ion concentrations and Bisphenol A

Lyda Patricia Sabogal-Paz; Luiza Cintra Campos; Anna Bogush; Melisa Canales

doi:10.1016/j.scitotenv.2019.135078

Household slow sand filters in intermittent and continuous flows to treat water containing low mineral ion concentrations and Bisphenol A

Sci Total Environ. 2020 Feb 1:702:135078. doi: 10.1016/j.scitotenv.2019.135078. Epub 2019 Nov 1.

Authors

Lyda Patricia Sabogal-Paz¹, Luiza Cintra Campos², Anna Bogush³, Melisa Canales²

Affiliations

¹ Department of Hydraulics and Sanitation, São Carlos School of Engineering, University of São Paulo, Trabalhador São-Carlense Avenue, 400, São Paulo 13566-590, Brazil. Electronic address: lysaboga@sc.usp.br.
² Department of Civil, Environmental and Geomatic Engineering, University College London, Gower Street, London WC1E 6BT, United Kingdom.
³ Department of Earth Sciences, University College London (UCL), Gower Street, London WC1E 6BT, United Kingdom.

PMID: 31715392
DOI: 10.1016/j.scitotenv.2019.135078

Abstract

Household slow sand filter (HSSF) has been used as an alternative to drinking water treatment in rural communities worldwide; however, its performance to treat influent water with quality similar to rainwater still needs further studies. Rainwater presents low pH and slight mineral ion concentrations, an aspect that can modify the filter media and consequently the HSSF efficiency. Furthermore, house roofs used in rainwater harvesting can be made of plastic. Therefore, it can introduce chemicals such as Bisphenol A (BPA) in the water. In this context, two pilot-scale HSSFs operated in continuous and intermittent flows were evaluated to treat water containing BPA and low mineral ion concentrations in order to assess the filter performance. Filter media leaching was noticed in the trials; thus, filter media and construction material selection must be carefully evaluated to eliminate risks of pollutant occurrence in drinking water. Operational differences between continuous and intermittent flows influenced the HSSF efficiency for BPA and DOC removals; even so, the filters' performance was low probably due to the slow schmutzdecke development. According to tracer test results, HSSF can be classified as a plug flow reactor and strategies to improve its hydraulic performance are not required.

Keywords: Biosand filter; Decentralised treatment; Drinking water; Endocrine disruptor; Rainwater.