Potential of biological arsenite oxidation in sand filtration units at arsenic\u2013iron removal plants (AIRPs) in Bangladesh

Mohammad Mosleh Uddin,S M Atiqul Islam,Hiroaki Furumai,Futoshi Kurisu,Ikuro Kasuga

doi:10.1007/s13201-019-0932-x

Abstract

This study is aimed to investigate biological oxidation of arsenic [As(III)] in sand component of arsenic–iron removal plant (AIRP). Water and sand samples were collected from the municipal and household AIRP units (MAIRP and HAIRPs) at Manikganj district, Bangladesh. These samples were analyzed using arsenic speciation cartridge with inductively coupled plasma-mass spectrometry for arsenic and iron detection and phylogenetic analysis based on aoxB gene sequencing. It was observed that arsenic concentration in the raw water, before and after sand filtration, ranged from 13.0–81.0 to 4.0–21.0 μg/L, respectively, which majorly contained reduced arsenic [As(III)] in the inlet and oxidized arsenic [As(V)] in the outlet. The results of our batch experiments showed that indeed sand unit of MAIRP oxidized As(III) with 36 g/h estimated biological oxidation potential which was considered enough to oxidize all the As(III) loading (6.3 g/h) in the influent. Additionally, bacterial arsenite oxidase gene (aoxB) was detected in the sand sample and has 80% sequence similarity with Polymorphum gilvum, an alphaproteobacteria on the phylogenetic tree. This study, therefore, revealed that AIRP sand units have enough potential of biological activity to ensure overall arsenic removal through As(III) oxidation. However, future research is necessary to unfold the basic mechanistic approach explored in this plant for further modification if need arises.

Highlights

Arsenic water contamination is a common problem among the indigenous of Bangladesh where estimated population of about 35 million are consuming water with arsenic level above 50 μg/L and fivefold higher than the World Health Organization (WHO) guideline (BGS and DPHE 2001; WHO 2011)
We identified the bacterial gene for arsenite oxidation in the arsenic–iron removal plant (AIRP) sand samples
The concentration of total dissolved arsenic in that raw water of municipal AIRP (MAIRP) as presented in Fig. 2 is 13 μg/L which is considerable lower than the standard value for Bangladeshi drinking water (50 μg/L) but higher when compared with the WHO guideline value (10 μg/L)

Summary

Introduction

Arsenic water contamination is a common problem among the indigenous of Bangladesh where estimated population of about 35 million are consuming water with arsenic level above 50 μg/L (national standard level) and fivefold higher than the World Health Organization (WHO) guideline (BGS and DPHE 2001; WHO 2011). Water analysis of the affected area has revealed to contain high level of As(III) species rendering the water unsafe for drinking. The previous studies have shown that ground water contained oxyanions of arsenic species (Cullen and Reimer 1989; Masscheleyn et al 1991). The predominant form in well-oxidized water is As(V), whereas As(III) occurs mainly in reduced environments. As(III) has a toxicity that is sixty times greater than that of As(V) and is difficult to remove without oxidation (Kim et al 2003)

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Conclusion