Application of Octacalcium Phosphate with an Innovative Household-scale Defluoridator Prototype and Behavioral Determinants of its Adoption in Rural Communities of the East African Rift Valley

Abstract

Natural fluoride contamination of drinking water is a serious issue that affects several countries of the world. Its negative health impact is well documented in the East African Rift Valley, where water consumption with fluoride ( $F^{-}$ ) concentration greater than 1.5 mg/L can cause fluorosis to people. Within the framework of the European Union (EU) Horizon 2020 FLOWERED project, we first designed an effective defluoridation device based on innovative application of octacalcium phosphate (OCP) and then explored its acceptance within rural communities. The prototype (FLOWERED Defluoridator Device [FDD]) essentially is composed of a 20-L tank and a recirculating pump that guarantees the interaction between water and OCP. The device is powered by a car battery for a fixed pumping working time using a fixed amount of OCP for every defluoridation cycle. The results of tests performed in the rural areas of Tanzania show that a standardized use of the prototype can lower the dissolved $F^{-}$ from an initial concentration of 21 mg/L to below the World Health Organization (WHO) drinkable limit of 1.5 mg/L in 2 h without secondary negative effects on water quality. The approximate cost of this device is around US$220, whereas that of OCP is about $0.03/L of treated water. As with any device, acceptance requires a behavioral change on behalf of rural communities that needed to be investigated. To this end, we piloted a survey to explore how psychological and socioeconomic factors influence the consumption of fluoride-free water. Results show that the adoption of FDD and OCP is more appealing to members of the rural communities who are willing to pay more and have a high consumption of water. Moreover, we suggest that given the low level of knowledge about fluorosis diseases, the government should introduce educational programs to make rural communities aware of the negative health consequences. Integr Environ Assess Manag 2020;16:856-870. © 2020 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Keywords: Defluoridation method; Fluoride contamination of groundwater; Fluorosis; Octacalcium Phosphate (OCP); RANAS behavioral model.

Figure 1

Range and distribution of F⁻ contamination in 213 samples of natural water of EARV (Giaciri and Davies 1993; Tekle‐Haimanot et al. 2006; Ghiglieri et al. 2012; Olaka et al. 2016; Malago et al. 2017). Red squares represent the number of samples in each range. EARV = East African Rift Valley.

Figure 2

Sketch map of fluorotic regions of Tanzania, extrapolated from Malago et al. (2017). The red circle indicates the area of defluoridation tests and interviews.

Figure 3

The FLOWERED Defluoridator Device (FDD) and its recirculating water circuit.

Figure 4

Site of defluoridation experiment in rural areas around Mount Meru, Northern Tanzania. On the left side the FLOWERED Defluoridator Device (FDD) during defluoridation test and behind a typical water point used for human and animal consumptions.

Figure 5

The plots show the removal trend of dissolved F^– by 80 g of OCP in 20 L (S/L = 4 g/L) of 3 different natural waters (A = BUL, B = NGOb, C = KYU) in different step times and different initial F concentrations. BUL = Bule Bule spring, Tanzania; KYU = Ngarenanyuki borehole, Tanzania; NGO = Maji ya Chai spring, Tanzania; OCP = octacalcium phosphate.

Figure 6

XRD patterns of standard FAP (reference ICSD pattern n. 00‐015‐0876) (A); sorbent recovered after KYU experiment (B); sorbent after NGOb experiment (C); sorbent after BUL experiment (D); OCP before experiment (E). BUL = Bule Bule spring, Tanzania; FAP = fluorapatite; ICSD = Inorganic Crystal Structure Database; KYU = Ngarenanyuki borehole, Tanzania; NGO = Maji ya Chai spring, Tanzania; OCP = octacalcium phosphate.