Results of the First Improvement Step Regarding Removal Efficiency of Kanchan Arsenic Filters in the Lowlands of Nepal—A Case Study
Abstract
:1. Introduction
2. Materials and Methods
3. Results and Discussion
- CS = Concrete square filter;
- PR = Plastic round filter;
- Res. = Residence time in minutes.
4. Future Improvements
- (i)
- Installation of the upper sand bed for all filters in order to prevent the nails from drying and moving while pouring ground water as well as diminishing the flow rate;
- (ii)
- Regulation of the outflow by placing a tap at the outlet or by raising the outlet from the plastic bucket to above the level of the nail bed;
- (iii)
- Replacing nails and sand on a regular basis;
- (iv)
- Monitoring of the water quality and filter conditions by trained local inhabitants;
- (v)
- Proper and regularly repeated instructions for the users.
5. Conclusions
- (i)
- Geological background, e.g., Fe and As concentrations of the ground water itself [9];
- (ii)
- Condition and aging of the material intended to remove As efficiently: nails and sand. Both nails and sand must be changed regularly. Sand, especially, has to be replaced on a yearly base (see filter SN51) in order to maintain its absorbing capacity;
- (iii)
- The nails of the nail bed have to be wet constantly but not immersed in water in order to promote oxidation and formation of Fe(III)hydr(oxides);
- (iv)
- Prevention of the formation of holes and dents within the nail bed, as the ground water has to be precluded to flow through the nail bed in nail-free channels. The ground water has to be poured slowly and carefully in order to prevent moving of the nails;
- (v)
- Sufficient contact time between ground water and nails. A high concentration of As and a low concentration of Fe requires an increased contact time.
Funding
Data Availability Statement
Acknowledgments
Conflicts of Interest
References
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Tube Well | Fe (mg/L) | As (µg/L) | Res. Time Original | R1 Original | R2 Original | OR Original | Fe (mg/L) | As (µg/L) | Res. Time New 2018 | R1 New 2018 | R2 New 2018 | OR New 2018 | Fe (mg/L) | As (µg/L) | Respective Time New 2 2019 | R1 New 2 2019 | R2 New 2 2019 | OR New 2 2019 |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
SN14 CS | 1.44 | 622.6 | 15.1 | 30.1 | −25.0 | 12.6 | 1.15 | 644.4 | 7.8 | 18.0 | 89.6 | 91.5 | 1.30 | 640.6 | 15.5 | 14.3 | 31.3 | 41.2 |
SN26 PR | 3.75 | 266.3 | 8.1 | 54.5 | −10.4 | 49.8 | 1.70 | 326.3 | 7.8 | 10.3 | 70.7 | 73.7 | 1.74 | 328.7 | 3.9 | 22.4 | 52.5 | 63.1 |
SN33 PR | 2.60 | 363.6 | 12.9 | 15.6 | 51.2 | 58.8 | 1.86 | 363.4 | 16.1 | 17.7 | 37.0 | 48.1 | 1.60 | 401.6 | 17.0 | 27.7 | 27.9 | 47.9 |
SN35 PR | 1.98 | 354.7 | 6.8 | 43.7 | 32.1 | 61.8 | 1.54 | 333.3 | 14.2 | 12.1 | 50.1 | 56.1 | 1.68 | 332.3 | 13.6 | 48.7 | 20.0 | 58.9 |
SN51 PR | 1.23 | 200.1 | 12.0 | 8.4 | 24.6 | 31.0 | 0.30 | 239.8 | 5.4 | 7.5 | 92.7 | 93.2 | 1.07 | 259.8 | 4.7 | 17.8 | 46.7 | 53.7 |
SN53 PR | 1.50 | 260.8 | 11.0 | 30.1 | 27.7 | 49.6 | 0.78 | 220.6 | 12.1 | 24.7 | 21.8 | 36.6 | 1.19 | 229.8 | 10.9 | 13.4 | 26.8 | 36.6 |
SN54 PR | 1.62 | 281.7 | 9.8 | 17.3 | 35.6 | 46.7 | 1.53 | 277.8 | 9.7 | 22.9 | 40.2 | 54.0 | 1.21 | 265.2 | 21.3 | 39.3 | 3.8 | 41.6 |
SN55 CS | 1.88 | 278.4 | 6.6 | 15.7 | 46.1 | 54.6 | 0.64 | 215.5 | 38.8 | 52.0 | 23.2 | 63.1 | 1.63 | 232.5 | 22.0 | 5.0 | 62.3 | 64.2 |
SN57 PR | 2.73 | 179.6 | 26.4 | 37.9 | 44.8 | 65.7 | 2.31 | 188.1 | 29.4 | 28.2 | 49.3 | 63.6 | 2.12 | 214.4 | 29.4 | 35.4 | 47.3 | 66.0 |
SN62 PR | 1.74 | 222.2 | 12.0 | 139 | 48.4 | 55.6 | 1.57 | 208.9 | 12.6 | 44.5 | 43.1 | 74.0 | 1.71 | 208.6 | 9.0 | 22.7 | 73.5 | 79.5 |
SN63 PR | 2.25 | 158.3 | 5.7 | 28.0 | 90.5 | 93.2 | 2.60 | 96.54 | 14.9 | 18.8 | 67.9 | 73.9 | 2.29 | 98.58 | 12.3 | 28.5 | 59.4 | 70.9 |
SN64 PR | −0.27 | 100.66 | 9.7 | −71.2 | 39.5 | −3.5 | 2.21 | 164.8 | 13.6 | 23.0 | 59.6 | 68.9 | −0.01 | 14.54 | 10.3 | −17.1 | −70.5 | −99.6 |
SN66 PR | 2.87 | 265.6 | 10.0 | 55.3 | −2.4 | 54.2 | 2.65 | 257.3 | 13.6 | 25.4 | 48.9 | 61.9 | 2.15 | 242.8 | 14.2 | 34.3 | 37.0 | 58.6 |
SN67 CS | 1.26 | 169.0 | 6.1 | 31.7 | 11.1 | 39.3 | 1.77 | 145.1 | 24.3 | 74.5 | 80.7 | 1.16 | 155.4 | 5.7 | 21.5 | 72.6 | 78.5 | |
SN68 PR | 1.18 | 192.9 | 6.6 | 15.3 | 48.0 | 56.0 | 1.08 | 169.0 | 18.1 | 6.6 | 40.7 | 44.7 | 0.002 | 192.9 | 25.8 | 17.5 | 11.8 | 27.2 |
SN69 PR | −0.27 | 280.3 | 19.8 | −80.8 | 13.5 | −56.5 | 0.85 | 398.6 | 23.9 | −7.0 | 22.0 | 16.6 | 0.79 | 471.8 | 12.9 | 18.7 | 54.0 | 62.6 |
SN70 CS | 0.95 | 502.1 | 5.8 | 10.7 | 29.0 | 36.6 | 0.40 | 470.7 | 6.5 | 1.6 | −9.9 | −8.1 | 0.53 | 480.1 | 5.2 | 2.0 | −6.0 | −3.9 |
SN72 PR | 2.39 | 205.4 | 29.8 | 10.0 | 42.6 | 48.3 | 1.74 | 204.8 | 24.5 | 17.5 | 68.2 | 73.8 | 1.63 | 197.1 | 26.5 | 20.0 | 60.3 | 68.3 |
SN76 PR | 1.17 | 140.5 | 8.7 | 7.3 | −1.6 | 5.8 | 0.34 | 20.0 | 8.4 | −24.8 | −61.4 | −101.4 | 0.88 | 139.1 | 9.0 | 16.3 | 66.6 | 72.0 |
SN56 PR | 1.40 | 145.1 | 5.2 | 9.9 | 76.5 | 78.8 | 1.40 | 145.1 | 5.8 | 11.2 | 78.1 | 80.6 | 1.36 | 165.1 | 10.3 | 8.3 | 32.7 | 38.3 |
SN73 PR | 1.94 | 446.6 | 10.3 | 9.7 | 58.8 | 62.7 | 1.94 | 446.6 | 11.0 | 45.3 | 33.0 | 63.3 | 4.22 | 556.9 | 8.4 | 92.0 | −133.0 | 81.3 |
SN1A PR | 2.11 | 44.57 | 9.7 | 48.8 | 75.1 | 87.2 | 2.11 | 44.57 | 10.3 | 26.4 | 82.0 | 86.7 | 4.59 | 96.23 | 9.7 | 77.2 | 41.4 | 86.6 |
SN1B PR | 1.03 | 200.1 | 24.8 | 7.3 | 50.3 | 54.0 | 1.03 | 200.1 | 25.8 | 11.8 | 45.1 | 51.6 | 0.80 | 208.0 | 21.7 | 8.3 | 20.8 | 27.4 |
SN1C CS | 5.27 | 114.3 | 29.1 | −4.6 | 91.8 | 91.5 | 5.27 | 114.3 | 20.2 | 23.4 | 89.9 | 92.3 | 6.40 | 136.2 | 35.5 | 34.9 | 92.4 | 95.0 |
SN2A CS | 1.03 | 161.7 | 11.6 | 22.0 | 35.5 | 49.6 | 1.03 | 161.7 | 12.4 | 12.6 | 46.1 | 52.9 | 1.17 | 166.9 | 10.8 | 6.4 | −52.3 | −42.5 |
SN2B CS | 1.03 | 161.7 | 7.0 | 14.6 | 51.1 | 58.2 | 1.03 | 161.7 | 6.0 | 18.7 | 55.3 | 63.7 | 1.17 | 166.9 | 3.9 | 50.8 | −73.9 | 14.4 |
SN3A CS | 1.77 | 145.1 | 6.8 | 6.3 | 76.6 | 78.1 | 1.77 | 145.1 | 7.1 | 21.6 | 73.9 | 79.6 | 1.24 | 152.0 | 6.8 | 15.9 | −60.8 | −35.2 |
SN4A CS | 1.27 | 735.6 | 32.6 | 17.3 | 96.5 | 97.1 | 1.27 | 735.6 | 31.7 | 39.4 | 95.1 | 97.1 | 0.38 | 634.3 | 32.6 | 12.5 | 93.4 | 94.3 |
SN4B CS | 0.05 | 144.8 | 7.0 | 18.2 | 63.7 | 70.3 | 0.05 | 144.8 | 7.0 | 22.2 | 47.3 | 59.1 | 0.05 | 142.5 | 7.0 | 7.0 | 12.3 | 18.5 |
SN4C PR | 0.19 | 119.5 | 3.5 | 8.1 | 56.1 | 59.7 | 0.19 | 119.5 | 3.9 | 22.6 | 48.1 | 59.8 | 0.20 | 108.6 | 3.9 | 33.8 | 37.2 | 58.4 |
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Mueller, B. Results of the First Improvement Step Regarding Removal Efficiency of Kanchan Arsenic Filters in the Lowlands of Nepal—A Case Study. Water 2021, 13, 1765. https://doi.org/10.3390/w13131765
Mueller B. Results of the First Improvement Step Regarding Removal Efficiency of Kanchan Arsenic Filters in the Lowlands of Nepal—A Case Study. Water. 2021; 13(13):1765. https://doi.org/10.3390/w13131765
Chicago/Turabian StyleMueller, Barbara. 2021. "Results of the First Improvement Step Regarding Removal Efficiency of Kanchan Arsenic Filters in the Lowlands of Nepal—A Case Study" Water 13, no. 13: 1765. https://doi.org/10.3390/w13131765