Mechanisms and efficacy of disinfection in ceramic water filters: A critical review

Figures & data

Table 1. Exclusion criteria for review.

Ceramic Water Filters	Silver Disinfection	Non-Silver Disinfection
(1) Community User-based Field Studies (2) Studies that do not evaluate bacteria removal as part of the study	(1) Non-drinking-water- treatment applications (2) Non-nanoparticle silver (3) Photocatalytic research (4) Studies that do not evaluate bacteria removal as part of the study	(1) Non-drinking-water-treatment applications (2) Non-nanoparticles (3) Photocatalytic research (4) Studies that do not evaluate bacteria removal as part of the study (5) Silver-related nanoparticle research

Table 2. Summary of CWF pot parameters and performance outcomes.

Reference	Pot/ Disk	Minimum LRV^1	Maximum LRV	CWF^2/ CWF + Ag^3	%Firing Material	By Weight or Volume	Firing Material Sieve Size (<x)(mm)	Firing Material Type	Maximum Firing Temperature	Average Flowrate (L/h)
(Abebe et al., 2015)	POT	2.4	4.3	CWF	50	vol^5	0.595	SD^7	NR	1.7
(Bielefeldt et al., 2009)	POT	0.4	4.05	CWF	40	vol	1.2	SD	887	1.7-1.9
	POT	0.5	4.45*	CWF + Ag	40	vol	1.2	SD	887	0.8-1.8
(Brown, 2007)	POT	2	2.6	CWF + Ag	NR^4	NR	NR	RH^8	870	2
	POT	1.5	2.6	CWF	NR	NR	NR	RH	870	2
(Clark & Elmore, 2011)	POT	1.2	3.4	CWF	10	wt^6	4.8	SD	NR	1.2
(Guerrero-Latorre, et al., 2015)	POT	0.68	2.9	CWF	23	wt	0.25	RH	950	2.25
(Lantagne et al., 2010)	POT	3.1	6.1*	CWF + Ag	40	vol	NR	SD	NR	1.5
	POT	3	6	CWF + Ag	47	vol	0.0003	SD	NR	1.5
(Lucier et al., 2017)	POT	2	6.25	CWF	47	vol	0.0003	SD	870	0.8385
	POT	3	6.68	CWF + Ag	47	vol	0.0003	SD	870	1.129
(Mikelonis et al., 2016)	POT	1	1.5	CWF	20	wt	NR	RH	NR	3.6
	POT	1.9	4.5*	CWF + Ag	20	wt	NR	RH	NR	3.6
(Kowalski, 2008)	POT	0.446	3.753*	CWF	40	vol	NR	SD	NR	0.6-0.8
	POT	0.461	5.183*	CWF + Ag	40	vol	NR	SD	NR	0.6-0.8
(Panasewicz, 2011)	POT	2	2.3	CWF	NR	NR	NR	SD	NR	1.8
	POT	3.75	4	CWF + Ag	NR	NR	NR	SD	NR	2
	POT	1.95	2.95	CWF + Ag	24	wt	NR	RH	NR	1.4
(Soppe et al., 2015)	POT	1.5	3.5	CWF	24	wt	0.5	RH	885	5.21
	POT	2.1	4.5	CWF	26	wt	0.5	RH	885	9.194
	POT	1.5	4	CWF	28	wt	0.5	RH	885	14.725
	POT	1.5	3.25	CWF	29	wt	0.5	RH	885	16.535
	POT	1.5	3.75	CWF	31	wt	0.5	RH	885	19.75
(van Halem et al., 2017)	POT	0.8	1	CWF	24	wt	0.5	RH	NR	3.5
	POT	0.75	2	CWF	28	wt	0.5	RH	NR	11.5
	POT	0.75	2.5	CWF	31	wt	0.5	RH	NR	19
	POT	1.1	1.75	CWF + Ag	24	wt	0.5	RH	NR	3.5
	POT	0.85	1.5	CWF + Ag	28	wt	0.5	RH	NR	11.5
	POT	0.85	1.75	CWF + Ag	31	wt	0.5	RH	NR	19
(Varkey & Dlamini, 2012)	POT	NR	4*	CWF	50	NR	0.3	SD	850	NR
	POT	NR	4*	CWF	66	NR	0.3	SD	850	0.05
	POT	NR	4*	CWF	50	NR	0.6	SD	850	NR
	POT	NR	4*	CWF	66	NR	0.6	SD	850	0.11
	POT	NR	3.98	CWF	50	NR	0.9	SD	850	NR
	POT	NR	3.98	CWF	66	NR	0.9	SD	850	0.14
(Yakub et al., 2013)	POT	3.17	8.17*	CWF	50	vol	0.00107	SD	955	1.65
	POT	5.82	6.9	CWF	35	vol	0.00051	SD	955	0.5

* = 100% of E. coli was removed; 1 LRV = Log Removal Value; 2 CWF = Ceramic Water Filter (no silver); 3 CWF + Ag = Ceramic Water Filter (with silver); 4 NR = Not Reported; 5 vol = By Volume; 6 wt = By Weight; 7 SD = Sawdust; 8 RH = Rice Husks.

Table 3. Summary of CWF disk parameters and performance outcomes.

Reference	Pot/ Disk	Minimum LRV^1	Maximum LRV	CWF^2/ CWF + Ag^3	%Firing Material	By Weight or Volume	Firing Material Sieve Size (<x)(mm)	Firing Material Type	Maximum Firing Temperature	Average Flowrate (L/h)
(Rayner et al., 2013)	DISK	2.2	6.7*	CWF + Ag	15	wt	1.19	SD	550	0.03
(Rayner et al., 2017)	DISK	1.55	2.7	CWF	14	wt^6	0.6	SD^7	NR^4	0.02
	DISK	3.15	4.7	CWF	17	wt	0.6	SD	NR	0.02
	DISK	2.5	4.95	CWF	20	wt	0.6	SD	NR	0.03
	DISK	2.1	4.1	CWF	24	wt	0.6	SD	NR	0.21
	DISK	2.85	6.3	CWF	14	wt	1.19	SD	NR	0.03
	DISK	1.3	4.1	CWF	17	wt	1.19	SD	NR	0.1
	DISK	1.55	4.9	CWF	20	wt	1.19	SD	NR	0.125
	DISK	1	2.7	CWF	11	wt	2.38	SD	NR	0.07
	DISK	0.6	4.2	CWF	14	wt	2.38	SD	NR	0.0875
	DISK	1.3	2.4	CWF	18	wt	0.6	RH^8	NR	0.19
	DISK	0.6	2.8	CWF	19	wt	0.6	RH	NR	0.195
	DISK	0.8	1.8	CWF	25	wt	0.6	RH	NR	0.378
	DISK	0.7	2	CWF	8	wt	1.19	RH	NR	0.055
	DISK	0.8	2.2	CWF	12	wt	1.19	RH	NR	0.055
	DISK	0.7	1.5	CWF	17	wt	1.19	RH	NR	0.295
	DISK	0.55	2.5	CWF	10	wt	2.38	RH	NR	0.4
	DISK	0.5	2.2	CWF	17	wt	2.38	RH	NR	0.64
	DISK	0.35	1.6	CWF	25	wt	2.38	RH	NR	1.25
(Nunnelley et al., 2016)	DISK	4.8	5.9	CWF	NR	NR	0.841	SD	NR	NR
	DISK	4	5.6	CWF + Ag	NR	NR	0.841	SD	NR	NR
(Oyanedel-Craver & Smith, 2008)	DISK	3.1	5.4	CWF	10	wt	NR	F^9	900	1.17234
	DISK	5.3	6.3	CWF + Ag	10	wt	NR	F	900	1.17234
(Scannell, 2016)	DISK	3.25	4.1	CWF	NR^4	NR	0.297	SD^7	890	0.1785
	DISK	3.9	4.1	CWF	NR	NR	0.433	SD	890	0.132
	DISK	2	4.75	CWF	NR	NR	0.569	SD	890	0.1455
	DISK	2.75	3.6	CWF	NR	NR	0.705	SD	890	0.4275
	DISK	3.25	3.5	CWF	NR	NR	0.841	SD	890	0.309
	DISK	2.5	2.75	CWF	NR	NR	0.297	RH^8	890	0.148
	DISK	1.5	2.5	CWF	NR	NR	0.433	RH	890	0.144
	DISK	1.5	2.75	CWF	NR	NR	0.569	RH	890	0.222
	DISK	1.9	2.25	CWF	NR	NR	0.705	RH	890	0.445
	DISK	1.6	2.5	CWF	NR	NR	0.841	RH	890	0.328
(Servi et al., 2013)	DISK	2.25	3.98	CWF	20	wt^6	0.42	RH	NR	0.0134
	DISK	1.6	2.6	CWF	20	wt	0.59	RH	NR	0.0123
	DISK	2.3	3.65	CWF	20	wt	0.71	RH	NR	0.0783
	DISK	0.4	0.8	CWF	20	wt	0.85	RH	NR	1.92
	DISK	0.75	0.9	CWF	20	wt	1	RH	NR	1.5
(Zhang & Oyanedel-Craver, 2013)	DISK	NR	4.42	CWF + Ag	10	wt	NR	F^9	900	0.222
	DISK	4.22	4.34	CWF	10	wt	NR	F	900	0.222

* = 100% of E. coli was removed; 1 LRV = Log Removal Value; 2 CWF = Ceramic Water Filter (no silver); 3 CWF + Ag = Ceramic Water Filter (with silver); 4 NR = Not Reported; 5 vol = By Volume; 6 wt = By Weight; 7 SD = Sawdust; 8 RH = Rice Husks; 9 F = Flour.

Table 4. Dissolved silver (Ag+) concentration resulting from Ag-NP conversion at various pH and dissolved oxygen levels. (Data adapted from Liu and Hurt (2010)).

pH	Incubation Time (hours)	Dissolved Silver Concentration (mg/L)
Dissolved Oxygen Concentration: 9.1 mg/L
9	24	0.03
8	24	0.085
7.4	24	0.12
5.68	24	0.29
5.6	24	0.315
5	24	0.39
4	24	0.58
5.68	3	0.055
5.68	6	0.115
5.68	12	0.17
Dissolved Oxygen Concentration: <0.1 mg/L
5.68	3	0.005
5.68	6	0.002
5.68	12	0.002
5.68	24	0.002
4	24	0.05

Table 5. Summary of elution data from CWFs painted or co-fired with silver nanoparticles.

Reference	Mass of Silver Applied	Silver Application Method	Elution (mg/L)	Comment
(Oyanedel-Craver & Smith, 2008)	0.0028 − 0.036 mg Ag/g Filter	Painted	0.025–0.5	Water quality not reported
(van der Laan et al., 2014)	300 mL of 0.00215 M Solution	Painted	0.02–0.225	Natural surface water used for entire test
(Mikelonis et al., 2016)	0.018 mg Ag/g Filter	Painted	0–0.8	Influent water was either natural dugout water or natural rainwater. 4 different nanoparticle stabilizing agents evaluated
(Mittelman et al., 2015)	0.03 mg/g Filter	Painted	0.03–1	Influent water with 10 mM NaNO3. Filters painted with both AgNO3 and Ag-NP. Range is difference between initial and after 160 pore volumes of filtration
(Kowalski, 2008)	300 mL of 0.00215 M Solution	Painted	0.004–0.09	Water quality not reported. Results for Potters for Peace filters reapplied with silver in 2003. Experimentation conducted on filters before present study.
(Ehdaie et al., 2020)	9.28 mg Ag/g Filter Tablet	Co-Fired	0.15	Water chemistry not reported. Co-fired filters are tablets submerged in water. Applied silver concentration extrapolated.
	92.8 mg Ag/g Filter Tablet	Co-Fired	5
(Lyon-Marion et al., 2018)	0.05 mg Ag/g	Co-Fired	0.01125	10 mM NaNO3 in synthetic feed water Concentration within first 20 Pore Volumes of filtration. More silver released from filters painted with AgNO3 than Ag-NP (painted).
	0.03 mg Ag/g	Painted	0.1175–0.1593
(Ren & Smith, 2013)	2.76 mg Ag/g Filter	Co-Fired	0.003–0.004	Synthethic Hard Water used in feed (Alkalinity 110-120 mg/L CaCO3) Elution slightly increases when influent flowrate increases.
	27.6 mg Ag/g Filter	Co-Fired	0.009–0.015
	2.76 mg Ag/g Filter	Painted	0.008–11	Same influent water used as above. Elution decreases log-linearly, decreasing faster after influent flowrate increased.
	2.76 mg Ag/g Filter	Dipped	0.005–11
(Jackson & Smith, 2018)	24.8 mg/gFilter	Co-Fired	0.0025–0.1	Synthetic water tested with 10 mM phosphate buffer solution
	49.6 mg/g Filter	Co-Fired	0.0025–0.045
	4.96 mg Ag/g Filter	Painted	0.03–0.20
(Jackson et al., 2019)	0.1176 mg Ag/g Filter	Co-Fired	0.0005–0.0015	Natural groundwater used as influent. Effluent concentrations taken 14 h after filtration. Filter weight assumed from mass of clay used
	0.588 mg Ag/g Filter	Co-Fired	0.0025–0.008
	0.1176 mg Ag/g Filter	Painted	0.0115–0.028
(Ehdaie et al., 2017)	0.088 mg Ag/g Filter	Painted	0.007–0.046	Tested in natural water. Applied silver concentration extrapolated. Samples collected over 52 weeks in field study
	9.28 mg Ag/g Filter Tablet	Co-Fired	0.001–0.003	Tested in natural water. Data from tablets submerged in water. Samples collected over 52 weeks in field study
(Nunnelley et al., 2016)	5.35 mg/filter	Painted	0.025–2	Influent water with 10 mM phosphate buffer solution. Filter mass not reported. Silver concentration decreases exponentially with time
	26.75mg/filter	Co-Fired	0.002–0.2
	53.5 mg/filter	Co-Fired	0.002–0.03

Abebe, L. A. et al., (2015). Point-of-use removal of cryptosporidium parvus from water: independent effects of disinfection by silver nanoparticles and silver ions and by physical filtration in ceramic porous media. Environmental Science & Technology, 49, 12958–12967.

 PubMed Web of Science ®Google Scholar

Bielefeldt, A. R., Kowalski, K., & Summers, R. S. (2009). Bacterial treatment effectivenesss of point-of-use ceramic water filters. Water Research, 43(14), 3559–3565. https://doi.org/https://doi.org/10.1016/j.watres.2009.04.047

 PubMed Web of Science ®Google Scholar

Brown, J. (2007). Laboratory and field effectiveness of low-cost ceramic filters for drinking water treatment in Cambodia. In: Effectiveness of ceramic filtration for drinking water treatment in Cambodia. University of North Carolina. (PhD Thesis), pp. 51–110.

 Google Scholar

Clark, K. N., & Elmore, A. C. (2011). Bacteria removal effectiveness of ceramic pot filters not applied with colloidal silver. Water Supply, 11(6), 765–772. https://doi.org/https://doi.org/10.2166/ws.2011.012

 Google Scholar

Guerrero-Latorre, L., Rusiñol, M., Hundesa, A., Garcia-Valles, M., Martinez, S., Joseph, O., Bofill-Mas, S., & Girones, R. (2015). Development of improved low-cost ceramic water filters for viral removal in the Haitian context. Journal of Water, Sanitation and Hygiene for Development, 5(1), 28–39. https://doi.org/https://doi.org/10.2166/washdev.2014.121

 Web of Science ®Google Scholar

Lantagne, D., Klarman, M., Mayer, A., Preston, K., Napotnik, J., & Jellison, K. (2010). Effect of production variables on microbiological removal in locally-produced ceramic filters for Household water treatment. International Journal of Environmental Health Research, 20(3), 171–1619. https://doi.org/https://doi.org/10.1080/09603120903440665

 PubMed Web of Science ®Google Scholar

Lucier, K. J., Dickson-Anderson, S. E., & Schuster-Wallace, C. J. (2017). Effectiveness of silver and copper infused ceramic drinking water filters in reducing microbiological contaminants. Journal of Water Supply: Research and Technology, 66(7), 528–536.

 Web of Science ®Google Scholar

Mikelonis, A. M., Youn, S., & Lawler, D. F. (2016). DLVO approximation methods for predicting the attachment of silver nanoparticles to ceramic membranes. Langmuir : The ACS Journal of Surfaces and Colloids, 32(7), 1723–1731. https://doi.org/https://doi.org/10.1021/acs.langmuir.5b04675

 PubMed Web of Science ®Google Scholar

Kowalski, K. (2008). The disinfection efficiency of E. coli by the ceramic water filter. In: Removal of virus-sized particles and E. coli by the potters for peace ceramic water filter (pp. 114–208). Masters of Science.

 Google Scholar

Panasewicz, L. (2011). Evaluation of enhanced ceramic water filtration (ECWF) Systems for the removal of turbidity and bacteria for househods in developing countries. Master f Science Thesis at the University of Colorado at Boulder Department of Civil, Environmental and Architectural Engineering.

 Google Scholar

Soppe, A. I. A., Heijman, S. G. J., Gensburger, I., Shantz, A., van Halem, D., Kroesbergen, J., Wubbels, G. H., & Smeets, P. W. M. H. (2015). Critical Parameters in the production of ceramic pot filters for household water treatment in developing countries. Journal of Water and Health, 13(2), 587–599. https://doi.org/https://doi.org/10.2166/wh.2014.090

 PubMed Web of Science ®Google Scholar

van Halem, D., van der Laan, H., Soppe, A., & Heijman, S. (2017). High flow ceramic pot filters. Water Research, 124, 398–406. https://doi.org/https://doi.org/10.1016/j.watres.2017.07.045

 PubMed Web of Science ®Google Scholar

Varkey, A., & Dlamini, M. D. (2012). Point of use water purification using clay pot water filters and copper mesh. Water Sa, 38(5), 721–726. https://doi.org/https://doi.org/10.4314/wsa.v38i5.10

 Web of Science ®Google Scholar

Yakub, I., Plappally, A., Leftwich, M., Malatesta, K., Friedman, K. C., Obwoya, S., Nyongesa, F., Maiga, A. H., Soboyejo, A. B. O., Logothetis, S., & Soboyejo, W. (2013). Porosity, flow and filtration characteristics of frustum-shaped ceramic water filters. Journal of Environmental Engineering, 139(7), 986–1161. https://doi.org/https://doi.org/10.1061/(ASCE)EE.1943-7870.0000669

 Web of Science ®Google Scholar

Rayner, J., Zhang, H., Schubert, J., Lennon, P., Lantagne, D., & Oyanedel-Craver, V. (2013). Laboratory investigation into the effect of silver application on the bacterial removal efficacy of filter material for use on locally produced ceramic water filters for household drinking water treatment. ACS Sustainable Chemistry & Engineering, 1(7), 737–745. https://doi.org/https://doi.org/10.1021/sc400068p

 Web of Science ®Google Scholar

Rayner, J., Luo, X., Schubert, J., Lennon, P., Jellison, K., & Lantagne, D. (2017). the effects of input materials on ceramic water filter efficacy for household drinking water treatment. Water Supply, 17(3), 859–869. https://doi.org/https://doi.org/10.2166/ws.2016.176

 Google Scholar

Nunnelley, K., Smith, J. A., Smith, M. Y., & Samie, A. (2016). A new method for nanosilver application in ceramic water filters [Paper presentation]. s.l., s.n. https://doi.org/https://doi.org/10.1061/9780784479865.031

 Google Scholar

Oyanedel-Craver, V. A., & Smith, J. A. (2008). Sustainable colloidal-silver-impregnated ceramic filter for point-of-use water treatment. Environmental Science & Technology, 42(3), 927–933. https://doi.org/https://doi.org/10.1021/es071268u

 PubMed Web of Science ®Google Scholar

Scannell, L. W. (2016). Removal of bacteria. In: An analysis of performance criteria of porous ceramic water filter production methods. Proquest Dissertation Publication. (Thesis), pp. 59–75.

 Google Scholar

Servi, A. T., Kang, P. K., Frey, D., & Murcott, S. (2013). A holistic optimization framework for improving ceramic pot filter performance. San Jose, s.n.

 Google Scholar

Zhang, H., & Oyanedel-Craver, V. (2013). Comparison of the Bacterial removal performance of silver nanoparticles and a polymer based quaternary amine functiaonalized silsesquioxane coated point-of-use ceramic water filters. Journal of Hazardous Materials, 260, 272–277. https://doi.org/https://doi.org/10.1016/j.jhazmat.2013.05.025

 PubMed Web of Science ®Google Scholar

Liu, J., & Hurt, R. H. (2010). Ion release kinetics and particle persistence in aqueous nano-silver colloids. Environmental Science & Technology, 44(6), 2169–2175. https://doi.org/https://doi.org/10.1021/es9035557

 PubMed Web of Science ®Google Scholar

van der Laan, H., van Halem, D., Smeets, P. W. M. H., Soppe, A. I. A., Kroesbergen, J., Wubbels, G., Nederstigt, J., Gensburger, I., & Heijman, S. G. J. (2014). Bacteria and virus removal effectiveness of ceramic pot filters with different silver applications in a long term experiment. Water Research, 51, 47–54. Volume https://doi.org/https://doi.org/10.1016/j.watres.2013.11.010

 PubMed Web of Science ®Google Scholar

Mittelman, A. M., Lantagne, D. S., Rayner, J., & Pennell, K. D. (2015). Silver dissolution and release from ceramic water filters. Environmental Science & Technology, 49(14), 8515–8522. https://doi.org/https://doi.org/10.1021/acs.est.5b01428

 PubMed Web of Science ®Google Scholar

Ehdaie, B., Su, Y.-H., Swami, N. S., & Smith, J. A. (2020). Protozoa and virus disinfection by silver- and copper-embedded ceramic tables for water purification. Journal of Environmental Engineering, 146(4), 04020015. https://doi.org/https://doi.org/10.1061/(ASCE)EE.1943-7870.0001664

 Web of Science ®Google Scholar

Lyon-Marion, B. A., Mittelman, A. M., Rayner, J., Lantagne, D. S., & Pennell, K. D. (2018). Impact of chlorination on silver elution from ceramic water filters. Water Research, 142, 471–479. Volume https://doi.org/https://doi.org/10.1016/j.watres.2018.06.008

 PubMed Web of Science ®Google Scholar

Ren, D., & Smith, J. A. (2013). Retention and transport of silver nanoparticles in a ceramic porous medium used for point-of-use water treatment. Environmental Science & Technology, 47(8), 3825–3832. Volume https://doi.org/https://doi.org/10.1021/es4000752

 PubMed Web of Science ®Google Scholar

Jackson, K. N., & Smith, J. A. (2018). A new method for the deposition of metallic silver on porous ceramic water filters. Journal of Nanotechnology, 2018, 1–9. https://doi.org/https://doi.org/10.1155/2018/2573015

 Web of Science ®Google Scholar

Jackson, K. N., Smith, J. A., & Edokpayi, J. N. (2019). New method for the deposition of metallic silver and metallic copper on full-size porous ceramic water filters. Environmental Engineering Science, 36(1), 2–11. https://doi.org/https://doi.org/10.1089/ees.2018.0149

 Web of Science ®Google Scholar

Ehdaie, B., Rento, C. T., Son, V., Turner, S. S., Samie, A., Dillingham, R. A., & Smith, J. A. (2017). Evaluation of silver-embedded ceramic tablet as a primary and secondary point-of-use water purification technology in limpopo province. Plos One, 12 (1), e0169502. https://doi.org/https://doi.org/10.1371/journal.pone.0169502

 PubMed Web of Science ®Google Scholar