Expanded clay aggregates multi-functionality for water purification: Disinfection and adsorption studies

Figures & data

Table 1. Review of the usage of Expanded Clay Aggregate in Water Purification

Authors	Adsorbent	Contaminant(s) of study	Outcome
(Johansson, 1997)	LECA LECA+CaCO3	Phosphorus from wastewater	Higher P-sorption was observed for LECA+CaCO3 more than LECA
(Melin & Odegaard, 1999)	ECA	TOC, COD, colour and ozonated humid water	Removal rate between 57–75% for all experiment was achieved
(Nath & Goldberg, 2003)	Sintered LECA with addition of carbonates of calcium and or magnesium as flux materials	phosphorus	High phosphorus binding capacity with very good hydraulic conductivity
(Yaghi & Hartikainen, 2014)	LECA Al or Fe oxide coated LECA	Removal of Arsenite (AS^III) and impact of Phosphorous on removal efficiency	Enhanced sorption of AS^III at pH 7, 68 µg g^−1 and 114 µg g^−1 for LECA and Al or Fe modified LECA respectively
(Noori et al., 2014)	Natural LECA, H2O2 and MgCl2 modified LECA	Fluoride	At pH 6, fluoride was reduced from 10 g/l initial concentration to 0.39 mg/l, 1.0 mg/l and 0.075 mg/l for Natural LECA, H2O2 and MgCl2 modified LECA respectively at sorption capacities; 8.53 mg/g, 17.83 mg/g and 23.86 mg/g.
(Bahmanpour et al., 2017)	LECA granules and powder	COD, BOD, TSS, nitrate and phosphate in dairy industry wastewater	Efficiency of COD removed after 20hrs is 65.9% TSS& BOD had great reduction Nitrate = 63.87% Phosphate—reasonable reduction
(Łopata et al.,)	ECA	Phosphorous and Nitrogen on river water	12–16% removal efficiency for phosphorus and 5–6% for Nitrogen
(Kalhori, E.M., Al-Musawi, T.J., Ghahramani, E., Kazemian, H., Zarrabi, M., 2017)	LECA MgO-modified LECA	metronidazole (MNZ)	Removal efficiency of MNZ increased by 8% with addition of carbonates for LECA and total removal of MNZ for MgO/LECA. Maximun adsorption capacity under optimum conditions are 56.31 to 84.55 mg/g for LECA and MgO/LECA respectively
(Gisvold et al., 2018)	Zeolite containing LECA	Ammonium from domestic wastewater	High ammonium removal at high ammonium loading rate by a combination of nitrification and ion exchange

Table 2. Mixture Design and Description

Code	Clay (vol. %)	Rice Husk (vol.%)	Plasticizer (g)	Calcination Temperature (^0C)
GI-1	100% Kutigi	—	5	1100
GI-2	100% Kutigi	—	5	1200
GI-3	100% Minna	—	—	1100
GI-4	40% Kutigi + 40% Minna	20	—	1100
GI-5	40% Kutigi + 40% Minna	20	—	1200
GI-6	85% Kutigi	15	5	1100
GI-7	85% Kutigi	15	5	1200
GI-8	100% Minna	—	—	1200

Figure 1. Flow Process of Expanded Clay Production: (a) clay-rice husk mixture, (b) pelletized adsorbent prior to drying and firing, (c) firing in a locally constructed furnace (d) ball-shaped ceramic granulate with porous core, (e) ECA was cracked to expose the surface with internal pores

Figure 2. Surface image of ECA particle under a scanning electron microscope (SEM) showing cavities; (a) GI-1 exposes the stack sheet structure of kaolin; (b) GI-2; stack sheet morphology (c) GI-3—showing long, slender and fibrous aggregate of sillimanite and hexagonal flakes; (d) GI-4—mixed surfaces of sheet platelets and hexagonal flakes; (e) GI-5—mixed surfaces of sheet platelets and hexagonal flakes; (f) GI-6—multi-porous well defined flakes; (g) GI-7 multi-porous well defined flakes with more connected pores-; (h) GI-8—possess long, slender and fibrous aggregates of sillimanite with more pores than GI-3

Table 3. Surface area/pore analysis of the ECAs

Sample	Surface area (m^2/g)	Pore Volume (cc/g)	Pore Size (nm)
GI-1 GI-2 GI-3 GI-4 GI-5 GI-6 GI-7 GI-8	468.948 542.265 530.442 477.203 471.270 475.120 566.998 456.143	0.134 0.180 0.136 0.195 0.190 0.128 0.163 0.132	2.131 2.072 2.113 2.853 2.118 2.153 2.132 2.133

Figure 3. XRD plots of ECA at 1100°C and 1200°C showing mineralogy. (a) 100% Kutigi clay; (b) 100% Minna; (c) 40% Kutigi+40% Minna + 20% rice husk; (d) 85% Kutigi + 15% rice husk

Table 4. Physical Parameters of sterile water after soaking ECA adsorbents in it for 24 hours

Sample Name	GI-1	GI-2	GI-3	GI-4	GI-5	GI-6	GI-7	GI-8
Temp (^0C)	27.2	27.1	27.1	27.0	26.9	26.9	26.9	27.0
Conducti vity (µs/cm)	38.6	36.0	48.2	80.8	58.1	62.8	34.1	47.9
TDS (mg/l)	17.2	16.0	21.6	36.7	26.3	28.4	15.2	19.2
Salinity (%)	−0.2	−0.2	−0.1	−0.1	−0.1	−0.1	−0.2	−0.1
pH	6.6	8.0	9.2	8.8	9.2	7.5	8.3	9.0

Figure 4. The antibacterial efficiency of ECA adsorbent on E. Coli bacteria before filtration at 10⁵ CFU/ml raw water and after filtration. The adsorbents have excellent reusability as they maintained high disinfection efficiency after 6 recycling

Figure 5. Phosphate and Nitrate reduction efficiencies; (a) phosphate concentration reduction for adsorbents calcined to 1100°C: GI-1 > GI-6 > GI-3 > GI-4; (b) Phosphate concentration reduction for adsorbents calcined to 1200°C: GI-2 > GI-7 > GI-8 > GI-5; (c) Nitrate concentration reduction for adsorbents calcined to 1100°C: GI-1 > GI-3 > GI-4 > GI-6; (d) Nitrate concentration reduction for adsorbents calcined to 1200°C: GI-2 > GI-5 > GI-8 > GI-7

Figure 6. Adsorption of Pb (II) and As (III) on ECA, 25°C and pH 5.0 (a, c) Langmuir adsorption isotherms for Pb and As respectively; (b, d) Freundlich adsorption isotherms for Pb and As respectively: (e, f) Adsorption kinetics for Pb and As respectively

Figure 7. Effect of pH on adsorption; (a) Pb II; (b) As III. Experimental conditions: temperature 27 °C, contact time 40 min, adsorbent dose 0.1 g/100 ml

Figure 8. Effect of adsorbent dose on adsorption of Pb II and As III. Experimental conditions: temperature 27 °C; contact time 40 min; pH 6; (a) adsorbents are calcined to 1100°C; (b) adsorbents are calcined to 1200°C

Figure 9. Cyclic experiments for the Pb (II) adsorption shaken for 30 minutes at 25°C regenerated with 0.01 M Na₂ EDTA

Figure 10. Cyclic adsorption experiments for As (III) shaken for 30 minutes at 25°C regenerated with 0.1 M NaOH

Johansson, L. (1997). The use of leca (light expanded clay aggregates) for the removal of phosphorus from wastewater. Water Science and Technology, 35(5), 87–93. https://doi.org/10.1016/S0273-1223(97)00056-5

 Web of Science ®Google Scholar

Melin, E. S., & Odegaard, H. (1999). Biofiltration of Ozonated Humid Water in Expanded Clay Aggregate Filters. Water science and technology, 40(9), 165–172. https://doi.org/10.1016/S0273-1223(99)00653-8

 Web of Science ®Google Scholar

Nath, G. M., & Goldberg, J. B. (2003). Light Expanded Clay aggregates for Phosphorus Removal.U.S. Patent No. 6,627,083. Washington, DC: U.S. Patent and Trademark Office. (pp. 12).

 Google Scholar

Yaghi, N., & Hartikainen, H. (2014). Effect of Phosphate on the Sorption of Arsenite onto Aluminum – or Iron – Oxide Coated Light Expanded Clay Aggregate (LECA)., 3(4), 11–17.

 Google Scholar

Noori, M., Kazemian, H., Ghahramani, E., & Amrane, A. (2014). Defluoridation of water via light weight expanded clay aggregate (LECA): Adsorbent characterization, competing ions, chemical regeneration, equilibrium and kinetic modeling. Journal of the Taiwan Institute of Chemical Engineers, 49, 19–26. https://doi.org/10.1016/j.jtice.2014.02.009

 Google Scholar

Bahmanpour, H., Habashi, R., & Hosseini, S. M. (2017). Investigating the Efficiency of Lightweight Expanded Clay Aggregate (LECA) in Wastewater Treatment of Dairy Industry. Anthropogenic Pollution Journal, 1(1), 9–17. https://doi.org/10.22034/apj.2017.1.1.917

 Google Scholar

Łopata, M., Czerniejewski, P., Wiśniewski, G., & Czerniawski, R. (2017). The Use of Expanded Clay Aggregate for the Pretreatment of Surface Waters on the Example of a Tributary of Lake Klasztorne Górne in Strzelce Krajenskie. Limnological Review, 17(1), 3–9. https://doi.org/10.1515/limre-2017-0001

 Google Scholar

Gisvold, B., Ödegaard, H., & Föllesdal, M. 2018. Nitrate and phosphate levels positively affect the growth of algae species found in Perry Pond, November, 107–114. https://iwaponline.com/wst/article-pdf/41/9/107/427700/107.pdf

 Google Scholar

Data Availability Statement

The data that support the findings of this study are available from the corresponding author, G.O. Ihekweme, upon reasonable request https://repository.aust.edu.ng//xmlui/gina ihekweme.