Adsorption modelling and fixed-bed column study on milk processing industry wastewater treatment using chitosan zinc-oxide nano-adsorbent coated sand bed

doi:10.21203/rs.3.rs-2004838/v1

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Adsorption modelling and fixed-bed column study on milk processing industry wastewater treatment using chitosan zinc-oxide nano-adsorbent coated sand bed

https://doi.org/10.21203/rs.3.rs-2004838/v1

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published 27 Dec, 2022

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The milk processing industry produces a large amount of effluent that contains a lot of organic contaminants. Effluents, if improperly disposed of, can have serious environmental and public health consequences. The goal of this study is to create chitosan-zinc oxide nano-adsorbent coated sand (CZOCS) for getting rid of milk processing industry wastewater (MPIW) in a safe way. The developed adsorbent was characterised, and the presence of a zinc coating on the sand surface was confirmed. The goal of this study was to reduce organic contaminants in MPIW. There has been no evidence of CZOCS being used for industrial wastewater treatment to date. The effectiveness of the adsorbent and the performance of the column were examined using column adsorption experiments. The influence of filtration time and height of the bed on breakthrough curves was also investigated. Different kinds of kinetic models have been used to forecast breakthrough curves employing experimental data. Statistical and error function parameters were used to choose the best model. Among these models, the Thomas model was shown to be the best fit. Breakthrough and exhaustion times were shown to be higher as the bed height increased. The CZOCS has high reusability and could be used for up to six cycles of organic pollutant adsorption. Aside from that, novel CZOCS was used to clean real MPIW, making it one of the most promising adsorbents.

Chitosan zinc-oxide

Fixed-bed column

Kinetic models

Milk processing industry

Nano-adsorbent coated sand and Wastewater

Table 1 Parameters considered in fixed-bed column adsorption study for adsorption BOD and COD using CZOCS

Pollutant	Z	pH	C₀	m_adsorbent	Q_t	𝑉_𝐵	Q_y
BOD	10	6	500	118.00	51	30.60	10
	20	6	500	236.00
	30	6	500	354.00
	40	6	500	472.00
COD	10	6	3000	115.18	43	25.80
	20	6	3000	230.36
	30	6	3000	345.54
	40	6	3000	460.72

Z = Bed height (cm); C₀= Influent concentration (mg/L); m_adsorbent = Mass of adsorbent (g);
Q_y= Influent flow rate (mL/ min); Q_t = Total flow time of influent (h); 𝑉_𝐵= Total volume of influent sent (L).

Table 2 Physical and chemical characteristics of activated sand and CZOCS

Characteristics	Activated sand	CZOCS
BET surface area (m²/g)	2.87	6.20
Total zinc on coated sand (mg/g)	-	40.47
Acid-resistance [(A/B)×100] (%)	-	36.41
Alkali-resistance [(A/B)×100] (%)	-	3.11

A= Dissolved ZnO; B= Total ZnO

Table 3 Effect of CZOCS filter bed height on adsorption capacity of column for BOD and COD reductions at breakthrough and exhaustion points

Pollutant	Z (cm)	pH	C₀	m _adsorbent(g)	C_B(mg/L)	t_B (h)	C_E(mg/L)	t_E (h)	𝑞_𝐵 (mg/g)	q_E (mg/g)
Pollutant	Z (cm)	pH	C₀	m _adsorbent(g)	C_B(mg/L)	t_B (h)	C_E(mg/L)	t_E (h)	𝑞_𝐵 (mg/g)	q_E (mg/g)
BOD	10	6	500	118.00	100.05	8.23	475.00	27.47	313.84	611.04
	20			236.00	99.96	16.96	474.84	37.60	646.77	836.67
	30			354.00	100.00	20.69	475.13	45.27	789.18	1006.73
	40			472.00	99.96	28.28	475.20	49.00	1078.48	1089.63
COD	10	6	3000	115.18	599.83	11.86	2850.15	33.00	2779.58	4512.29
	20			230.36	600.37	15.29	2850.96	34.20	3584.32	4675.03
	30			345.54	601.11	25.04	2850.71	37.17	5867.84	5081.11
	40			460.72	599.92	30.27	2850.84	40.97	7095.08	5600.81

Z = Bed height, C₀= Influent concentration (mg/L), m_adsorbent = Mass of adsorbent (g), C_B= Break effluent concentration (mg/L) (Interpolated), t_B= Time to break through (h) (Interpolated), C_E= Exhaustion effluent concentration (mg/L) (Interpolated), t_E = Time to exhaustion (h) (Interpolated), q_B= Adsorption capacity at 20% breakthrough (mg/g), q_E= Adsorption capacity at 95% exhaustion (mg/g)

Table 4 Influence of bed height on kinetic parameters of adsorption models

Pollutant	Bed height (cm)	Thomas		Yoon-Nelson		Adams-Bohart
Pollutant	Bed height (cm)	𝐾_Th × 10^-4 (L/min mg)	𝑞₀ (mg/g)	𝐾_YN (min^-1)	𝜏 (h)	K_AB × 10^-4 (L/mg min)	𝑁₀ (mg/L)
BOD	10	39.63	661.60	0.198	15.61	66.05	13.20
	20	36.46	966.80	0.177	22.82	48.75	17.02
	30	35.49	1256	0.172	29.65	27.23	46.99
	40	34.43	1584	0.155	34.98	11.23	58.95
COD	10	7.54	4710	0.226	18.08	67.08	29.95
	20	7.07	5477	0.212	21.03	41.24	31.73
	30	6.92	6895	0.207	26.96	19.07	33.59
	40	5.39	7021	0.181	33.44	12.74	53.58

𝐾_Th = Thomas kinetic coefficient (mL/min mg), 𝑞₀ =Adsorption capacity (mg/g), 𝐾_YN= Yoon-Nelson constant (min^-1),
𝜏 = Time required for 50% adsorbate breakthrough (h), K_AB= Kinetic constant (L/mg min), N₀= Saturation concentration (mg/L)

Table 5 Effect of CZOCS filter bed on estimated values for statistical parameters of adsorption models

Pollutant	Bed height (cm)	Thomas				Yoon-Nelson						Adams-Bohart
Pollutant	Bed height (cm)	R²	Adj-R²	SSE	RMSE		R²	Adj-R²	SSE	RMSE	R²		Adj-R²	SSE	RMSE
BOD	10	0.9256	0.9241	26.30	0.7327		0.9256	0.9241	26.30	0.7327	0.8840		0.8844	0.670	0.1182
	20	0.9942	0.9941	2.528	0.2271		0.9942	0.9941	2.528	0.2271	0.8789		0.8788	0.209	0.0660
	30	0.9791	0.9787	7.416	0.389		0.9791	0.9787	7.416	0.3890	0.8975		0.8971	0.325	0.0823
	40	0.9541	0.9532	12.87	0.5124		0.9541	0.9532	12.87	0.5124	0.8771		0.8769	2.651	0.2350
COD	10	0.9823	0.9819	5.355	0.3614		0.9823	0.9819	5.355	0.3614	0.8729		0.8722	1.831	0.2113
	20	0.9939	0.9938	2.073	0.2249		0.9939	0.9938	2.073	0.2249	0.8719		0.8712	2.201	0.2317
	30	0.9356	0.9340	19.66	0.6924		0.9356	0.934	19.66	0.6924	0.8334		0.8318	6.439	0.3963
	40	0.8859	0.8831	27.95	0.8257		0.8859	0.8831	27.95	0.8257	0.8340		0.8324	7.464	0.4267

SSE= Sums of squared error, R²= Regression co-efficient, Adj-R²= Adjusted regression co-efficient, RMSE= Root mean square error

Table 6 Error function values of the adsorption models

Pollutant	Bede height	Thomas			Yoon and Nelson			Adams-Bohart
Pollutant	Bede height	ERRSQ	HYBRID	MPSD	ERRSQ	HYBRID	MPSD	ERRSQ	HYBRID	MPSD
BOD	10	198.30	1,33,852.60	65,587.77	2089.14	16,54,389.13	8,10,650.67	16,714.16	19,06,186.55	8,50,695.71
	20	12.86	502.08	246.02	707.20	3,13,202.42	75,853.59	8,318.51	17,36,113.70	93,431.41
	30	848.54	37,910.46	18,576.12	1931.54	14,60,925.70	1,53,469.18	29,897.77	1,44,36,630.01	70,73,948.70
	40	1954.3	12,16,442.34	5,96,056.75	2618.84	52,32,618.67	25,63,983.15	44,029.58	1,46,41,044.88	71,74,111.99
COD	10	8472.16	22,716.59	9313.8	26,538.78	2,05,793.81	84,375.46	40,852.64	63,81,25,658.31	26,16,31,519.91
	20	2231.99	21,746.72	8916.15	7091.47	1,40,247.33	57,501.40	26,824.83	67,49,711.28	27,67,381.62
	30	3380.07	29,125.45	15,272.52	19,265.41	2,11,622.24	86,765.11	31,854.07	1,13,74,239.64	46,63,438.25
	40	11,072.40	37,250.04	11,941.43	27,638.67	10,99,665.13	4,50,862.70	1,06,918.25	1,70,67,97,482.55	69,97,86,967.84

Table 7 Realistic treatment of MPIW by CZOCS

Effluent characteristics	Before treatment		After treatment		% RE		CPCB Standards
TDS (mg/L)	2533.18		674.24		73.38		<2100 mg/L
TSS (mg/L)	1670.09		194.35		88.36		<200 mg/L
Turbidity (NTU)	762.14		7.81		98.97		----------------
EC (µS/cm)	2.53		1.68		33.59		-----------------
pH	5.28		8.67				6.5 to 8.5
BOD (mg/L)	1005.16		93.66		90.68		< 100 mg/L
COD (mg/L)	10737.87		216.8		97.98		< 250 mg/L
Sulphate (mg/L)	217.87		2.22		98.98		< 2.8 mg/L
Phosphate (mg/L)	36.9		4.37		88.15		< 5.00 mg/L
Ammoniacal nitrogen (mg/L)	130.26		48.18		63.01		< 50 mg/L
Nitrate nitrogen (mg/L)	365.96		7.01		98.08		< 10 mg/L
Chloride (mg/L)	856.12		98.82		88.45		< 100 mg/L
Co-existing pollutants (mg/L)
Al		1.37		0.2		85.4
Cu		0.17		Nil		------
Fe		1.18		0.34		71.18
Mg		4.82		2.05		57.46
Mn		0.74		0.35		52.70
Ni		0.43		0.16		62.79
Sr		0.12		Nil		------
Zn		0.94		0.22		76.59

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Editorial decision: Major Revision
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Adsorption modelling and fixed-bed column study on milk processing industry wastewater treatment using chitosan zinc-oxide nano-adsorbent coated sand bed

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