Treatment of coffee processing wastewater using Moringa stenopetala seed powder: Removal of turbidity and chemical oxygen demand

Figures & data

Figure 1. Wastewater before and after treatment with different adsorbent dose (i.e. 20, 30, 40, 50, 60, 70, 80, 90, 100, and 110 mg L⁻¹ adsorbent dose from left to right respectively).

Figure 2. SEM surface image of the Moringa stenopetala seed powder.

Figure 3. XRD pattern of Moringa stenopetala seed powder.

Table 1. Freundlich and Langmuir adsorption isotherm constants

Parameters		Langmuir constants			Freundlich constants
	Q^o (mg/g)	RL	b (1/mg)	R^2	RF (1/mg)	N	R^2
COD	714.3	0.031	0.006	0.9958	109.4	1.3	0.9814
Turbidity	87.125	0.0084	1.524	0.999	88.53	6.5	0.991

Where, b is the Langmuir constants and C_o the initial COD level (mg/L). R_L value indicates the type of isotherm.

Table 2. Removal efficiency of physical parameters from coffee processing wastewater through adsorption by M. stenopetala seed powder along with world health organization (WHO) permissible limits discharged to water system

Physical parameters		Colour	Odour	Temp. (^oC)	pH	TS (mg L^−1)	TSS (mg L^−1)	TDS (mg L^−1)
Before treatment		Dark brown	Unpleasant	28	3.7	4,125	1,450	2,660
After treatment	15 min	Light greenish brown	Pleasant	–	4.6	3,567	1,215	2,335
	30 min	Light greenish brown	Pleasant	–	5.4	835	345	498
	45 min	Light greenish brown	Pleasant	–	6.2	467	109	362
	60 min	Light greenish brown	Pleasant	–	6.7	200	67	138
	75 min	Light greenish brown	Pleasant	–	6.9	80	18	66
	90 min	Light greenish brown	Pleasant	–	7.1	56	15	46
	105 min	Light greenish brown	Pleasant	–	6.9	43	7	29
	120 min	Light greenish brown	Pleasant	–	7.1	15	na	13
	135 min	Light greenish brown	Pleasant	–	7.0	na	na	na
	150 min	Light greenish brown	Pleasant	25.5	7.0	na	na	na
WHO permissible limit		Colorless	Odorless	20–25	6.8–8.5	—	35	1500

Note: Temp. = Temperature, TS = Total solid, TSS = Total suspended solid and TDS = Total dissolved solid, na = not available

Table 3. Removal efficiency of chemical parameters of coffee processing wastewater through adsorption by M. stenopetala seed powder along with WHO permissible limits discharged to the water system

Chemical parameters		DO (mg L-1)	Electrical Conductivity (µS cm^−1)	COD (in mg L^−1)
Before treatment		3	Innumerable	12,905
After treatment	15 min	6	800	2,269
	30 min	6.5	350	978
	45 min	6.7	150	128
	60 min	7	80	121
	75 min	7.2	70	123
	90 min	7.5	55	122
	105 min	8.1	38	121
	120 min	8.4	29	122
	135 min	8.2	21	122
	150 min	8.1	12	121
WHO permissible limit		6–8.5	750	150

Table 4. Removal efficiency of bacterial load of coffee processing wastewater through adsorption by M. stenopetala seed powder along with WHO permissible limits discharged to the water system

Biological parameters (cfu mL^−1)		AMB	TC	FC
Before treatment		TNC	TNC	1.5 x 10^4
After treatment	15 min	2.50 x 10^9	2.5 x 10^6	5.0 x 10^3
	30 min	1.8x 10^8	1.1 x 10^5	1.0 x10^3
	45 min	7.3 x 10^6	3.0 x 10^3	2.0 x 10^2
	60 min	1.5 x 10^5	1.4 x 10^2	1.0 x 10^1
	75 min	3.0 x 10^3	–	–
	90 min	1.0 x 10^2	–	–
	105 min	–	–	–
	120 min	–	–	–
	135 min	–	–	–
	150 min	–	–	–
WHO permissible limit		1 x 10^3	Zero	Zero

AMB = Aerobic mesophilic bacteria; TC = Total coliform; FC = Feacal coliform; TNC = Too numerous to count

Figure 4. Effect of experimental parameters (a) adsorbent dose and (b) contact time on removal efficiency of turbidity and COD.