Table 2.

List of plant material investigated as natural coagulants to remove turbidity. RT = room temperature, n.a. = not available

Natural coagulant	Test sample of water	Type of extraction	Contact time	Initial turbidity	Temperature (°C)	Optimum coagulant dose (g/L)	Optimum pH	Turbidity removal efficiency (%)	References
Abelmoschus esculentus	Palm oil mill effluent	Fresh Okra	Fast stirring for 2 min Slow stirring of 60 rpm for 30 min	7700—13,600	n.a	116	3.2	94.97	(Khoo et al., 2021)
Trigonella foenumgraecum		Fenugreek seeds				4.1
Trigonella foenum-graecum	Palm oil mill effluent	Fenugreek seeds	Fast stirring for 2 min Slow stirring of 60 rpm for 30 min	7700—22,200	n.a	0.409	3.17	94.97	(Mohammad Lanan et al., 2020)
Abelmoschus escluentus		Fresh Okra				5.77
Citrus aurantiifolia and Citrus microcarpa	Synthetic water using kaolin	Peel extract	Fast stirring of 120 rpm for 3 min Slow stirring of 50 rpm for 20 min	115.83	n.a	0.05	6.5	77.60	(Dollah et al., 2020)
Tacca leontopetaloides	Raw leachate	T. leontopetaloides tuber	Fast stirring of 200 rpm for 4 min Slow stirring of 40 rpm for 30 min	218	RT	0.24	3	76.99	(Makhtar et al., 2021)
M. oleifera	Wastewater treatment plant	M. oleifera seeds	-	287 ± 3	22.4	15	6.8	97.30	(Vunain et al., 2019)
	Surface water	M. oleifera seeds	Fast stirring of 120 rpm for 2 min Slow stirring of 50 rpm for 30 min	n.a	27 ± 0.5	0.15	6.2	Rainy season 87.8 to 93.3 Dry season 85.7 to 94.3	(Nhut et al., 2020)
	Raw water	M. oleifera seeds	Initial stirring of 50 rpm for 15 min Fast stirring of 150 rpm for 10 min Slow stirring of 50 rpm for 15 min	15.6 ± 0.64	RT	1.64	n.a	82.04	(Pandey et al., 2020)
M. oleifera	River water Pond water Ground water	M. oleifera seeds	n.a	Stream: 20.5 Pond: 125 Well: 10.7	n.a	4.5 6 2.6	6.8 5.3 7	95.56 66.96 90.37	(Egbuikwem and Sangodoyin, 2013)
M. oleifera	River water	M. oleifera pods	Fast stirring of 200 rpm for 2 min Slow stirring of 40 rpm for 5 min	632 ± 3.20	n.a	12	7.45	99.20	(Jodi et al., 2012)
M. oleifera	Ground water	M. oleifera seeds	Stirring for 45 min at 110–120 rpm	12.4 ± 0.02	n.a	15	8	75	(Mangale Sapana et al., 2012)
M. oleifera	River water	M. oleifera seeds	Between 5 and 60 min	123.3	n.a	1.6	7.5	> 85	(Sánchez-Martín et al., 2012)
M. oleifera	Pond water	M. oleifera seeds	n.a	130.1	27	n.a	7.6	76.36	(Yongabi et al., 2011)
M. oleifera	River water	M. oleifera seeds	n.a	n.a	10	5	7.5	71.02	(Beltrán-Heredia and Sánchez-Martín, 2009)
M. oleifera	Tap water (kaolin)	M. oleifera seeds	n.a	105	20 ± 1	1	7.6	93.33	(Ndabigengesere and Subba Narasiah, 1998)
Cassava peels	Wastewater treatment plant	Cassava peels starch	n.a	194 ± 14.43	n.a	44.8	6	60.19	(Kumar et al., 2020)
Quercus branti	Synthetic turbid water using kaolin suspension	Oak fruit	Fast stirring of 200 rpm for 1 min Slow stirring of 70 rpm for 30 min	20 to 250	RT	6.22	n.a	63.5	(Jamshidi et al., 2020)
Pistachio green	Synthetic turbid water using kaolinite	Pistachio green hull	n.a	300	n.a	5	5	88	(Nasrabadi et al., 2020)
Guazuma ulmifoliya	Synthetic dairy wastewater	G. ulmifolia stem barks	Fast stirring of 200 rpm for 1 min Slow stirring of 30 rpm for 15 min	698 ± 9.4	n.a	77.58	5	95.8	(Muniz et al., 2020)
Cactus	Wastewater treatment plant	Cactus pads	Fast stirring of 160 rpm for 5 min Slow stirring of 40 rpm for 25 min	50	17 ± 1	2.8	12	98.33	(Ayat et al., 2021)
Cactus opuntia (ficus-indica)	Tailings pond water	Cactus mucilage	n.a	80 ± 2	23 ± 1	0.5	6	98	(Wan et al., 2019)
						0.5	8.89	91.49
Cactus opuntia (ficus-indica)	Stimulated industrial water-based paint wastewater	Eluted on 3 N NaCl	n.a	n.a	n.a	n.a	n.a	78.43	Vishali and Karthikeyan (2015b)
						30	n.a	80.44
						n.a	5	99.67
						100	n.a	94
Opuntia ficus-indica	Oil sands process-affected water	Cladodes of Opuntia ficus indica	n.a	n.a	n.a	1.5	7–8	98	(Choudhary et al., 2019b)
Pine cone	Synthetic turbid water	Pine cones	n.a	67, 69, 71 and 75	n.a	0.5	2	77	(Hussain et al., 2019)
							12	76
Cicer arietinum	Palm oil mill effluent	Chickppea seeds	n.a	17,600	n.a	2.6	6.69	86	(Choong Lek et al., 2018)
Flower of Musa sp.	Effluents from the processing of iron ore	Extraction of tannins	Fast stirring for 2 min Slow stirring for 15 min	86,500	n.a	8.5	6.25	97.58	(Vaz et al., 2018)
Maerua decumbent	Paint industry wastewater	M. decumbent roots	Fast stirring of 180 rpm for 3 min Slow stirring of 20 rpm for 30 min	2575	20 ± 2	1	5.56	99.24	(Kakoi et al., 2017)
Corn and potato	Synthetic turbid water using kaolin suspension	Conventional starches	Fast stirring of 100 rpm for 2 min Slow stirring of 40 rpm for 20 min	165 ± 5	25 ± 1	0.12	4	50	Choy et al. (2016)
Plantago ovata	Raw surface water	Plantago seeds extracted by using FeCl3-induced extract	Fast stirring of 120 rpm for 1 min Slow stirring of 45 rpm for 10 min	76	24	0.025	< 8	95.6	Ramavandi (2014)