Phytoremediation of Industrial Wastewater using Water Hyacinth 239

through food-chain magnification (Rai and Tripathi 2008, Pramanik et al. 2021). Different removal

methods like electrolysis, ion exchange, precipitation, absorption and reverse osmosis are used

to remove heavy metals. These methods are quite expensive and are comparatively ineffective,

producing a large amount of waste that is difficult to dispose of. The development of cost-effective

and alternative methods for the removal of toxic substances from wastewater is a necessity (Rai and

Tripathi 2007). The use of living plants to remove toxic substances from the water and soils could

be one of the alternatives and viable processes (Rai 2009). Plants have the capability to accumulate

metals (Co, Ca, Fe, Cu, Ni, Mo, Mg, Mn, Na, Ni, Se, V and Zn) and non-essential metals (Al, As, Au,

Cd, Cr, Hg, Pb, Pd, Pt, Sb, Te, Tl and U) under different concentration (Djingova and Kuleff 2000).

Three different patterns have been observed during the uptake of heavy metals by plants (i). True

exclusion (metals are limited during entering), (ii). Shoot exclusion (root accumulates the metals

but restricts translocation to the shoot system), and, (iii). Accumulation (plant parts concentrate the

metals) (Zavoda et al. 2001, Kamal et al. 2004).

Textile wastewaters are a serious polluting threat as they contaminate the environment; without

proper treatment, they lead to irreversible persistent changes in the environment. Textile wastes

include dyes and have high Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD),

Total Suspended Solids (TSS), Total Nitrogen (TN), heavy metals, phosphates and greases, etc.

Dyes are well-known toxins which can directly affect the aquatic ecosystem (Ekanayake et al. 2021).

The pulp and paper industries are one of the major causes of aquatic pollution in India (Saadia

and Ashfaq 2010, Singh et al. 2022). The major pollutants in paper and pulp industries are high in

TSS, Total Dissolved Solids (TDS), Total Nitrogen (TN), adsorbable organic halides (AOX), heavy

metals, as well as have high COD. A large amount of this contaminated wastewater is generated and

discharged during the paper-making process, which negatively impacts wild and human life. The

impurities should be removed or minimized before being discharged into the environment (Singh

et al. 2022, Ashrafi et al. 2015).

Similar to the textile and paper industries, the Indian dairy industry generates wastewater which

is a major cause of concern. Six to seven liters of effluent is generated while processing one liter

of milk (Porwal 2015). High levels of BOD, COD, hardness, along with ions like K⁺, Na⁺ and Cu²⁺

ions are detected in water close to the industry due to inappropriate disposal of effluents in rivers

(Kaur et al. 2018). To reduce the release of these environmental pollutants from such industries,

many researchers are trying to develop sustainable, cost-effective treatment practises for cleaning

the industrial effluents.

Phytoremediation is one such technique being researched to clean up wastewater generated from

industrial and domestic discharge for consumption of fresh water. Eichhornia crassipes, i.e., Water

Hyacinth (WH) is one of the promising plants popularly tested for phytoremediation of various

wastewater streams (Koley et al. 2022). This aquatic macrophyte is a large-leaved, noxious, free-

floating aquatic weed that belongs to the family Pontederiaceae. WH is a free-floating angiosperm

having roots, short to long stems, broad, glossy leaves and lavender flowers, usually found in

shallow water. Due to its rapid reproduction rate, it covers the water surface by forming a thick mat.

Owing to its fast-growing and high nutrient uptake ability, WH is used in constructed wetlands to

uptake pollutants from different wastewater sources. Even though there are many sustainable uses

of WH, most research has been done on how to use it to clean up nutrients and contaminants, like

heavy metals, from industrial and urban wastewater (Koley et al. 2022, Sinha et al. 2021, Qin et al.

2020, Ansari et al. 2016, Elangovan et al. 2008).

This chapter aims to review and generalize the observations from different studies on

wastewater remediation of lignocellulosic processing (paper and pulp and textile) industries in

addition to dairy industries from the perspective of the Indian ecosphere. Additionally, the well-

established capabilities of E. crassipes can assist in the remediation of toxic pollutants, including

heavy metals and organic pollutants and other hazardous industrial pollutants, apart from its use in

various documented sustainable practises.