**3. Chemistry of water hyacinth**

Even though the chemical composition and characteristics of WH plants vary depending on the collecting locations and the environmental circumstances of growth sites, a WH plant can have a wide range of chemical compositions. Several studies confirmed that fresh WH plant has 95% moisture content, 0.04% nitrogen, 1.0% ash, 0.20% K2O, 0.06% P2O5, and 3.5% organic matter. On a dry-weight basis, it has 75.8% organic matter, 1.5% nitrogen, and 24.2% ash. The ash also contains 28.7% K2O, 1.8% Na2O, 12.8% CaO, 21.0% Cl, and 7.0% P2O5. Through the analysis of the Kjeldahl technique, the WH plant yields: 0.72 g methionine, 4.72 g phenylalanine, 4.32 g threonine, 5.34 g lysine, 4.32 g isoleucine, 0.27 g valine, and 7.2 g leucine per 100 g crude protein (crude protein = quantity of nitrogen 6.25) [36–39]. Furthermore, Lara et al. [40] presented the proximate analysis of the dried biomass of WH in **Table 1**.


#### **Table 1.**

*Analysis of dried WH biomass [39–41].*

WH biomass also comprises chemical elements, such as Na, Mg, Al, Si, P, S, Cl, K, Ca, Mn, and Fe, with carbon and oxygen having the highest amounts see **Table 1** [39]. Ogamba et al. [41] also reported the composition of metabolites in WH biomass, shown in **Table 1**.
