Exploring the efficacy of powered guar gum (Cyamopsis tetragonoloba) seeds, duckweed (Spirodela polyrhiza), and Indian plum (Ziziphus mauritiana) leaves in urban wastewater treatment

The efficiency of aqueous extract of powdered guar gum seed (Cyamopsis tetragonoloba), duckweed fronds (Spirodela polyrhiza), and Indian plum leaves (Ziziphus mauritiana) was tested to remove nitrate, sulphate, phosphate, and chemical oxygen demand from urban wastewater in this study. Coagulants were applied in four different doses (1, 2, 3, and 5 mL/L) without adjusting the pH of it in wastewater treatment and changes in wastewater parameters were measured. The crude extract of guar gum seed, Indian plum leaves, and duckweed exhibited the removal activities 71.7-95.03% (nitrate), 78.3-95.9% (phosphate), and 83.1-99.6% (sulphate). Nitrate removal was highest (93.5%), followed by phosphate (83.4%) and sulphate (77.7%). The 3 mL/L dose of coagulant showed the best results of wastewater treatment, followed by 2 mL/L, 1 mL/L, and 5 mL/L. Chemical oxygen demand reduction was also in a good range (73.2-79.08%) with 3 mL/L dose for all studied coagulants. pH reduced significantly in all setups of wastewater spiked with plant coagulants. The chemical analysis of Fourier transforms infrared (FTIR) spectroscopy of aqueous extract and plant powder indicates the presence of functions groups like - OH, -COOH, -NH, C=O, C-C R-CHO, C=C-CO-OH, C-H, and R-NH2, in raw coagulants. Overall, results indicate the possible utility of guar gum seed, duckweed, and Indian plum leaf powder as low-cost natural materials for treatment of urban wastewater. However, few high doses of coagulants showed a slight increase in chemical oxygen demand in wastewater, which can be moderated by purifying the active compounds responsible for coagulation activities. (C) 2020 Elsevier Ltd. All rights reserved.