Evaluation of water lettuce, giant salvinia and water hyacinth systems in phytoremediation of domestic wastewater

Gasim Hayder,Hauwa Mohammed Mustafa

doi:10.2166/h2oj.2021.096

Gasim Hayder, Hauwa Mohammed Mustafa

Open Access

https://doi.org/10.2166/h2oj.2021.096

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Abstract

Abstract The objective of this research was to ascertain the best conditions for efficient applications of water lettuce, giant salvinia and water hyacinth in improving the quality of low strength domestic wastewater. Water quality assessment of the wastewater samples before (influent) and after treatment (effluent) with effect to retention times (6, 12 and 24 h) was analysed. The outcome of the study at 6 h retention showed that water lettuce (6.8–7.0 pH, 50.5% colour, 46.7% biochemical oxygen demand (BOD) and 37.8% chemical oxygen demand (COD)), giant salvinia (6.9–7.1 pH, 40.5% colour, 60% BOD and 43.2% COD) and water hyacinth (6.7–6.9 pH, 45.5% colour, 53% BOD and 35.1% COD) reduction values were achieved. At 12 h retention, water lettuce (6.6–7.0 pH, 57.2% colour, 77.1% BOD and 74.6% COD), giant salvinia (6.4–6.8 pH, 81.1% colour, 66.7% BOD and 72.2% COD) and water hyacinth (6.4–6.7 pH, 61.9% colour, 70% BOD and 61.1% COD) reduction values were achieved. Similarly, for 24 h retention, water lettuce (6.6–7.0 pH, 76.7% colour, 53.2% BOD and 70.3% COD), giant salvinia (6.6–7.0 pH, 91.4% colour, 74.7% BOD and 81.0% COD) and water hyacinth (6.4–6.9 pH, 74% colour, 58% BOD and 67.2% COD) reduction values were achieved. These findings indicated that the retention times of 12 and 24 h provided suitable conditions to break down the organic contaminants present in the shallow ponds.

Highlights

Diverse approaches have been introduced for amending pollution over the past 50 years
The results obtained from the phytoremediation treatment of secondary treated water samples using water lettuce, giant salvinia and water hyacinth systems at different retention times (6, 12 and 24 h) are presented in Table 1 and subsequent sections
The overall average chemical oxygen demand (COD) value for water lettuce, giant salvinia and water hyacinth effluent samples at the retention time of 24 h was found to be 50.3, 35.7 and 64 mg/L as against the overall average COD value of the influent sample of 108.8 mg/L. These results indicated that at 24 h retention time, giant salvinia plants have better properties in decreasing the COD concentrations of the influent samples, whereas the water hyacinth plants were more effective in reducing the COD concentrations of the influent samples at 12 h retention time

Summary

Introduction

Diverse approaches have been introduced for amending pollution over the past 50 years. Government policies and communal views supported these approaches, which are more inclined towards biological treatment methods than the conventional methods (Ekperusi et al 2019). Biological methods, such as anammox technology, microbial fuel cells, anaerobic treatment and algal technology, have been employed in wastewater treatment. Despite the efficiency of the activated sludge process in the reduction of water pollutants, high energy consumption (0.3–0.6 kW h mÀ3) is a huge factor that hinders its application in biological wastewater treatment (Daverey et al 2019). Phytoremediation using hydroponic methods is cheap, simple to operate, requires little energy and it is a sustainable option for domestic wastewater treatment (Worku et al 2018)

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