Reclamation of wastewater in wetlands using reed plants and biochar

Abstract

To cope with water crisis, wastewater reuse has been introduced as a potential source for irrigation. On the other hand, irrigation with wastewater may negatively affect the surroundings. In this study, reed plant (Phragmits australis) and its biochar were tested as low-cost treatments to enhance the efficiency of wastewater reclamation in wetlands within only 72 h. The investigated water was of low irrigation quality and exhibited high contents of BOD5 and fecal coliform. Moreover, this water contained high levels of soluble cations and anions; besides, being marginally contaminated with Cu, Mn and Cd. After 2 days in the sedimentation unit, wastewater was subjected to three reclamation treatments in parallel (each lasted for 24 h): (1) a “sand & gravel bed”, (2) “reed plants grown on a sand & gravel bed” and (3) “biochar + a sand & gravel bed”. The results showed that all treatments decreased BOD5, fecal coliform, total cations and anions, with superiority for the second and third treatments. The levels of the potentially toxic elements also decreased to values within the permissible levels. Although the aforementioned wastewater treatment processes upgraded the quality of this water, it remained in the poor grade. Biochar or reed plants grown on sand and gravel beds significantly improved wastewater quality to the medium quality grade, with superiority for biochar treatment. In conclusion, investigated treatments are guaranteed in wetlands for wastewater reclamation; yet, further protocols should be followed to achieve safe handling of this water and attain the sustainable goals.

The Use of Constructed Wetlands to Treat Effluents for Water Reuse

“…Another possibility of optimizing processes involving CWs, reducing the time needed to remove contaminants in VFCW, is the use of biochar from the plant used in the treatment unit. When using biochar obtained from Phragmits australis, a significant reduction was observed in fecal coliforms, COD and BOD, and the metals Cu, Mn, Cd, and Al in only 72 h [64]. Those results indicated that the wastewater quality was highly improved by the biochar treatment.…”

“…However, it was still not enough to reach reuse levels, with stricter requirements regarding the removal of the main physical, chemical, and biological parameters. Moreover, contaminant desorption mechanisms for this type of biochar must be considered in further investigations [64].…”

Introductory Chapter: Climate Change and Climate-Smart Greenhouses

“…Recycling agricultural waste can significantly reduce greenhouse gas emissions, with over 5.6 billion mega grams of carbon potentially sequestered from the 18 billion wasted annually worldwide [80]. This can be achieved by converting organic residues into biochar, produced under limited oxygen conditions [81][82][83][84][85][86]. Biochar reduces easily oxidized carbon content, decreasing microbial metabolic activity by 47% [87], leading to longer soil retention when used as a soil amendment [88][89][90] or organic fertilizer [91,92].…”

Evaluating the removal efficiency of potentially toxic elements (PTEs) from a shale deposit by citric acid

“…Shale deposits, rich in clay minerals (Wilson and Wilson, 2014), can be used successfully to improve the characteristics of sandy soils (Eldardiry and Abd El-Hady, 2012;Hassan et al, 2016); yet contaminant founds in these shales should be lessened, prior to their use, to meet the acceptable environmental levels (Khurramovna et al, 2021). Potentially toxic elements are of special concern because these contaminants do not undergo biodegradation (Hashim et al, 2017;Abbas and Bassouny, 2018;Farid et al, 2019); hence possessing long term negative environmental impacts (Abdelhafez et al, 2015;Elshazly et al, 2019;Abdelhafez et al, 2021;Sarhan et al, 2021;Abd-El-Hady and Abdelaty, 2022;Asaad et al, 2022;Hussein et al, 2022;El-Shwarby et al, 2022;Mekawi et al, 2023).…”