Alkaline-extracted cyanide from cassava wastewater and its sole induction of chromosomal aberrations in Allium cepa L. root tips

• Published in: Environmental technology Vol. 43; no. 20; pp. 3097 - 3106
• Main Authors: Ogunyemi, Adewale Kayode, Abayomi, Akeem Akindele, Opawale, Rachael Oluwatosin, Samuel, Titilola Aderonke, Ilori, Matthew Olusoji, Amund, Olukayode Oladipo, Alo, Babajide Ibitayo
• Format: Journal Article
• Language: English
• Published: England Taylor & Francis 06-09-2022; Taylor & Francis Ltd
• Subjects: alkali; Allium cepa; Allium cepa L; Cassava; cassava wastewater; Chemical analysis; Chemical degradation; Chemical pollutants; Chemical pollution; Chromosome aberrations; Cyanides; Cyano compounds; Cytotoxicity; Effluents; Environmental management; Environmental regulations; Factories; Fluxing; Genotoxicity; genotoxicity hydrolysis; Pollutants; Silver; Silver nitrate; Sodium hydroxide; Tips; Toxicity; Waste management; Wastewater; Wastewater management; Nigeria; chromosome aberrations; genotoxicity hydrolysis; alkali; cassava wastewater; Allium cepa L; cytotoxicity
• ISSN: 0959-3330; 1479-487X
• DOI: 10.1080/09593330.2021.1916088

Cassava, a staple crop in Nigeria, processed by numerous factories in rural and suburban locations is known to contain some level of cyano compounds. Lack of stringent environmental regulations on the management of cassava wastewater (CWW) from cassava-processing factories had led to its indiscriminate discharge on the environment. CWW samples were obtained from cassava-processing factories from selected states (Lagos (A), Oyo (B), Ogun 1 (C1), Ogun 2 (C2) and Cross River (D)) in Nigeria to determine the cytotoxic and genotoxic effects of extracted cyanide from the wastewaters. The cyanide was hydrolysed via chemical degradation utilizing 1.25 M NaOH and subsequently titrated using silver nitrate with p-dimethylaminobenzalrhodamine as indicator. Further, in order to explore the potential toxicity of this pollutant present in the effluent, a battery of short-term biological assay (Allium cepa chromosomal aberration test) was used. Bulbs with roots of Allium cepa L. were treated with different concentrations (0.05%, 0.1%, 0.2%, 0.4% and 0.8%) of CWW, and after 48 h, the root tips were processed for cytological studies by the aceto-orcein squash procedure. The results revealed that cyanide concentrations on re-fluxing were in the range of 1.0 and 1.3 mg/L. All concentrations induced a number of chromosomal aberrations in the root tip cells. The mitotic index decreased significantly (p < 0.05) with increasing concentration. The cytotoxic effects showed strong concentration-dependent root growth inhibition with EC
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values of 30%, 20%, 37%, 43% and 22% for A, B, C1, C2 and D, after 72 h. The findings thus indicate that alkali treatment is very efficient in degrading the cyanide content of CWW and has shown that the combination of physico-chemical analysis along with the sole toxicity assessment could provide valuable information about the sole toxicity of cyanide as a chemical pollutant present in the cassava effluent.