Determining greywater quality and its potential impact on the environment and okra seeds germination

Abstract

Proper wastewater management is an essential step of the path to a healthier life, especially in crowded areas such as universities. The objective of this study was to contribute to the management of greywater generated from the restaurant of university Joseph KI-ZERBO in Burkina Faso. To do this, a qualitative characterization of the different types of greywater produced in the restaurant and an evaluation of the impact of these waters on the germination of okra seeds were carried out. The physico-chemical characterization has shown high organic pollution of kitchen and shower greywater with average values of 2717.17 and 846.17 mg/L for COD and 1251 and 566.75 mg/L for BOD₅ respectively. In addition, the nutrients contents were high (average values of 632.70 and 491.33 mg/L for NO₃^- ; 46.33 and 48.88 mg/L for PO₄^3-) and could have a negative impact on the environment like the eutrophication of rivers in the “Bangr Weogo Park” used for leisure in Ouagadougou. For all greywater sources, the microbiological pollution was high with fecal coliforms and E. coli contents of 7.8 x 10⁴ to 1.83 x 10⁶ CFU/100mL and 6.57 x 10⁴ to 2.08 x 10⁶ CFU/100mL respectively; in addition, they contained helminth eggs such as Ascaris lumbricoides at an average concentration of 43 eggs/L, highlighting the potential health risk. Besides, the Sodium Absorption Ratio (SAR) values were high ranging from 9.89 to 31.66. Despite the presence of chemical and microbial pollutants, the different greywaters allowed the germination of okra seeds. However, parameters such as sodium, conductivity and SAR influenced the elongation of the radicles. Given the ecological and agricultural advantages that can be derived from good greywater management in the Sahelian context, their treatment could be undertaken through biological methods since the COD/BOD₅ ratios were less than 3.