Assessment on Overall Efficiency of Urban Grey Water Treatment by Vermifiltration in Hot Climate: Enhanced Pollutants Removal

• Published in: Environmental technology p. 1
• Main Authors: Ndiaye, Awa, Andrianisa, Harinaivo A, Saapi, Sidesse S Y, Changotade, Odilon A, Adugna, Amare T, Konate, Yacouba, Maiga, Amadou H
• Format: Journal Article
• Language: English
• Published: England 21.12.2018
• Subjects: wastewater; vermifilter; Sub-Saharan Africa; pollutants; low-cost technology
• ISSN: 0959-3330

Vermifiltration technology using Eudrilus Eugeniae could be an alternative low-cost option for the treatment of urban grey water, which is highly polluted with high concentrations of surfactants, sodium and cooking oil. In this study, the effects of these pollutants on performance of a vermifiltration system was tested over a period of 6 to 8 weeks by enriching raw grey water with various concentrations of anionic surfactants (0, 15, 45 and 135 mg/L), sodium (0, 1, 2 and 4 g/L) and refined palm cooking oil (0, 250 and 500 mg/L). The vermifilter system was made of gravel, sand and sawdust layers from the bottom to the top, on which 200 earthworms were added. The grey water used in this study was previously used for dishwashing and laundry by an urban poor household. The greywater quality was compared with the effluent to evaluate the system performance. BOD , COD, TSS and E. coli removal efficiencies ranged from 93-98%, 68-93%, 88-96% and 1.4-3 ULog, respectively, which are within the range of efficiencies reported in the literature. High proportion of surfactants (95-99%) and oil (84-89%) were removed but sodium was not removed. Instead, an increase in sodium concentrations was observed in the filter over the experimental period. Statistical analysis shows that BOD , COD, TSS and E. coli removal efficiencies were independent of surfactants, cooking oil and sodium concentrations (p < 0.05). Thus, short term or accidental exposure of the vermifilter to high concentrations of these three pollutants did not have significant effect on the system performance. Highlights: Urban poor grey water was highly concentrated in Sub-Saharan Africa Low-cost technology such as vermifiltration process was suitable for grey water treatment in hot climate Vermifiltration system improved grey water quality with considerable pollutants removal High levels of chemical pollutants do not have significant effect on vermifiltration performance.