Fate of filter materials and microbial communities during vermifiltration process

Amare T Adugna; Harinaivo A Andrianisa; Yacouba Konate; Amadou H Maiga

doi:10.1016/j.jenvman.2019.04.076

Fate of filter materials and microbial communities during vermifiltration process

J Environ Manage. 2019 Jul 15:242:98-105. doi: 10.1016/j.jenvman.2019.04.076. Epub 2019 Apr 24.

Authors

Amare T Adugna¹, Harinaivo A Andrianisa², Yacouba Konate², Amadou H Maiga²

Affiliations

¹ Addis Ababa Science and Technology University, AASTU, College of Biological and Chemical Engineering, Department of Environmental Engineering, P.O. Box 16417, Addis Ababa, Ethiopia. Electronic address: amare.tiruneh@aastu.edu.et.
² International Institute for Water and Environmental Engineering, 2iE, 01 BP 594, Ouagadougou 01, Burkina Faso.

Abstract

The fate of filter materials and microbial communities during the vermifiltration process were studied for 5 months while treating the concentrated greywater. Four filters were filled with 10 cm gravel of which a layer of medium size gravel (5 cm thickness, aggregate size 20-40 mm) at the bottom and a layer of coarse gravel (5 cm thickness, aggregate size 10-20 mm) at the top, then filled with 20 cm sand (d₆₀ = 0.2 mm, d₁₀ = 0.118 mm). Finally, Vermifilter 1 (VF1), control unit and Vermifilter 2 (VF2), were filled with 40 cm fine sawdust (0.05-5 mm) but Vermifilter 3 (VF3), was filled with 40 cm cow dung (0.05-5 mm). Three filters were inoculated with 200 individuals of Eudrilus eugeniae except for the control unit which was filled with sawdust. Five sampling ports were installed on the wall of the filters at 10 cm intervals with reference to the surface of the top layer. Three of the filters were supplied with concentrated greywater and VF1 was supplied with drinking water at the hydraulic loading rate of 16 L m^-2.d^-1 on batch basis, i.e., four times a day at 8:00 a.m., 11:00 a.m., 2:00 p.m. and 5:00 p.m. Weekly, samples from influent and effluent, and monthly, samples of filter materials collected via sampling ports, were collected and analyzed.The removal efficiencies of biological oxygen demand (BOD₅), total chemical oxygen demand (tCOD), and dissolved chemical oxygen demand (dCOD) of VF2 and VF3 were 5-7% higher than the control unit, but little differences were observed in terms of total suspended solids (TSS). However, the removal efficiencies of nutrients for the control unit was slightly better than VF2 and VF3. The pH and Moisture content (MC) of filter materials increased along the depth, but percentage of volatile solids to total solids (VS/TS) decreased through time due to the high number of microbial communities and earthworms dominating the top layer compared to the bottom. The performance of VF2-sawdust was slightly better than VF3-cow dung to treat concentrated greywater.

Keywords: Cow dung; Eudrilus eugeniae; Filter materials; Sawdust; Vermifiltration.

MeSH terms

Animals
Biological Oxygen Demand Analysis
Cattle
Female
Filtration
Microbiota*
Oligochaeta*
Waste Disposal, Fluid
Water Purification*