Various configurations of vegetated bed systems with a variety of macrophytes have been tested experimentally in Cameroon, for the treatment of domestic wastewater. The aim of this work was to assess the growth and biomass production of Fuirena umbellata (Cyperaceae) and its potentials in the removal of faecal bacteria and nutrients from primarily treated domestic effluent. A wetland vegetated with this macrophyte and a non-vegetated wetland (control) were continuously fed with primarily treated domestic wastewater at an estimated loading rate of 205 Litres/day in dry and rainy seasons for two consecutive years. Physicochemical and microbiological parameters of the effluent were monitored at the inflow and outflows of the wetlands alongside with the growth and productivity attributes of the young plants during each season. The density of plants ranged in the wetland from 17 -185 plants/ m 2 and from 11 -146 plants/m 2 respectively during the first and the second years. More biomasses were instead produced in the dry seasons than in the rainy seasons but with no significant differences observed. As for nutrients removal, higher efficiencies were observed in the vegetated wetland (45% -73%) compared to the non-vegetated control (17% -66%). Similar trends were observed for the faecal bacteria but with no significant differences between the seasons. However, the vegetated beds were significantly more efficient than the non-vegetated control in the reduction of many physicochemical parameters and faecal bacteria. This varied with the seasons.
The aim of this study was to evaluate the removal of faecal bacteria and nutrients from domestic wastewater, in surface flow wetlands vegetated with Echinochloa pyramidalis. Horizontal surface flow (HSF) wetlands were fed with primarily treated domestic wastewater at organic loading rates varying from 20.74 to 27.15 g BOD/m 2 /day for two consecutive years. Water samples were collected at two weeks interval from the inflow and the outflow of the treatment wetlands for physicochemical and faecal bacteria analyses. Physicochemical parameters with highest removal rates were total suspended solids (TSS, 62-80%), Nitrates (57-73 %) and PO 4-3 (57-84 %). Faecal indicators reductions of 1.4 and 0.3 log units (1 st year) and 1.15 and 0.65 log units (2 nd year) were respectively recorded in the vegetated and the control wetlands. Reductions of total coliforms, faecal coliforms and faecal streptococci were significantly higher in the vegetated wetland than in the non-vegetated control in both seasons of the first year. In the contrary, there was no significant difference in the removal rates of faecal indicators between vegetated wetland and the non-vegetated control during the dry season of the second year. Wetlands vegetated with E. pyramidalis was proven to be continuously efficient in the removal of faecal indicators for the two years of study, with no significant differences between the seasons of the year and between the years.
Several macrophytes are being tested in experimental wetlands systems in Cameroon, for the treatment of domestic wastewater. The aim of the present research was to assess the performances of a yard scale surface flow wetland vegetated with Echinochloa crus-pavonis, ISSN 2157-6076 2013 www.macrothink.org/jbls 252 in the removal of nutrients and faecal bacteria from primarily treated effluent. A wetland vegetated with the macrophyte and a non-vegetated wetland (control) were continuously fed with primarily treated domestic wastewater at organic loading rates varying from 20.74 to 27.15 g BOD/m 2 /day in dry season and the rainy season for two consecutive years. Journal of Biology and Life SciencePhysicochemical and microbiological characteristics of water were monitored at the entries and exits of the wetlands alongside the growth attributes of the young plants during each season. Plant densities in the bed increased with time during each season of the experiment, and not significantly lowered during the following season after harvest. Percentage removal ranges of 89-95 % and 75-93 % were observed for faecal bacteria during the dry and the rainy seasons respectively in the vegetated beds, as compared to ranges of 25-71 % and 24-73 % recorded in the control bed. The same trend was observed for nitrates and orthophosphates with removal rates of up to 62 % and 82 % respectively as compared to 40 % and 47 % recorded in the control. The vegetated bed was significantly more efficient than the control in the reduction of several parameters, but this varied with seasons.
Résumé Les échantillons destinés à l’étude des algues ont été prélevés par grattage sur différents types de substrats et par expression de macrophytes immergées dans deux sites marécageux situés dans la région Ouest du Cameroun. Les observations au microscope optique ont permis d’observer les organismes encore vivants dans leur déplacement et de noter des détails qui pourraient disparaître du fait de la fixation. Les comptages ont été faits suivant des transects verticaux choisis au hasard sur la lame jusqu’à obtention de 200 individus au moins. Les données floristiques ont été ensuite soumises à une Analyse Factorielle des Correspondances (AFC). Les résultats obtenus montrent que la répartition des espèces dans l’espace semble être contrôlée, principalement, par la pollution organique. La variabilité spatiale de cette pollution organique pourrait être expliquée par la direction privilégiée des polluants organiques due aux courants d’eau, ou par une inégale distribution dans l’espace des différentes espèces de macrophytes. Le mélange des espèces de préférences écologiques différentes dans le même échantillon, de même que la contradiction entre l’écologie de certaines espèces connues de la littérature et celle déduite des paramètres chimiques mesurés, pourraient être attribués à la variabilité à courte échelle de temps des conditions physico-chimiques, en relation avec les caractéristiques du climat local.
The use of biochar in constructed wetlands for domestic wastewater treatment is gradually being acclaimed by environmentalist due to its high specific surface area and porosity. In this study, the effectiveness of Corn Cob Biochar (CCB) and Rice Husk Biochar (RHB) in vertical flow constructed wetlands vegetated with Echinochloa pyramidalis was studied with sand as common reference material. The filters were fed with primarily treated domestic wastewater at a hydraulic loading rate of about 350 L/m2/day for 6 months. Water samples were collected monthly for physicochemical and bacteriological analysis and plant growth assessed every two weeks throughout the study. Biochar filters were highly performant in wastewater improvement with no significant differences between the biochar types. Both biochars were more efficient than sand in the removal of COD, BOD, true colour, TSS and TDS. However, sand filters performed better in the reduction of nutrients. All wetlands showed positive plant growth though the plants did not significantly affect the performance of the different filters for most parameters. However, a better plant growth was observed in the CCB filters. The study shows that CCB and RHB can effectively replace sand as substrates in constructed wetlands for wastewater treatment.
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