Performances of a Yard-Scale Surface Flow Wetland Vegetated with Echinochloa Crus-Pavonis in the Removal of Nutrients and Faecal Bacteria from Domestic Wastewater

Abstract

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.

Growth Characteristics of <i>Fuirena umbellata</i> in a Surface Flow Constructed Wetland and Its Influence in Nutrients and Faecal Bacteria Removal from Domestic Wastewater in Cameroon

“…No significant differences were noticed in the removal of the two species in this work. These results are similar to those reported by [25].…”

“…These potentials included biomass production in vegetated bed systems, their ability in faecal sludge dewatering improvement as well as biosolids recovery, their responses to salinity stress, the nutritional potentials as fodder after harvest from treatment beds as well as their potentials in the removal of bio-indicators of faecal contamination from wastewater [14] [17] [21] [22] [23] [24] [25]. But there has been no concern on the ability of Fuirena umbellata on biomass production in constructed wetlands, nutrients removal and in the reduction of bio-indicators of faecal contamination from wastewater, despite its presence and proliferation in natural polluted and non-polluted wetlands.…”

Wastewater Treatment Potentials of Vegetated Beds with <i>Brillantaisia cf. bauchiensis</i> Hutch & Dalz and <i>Polygonum salicifolium</i> Brouss ex Wild in the Western Highlands of Cameroon

“…However, some plants especially those closer to the gabions at the inlet showed a stunted growth probably due to the high concentration of wastewater at the inlet during the dry season. This linear growth in growth parameters was also observed by[14] [15] using Echinochloa crus-pavonis and Fuirena umbellata respectively.…”

“…It is observed that more biodegradation of organic matter occurred in the wetland treatment beds such that the amount of phosphate in the outflow was more than the inflow especially in the treatment bed vegetated with Brilantaisia bauchiensis followed by the bed with Polygonum salicifolium. The high growth and the linear growth of these plants in the wastewater treatment station is probably due to the availability of nutrients particularly Nitrogen and phosphorus present in the water which probably resulted from the transformations of nitrates and phosphates since these compounds were abundantly available in the wastewater but were removed more in the vegetated beds than in the control [14] [15]. It is evident that the presence of wastewater significantly increased growth of shoots and plant density in CW [15] [32].…”

“…This slow growth might have been due to the fact that the experiment was started in the dry season with the plants receiving more concentrated wastewater with mineralized pollution. The plants grew rapidly with the coming of the rainy season with the highest growth registered within the last weeks of the study when the wastewater was more diluted with constant rain fall[14] [15] [16] [28][29]. However, some plants especially those closer to the gabions at the inlet showed a stunted growth probably due to the high concentration of wastewater at the inlet during the dry season.…”