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

Abstract

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.

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

“…The growth parameters increased very slowly during the domestication phase as the plants were still struggling to adapt in their new but more polluted environment Wastewater is rich in nutrients that enrich and nourish the soil. Plants growing in wastewater constructed environment make use of these nutrients for their growth and development [15] [17]. The plants species in the CW showed increase in plants height and diameter has a function of the rich nitrate and phosphate habitat that the plants absorded for its metabolism.…”

“…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].…”

“…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]. The high growth of Brilantaisia bauchiensis in the CW was probably due to large surface area exposed for maximum sun light and an intimate relationship between growth of the plant and chlorophyll content as wastewater contains nutrients that promote growth in the number of green leaves and leaf area per plant [33].…”

“…This was normal because the macrophytes absorded the nitrates and orthophosphates for their biochemical synthesis and reduce the conductivity and the amount of total dissolved solids. However, the fact that there was no significant difference showed that there was more aerobic breakdown of the wastewater and release of mineralized pollution as the oxygen at the rhizosphere by the plant roots [15]. (Figure 11(a)), this value was still higher than the minimum required value of 50 mg/l for wastewater discharge [43] [44].…”

“…Therefore, wetland macrophytes should be identified locally for ecological wastewater management. Some wetland macrophytes tested for this purpose proved to produce high biomasses with high remediation potentials [16] [13] [14] [15] but these were not wetland species of medicinal importance like Brillantaisia bauchiensis or B. fulva (Acanthaceae) and Polygonum salicifolum (Polygonaceae) used as food for welfare and healthcare in the Western Highlands of Cameroon [22].…”