Wastewater Treatment Potentials Assignment Papers.


The objective of this study was to evaluate the potentials of beds vegetated with medicinal species (Brillantaisia bauchiensis and Polygonum salicifolium) in a constructed wetland for domestic wastewater treatment in the Western Highlands of Cameroon.Wastewater Treatment Potentials Assignment Papers.


The study was carried out between March and September 2017 on plants collected from a natural wetland in Penka-Michel. The two plants species selected based on their ethnobotanical importance were transplanted and allowed to grow to maturity in a prepared natural wetland at Penka-Michel and a constructed wetland for domestic wastewater treatment on the campus of the University of Dschang. Growth parameters were followed for the two plants species in both wetlands. The physicochemical parameters and faecal bacteria concentrations were measured only for the vegetated and non-vegetated/control beds in the constructed wetland. Overall, the two plants species showed increased growth in height, diameter, leaf number and plants density.Wastewater Treatment Potentials Assignment Papers. The change in diameter and density were very significantly influenced by species type in the constructed wetland than in the natural wetland. Generally, plant growth in height, diameter and density were higher with B. bauchiensis in the constructed wetland than with P. salicifolium in both wetlands. The mean faecal bacteria removal was higher in the vegetated beds for some bacteria than in the non-vegetated/control bed. There was a significant difference in the reduction efficiency of TSS, turbidity, BOD, Faecal streptococci and Total coliforms bacteria between the inflow and the outflow of some treatment beds especially the bed vegetated with Brillantaisia bauchiensis. There were correlations between the two plants species as concerns increased plants height, diameter, leave number, shoot number and nutrients uptake in the constructed wetland beds compared with the natural wetland.Wastewater Treatment Potentials Assignment Papers.
Wastewater, Vegetated Beds, Medicinal Macrophytes, Brillantaisia bauchiensis and Polygonum salicifolium
1. IntroductionThe negative impact of the increase in world’s population from 6 billion in 2013 to over 7.5 billion people in 2018 with Africa having about 1.3 billion and 24.054 million people in Cameroon directly affects the environment. It causes various adverse efffects on living organisms and an imbalance on the ecosystem affecting drinking water sources, biodiversity, health and reproduction of species [1] [2] [3] .Aquatic macrophytes are large water tolerant vascular plants visible to the naked eye and have at least their vegetative parts growing permanently or periodically in an aquatic habitat [4] . Wastewater Treatment Potentials Assignment Papers. Wetlands are vital and most biologically diversed forms of ecosystems that are transitional between terrestrial and aquatic environments supporting predominantly hydrophytes [5] [6] . They serve as perennial sources of water, avenue for recreation, navigation, cattle grazing, resources for fuels, fodder, and habitat for wildlife. They harbour a huge number of medicinal plant species, and also are ecologically very important filters of pollutants in solving the pollution problem by using adapted macrophytes to improve the quality of the wastewater and run offs that they receive [7] [8] [9] [10] .Wastewater Treatment Potentials Assignment Papers. Wetland macrophytes are naturally adapted to an anoxic and hypoxic stress conditions by making atmospheric oxygen available through aerenchyma tissues at the rhizosphere [11] . They are capable of stabilizing the substrate in constructed wetland (CW) by providing good condition for physical filtration and a huge surface bacteria growth and removal. Some wetland macrophytes like Echinochloa pyramidalis, E. crus-pavonis, Fuirena umbellata and Leersia hexandra amongst others have been tested for domestic wastewater treatment and these macrophytes under stress conditions of pollution produced high biomass in CW which can be valourised [12] – [17] .To avoid causing constant and perpetual disequilibrium in ecosystems, wastewater needs to be properly treated before discharge and CW technologies are used nowadays to mimic the natural wetlands for wastewater treatment purposes. They are designed as surface flow (SF) or sub-Surface flow (SSF) systems using emergent macrophytes and floating macrophytes as used in lagoons systems to remediate wastewater with several hydrological, biogeochemical and biological benefits. Wastewater Treatment Potentials Assignment Papers. Hence, from a biogeochemical viewpoint, the main function of a CW is the temporary storage and/or removal of chemical substances such as total suspended solids (TSS), Chemical Oxygen Demand (COD) and Biochemical Oxygen Demand (BOD) as well as organic compounds (Phosphorus and Nitrogen) removal [18] .The high production and indiscriminate discharge of domestic wastewater from homes and agro-industries into natural wetlands without any treatment has contaminated wetlands and greatly affected the biodiversity in these important ecosystems and is a source of many diseases affecting humans [19] [20] .Wastewater Treatment Potentials Assignment Papers. This problem can be solved using the ecotechnology of constructed wetland systems vegetated with wetland plants [21] [18] . This ecotechnology is environmentally friendly and the species used are unfortunately not transferable. 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] .It was in this light that this study was undertaken using the above mentioned wetland medicinal plants species to investigate their phytoremediation potentials of domestic wastewater in constructed wetlands.2. Material and Methods2.1. Location of the Experimental SetupThe experimental setup was a Yard-Scale natural wetland in Penka―Michel located at latitude 5˚27’43.1″N and longitude 10˚14’09.3″E and the constructed wetland for domestic wastewater treatment located on the Dschang University campus on latitude 5˚26’39.9″N and longitude 10˚04’18.3″E.Wastewater Treatment Potentials Assignment Papers. The climate in this region is of equatorial type with 4 months of dry season between mid-November and mid-March, and 8 months of rainy season between mid-March and mid-November. Annual precipitations are estimated to range between 1433 mm and 2137 mm, while annual mean temperature is estimated at 20.8˚C with thermal amplitude of 2˚C.2.2. Design of the Experimental WetlandsThe prepared natural wetland had a surface area of (4 × 2 m2) while the constructed wetland comprised of a 3 m3 digester, a distribution gutter (3 m3) and three wetland beds (WB1, WB2 and WB3) of volume (4 × 2 × 0.6 m3). Wastewater Treatment Potentials Assignment Papers. All these, were constructed using cement blocks filled with concrete and the insides of the structures were plastered with a mixture of concrete, then smoothen with cement (CIMENCAM) mixed Sikalite® and ZUM AbdichtenTM was applied for water tightness. A slope of about 1% was respected at the bottom of each wetland bed to ease the flow of water from the inflow to the outflow. The constructed wetland beds were then connected to the distribution gutter by polyvinylchloride (PVC) pipes, each having a tap to control the flow rate and to ensure the continuous flow of wastewater into the wetland beds. The entire system was then linked by a PVC pipe to the deteriorated and abandoned conventional wastewater treatment system pre-existing, which served as the primary treatment system (Figure 1).2.3. Design of the Constructed Wetland Bed SystemGabions of 30 cm made up of stones of 5 – 8 cm in diameter were arranged at the inflow and outflow zones of the wetland beds. The outflow structures are fitted to enable the regulation of water level in the wetland. The main filter substrate is a 45 cm thick column of sand having particle size of about 2 mm in diameter (Figure 2).2.4. Choice of Local Macrophytes for Domestic Wastewater TreatmentMacrophytes used in constructed wetland beds are preferably annual herbs with erect stem.Wastewater Treatment Potentials Assignment Papers. Hence, the chioce of the two macrophytes species was based on two broad criteria: physiology (Plant life form, plant lifecycle, stem type and cuticle thickness) and fedelity index (the citation of plant as medicinal by traditional practitioners) [22] . The following scale of preference was constructed with assigned values to sum upto 20 points (Table 1) which enabled the selection of the plants with the highest value. Wastewater Treatment Potentials Assignment Papers.