Comparative assessment of the wastewater treatment efficiency and growth characteristics of Cyperus Papyrus and Colocasia Esculenta for wetland

Abstract

Extensive wetland loss recorded has been mainly attributed to agricultural and industrial expansion among other drivers. Studies regarding wetland plants such as papyrus and cocoyam have been done but analyzing the growth competition of papyrus and cocoyam growing under similar conditions has been lacking. The goal of this study was to generate knowledge on the performance of papyrus when grown under similar conditions with cocoyam to contribute to wetland restoration. This was done by comparing the wastewater treatment efficiency and morphological characteristics of papyrus and cocoyam growing under similar conditions. Plants obtained from Lubigi wetland were acclimatized to wastewater for 4 weeks, weighed and taken into the experimental buckets of 50 L. Morphological characteristics including, height, shoots, roots and physico-chemical parameters such as electrical conductivity (EC) and nutrient removal changes were monitored every after 14 days for 5 months. EC was done in-situ while a water sample from each bucket was taken to the Directorate of Water Resources Laboratory in Entebbe for plant nutrient (Ammonia-nitrogen, Nitrate-nitrogen, orthophosphate, total nitrogen and total phosphorous) analysis. Counting roots was done at the end of the experiment after harvesting the plants. One-way Analysis of Variance among the different treatment sets was performed in Minitab for the different measured parameters at 5% significance level. Tukey‟s post hoc test was also conducted for significant results. The results generally indicated that EC and nutrient removal efficiency was highest in papyrus (monoculture) with the exception of orthophosphate, although there was generally no significant difference from that of the combination (papyrus with cocoyam). Papyrus from monoculture had the highest mean height, shoot and root increment, while cocoyam from the combination registered the lowest mean values. Mean aboveground biomass from both cocoyam plants were significantly lower than that of both papyrus plants while papyrus (monoculture) recorded the highest and cocoyam (combination) had the lowest. Papyrus (monoculture) and cocoyam (combination) recorded the highest and lowest mean belowground biomass respectively. Conclusively, planting papyrus with cocoyam reduces cocoyam‟s ability to develop morphologically, lowering its abilities of primary production as papyrus strangles it with a complex root mat structure and reduces light penetration to cocoyam plants.