Integrated Efficacy Assessment of Constructed Wetland for Nutrients and Organics Removal in Piggery Wastewater Under Tropical Conditions

Abstract

Piggery effluent is composed of a large percentage of water which makes it a target for exploitation such as in reuse for agriculture but its disposal without treatment leads to contamination of both surface and subsurface water resources. The study investigated the treatment of piggery wastewater in constructed wetlands under selected hydraulic retention times (HRTs). Two HRTs (3 and 5 days) were used to monitor the contaminant reduction efficiencies (CREs) of the CW at the outlet of the treated effluents. Standard methods were used to analyse the contaminants (nutrients and organics) for the characterization of the effluent quality. The data collected were analysed using one-way ANOVA for the CREs at P < 0.05. The CRE values for the 3- and 5-day HRTs were found to be 62.50 and 58.33%, 51.70 and 51.91%, -2.07 and 9.01%, -20.46 and -12.48%, 84.76 and 86.84%, 61.87 and 60.43% and 77.60 and 74.90% for TN, TP, Ca, Mg, Na, COD and BOD respectively. As expected, the wastewater injected into the constructed wetland system was treated, and for both HRTs, a sizable amount of the nutrients present in the wastewater were retained by the substrate. Furthermore, the macrophytes absorbed a portion of the wastewater nutrients. The results of the study gave insight into the effectiveness of Coix lacryma J. CWs at the chosen HRTs.