Performance assessment of horizontal and vertical surface flow constructed wetland system in wastewater treatment using multivariate principal component analysis

Abstract

This study aimed to compare the horizontal flow (HFCW) and vertical flow (VFCW) constructed wetland systems in treating dairy wastewater (DWW) and simultaneously harvesting plant biomass from units. The HFCW and VFCW were designed at lab-scale using cattail (Typha angustifolia) and changes in DWW parameters: pH, EC, TSS, NO3-N, NH4-N, PO4−3, SO4−2, Na, K, BOD5, COD and heavy metals (Fe, Cr and Ni) were investigated for 9 months. A setup without plant stand acted as control. The VFCW outperformed to HFCW in terms of removal of NH4-N, PO4−3, BOD5, COD, and heavy metals while NO3-N and SO4−2 showed high removal in HFCW. The principal component analysis (PCA) identified three major components from the 9 major variables accounted for 80.05 and 86.68 of the datasets in HECW and VFCW, respectively. The degree of variance suggested the high performance of VFCW than HFCW. The PCA showed slight variations in functioning of both systems in terms of interdependences of organic and inorganic pollution abetments. The biomass yield of Typha showed great variations between HFCW and VFCW system and relatively the VFCW produced more Typha biomass. The high heating value (HHV) calculated on the basis of proximate and ultimate results indicates that Typha biomass can be used as potential feedstock for renewable energy operations. The Typha based VFCW for dairy wastewater treatment can targets multiple purposes: nutrient capture, habitat restoration, bioenergy, carbon offsets, and water quality credits.