Wastewater Treatment by Phytoremediation in Constructed Wetland A Comparative Study Using Chrysopogon zizanioides and Phragmites karka

Abstract

Constructed wetland technology has been applied for the wastewater treatment. The study was carried out in experimental design wetlands (horizontal type) at Khwopa college premise to treat the wastewater from kitchen, laboratory and toilet for the sixmonth

duration. The main objective of the study was to find out the efficiency of constructed wetland by using Vetiver (Chrysopogon zizanioides) and common reed (Phragmites karka) in terms of set design parameters (BOD 5 , COD, NO -N, TP, Chloride, CO , Total coliform) and determine the morphological changes in the reeds. Besides, the changes in soil macronutrient changes were also studied in terms of OC, total nitrogen and phosphorous. Two individual and one mixed ponds were used for the selected reeds. The results showed that on the sixth month the overall concentration of BOD 5 2 , COD, NO 3 - N, TP, Free CO 2 3 and Chloride content in the effluent after treatment were reduced by 84.70%, 77.64%, 90.98%, 87.5%, 36%, 81.13% by Chrysopogon zizanioides pond 61.53%, 34.22%, 81.88%, 55%, 12%, 52.83% by Phragmites karka pond, 76.92%, 36.08%, 84.13%, 60%, 62.5%, 20% by the mixed pond and 38.46%, 25.49%, 29.97%, 32.5%, 4%, 26.41% by the control respectively at their outlets. The percent organic carbon in the soil was decreased in Vetiver pond (3.13% to 0.22%), mixed pond (2.90% to 0.95%), control pond (3.13% to 1.47%) and Common reed pond (2.54% to 1.51%). The Nitrogen in the soil also showed decreasing value from 0.24%, 0.20%, 0.22% and 0.24% in Chrysopogon zizanioides pond, Phragmites karka pond, mixed pond and control pond before plantation to 0.04%, 0.13%, 0.09% and 0.12% after six months respectively. Likewise the available phosphorous in the soil was also found decreased. Among the morphological, physical, chemical, microbial and soil parameters Chrysopogon zizanioides showed maximum height increment, reduced value of physical and chemical parameters of soil as well as wastewater compared to Phragmites karka pond, mixed and control pond along with the plants growth. Comparing the relationship among those parameters it was found that wastewater after passing through soil and plants, the toxic chemicals were absorbed and transformed to useful parameters by soil microorganisms and plant roots which were either used as food for plants and soil organisms or released back to the atmosphere by the mechanism of gaseous cycle.