Abstract:
Water pollution has always been a matter of environmental concern around the sphere. With water shortage throughout world appropriate methods for water treatment are key objective for sustaining limited water resources. Constructed wetlands propose an effective mean for reducing environmental pollution by utilizing wetland vegetation. The present study was conducted at NUST H-12 to evaluate performance efficiency of constructed wetland and exploring the endophytes assisting phytoremediation. Selected macrophytes were Pistia stratiotes (water lettuce) and Centella asiatica (Pennywort). The evaluated water quality parameters were; Chemical oxygen demand (COD), Total suspended solids (TSS), Total dissolved solids (TDS), Electric conductivity (EC), pH, Total phosphates (TP), Dissolved oxygen (DO), Temperature, Total coliforms and Fecal coliforms. For isolation of endophytes roots and leaves of water lettuce and pennywort were explored. Water quality parameters were measured at four units (pilot scale unit, Lab scale unit, parallel unit and control unit. Results from 6 months studies depicted removal efficiency was high in summers due to improved plant growth. Highest rainfall was recorded for month of March as a result effluent concentration was considerably low. In all cases removal efficiency of parallel unit was found comparatively high due to more retention of wastewater. For both plants most significant removal efficiencies were recorded as TSS (62 and 83 %) DO (53 and 64 %) COD (74 and 87 %) TP (64 and 81 %) and Total coliforms (99 and 98 %). Results illustrated Centella was more effective phytoremediation agent. 10 microbial strains were isolated from Pistia and Centella and were identified by gene sequencing. Predominant genera reported were Bacillus and Pseudomonas. Results signified that a well-constructed and operated wetland is capable of enhancing water quality. Technical feasibility of CWs may be demonstrated by Pilot scale system making them suitable technology for Pakistan.
