Taufique Ahmed Sial Mehran University of Engineering and Technology Jamshoro Abdul Majid Teewno Mehran University of Engineering and Technology Sheeraz Ahmed Memon Mehran University of Engineering and Technology Jamshoro Rasool Bux Mahar Mehran University of Engineering and Technology Jamshoro Muhammad Safar Korai Mehran University of Engineering and Technology Jamshoro Abstract

Constructed wetland is a natural, economical and environment friendly option for leachate treatment. The aquatic plants and microorganisms are the main players for the treatment of leachate and are conspicuous favoring feature for any wetland due to their contaminant treatment efficiency. There are several other features which limit or enhance the performance of wetlands. Temperature is one of the factors which influence the performance of any wetland and can improve overall efficiency of the constructed wetland. Deep study of oxygen function reveals that accumulation of oxygen to the liquid or soil of the wetland either by photosynthesis or direct from atmosphere. Organic mailer and nitrification process made possible by transfer of oxygen to rhizosphere through macrophytes and macrophytes grow well in growing season in the presence of sunlight and temperature. The argument is well supported through facts revealed by scientific observations. The natural process of photosynthesis only occurs in the presence of sunlight. Hence main performance of macrophytes depends upon their biomass production and fixation of oxygen to the rhizosphere in growing season, which ultimately enhances the efficiency of wetlands for contaminant removal. This review is to establish the fact that Typha latifolia, Phragmites australis and Scripus Validus are main hydrophytes depict best results in biogeochemical process for contaminant removal from wetlands in hot season except for the Total Suspended Solid (TSS) which does not show considerable difference due to the climate. This fact reveals that the macrophytes are more productive in the warm climate in comparison to cold one. The Typha latifolia, Phragmites australis and Scripus validus are the most common species of macrophytes which are very much affective in contamination removal process especially in temperate or tropical region where climate is above 30oC. The available data of different research papers establishes the fact that wetlands are the low-cost, eco-friendly and efficient solution for majority of contaminants removal. It has also been established that the Tropical and temperate regions enhance efficiency of all parameters up to 10% due to higher temperature.

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