Effect of Aquatic Plants on Phosphorus Removal and Electrical Conductivity Decrease in Municipal Effluent

Phosphorus (P) is one of essential elements for living organisms, though its critical concentration in surface and ground waters impose a serious problem such as eutrophication. So treatment of polluted waters is required before discharging to water resources. One of effective ways to decrease water pollution is using aquatic plants. An experiment was conducted in pilots with a closed flowing system on two plants, elodea (egria densa) and duck weed (lemna minor) with four treatments and three replications. Data were analyzed in a factorial completely randomized design. Treatments included effluent with and without the plants, and effluent diluted (dilution grade 1/2) with and without the plants. Total dissolved P, electrical conductivity (EC) and pH value were measured after 8, 16 and 24 days in effluent samples. The results showed that pH value decreased up to 0.2 units during of 24 days of the experiment, but there was found no significant difference (p≤0.05) in pH values among the treatments. Both plants decreased EC about 7 % relative to the control (without plant) after 24 days. The plants were also effective in reducing total dissolved phosphorus, so that duck weed and elodea decreased total dissolved P in the effluent about 49 and 7%, respectively. It is concluded that duck weed is more effective in the P removal from the effluent than the other plant.