Treatment of coke oven effluents by duckweeds ponds - A laboratory scale study

Abstract

Duckweeds are small; floating aquatic plants belongs to Lemnaceae, capable to degrade phenol in wastewater.Synthetic wastewater, similar to the characteristics of coke-plant effluents, was prepared in the laboratory, and tested the degradation efficiency in terms of reduction of COD and phenol under different organic loading rate (OLR) at 4 d and 8 d of hydraulic detention time (HRT).Artificial duckweeds ponds were kept in outdoor conditions and meteorological parameters were monitored and used for the estimation of evapo-transpiration rate and degradation of phenol.From the present experiment, it can be concluded that, for phenol concentration of 250 mg/L, 4 d detention is sufficient for the removal of 91% phenol.At higher phenol concentration of 600 mg/L, a detention time of 8 d is essential.If phenol concentration in the effluent exceeds greater than 800 mg/L pretreatments wastewater is required.A design example for the treatment of low temperature coal carbonization wastewater by duckweeds pond system also given.