Feasibility of Copper Removal from Wastewaters by Using Compost as a Natural Sorbent

The adsorption process is one of the important methods of separation in which liquid phase or gas particles are separated by a solid phase called absorbent. The main advantages of adsorbents include high efficiency, low cost and minimization of chemical or biological sludge.

In this study compost as natural and low cost adsorbent is used to remove the heavy metal copper from waste water. At first the influence of parameters such as initial concentration of copper, amount of adsorbent, contact time at constant flow rate on the adsorption process was checked in batch system. Removal efficiency of Cu2+ ions with initial concentration of 100 ppm in constant amount of adsorbent was more than 90%.

The results indicated that compost has a very good performance for the removal of copper. To analyse the isotherm of Cu2+ adsorption onto compost different models were applied. The Cu2+ ions adsorption onto compost was better defined by the Freundlich model. Evaluation of the performance of adsorption process in continuous system showed that that maximum efficiency is related to the time that 25% of the remaining columns were filled by granular compost and the rest was filled by powder compost. Also with increasing concentrations of copper, the metal removal rate increased. It was also observed that the time of the process leading to increased removed so that at this system the removal after 15 minutes for all concentrations reached up to 100%.

The results showed that by using compost as adsorbent agent, more than 90% of copper metal can be removed at aqueous solutions. Also, by calculating the separation coefficient based on Langmuir isotherm, it is observed that the separation coefficient for compost used is in the range of 0 to 1, and this indicates the desirability of the adsorbent.