Treatment of copper-contained jewellery wastewater by precipitation and adsorption using rice husk charcoal

The wastewater from the jewellery industry generally contains a large amount of metal. Metal removal can be done with many techniques, including precipitation and adsorption. Precipitation is done to convert the metal content from the dissolved phase to a solid that is easily precipitated. Generally, precipitation is unable to separate one hundred percent of metal content, so further processing is needed, i.e. adsorption. This research was done by using rice husk which is an agricultural waste in Indonesia. The rice husk is burnt to charcoal, then activated with acid. A SEM-EDX analysis was conducted to obtain a surface description of rice husk charcoal before and after use in the adsorption process. The results showed that the copper content in the jewellery wastewater can be adsorbed with a 40-50 mesh rice husk charcoal and the adsorption process follows the Freundlich isotherm model with R2 value of 0.9625.