Removal of copper metal through a hybrid bio-chemical precipitation process / Nurul Fariha Lokman

Conventionally, heavy metals are being removed by chemical precipitation process using carbo nates and hydroxides. Sulphide is one of the alternatives anions added for chemical precipitation to precipitate out copper effectively, but at significantly high costs and not environmental friendly. The uniqueness of this study is sulphide being produced through a biological process using sulphate reducing bacteria (SRB) to precipitate heavy metal. The novelty of this study relics on the significance of using two separate reactors, namely the upflow anaerobic sludge blanket (UASB) reactor and precipitator reactor. The substrates including glucose and sodium sulphate are left under anaerobic condition in the UAS B reactor. While, the copper added as a substrate is left in the precipitator reactor. The SRB in the UASB reactor reduce sulphate to hydrogen sulphide gas. Then, the biologically produced hydrogen sulphide gas was used for copper precipitation in the precipitator reactor. The efficiencies of the process can be evaluated separately since these pro cesses take place in two different reactors. This research intends to quantify the amount of methane gas that can be produced in the UASB reactor under limited sulphate condition and to quantify the biological production of sulphide and hydrogen sulphide gas in the UASB reactor under excess sulphate condition. In addition, it is the aim of this study to evaluate the efficiency of copper metal removal through precipitation process using biologically produced sulphide. Results showed that 79.25% of methane can be recovered and very minimal sulphide was produced under condition of low sulphate concentration. However, when the sulphate concentration is high, only 14.42% of methane produced with increasing of 76% sulphide produced. Furthermore, the hydrogen sulphide gas remained in precipitator reactor was 66%. However, only 14% of sulphide has been used to precipitate copper with efficiency of 87% in the precipitator reactor. Therefore, this process has great potential to be adopted in industries to treat industrial wastewater with copper based problems.