Bioremoval of Zinc and Copper in Wastewater by Living Microalgae

One of the major causes of pollution is heavy metal contamination due to anthropogenic activities. Heavy metals are toxic to living organisms and are not chemically and biologically degradable. Various methods have been developed over the years to remove heavy metals such as chemical precipitation, membrane technology and electrochemical treatment. However, these methods are not practical as they produce toxic sludge, consume large amount of energy and are inefficient at low concentration of heavy metal. Removal of heavy metals by using microalgae is an alternative method designed to replace the conventional technologies. Generally, wastewater discharge carries more than one type of heavy metal. Hence, the study on the effects of a combination of heavy metals can represent the actual environment. This research work focuses on the bioremoval of zinc and copper by using a marine algae Nannochloropsis oculata. The main objectives are to investigate the bioremoval of combined heavy metals by using living microalgae, effect of pH value as well as ionic strength on the bioremoval process. Samples are collected every 24 hours. The metal content is quantified by using Microwave Plasma Atomic Emission Spectroscopy (MP-AES). It was found that the bioremoval by living N. oculata is more affected by its growth which is dependent on the pH value and ionic strength of the medium and types of heavy metal it is exposed to. N. oculata also shows that it is not tolerant towards copper and the bioremoval in medium of zinc and copper mixture shows non-interactive effect when compared to experiment medium with zinc and copper individually. Bioremoval by living N. oculata also exhibits fluctuations.