Bioremediation of petroleum products impacted freshwater using locally available algae

Abstract

Bioremediation seeks to degrade or decompose toxic pollutants in the environment into less harmful ones using organisms. This is achieved when the organisms metabolize the pollutants for cellular growth. Algae grow naturally in puddles, drainages and on wet soils and could constitute a nuisance when they cause accidents. This work attempts to investigate the possibility of using naturally occurring algae to reduce hydrocarbon counts in waters contaminated with petroleum products such as petrol, kerosene, diesel and sump oil. Algae were collected from a puddle near Nsukka Fire Service Station. Aliquots of 2 L of tap water with algae properly dispersed were poured into 39 transparent plastic containers and placed in a screened house. Various concentrations of 2.5 ml/L, 5 ml/L and 7.5 ml/L of pollutants were introduced in three replicates. A control was set up without these. Physico-chemical (pH, dissolved oxygen content, nitrates, phosphates, ammonia, copper, zinc, iron and magnesium) and phycological analysis were carried out using standard methods at the beginning and end of the experiment that lasted for 40 days. Cyanobacteria (Oscillatoria) and Chlorophyta (Spirogyra) were dominant at the onset. Later, more growth of Chlorophyta (Clostrium, Spirogyra, Ulothrix and Ankistrodesmus) and Cyanobacteria, (Aphanizomenon, Oscillatoria, Microcystis) were observed, while Bacillariophyta (Navicula and Pinnularia) and Dinophyta (Peridinium) were low. Results showed a drop in temperature, pH, oxygen percentage saturation, total alkalinity and hydrocarbon and increase in nitrate nitrogen, phosphate, magnesium, iron and zinc with time.