Enhanced growth and nutrients removal efficiency of Characium sp. cultured in agricultural wastewater via acclimatized inoculum and effluent recycling

Abstract

Effective wastewater treatment by microalgae depends on its ability to grow well in the wastewater. This is particularly challenging in concentrated agricultural wastewater such as Palm oil Mill Effluent (POME) where light is limited. This study assessed the effect of acclimatized inoculum in combination with POME dilution using final effluent discharge to improve microalgae growth. A native microalgae, Characium sp. that exhibited superior growth rate from preliminary study was used. Firstly, the effect of inoculum density and POME concentration on the maximum specific growth rate (μmax) was investigated. From the result, the highest μmax of 0.57 was achieved by 0.5gL−1 inoculum in 50% POME concentration. In the second stage, analysis was continued using acclimatized inoculum cultured into 50% POME diluted with final effluent and distilled water respectively. Findings showed that dilution using final effluent produced remarkably higher μmax of 1.87 compared to 1.06 when diluted with distilled water. It also successfully removed 21.5% of Chemical Oxygen Demand (COD), 80.0% of Total Nitrogen (TN) and 89.9% of Total Phosphorus (TP), within five (5) days of cultivation. Outcome of this study suggested that microalgae growth in wastewater can be stimulate, via feasible acclimatization and recycling of final effluent as dilution water. This improved growth will imply better performance in the bioremediation of the wastewater.