Microalgae-bacteria interaction in palm oil mill effluent treatment

•Growth of microalgae increased in unsterilized palm oil mill effluent than in sterilized.•Higher chemical oxygen demand and phosphate removals in unsterilized palm oil mill effluent.•Organic carbon and nutrients were removed by microalgae-bacteria biomass.•Firmicutes percentage decreased after palm oil mill effluent was treated with microalgae.•Actinomycetes percentage increased after was treated with microalgae.