An aliquot of 50 mL samples was clarified by centrifugation (Hettich Zentrifugen Universal 1200, Germany) at 6000 rpm for 3 min in order to separate the microalgae biomass and produce clear water to perform water quality analysis.
Centrifugation is
one of the fastest and most effective separation method for recovering
suspended algae without the aid of chemical additives
(Christenson and Sims, 2011). Ammonia and orthophosphate
determination were carried out in accordance with two standard
methods, namely the Phenate method and the Vanadomolybdo
Phosphoric Acid method based on APHA (2012). The concentration
of nutrient were analyzed using Dual-Beam UV–Vis
Spectrophotometer (Shimadzu UV-1800, Japan) and the data were
simultaneously recorded in Microsoft Office Excel™.