Study On The Effect Of Nitrite And Free Nitrous Acid On Cultivation Of Microalgae
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Date
2021-06-01
Authors
Chan, Jyh Loong
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Chlorella vulgaris was widely used as potential nutrients elimination microalgae in
wastewater treatment plant due to its high removal efficiency of total nitrogen (TN) and total
phosphorous (TP). The aim of this study was to study the effect of nitrite addition on
microalgae cultivation by introduce 0 mg/L, 50 mg/L, and 100 mg/L of nitrite into batch
reactors respectively, to investigate the effect of free nitrous acid (FNA) on microalgae
cultivation by controlling microalgae cultivation condition in pH 4, 6, and 8 with addition 50
mg/L of nitrite into batch reactors respectively, and to evaluate the influence of FNA
concentration on the extracellular polymeric substances (EPS) secretion from microalgae by
conducting EPS extraction as well as proteins and polysaccharides analysis. The results show
that 50 mg/L of nitrite introduced into microalgae cultivation had highest growth rate in the
result of oxygen inhibition had been eliminated, while 100 mg/L of nitrite introduced into
microalgae cultivation had lowest growth rate because of high FNA concentration presented.
Moreover, microalgae cultivation with addition 50 mg/L of nitrite and pH 4 culturing
condition show the lowest growth rate, and the growth rate for microalgae cultivated at pH 8
had slightly higher than microalgae cultivated at pH 6. From the aspects of proteins and
polysaccharides released in EPS, the peak points for protein (PN) concentration released with
condition of pH 4, 6, 8 were 156.06 ug/mL (at first day), 171.35 ug/mL (at seventh day), and
173.71 ug/mL (at ninth day), while polysaccharide (PS) released with pH 4 was up to 91.02
ug/mL at third day and reduced to 13.43 ug/mL at seventh day which almost similar trend
with others cultivation systems. In overall, microalgae cultivation with addition 50 mg/L of N
and pH culturing condition more than 6 could enhance the microalgae cultivation.