N:P RATIO OF SYNTETIC WASTEWATER IMPACT UPON CHANGING ON SPECIES, GROWTH RATE, CHEMICALCOMPOSITION OF MICROALGAE: BATCH CULTURE TECHNIQUE

Nita Rukminasari

Abstract


The aim of this study to examine the effect of N:P ratio of synthetic wastewater on changing species
composition, growth rate, carbohydrate content of microalgae. Microalgae was cultured for 14 days at 1 L round
flask bottles using batch culture with WC media and 24 hours light illumination. Nitrogen were consists of 5
concentrations, such as 10, 20, 30, 40 and 50 mg/L-N and for Phosphorus were used 5 concentration which were
2, 4, 6, 8 and 10 mg/L-P. Variables measured were growth rate based on optical density, species composition,
total fatty acid and carbohydrate content. There were 11 genus of algae found, which were Chlorella sp,
Oscillatoriasp, Scenedesmussp, Actinastrumsp, Chlorococcumsp, Coelastrumsp, Gleokininasp, Keratococcussp,
Merismopediasp, Monoraphidiumsp and Spirulina sp. Three species dominated at all NP treatments, such as
Oscillatoriasp, Chlorella sp and Scenedesmus sp. Samples with low P concentration were dominated by
Oscillatoriasp, while treatments with high P concentration were dominated by Chlorella sp and Scenedesmus sp.
The highest total cell abundance was found at treatment of 40 mg/L-N and 6 mg/L-P, account for 2,272,500
cell/mL. However, there was no particular pattern of total cell abundance among NP treatments. In general,
specific growth rate was slightly low at high P concentration for all N treatments. There was no clear pattern of
% carbohydrate per dry weight among NP treatments. The highest % carbohydrate per DW was 1.16% at lowest
N concentration (10 mg/L-N) and at the highest P concentration (50 mg/L-P). Treatment with 30 mg/L-N and 6
mg/L-P showed having the lowest % carbohydrate per DW.
Keywords : N:P ratio, synthetic waste water, microalgae, batch culture technique.


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