Kinetics Growth and Recovery of Valuable Nutrients from Selangor Peat Swamp and Pristine Forest Soils Using Different Extraction Methods as Potential Microalgae Growth Enhancers

Abstract

Soil extracts are useful nutrients to enhance the growth of microalgae. Therefore, the present study attempts for the use of virgin soils from Peninsular Malaysia as growth enhancer. Soils collected from Raja Musa Forest Reserve (RMFR) and Ayer Hitam Forest Reserve (AHFR) were treated using different extraction methods. The total dissolved nitrogen (TDN), total dissolved phosphorus (TDP), and dissolved organic carbon (DOC) concentrations in the autoclave methods were relatively higher than natural extraction with up to 132.0 mg N/L, 10.7 mg P/L, and 2629 mg C/L, respectively for RMFR. The results of TDN, TDP, and DOC suggested that the best extraction methods are autoclaved at 121 °C twice with increasing 87%, 84%, and 95%, respectively. Chlorella vulgaris TRG 4C dominated the growth at 121 °C twice extraction method in the RMRF and AHRF samples, with increasing 54.3% and 14%, respectively. The specific growth rate (µ) of both microalgae were relatively higher, 0.23 d−1 in the Ayer Hitam Soil. This extract served well as a microalgal growth promoter, reducing the cost and the needs for synthetic medium. Mass production of microalgae as aquatic feed will be attempted eventually. The high recovery rate of nutrients has a huge potential to serve as a growth promoter for microalgae.

Assessment of Aqueous Extraction Methods on Extractable Organic Matter and Hydrophobic/Hydrophilic Fractions of Virgin Forest Soils

“…The carbohydrate and N (mineral) concentrations were significantly higher than with the longer extraction time [ 34 ]. Soil weathering is usually a slow process at low temperature (~28 °C) and might not significantly change within a day [ 35 ].…”

Malaysian Virgin Soil Extracts as Natural Growth Enhancer for Targeted Green Microalgae Species

“…In addition, the collapse of chemical bonds could only occur when the activation energy was exceeded to disrupt the soil materials into carbon, nitrogen, and phosphorus compounds released in the soil extracts [29]. Hence, the autoclave methods assisted the supply of surplus energy which enabled the release of higher concentrations of DOC, TDN, and TDP in the soil extracts in comparison to natural extractions which occurred at a lower temperature, hampering the breakdown of any chemical bonds since the heat energy is too minimal to overcome the activation energy [19].…”

“…When the ratio of phosphorus was fixed to 0.1, the carbon to nitrogen ratio increased from 73.3:6.3 to 240.4:9.5 when the extraction methods were compared between natural extraction for 24 h and autoclave treatment method at 121 • C twice. Dead bacteria could be most likely responsible for the relatively low carbon to nitrogen ratio of soil extracts when natural extraction for 24 h was employed [19]. On the other hand, increased carbon to nitrogen ratio was observed when autoclave treatment methods were used, indicating the release of more carbon-rich compounds into the soil extracts [19].…”

“…The 96-well microplates culturing method was implemented to access the growth of Nannochloropsis oceanica, Chlorella sorokiniana, and Nannochloropsis oculata supplemented with soil extracts obtained from five different extraction methods, respectively following the methods outlined by Yaacob [19]. A maximum of 200 µL of solution can be accommodated by each well in the microplate.…”

Experiment and Kinetic Modeling of Soil Extract Effects on Dunaliella Primolecta Growth

“…Anaerobically treated sediments from the dairy waste area were also used as a nutrient source for bioenergy production by algae 10 . Studies by 11 and 12 have shown that soil extract from aquaculture sludge and forest soil has great potential as the enrichment media for microalgae cultivation.…”