Su Shiung Lam

Effect of Conway Medium and f/2 Medium on the growth of six genera of South China Sea marine microalgae.

A study was performed to determine the effect of Conway and f/2 media on the growth of microalgae genera. Genera of Chlorella sp., Dunaliella sp., Isochrysis sp., Chaetoceros sp., Pavlova sp. and Tetraselmis sp. were isolated from the South China Sea. During the cultivation period, the density of cells were determined using Syringe Liquid Sampler Particle Measuring System (SLS-PMS) that also generated the population distribution curve based on the size of the cells. The population of the microalgae genera is thought to consist of mother and daughter generations since these microalgae genera reproduce by releasing small non-motile reproductive cells (autospores). It was found that the reproduction of Tetraselmis sp., Dunaliella sp. and Pavlova sp. could be sustained longer in f/2 Medium. Higher cell density was achieved by genus Dunaliella, Chlorella and Isochrysis in Conway Medium. Different genera of microalgae had a preference for different types of cultivation media.

A Review of the “Omics” Approach to Biomarkers of Oxidative Stress in Oryza sativa

Physiological and ecological constraints that cause the slow growth and depleted production of crops have raised a major concern in the agriculture industry as they represent a possible threat of short food supply in the future. The key feature that regulates the stress signaling pathway is always related to the reactive oxygen species (ROS). The accumulation of ROS in plant cells would leave traces of biomarkers at the genome, proteome, and metabolome levels, which could be identified with the recent technological breakthrough coupled with improved performance of bioinformatics. This review highlights the recent breakthrough in molecular strategies (comprising transcriptomics, proteomics, and metabolomics) in identifying oxidative stress biomarkers and the arising opportunities and obstacles observed in research on biomarkers in rice. The major issue in incorporating bioinformatics to validate the biomarkers from different omic platforms for the use of rice-breeding programs is also discussed. The development of powerful techniques for identification of oxidative stress-related biomarkers and the integration of data from different disciplines shed light on the oxidative response pathways in plants.

Treatment of African catfish, Clarias gariepinus wastewater utilizing phytoremediation of microalgae, Chlorella sp. with Aspergillus niger bio- harvesting

This study focuses on the evaluation of the performance of Chlorella sp. in removing nutrient in aquaculture wastewater and its correlation with the kinetic growth of Chlorella sp. The treatment was applied with various Chlorella sp. inoculation dosage ranging from 0% to 60% (v/v) of wastewater. The optimum inoculation dosage was recorded at 30% (v/v) with effluent concentration of ammonia and orthophosphate recording at 0.012mgL(-1) and 0.647mgL(-1), respectively on Day 11. The optimum dosage for bio-flocculation process was obtained at 30mgL(-1) of Aspergillus niger with a harvesting efficiency of 97%. This type of development of phytoremediation with continuous bio-harvesting could promote the use of sustainable green technology for effective wastewater treatment.

Production of bio-fertilizer from microwave vacuum pyrolysis of palm kernel shell for cultivation of Oyster mushroom (Pleurotus ostreatus)

Microwave vacuum pyrolysis of palm kernel shell (PKS) was performed to produce biochar, which was then tested as bio-fertilizer in growing Oyster mushroom (Pleurotus ostreatus). The pyrolysis approach produced biochar containing a highly porous structure with a high BET surface area of up to 270m2/g and low moisture content (≤10wt%), exhibiting desirable adsorption properties to be used as bio-fertilizer since it can act as a housing that provides many sites on which living microorganisms (mycelium or plant-growth promoting bacteria) and organic nutrients can be attached or adsorbed onto. This could in turn stimulate plant growth by increasing the availability and supply of nutrients to the targeted host plant. The results from growing Oyster mushroom using the biochar recorded an impressive growth rate and a monthly production of up to about 550g of mushroom. A shorter time for mycelium growth on one whole baglog (21days) and the highest yield of Oyster mushroom (550g) were obtained from cultivation medium added with 20g of biochar. Our results demonstrate that the biochar-based bio-fertilizer produced from microwave vacuum pyrolysis of PKS shows exceptional promise as growth promoting material for mushroom cultivation.

A study on the optimal tank design and feed type to the growth of marble goby (Oxyeleotris marmorata Bleeker) and reduction of waste in a recirculating aquaponic system

AbstractMarble goby (Oxyeleotris marmorata Bleeker), a profitable aquaculture species, was cultured in partitioned tanks treated with a water recirculating aquaponic system (RAS). The influence of tank design (with partitions and PVC tubes of different sizes) and feed type (live food and minced fish) on the fish growth and waste production was investigated. The fish cultured in big partitions with PVC tubes showed higher growth (2.5 g/d) and feed intake (468 g/d) than other tank designs (growth: ⩽2.2 g/d; feed intake: ⩽433 g/d). The growth of fish fed with live tilapia (Oreochromis niloticus) (2.5 g/d) was significantly higher than that of fish fed with live carp (Cyprinus carpio) (1.9 g/d) and minced scads (Decapterus russellii) (1.6 g/d). Fish fed with minced scads showed the highest waste production (ammonia nitrogen (TAN): 262 mg/kg d; 5-d biochemical oxygen demand (BOD5): 434 mg DO/kg d; total suspended solid (TSS): 2.1 g/kg d) compared to those fed with live food (tilapia and carp) (TAN: ⩽208 mg/kg ...

Pyrolysis production of fruit peel biochar for potential use in treatment of palm oil mill effluent

Fruit peel, an abundant waste, represents a potential bio-resource to be converted into useful materials instead of being dumped in landfill sites. Palm oil mill effluent (POME) is a harmful waste that should also be treated before it can safely be released to the environment. In this study, pyrolysis of banana and orange peels was performed under different temperatures to produce biochar that was then examined as adsorbent in POME treatment. The pyrolysis generated 30.7-47.7 wt% yield of a dark biochar over a temperature ranging between 400 and 500 °C. The biochar contained no sulphur and possessed a hard texture, low volatile content (≤34 wt%), and high amounts of fixed carbon (≥72 wt%), showing durability in terms of high resistance to chemical reactions such as oxidation. The biochar showed a surface area of 105 m2/g and a porous structure containing mesopores, indicating its potential to provide many adsorption sites for use as an adsorbent. The use of the biochar as adsorbent to treat the POME showed a removal efficiency of up to 57% in reducing the concentration of biochemical oxygen demand (BOD), chemical oxygen demand COD, total suspended solid (TSS) and oil and grease (O&G) of POME to an acceptable level below the discharge standard. Our results indicate that pyrolysis shows promise as a technique to transform banana and orange peel into value-added biochar for use as adsorbent to treat POME. The recovery of biochar from fruit waste also shows advantage over traditional landfill approaches in disposing this waste.

Microwave pyrolysis with KOH/NaOH mixture activation: A new approach to produce micro-mesoporous activated carbon for textile dye adsorption

A micro-mesoporous activated carbon (AC) was produced via an innovative approach combining microwave pyrolysis and chemical activation using NaOH/KOH mixture. The pyrolysis was examined over different chemical impregnation ratio, microwave power, microwave irradiation time and types of activating agents for the yield, chemical composition, and porous characteristic of the AC obtained. The AC was then tested for its feasibility as textile dye adsorbent. About 29 wt% yield of AC was obtained from the banana peel with low ash and moisture (<5 wt%), and showed a micro-mesoporous structure with high BET surface area (≤1038 m2/g) and pore volume (≤0.80 cm3/g), indicating that it can be utilized as adsorbent to remove dye. Up to 90% adsorption of malachite green dye was achieved by the AC. Our results indicate that the microwave-activation approach represents a promising attempt to produce good quality AC for dye adsorption.

Optimization of cell disruption methods for efficient recovery of bioactive metabolites via NMR of three freshwater microalgae (chlorophyta)

This study demonstrates the use of NMR techniques coupled with chemometric analysis as a high throughput data mining method to identify and examine the efficiency of different disruption techniques tested on microalgae (Chlorella variabilis, Scenedesmus regularis and Ankistrodesmus gracilis). The yield and chemical diversity from the disruptions together with the effects of pre-oven and pre-freeze drying prior to disruption techniques were discussed. HCl extraction showed the highest recovery of oil compounds from the disrupted microalgae (up to 90%). In contrast, NMR analysis showed the highest intensity of bioactive metabolites obtained for homogenized extracts pre-treated with freeze-drying, indicating that homogenizing is a more favorable approach to recover bioactive substances from the disrupted microalgae. The results show the potential of NMR as a useful metabolic fingerprinting tool for assessing compound diversity in complex microalgae extracts.

Removal of pesticide in agricultural runoff using granular-activated carbon: a simulation study using a fixed-bed column approach

AbstractThe use of pesticide and its subsequent release to the environment is a major concern for modern society as concerns over environmental pollution associated with toxic emission are recognized due to contaminants present in pesticide (particularly malathion). Adsorption process using activated carbon is among the most effective techniques for the removal of pesticides in the treatment of various waste streams. The adsorption of pesticide containing malathion in agricultural runoff was investigated using granular-activated carbon (GAC) as the adsorbent; GAC made of coconut, and palm shells were used and their effectiveness in retaining the pesticide is discussed. A fixed-bed column test was performed to simulate the actual condition of adsorption in a continuous manner in a filtration process. Different flow rates were used to evaluate their effects on the column performance, where different breakthrough curves were obtained. The Adam–Bohart breakthrough curve equation was used to predict the breakt...

Prospect of parallel biodiesel and bioethanol production from jatrophacurcas seed

This study focuses on the utilization prospect of JatrophaCurcas seed solely as transport sector renewable fuel for producing biodiesel and bioethanol in a parallel system. Diesel (biodiesel) and petrol (bioethanol as petrol additive) engine fuel could be produce from J. Curcas seed oil portion and its’ seed residue, respectively. Ultrasonic-assisted reactive extractions were used for simultaneous oil extraction and esterification/transesterification of J. Curcas seed. The use of acid/alkaline catalyst and ultrasound resulted in a completely de-oiled seed residual by extracting about 50% oil which is equivalent to the Soxhlet extraction performance. The seeds were being chemically and physically characterized with ultimate analyses and TGA for its suitability as bioethanol raw material. Ultimate analyses revealed similarity with other bioconversion feedstock having carbon and oxygen as the major chemical compositions; with slightly lower carbon content in the residuals due to the oil extraction during the in-situ process. However, TG profile exhibited better decomposition of mass in the ultrasonicated residues having easier accessible and better degradable fiber for bioethanol production process. These shown positive effects on the J. Curcasseed pre-treatment during biodiesel reactive extraction process and for further bioconversion toward bioethanol.