Ahmad Jusoh

A study on the optimal hydraulic loading rate and plant ratios in recirculation aquaponic system

The growths of the African catfish (Clarias gariepinus) and water spinach (Ipomoea aquatica) were evaluated in recirculation aquaponic system (RAS). Fish production performance, plant growth and nutrient removal were measured and their dependence on hydraulic loading rate (HLR) was assessed. Fish production did not differ significantly between hydraulic loading rates. In contrast to the fish production, the water spinach yield was significantly higher in the lower hydraulic loading rate. Fish production, plant growth and percentage nutrient removal were highest at hydraulic loading rate of 1.28 m/day. The ratio of fish to plant production has been calculated to balance nutrient generation from fish with nutrient removal by plants and the optimum ratio was 15-42 gram of fish feed/m(2) of plant growing area. Each unit in RAS was evaluated in terms of oxygen demand. Using specified feeding regime, mass balance equations were applied to quantify the waste discharges from rearing tanks and treatment units. The waste discharged was found to be strongly dependent on hydraulic loading rate.

Study on the removal of pesticide in agricultural run off by granular activated carbon

In this batch study, the adsorption of malathion by using granular activated carbon with different parameters due to the particle size, dosage of carbons, as well as the initial concentration of malathion was investigated. Batch tests were carried out to determine the potential and the effectiveness of granular activated carbon (GAC) in removal of pesticide in agricultural run off. The granular activated carbon; coconut shell and palm shells were used and analyzed as the adsorbent material. The Langmuir and Freundlich adsorption isotherms models were applied to describe the characteristics of adsorption behavior. Equilibrium data fitted well with the Langmuir model and Freundlich model with maximum adsorption capacity of 909.1mg/g. The results indicate that the GAC could be used to effectively adsorb pesticide (malathion) from agricultural runoff.

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.

The formation and characterisation of an asymmetric nanofiltration membrane for ammonia-nitrogen removal: effect of shear rate.

The focus of this research is to study the potential of nanofiltration membrane technology in removing ammonia-nitrogen from the aquaculture system. One of the major fabrication parameters that directly affect the separation performance is shear rate or casting rate during membrane fabrication. In this study, asymmetric polyethersulfone (PES) nanofiltration membranes were prepared at five different shear rates within the range of 67-400 s(-1). Membrane productivity and separation performance were assessed via pure water, salt and ammonia-nitrogen permeation experiments, and their structural properties were determined by employing the combination of the irreversible thermodynamic (IT) model, solution diffusion model, steric hindrance pore (SHP) model and Teorell-Meyers (TMS) model. The study reveals that the alteration of shear rate enormously affects the membrane morphology and structural parameters, hence subsequently significantly influencing the membrane performance. It was found that, membrane produced at the shear rate 200 s(-1) or equivalent to 10s of casting speed during membrane fabrications managed to remove about 68% of ammonia-nitrogen, in which its separation performance is the most favourable by means of highest flux and rejection ability towards unwanted solutes. Besides, from the research findings, nano-membrane technology is a potential candidate for the treatment of aquaculture wastewater.

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.

Nitrogen budget and effluent nitrogen components in aquaponics recirculation system

AbstractIn this study, the dynamics of nitrogen through aquaponics recirculation system was examined by developing a nitrogen budget. The model evaluated total ammonia nitrogen (TAN) production and removal in biofilters, identifying and quantifying the fate of nitrate nitrogen (-N) and determining the system maximum carrying capacity. Of the nitrogen input into the culture tank via feed, 83.8% was recovered from different pool: 39.4% as fish flesh (harvested), 2.1% as mortalities, 34.7% as dissolved inorganic forms of nitrogen and 7.6% as total organic nitrogen. The remaining 16.2% of nitrogen unaccounted for likely was lost as nitrogen gas due to passive denitrification and as volatization of ammonia. Average TAN in the culture tanks was 2.08 mg/L. Under current condition, system loading with fish biomass at average of 68.5% of the maximum predicted. The hydroponic troughs removal efficiency averaged 60.4% TAN per pass. From TAN production, 88% was removed in hydroponic troughs, 11% by passive nitrificat...

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 ...

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.

Balancing of nutrient uptake by water spinach (Ipomoea aquatica) and mustard green (Brassica juncea) with nutrient production by African catfish (Clarias gariepinus) in scaling aquaponic recirculation system

AbstractFrom both engineering and economic perspectives, goals of an aquaponic recirculation system are keeping a healthy environment for fish and plant, by eliminating toxic metabolites and growth-inhibiting substances. The type and quantity of waste excretions produced by the cultured organisms are also the important considerations, especially in designing the component system. Therefore, to be effective at nutrient removal, aquaponic systems should be sized correctly to balance fish output and nutrient uptake by plants. In this study, the plant component was isolated from the fish rearing operation so that nutrient removal could be evaluated independently. Two leafy green vegetables, i.e. water spinach (Ipomoea aquatica) and mustard green (Brassica juncea) were selected to evaluate the effectiveness of plant nutrient uptake to balance nutrient production from fish culture. Results indicated that nitrogen utilization efficiencies of water spinach and mustard green were 66.5 and 59.9%, respectively. In a...

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...