Development and Evaluation of Compact Aquaculture System for the Application of Zero Water-Exchange Inland Aquacultures

This study evaluated the performance of land-based compact aquaculture system integrating fibrous nitrifying biofilters and solid removal unit. The first experiment indicated that the compact aquaculture system with total biofilter length of 6.0 m and single solid separating was able to accommodate aquaculture weight as high as 5.0 kg/m3, which corresponded to nitrogen loading rates of 8.4 mg N/L/day. In the second experiment, more effective solid-liquid separation and good water quality were achieved when solid separating unit was replaced by filtration unit with Japanese mats as filtered media, and cleaning of biofilters and filtration unit was conducted in every 4 days. Next, the compact aquaculture system was employed to cultivate tilapia without water-exchange for 60 days using the described strategies. TAN and nitrite were well below acceptable limit of 1.0 mg N/L; suspended solids varied between 20 and 35 mg SS/L; and harvesting fish weights were 10.4 kg/m3. Fish survival rate at 97% and average growth rate of 3.45 g/day were reported. Finally, solid removal remained the critical factor for successful aquacultures in the compact system even under extensive or semi-intensive aquaculture cultivation, and finally nitrogen mass balance indicated that nitrification-denitrification were main treatment pathways while solid removal only prolonged the activity of nitrifying biofilters

Statistical optimization for alkali pretreatment conditions of narrow-leaf cattail by response surface methodology

Response surface methodology with central composite design was applied to optimize alkali pretreatment of narrow-leafcattail (Typha angustifolia). Joint effects of three independent variables; NaOH concentration (1-5%), temperature (60-100 ºC),and reaction time (30-150 min), were investigated to evaluate the increase in and the improvement of cellulosic componentscontained in the raw material after pretreatment. The combined optimum condition based on the cellulosic content obtainedfrom this study is: a concentration of 5% NaOH, a reaction time of 120 min, and a temperature of 100 ºC. This result has beenanalyzed employing ANOVA with a second order polynomial equation. The model was found to be significant and was able topredict accurately the response of strength at less than 5% error. Under this combined optimal condition, the desirable cellulosic content in the sample increased from 38.5 to 68.3%, while the unfavorable hemicellulosic content decreased from 37.6 to7.3%

Silica gel derived from palm oil mill fly ash

Agro-wastes, especially ash containing silica, are promising sources of silica for synthetic amorphous silica production. In this research, palm oil mill fly ash (POMFA) was used as a raw material for silica gel production. The response surface method-central composite design was applied to study and to optimize the temperature and stirring speed for silica extraction from POMFA using sodium hydroxide solvent. Filtrates were analyzed using inductively plasma optical emission spectroscopy to measure their silica content. At the optimum condition, 60.42±0.83% of the silica can be extracted from the POMFA. The extract silica was acidified using 10% (v/v) H2SO4 to form silica gel. The chemical composition, the phases, and the micrograph of silica gel product are similar to the commercial silica gel

Adsorption of Cu(II) and Zn(II) onto Activated Carbon from Oil Palm Empty Fruit Bunch Prepared by Two-Step Acid Treatment and Microwave-Assisted Pyrolysis

This study explores the feasibility of biochar-based activated carbon derived from oil palm empty fruit bunch (EFB) as a potential precursor for the preparation of activated carbon via 2-step H3PO4 activation under microwave-assisted pyrolysis (2ACEFB). The characterization of EFB and 2ACEFB was observed by FTIR and BET, and chemical composition was determined using proximate and elemental analysis data. The adsorptive removal of Cu(II) and Zn(II) from an aqueous solution was studied, and the effects of metal concentration and solution pH were also investigated. The pseudo-second-order equation was properly described, providing the best fit to the observed experimental data. The adsorption capacities of Cu(II) and Zn(II) onto the EFB were 20.28 and 18.06 mg/g, respectively, and improved by 2.04- and 1.89-fold onto the 2ACEFB. The potential of 2ACEFB was also proved by adsorbent reusability with five consecutive circles of the batch experiment without regeneration or treatment. This study demonstrated that 2ACEFB is an efficient adsorbent for eliminating heavy metals from aqueous solutions

PSU Quality Assurrance Newsletter Y.2 No.2

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