Biosorption of chromium (VI) by chitosan-immobilized acinetobacter haemolyticus

In this study, the ability of chitosan-immobilized Acinetobacter haemolyticus as biosorbent for chromium (VI) biosorption in batch system was investigate. Optimized parameter namely pH, contact time, biosorbent dosage and initial metal concentration obtained from the experiment was then applied for electroplating wastewater treatment. Biosorption using chitosan-immobilized Acinetobacter haemolyticus at pH 3, 8 hours contact time, 3% (w/v) of biosorbent dosage with 100 mg L 1 initial metal concentration resulted in maximum chromium (VI) uptake of 0.2 mg g 1. Using electroplating wastewater, the biosorption capacity of the chitosan immobilized Acinetobacter haemolyticus was 0.27 mg g 1 at pH 3 which is higher than unmodified pH

Batteries recycling process using local isolated thermopile culture

Batteries are used daily in many portable electronic devices. Therefore spent batteries represent, within the wastes, an important environmental pollutant in terms of heavy metals content. Considering the risk associated with uncontrolled disposal of these batteries a legislation on disposal and recycling of spent batteries must be formulated

Sugarcane bagasse as nutrient and support material for Cr(VI)-reducing biofilm

The high cost of culture growth medium is one of the problems faced in the scaling-up of biological processes involved in wastewater treatment. This makes it imperative to find a useful, cheap and easily available alternative source for culture growth medium. The present work highlights the use of sugarcane bagasse (SCB) to sustain the population of Cr(VI) reducing immobilized-biofilm system in a non-sterile condition. The locally isolated Cr(VI) reducing-resistant Acinetobacter haemolyticus was used as primary bacteria inside the sugarcane bagasse packed flow-through column and showed 92-99% Cr(VI) reduction ability during the adaptation stage using 10-100 mg/L of Cr(VI). During the column study, around 4 h (3.0 mL/min) was required to achieve complete reduction of 25 mg/L Cr(VI). The retention time increases with the increase in Cr(VI) concentration. The morphology of the immobilized cells was slightly changed in the presence of Cr(VI) as shown from the FESEM analysis. Phylogenetic analysis of the cultured bacterium from the biofilm samples suggested the dominance of Chitinophaga terrae, Laribacter hongkongensis, Ottowia thiooxydans, Rhizobium cellulosilyticum, Candidate division OP10, Pedobacter sp. as well as uncultured bacterium. Overall, sugarcane bagasse may be used as an excellent alternative and cost-effective growth medium for cultivation of A. haemolyticus as well as support material in a packed-bed Cr(VI) reduction system

Statistical and nature-inspired metaheuristics analysis on flexirubin production

Nowadays, demand for natural pigments has increased dramatically due to the awareness of the toxicity of some synthetic pigments. Because of the high cost of growth medium for natural pigment production, various studies have been carried out to explore medium which are less costly, such as agricultural waste. This study highlight on the application of firefly algorithm (FA) and bat algorithm (BA) in optimizing yellowish-orange pigment production (flexirubin) from the agricultural waste material. At present, response surface methodology (RSM) is the most preferred statistical method in optimizing pigment production. However, in the last two decades, nature-inspired metaheuristics approach has been used extensively in the fermentation process and have continually improve the efficiency in the optimization problem especially in pigment production. This study compared the analytics studies of RSM, FA and BA in the estimation of fermentation parameters (Lactose, Ltryptophan, and KH2PO4) in flexirubin production from Chryseobacterium artocarpi CECT8497T. All models provided similar quality predictions for the above three independent variables in term of flexirubin production with bat algorithm showing more accurate in estimation, with the coefficient value of 98.87% compare to RSM 98.20% and FA 98.38%

Comparison of particle swarm optimization and response surface methodology in fermentation media optimization of flexirubin production

At present, response surface methodology (RSM) is the most preferred method for fermentation media optimization. However, in the last two decades, artificial intelligence algorithm has become one of the most efficient methods for empirical modelling and optimization. One of the popular developed approaches is Particle Swarm Optimization (PSO), which is used in optimizing a problem. This paper focuses on comparative studies between RSM and PSO in fermentation media optimization for the production of flexirubin production using Chryseobacterium artocarpi CECT 8497T. Two methodologies were compared for in terms of their modeling, sensitivity analysis, and optimization abilities. All experiments were performed accordingly to box-behnken design (BBD), and the generated data was analyzed using RSM and PSO. The sensitivity analysis performed by both methods has given comparative results. Based on the correlation coefficient, the model developed with PSO was found to be superior to the model developed with RSM. The result shows that PSO gives a better pigmentation yield with optimal fermentation concentration

Zinc removal from wastewater using hydrogel modified biochar

In this study, hydrogel-(rice husk) biochar composite (HBC-RH) was prepared using acrylamide (AAm) as monomer, with N.N’-methylenebisacrylamide (MBA) as crosslinker, ammonium persulfate (APS) as initiator and rice husk biochar (RHB). The synthesized hydrogel-(rice husk) biochar composite was characterized for swelling capacity andthen utilized for the removal of zinc from wastewater. The optimum batch experimental conditions for this study were determined by evaluating the effect of solution pH, adsorbent dosage, adsorbate initial concentration and contact time. Langmuir isotherm best fitted the HBC-RH sorption of Zinc whereas the kinetic data were best described by pseudo second-order. The maximum monolayer sorption capacity of HBC-RH for zinc was 35.75mg/g

Preparation and characterization of Malaysian dolomites as a tar cracking catalyst in biomass gasification process

Three types of local Malaysian dolomites were characterized to investigate their suitability for use as tar-cracking catalysts in the biomass gasification process. The dolomites were calcined to examine the effect of the calcination process on dolomite’s catalytic activity and properties. The modifications undergone by dolomites consequent to thermal treatment were investigated using various analytical methods. Thermogravimetric and differential thermal analyses indicated that the dolomites underwent two stages of decomposition during the calcination process. The X-ray diffraction and Fourier-transform infrared spectra analyses showed that thermal treatment of dolomite played a significant role in the disappearance of the CaMg(CO3)2 phase, producing the MgO-CaO form of dolomite. The scanning electron microscopy microphotographs of dolomite indicated that the morphological properties were profoundly affected by the calcination process, which led to the formation of a highly porous surface with small spherical particles. In addition, the calcination of dolomite led to the elimination of carbon dioxide and increases in the values of the specific surface area and average pore diameter, as indicated by surface area analysis. The results showed that calcined Malaysian dolomites have great potential to be applied as tar-cracking catalysts in the biomass gasification process based on their favorable physical properties

Synthesis and optimization of nano-sized bacterial-based violacein pigment using response surface methodology

Violacein from Chromobacterium violaceum has raised the enthusiasm of researchers in conducting comprehensive studies on these pigments due to their diverse biological activities including antibacterial and antioxidant properties. However, a limitation related with the solubility of the violacein pigment, by which it is commonly dissolved in toxic solvents such as dimethyl sulfoxide and methanol instead of being soluble in biological fluids and water. Hence, this study provides a method to synthesis the violacein pigment in nanoscale through an encapsulation technique using chitosan-tripolyphosphate (Cs-TPP) nanoparticles. The synthesis of nanoparticles in this study involved ionic gelation between chitosan and tripolyphosphate (TPP), in which several parameters were taken into consideration in order to control the size and dispersion stability of the violacein pigment in the suspension. Preparation parameters, including the concentration of chitosan, TPP and pigment as well as the mass ratio of chitosan to TPP, were optimized using Response Surface Methodology (RSM). Minimum particle size of 149.0 nm with zeta potential of +23.40 mV was obtained at the optimal formulations of 2.33 mg/mL of chitosan, 1.5 mg/mL of TPP, and 1 ppm of violacein pigment and at mass ratio of chitosan:TPP of 7:1. This nano-sized violacein pigment is expected to be applied as safe additive, colorant, and therapeutic agents. Meanwhile, RSM in the study could provide the optimal formulations for producing stable nano-sized violacein pigment

Hydrogel biochar composite for arsenic removal from wastewater

Arsenic contaminated water is an environmental issue due to their toxicity. Acute arsenic poisoning has claimed the lives of many and causes adverse health risk to millions of people in several countries such as Bangladesh, India, and China. Effective removal of this contaminant can be obtained by adsorbing them onto low-cost adsorbents. In this study, hydrogel-biochar composite (HBC-RH) was successfully synthesized by embedding rice husk biochar into poly(acrylamide) hydrogel with N.N’-methylenebisacrylamide (MBA) as crosslinker. The synthesized HBC-RHs were characterized and utilized for the removal of arsenic from wastewater. The experimental parameters that influence the sorption process were investigated. The results obtained revealed that the effective removal of arsenic was found to be dependent on solution pH, sorbent dosage, initial contaminant concentration, and contact time. HBC-RH maximum monolayer sorption capacity for arsenic was 28.32 mg g−1 and the experimental data suggested that the arsenic sorption was best fitted by pseudo-second-order kinetic mode. Above all, HBC-RH can easily be separated from aqueous solution after accomplishing its mission, avoiding separation complications faced by powder adsorbents in aqueous media

Visualisation of latent fingerprints on non-porous object immersed in stagnant tap water using safranin-tinted Candida rugosa lipase reagent

Waterways have been frequently used for disposing evidence by perpetrators, especially during homicide, rendering difficulties for forensic fingerprint investigators since water may destruct the amino acid components of fingerprints. Although the use of small particle reagent for visualising the lipid components of a fingerprint has been suggested, its use must be reduced due to its toxicity on human as well as environment. Therefore, this present research has developed a new environmentally-friendly safranin-tinted Candida rugosa lipase reagent (i.e. Lipase-Glutaraldehyde-Safranin, Lip-GA-Saf) for visualising latent fingerprints on non-porous surface (aluminium foils) immersed for up to 4 weeks in stagnant tap water. Results revealed that the quality of latent fingerprints (Fingermark Quality Scale) developed using Lip-GA-SAF was statistically better in all the four different durations of immersion than that of using SPR (p<0.05). Declining quality of fingerprints over longer period of immersion was also observed for both the Lip-GA-SAF reagent and SPR developed fingerprints. Considering the better quality of fingerprints developed using Lip-GA-SAF reagent, its usefulness in forensic practical caseworks appears promising