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The palm oil industry has been one of the major economic contributors for Malaysia over the last decade. While contributing to the country's economic growth, the industry has inevitably produced a significant amount of waste materials which are harmful to the environment. Oil palm boiler ashes (OPBA) generated from boiler in mills are disposed in open landfills which are easily carried away by the wind. The disposed ash pollutes the air while spent earth, when left in landfills, produce a pungent odour. The present work investigated the possibility of refining palm oil with raw OPBA and pelletized OPBA as alternate bleaching adsorbents. The performance of different types OPBA (raw, enhanced and pelletized) was investigated to determine their bleaching efficiencies on carotenoid removal at various operating conditions. Crude palm oil samples were refined with these OPBA and compared with commercial bleaching earth to investigate the final refined oil colours. A final refined oil colour of 4.0R was obtained using 0.05 wt% of enhanced OPBA when bleached at 110 °C for 45 min under constant agitation (300 rpm) and subsequently deodorized at 265 °C for 1 h. This study has indicated that the use of enhanced OPBA which could achieve more than high removal of carotenoid could substitute commercial bleaching earths to produce a comparable final refined oil colour rating. The successful substitution of OPBA to replace the conventional bleaching earth in oil refining could significantly reduce the production cost. This is also a sustainable solution for the edible oil processing industries to mitigate the solid waste and contributes to a cleaner environment.

Dye effluents released from numerous dye-utilizing industries are harmful towards the environment and living things. Consequently, existence of dye effluent in environmental water bodies is becoming a growing concern to environmentalists and civilians. A long term sustainable and efficient dye effluent treatment method should be established to eliminate this issue. Dye wastewater should be treated first before release to minimize its negative impacts towards the environment and living things. However, due to lack of information on efficient dye removal methods, it is difficult to decide on a single technique that resolves the prevailing dye effluent issue. Therefore, this paper reviews existing research papers on various biological, chemical and physical dye removal methods to find its efficiency through percentage of dye removal. Although there are numerous existing tried and tested methods to accomplish dye removal, most of them have a common disadvantage which is the generation of secondary pollution to the environment. This paper highlights enzyme degradation (biological) and adsorption (physical) dye removal as these are known as one of the most efficient dye removal techniques these days. This paper also suggests the usage of a combined adsorbent as it is envisioned that this technique has better efficiency and is able to remove dyes at a faster rate.

Urease were known to catalyze the conversion of urea to ammonia and carbon dioxide. Microbial urease has demonstrated its benefits in wide biotechnological, agricultural, medicinal and engineering application. There are number of diverse microbial species contribute to urease activity in different natural habitats like soil, ocean and in various geological formation. For this study, urease bacteria were screened and isolate from acidic peat in Sarawak, Malaysia. Five distinct and diverse bacterial strains that were able to produce urease constitutively were selected to be characterized with respect to morphology, biochemical test, growth conditions and urease activity. The selected strain showed their capability to precipitate calcium carbonate (CaCO3). Hence, the isolates could be potential source of acid ureases that can be use in various industrial utilizations. 16S rRNA sequencing and phylogenetic analysis found that the selected isolates belong to the genus of Bacillus.

The large capacity of wastewater production due to rapid growth of industries has resulted in limited water resources. The need to protect and conserved water resources have enforced researchers worldwide to focus on the development of an effective, economical and environmentally friendly novel materials. In this study, green synthesis of zinc oxide nanoparticles (ZnONPs) using T. diversifolia leaf extract by hydrothermal method was loaded on the surface of flamboyant pods (Delonix regia) activated carbon (FPAC). The developed ZnONPs loaded on the surface flamboyant pods activated carbon (ZnONPs-FPAC) was used successfully to remove of methylene blue (MB) from aqueous solution. The developed FPAC, ZnONPs and ZnONPs-FPAC were characterized UV–Vis spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX), Transmission electron microscope (TEM) and Brunauer-Emmett-Teller (BET) techniques. The antibacterial activity of the synthesized FPAC, ZnONPs and ZnONPs-FPAC were screened and the results revealed that ZnONPs has an excellent antibacterial activity when compared. Batch adsorption studies were conducted to investigate the influence of process parameters such as initial concentration, contact time, pH, adsorbent dosage and temperature on MB uptake. The high BET surface area of 794.48 m2/g and mesoporous ZnONPS-FPAC developed gave good adsorption capacity of 186 mg/g. Equilibrium adsorption data of MB were modelled using Langmuir, Freundlich, Temkin and Dubinin–Radushkevich (D–R) isotherm model. The adsorption of MB onto ZnONPs-FPAC was best described by Freundlich model indicating surface heterogeneity, and pseudo-second-order kinetics according to % Δ q e (normalized standard deviation), SSE (sum of square error), and R2 (coefficient of determination) values. The results of the thermodynamic suggest that the adsorption process of MB onto ZnONPs-FPAC is endotherm, favourable, spontaneous, and physical. In nature. The reusability of ZnONPs-FPAC was examined upto five cycles with no significant loss in removal efficiency. The mean free energy (E), and Enthalpy ( Δ H ) values calculated, suggested that the adsorption mechanism of MB on ZnONPs-FPAC is dominated by physical adsorption.

The search for effective and sustainable methods to degrade and remove recalcitrant dyes from textile effluents is a major research endeavor, owing to the escalating environmental and health concerns arising from the discharge of coloured effluents into water bodies. Plant-based peroxidases represent a reliable bio-resource for sustainable treatment of coloured effluents with the capacity to offer a continuous process for high throughput operation. The present study investigates the potential use of soybean peroxidase and Luffa acutangula (luffa) peroxidase, extracted from bio-wastes of soybean hulls and luffa skin peels respectively, for enzymatic degradation of azo dye methyl orange from liquid effluents. The enzymatic dye removal process was studied based on the consistent enzymatic activities of crude soybean peroxidase and luffa peroxidase extracts, which were 0.373 U mL −1 and 0.355 U mL −1 respectively. The effects of several process parameters including reaction time, pH, temperature, enzyme dosage, initial dye concentration and hydrogen peroxide concentration were investigated to optimise the performance of the enzymatic treatment process. Soybean peroxidase demonstrated a maximum dye decolourisation efficiency of 81.4% under the conditions of 1 h incubation at 30 °C using 2 mM of hydrogen peroxide, 0.5 mL crude soybean peroxidase and 30 mg L −1 methyl orange at pH 5.0. Also, luffa peroxidase yielded a maximum decolourisation efficiency of 75.3% under the conditions of 40 min at 40 °C using 2 mM hydrogen peroxide, 1.5 mL crude luffa peroxidase and 10 mg L −1 methyl orange at pH 3.0.

Enzymes are known to catalyze reactions at high efficiency, operate at milder conditions and are biodegradable. Due to enzyme limitations such as sensitivity to environmental conditions, enzyme immobilization is often used. The commonly employed immobilization methods include adsorption, entrapment, covalent attachment and cross-linking. Many research works have now focused on the immobilization of enzymes on nanoscale support due to the higher surface area to volume ratio, effective enzyme loading, significantly enhanced mass transfer efficiency and minimization of diffusional problems. The application of enzyme incorporated nanotechnology in the treatment of dye wastewater is thus, of high interest. Therefore, this paper has critically reviewed (1) the current technologies available for dye wastewater treatment; (2) different methods utilized for enzyme immobilization; and (3) the application and performance of enzyme incorporated nanotechnology for dye wastewater treatment. We identified that there is high potential for enzyme incorporated nanotechnology to be implemented in dye wastewater treatment due to the high decolorization performance (e.g. laccase immobilized on Fe3O4/SiO2 nanoparticles achieved 99% decolorization of Procion Red MX-5B in 20 min). We have also identified the key challenges faced by enzyme incorporated nanotechnology in dye wastewater treatment that includes: (i) realization of lab scale experiments to industrial applications; (ii) lack of understanding of enzymes incorporated nanotechnology; (iii) recovery of immobilized enzyme; (iv) synthesis of hybrid nanoflowers; and (v) sustainability of the nanomaterials used.

The enantio-separation of racemic ibuprofen ester via enzymatic membrane reactor is studied. The lipase-catalyzed resolution technique integrates kinetic resolution (KR) with in situ racemization resulting in 100% optically pure product. A mathematical model of lipase-immobilized hollow fiber membrane reactor incorporating dynamic kinetic resolution (DKR) of racemic ibuprofen ester is proposed. In the process of developing theoretical models for DKR, two zones were considered: (i) enzymatic hydrolysis of substrate in membrane matrix support and (ii) simultaneous racemization of unreacted substrate outside the membrane. The first part of the modeling work emphasized on the derivation of DKR rate equations for both enantiomers, based on the enzymatic resolution mechanism. The second part of the DKR model was derived by considering the mass transfer in the DKR rate equation. The model was solved using two numerical methods by means of MATLAB® build-in solver. The first numerical technique was based on the explicit Runge–Kutta to solve the system of non-linear first-order ordinary differential equations (ODEs) of DKR reaction rate. The second approach was a collocation technique for solving the non-linear second-order ODEs of the convective hydrolysis–racemization phenomena in the membrane layer. A number of process parameters were studied in order to investigate their effects on the concentration profiles and separation efficiency in terms of enantiomeric excess, i.e. ees and eep by simulating the models. The model parameters include Bodenstein number, B0, Thiele modulus, Φ2 and dimensionless racemization constant, γ. The simulation results showed that the hollow fiber membrane operates effectively at B0 = 8.68, γ = 10, Φ2 = 1 with ees = 2% and eep = 98.5%.