Functionalization of sewage sludge char by partial oxidation with molecular oxygen to enhance its adsorptive properties

This study investigates the activation of sewage sludge char through partial oxidation with molecular oxygen with the goal to increase the concentration of oxygen-containing surface functional groups and to enhance its ammonium adsorption capacity. The effects of oxidation temperature (200–350 °C), oxygen concentration (5–21 vol %) and oxidation time (30–120 min) on the degree of char oxidation are analyzed. The results obtained by thermogravimetric and elemental analysis, and Fourier Transform Infrared and X-ray Photoelectron spectroscopy corroborate the incorporation of oxygenated functional groups on the surface of sewage sludge char either at low temperature (200 °C) using air or at higher temperature (350 °C) using 5% O2 for 30 min. The oxidation of sewage sludge char hardly increases its specific surface area. The operating conditions during oxidation must be carefully controlled to avoid runaway reactions that lead to total oxidation of char. The evolution of CO and CO2 during oxidation is a good indicator of the advance of the oxidation/burn-off reactions. The ammonium adsorption capacity of sewage sludge char increases after oxidation under mild operating conditions, providing support to the idea of onsite utilization of sewage sludge as ammonium adsorbent in waste water treatment plants. This would provide a step forward towards the implementation of a circular economy

Flammability, tensile and morphological properties of oil palm empty fruit bunches fibre/ pet yarn reinforced epoxy fibre retardant hybrid polymer composites

Oil palm empty fruit bunches (OPEFB) fiber is a natural fiber that possesses many advantages, such as biodegradability, eco-friendly, and renewable nature. The effect of the OPEFB fiber loading reinforced fire retardant epoxy composites on flammability and tensile properties of the polymer biocomposites were investigated. The tests were carried out with four parameters, which were specimen A (constant), specimen B (20% of fiber), specimen C (35% of fiber), and specimen D (50% of fiber). The PET yarn and magnesium hydroxide were used as the reinforcement material and fire retardant agent, respectively. The results were obtained from several tests, which were the horizontal burning test, tensile test, and scanning electron microscopy (SEM). The result for the burning test showed that specimen B exhibited better flammability properties, which had the lowest average burning rate (11.47 mm/min). From the tensile strength, specimen A revealed the highest value of 10.79 N/mm2. For the SEM morphological test, increasing defects on the surface ruptured were observed that resulted in decreased tensile properties of the composites. It can be summarized that the flammability and tensile properties of OPEFB fiber reinforced fire retardant epoxy composites were reduced when the fiber volume contents were increased at the optimal loading of 20%, with the values of 11.47 mm/min and 4.29 KPa, respectively

Harnessing the potential of ligninolytic enzymes for lignocellulosic biomass pretreatment

Abundant lignocellulosic biomass from various industries provides a great potential feedstock for the production of value-added products such as biofuel, animal feed, and paper pulping. However, low yield of sugar obtained from lignocellulosic hydrolysate is usually due to the presence of lignin that acts as a protective barrier for cellulose and thus restricts the accessibility of the enzyme to work on the cellulosic component. This review focuses on the significance of biological pretreatment specifically using ligninolytic enzymes as an alternative method apart from the conventional physical and chemical pretreatment. Different modes of biological pretreatment are discussed in this paper which is based on (i) fungal pretreatment where fungi mycelia colonise and directly attack the substrate by releasing ligninolytic enzymes and (ii) enzymatic pretreatment using ligninolytic enzymes to counter the drawbacks of fungal pretreatment. This review also discusses the important factors of biological pretreatment using ligninolytic enzymes such as nature of the lignocellulosic biomass, pH, temperature, presence of mediator, oxygen, and surfactant during the biodelignification process

Palm oil mill final discharge treatment by a continuous adsorption system using oil palm kernel shell activated carbon produced from two-in-one carbonization activation reactor system

This work aimed at removing a major amount of organic and inorganic pollutants existing in palm oil mill effluent (POME) final discharge by using an effective adsorbent from renewable sources. In this study, the treatment of effluent by a continuous system that had improved the removal efficiency as compared to the previous batch system is demonstrated. The renewable sources of oil palm kernel shell activated carbon (ACOPKS) has been produced using a two-in-one carbonization activation system, packed into a column for continuous adsorption system to reduce the concentration of biological oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS) and colour intensity of the palm oil mill effluent (POME) final discharge. The continuous adsorption system was tested using AC-OPKS dosages of 0.01–0.05 kg L−1 at a constant pH of 8.03 with different treatment times of 2–12 h and flow rates of 30–70 mL min−1 to determine the optimal adsorbent capacity. It was found that the optimal dosage of 0.04 kg L−1 , the flow rate of 50 mL min−1 and a treatment time of 10 h gave the highest adsorption capacity. In comparison with the batch system, this continuous adsorption system had improved the reduction of BOD, COD, TSS and colour intensity from 90 %, 68 %, 97 % and 83 % (using a batch system) to 93.52 %, 92.79 %, 94.84 % and 89.21 %, respectively (using a continuous system). The treated POME final discharge has the BOD value of 19.10 mg L−1 , which is below than the standard set (20 mg L−1 ) by the Department of Environment Malaysia (DOE) under the Environmental Quality Act 197

Medium optimization for chitinase production from Trichoderma virens using central composite design

Medium development for chitinase production by Trichoderma virens was first carried out using conventional method of one-factor-at-a-time. The medium was further optimized using Central Composite Design in which response surface was generated later from the derived model. An experimental design of four variables including various initial pH values, chitin, ammonium sulphate, and methanol concentrations were created using Design Expert® Software, Version 6.0. The design consists of 30 experiments, which include 6 replicates at center points. The optimal value for each variable are 3.0 g/L, chitin; 0.1 g/L, ammonium sulphate; 0.4% (v/v), methanol; and initial pH, 4.0 with predicted chitinase activity of 0.1495 U/mL. These predicted parameters were tested in the laboratory and the final chitinase activity obtained was 0.1471 U/mL, which is almost reaching the predicted value. The optimal medium design showed an improvement of chitinase activity of 80.9% compared to activity obtained from the original Absidia medium composition