A. W. Zularisam

Targeting N-acyl-homoserine-lactones to mitigate membrane biofouling based on quorum sensing using a biofouling reducer

Exploring novel biological anti-quorum sensing (QS) agents to control membrane biofouling is of great worth in order to allow sustainable performance of membrane bioreactors (MBRs) for wastewater treatment. In recent studies, QS inhibitors have provided evidence of alternative route to control membrane biofouling. This study investigated the role of Piper betle extract (PBE) as an anti-QS agent to mitigate membrane biofouling. Results demonstrated the occurrence of the N-acyl-homoserine-lactone (AHL) autoinducers (AIs), correlate QS activity and membrane biofouling mitigation. The AIs production in bioreactor was confirmed using an indicator strain Agrobacterium tumefaciens (NTL4) harboring plasmid pZLR4. Moreover, three different AHLs were found in biocake using thin layer chromatographic analysis. An increase in extracellular polymeric substances (EPS) and transmembrane pressure (TMP) was observed with AHL activity of the biocake during continuous MBR operation, which shows that membrane biofouling was in close relationship with QS activity. PBE was verified to mitigate membrane biofouling via inhibiting AIs production. SEM analysis further confirmed the effect of PBE on EPS and biofilm formation. These results exhibited that PBE could be a novel agent to target AIs for mitigation of membrane biofouling. Further work can be carried out to purify the active compound of Piper betle extract to target the QS to mitigate membrane biofouling.

Potential of porous Co3O4 nanorods as cathode catalyst for oxygen reduction reaction in microbial fuel cells

This study aims to investigate the potential of porous Co3O4 nanorods as the cathode catalyst for oxygen reduction reaction (ORR) in aqueous air cathode microbial fuel cells (MFCs). The porous Co3O4 nanorods were synthesized by a facile and cost-effective hydrothermal method. Three different concentrations (0.5mg/cm(2), 1mg/cm(2), and 2mg/cm(2)) of Co3O4 nanorods coated on graphite electrodes were used to test its performance in MFCs. The results showed that the addition of porous Co3O4 nanorods enhanced the electrocatalytic activity and ORR kinetics significantly and the overall resistance of the system was greatly reduced. Moreover, the MFC with a higher concentration of the catalyst achieved a maximum power density of 503±16mW/m(2), which was approximately five times higher than the bare graphite electrode. The improved catalytic activity of the cathodes could be due to the porous properties of Co3O4 nanorods that provided the higher number of active sites for oxygen.

Biofouling mitigation using Piper betle extract in ultrafiltration MBR

AbstractThe control of membrane biofouling in the presence of Piper betle extract (PBE) as a biofouling reducer (BFR) has been investigated. Response surface methodology (RSM) has been employed to mitigate extracellular polymeric substances (EPS), transmembrane pressure (TMP) rise-up control, and dye removal in membrane bioreactor. Factors investigated were: BFR dosage, air flow rate, and hydraulic retention time (HRT). Optimum conditions found to be BFR of 0.23 mg/mg mixed liquor suspended solids, HRT of 30.16 h, and air flow rate of 0.60 l/min, with predicted values as 28.28 mg/l of EPS, 24.16 kPa of TMP, and 95.65% dye removal, respectively. Validatory tests were carried out under the optimum conditions, which were closely agreed with the predicted values. These results depicted that RSM was one of the suitable methods to optimize the operating conditions to mitigate fouling in the presence of a BFR. PBE was verified to mitigate membrane biofouling via inhibiting autoinducers production. Furthermore, i...

Lead induced oxidative stress and alteration in the activities of antioxidative enzymes in rice shoots

Physiological responses of Oryza sativa L. to lead excess (10 and 50 μM) were studied in a hydroponic system after 48- and 96-h exposure. Accumulation of Pb in stressed rice shoots was concomitant with an increased metal concentration in the growth media and duration of exposure. The Pb stress resulted in an enhanced lipid peroxidation accompanied by altered activities of antioxidants. A substantial increase in α-tocopherol content of the Pb stressed rice shoots was observed suggesting its important role as an antioxidant. Among the antioxidant enzymes studied, activities of superoxide dismutase (SOD) and ascorbate peroxidase (APX) increased in the Pb-treated rice shoots, whereas that of catalase (CAT) declined. Activity of an important ascorbate-glutathione cycle enzyme, glutathione reductase (GR), also increased significantly in the Pb-treated shoots. The results suggest that Pb toxicity resulted in induction of oxidative stress in rice shoots, and α-tocopherol accumulation and upregulation of SOD, APX, and GR activities play an effective role in acclimatization to Pb stress.

Microbial Fuel Cells: Types and Applications

Microbial fuel cells (MFCs) are bioelectrochemical devices that convert the chemical energy present in organic or inorganic compounds into electric current by using microorganisms as the catalysts. MFCs are of different types; however, the basic designs used in the laboratories for its applications include double-chamber MFC, single-chamber MFC, upflow MFC and stacked MFC. Moreover, some other designs have also been used for the studies. The type of electrode materials and proton exchange membrane (PEM) used in MFCs has most significant role for its outcomes for different applications such as bioelectricity generation, wastewater treatment, bioremediation of toxic compounds, biohydrogen production and biosensors. Furthermore, MFCs are operated at the optimized parameters such as thermophilic temperatures, neutral pH, etc. to obtain more significant results for respective application. This chapter explores the various types of MFCs, the operational parameters to improve its performance and the most studied applications of the MFCs.

Comparison on characteristic of Mesoparticle Graphene Sand Composite (MGSC) using different types of sugar to remove methylene blue

This paper presents the green method to synthesis two types of adsorbent called mesoparticle graphene sand composite (MGSC) by using table sugar (MGSCts) and arenga palm sugar (MGSCaps) as different carbon sources to remove methylene blue acted as a dye model. Immobilisations of these materials on sand were introduced by using pyrolysis method without binder usage. Sand was treated by removing deleterious materials before sieved. The solutions of sugar were prepared and heated to 95 °C. The sand and sugar solutions were mixed and constantly stirred before putting them in furnace with nitrogen environment to produce MGSCts and MGSCaps. The composites were activated by using concentrated sulphuric acid to open the pores and maximise the capacity of absorbency. The analyses on the characteristic of both MGSCts and MGSCaps were conducted through field emission scanning electron microscope (FESEM), elemental dispersive x-ray (EDX) and elemental mapping (EM). FESEM analyses exhibited that the coating process was done uniformly as there were layers of coating sheets formation on the sand particles surfaces. After conducting EDX and EM, there were major elements found in both MGSCts and MGSCaps which were carbon, oxygen and silica. EM exhibited the distribution of these elements were scattered on the MGSCs surfaces. Removal of methylene blue was successfully carried out by using both MGSCts and MGSCaps, with maximum removal up to 40% at the first hour of contact time.

Kinetic and isotherm studies for nickel (II) removal using novel mesoparticle graphene sand composite synthesised from sand and arenga palm sugar

Nickel (II) is one of the most toxic contaminants recognised as a carcinogenic and mutagenic agent which needs complete removal from wastewater before disposal. In the present study, a novel adsorbent called mesoparticle graphene sand composite (MGSCaps) was synthesised from arenga palm sugar and sand by using a green, simple, low cost and efficient methodology. Subsequently, this composite was characterised and identified using field emission scanning electron microscope (FESEM), x-ray diffraction (XRD) and elemental mapping (EM). The adsorption process was investigated and optimised under the experimental parameters such as pH, contact time and bed depth. The results showed that the interaction between nickel (II) and MGSCaps was not ion to ion interaction hence removal of Ni (II) can be applied at any pH. The results were also exhibited the higher contact time and bed depth, the higher removal percentage of nickel (II) occurred. Adsorption kinetic data were modelled using Pseudo-first-order and Pseudo-second-order equation models. The experimental results indicated pseudo-second-order kinetic equation was most suitable to describe the experimental adsorption kinetics data with maximum capacity of 40% nickel (II) removal for the first hour. The equilibrium adsorption data was fitted with Langmuir, and Freundlich isotherms equations. The data suggested that the most fitted equation model is the Freundlich with correlation R2=0.9974. Based on the obtained results, it can be stated that the adsorption method using MGSCaps is an efficient, facile and reliable method for the removal of nickel (II) from waste water.