Evaluation of Hybrid Membrane Bioreactor (MBR) For Palm Oil Mill Effluent (POME) Treatment

The pollution load of palm oil mill effluent (POME) is in the range of 50,000 mg COD/L. With more than 500 palm oil mills, Malaysia produces some 13.9 million tonnes of crude palm oil annually and generates around 35 x 106 m3 POME. Typically, raw POME is difficult to degrade because it contains significant amounts of oil (tryacylglycerols) and degradative products such as di-and monoacylglycerols and fatty acids. The fatty acids composition (C12 – C20) of each of this fraction are different from one another and contribute to the high value of pollution load in POME. Thus POME has to be treated, usually in a series of anaerobic and aerobic treatment steps, for the organic matter to be degraded before the effluent is allowed to be discharged into public waterways. The objective of this study was to observe the performance of a hybrid membrane bioreactor (MBR) for POME. The raw POME was introduced into sequencing processes of anaerobic, anoxic and aerobic in order to achieve biological nutrient removal and the membrane modules were submerged into the aerobic zone. The critical flux of MBR using the flux-step method based on transmembrane pressure (TMP) was conducted as well as flux and permeability studies for assessing fouling in a membrane bioreactor operating at constant flux. The reactor was operated at a mixed liquor suspended solid (MLSS) concentration of 4000 to 8000 mg/l. The removal efficiency of COD, SS, TN and TP achieved were 94%, 98%, 83% and 64% respectively. The hybrid MBR was found to be able to degrade POME significantly and high quality effluent could be reused for various other applications.Keywords

Optimization of operating parameters of novel composite adsorbent for organic pollutants removal from POME using response surface methodology

The present work aimed to develop a novel composite material made up of activated cow bone powder (CBP) as a starting material for reducing chemical oxygen demand (COD) and ammonia-nitrogen (NH3eN) from palm oil mill effluent (POME). The optimization of the reduction efficiency was investigated using response surface methodology (RSM). Six independent variables used in the optimization experiments include pH (4e10), speed (0.27e9.66 rcf), contact time (2e24 h), particle size (1e4.35 mm), dilution factor (100e500) and adsorbent dosage (65e125 g/L). The chemical functional groups were determined using Fourier transform irradiation (FTIR). The elemental composition were detected using SEM-EDX, while thermal decomposition was investigated using thermo gravimetric analysis (TGA) in order to determine the effects of carbonization temperature on the adsorbent. The results revealed that the optimal reduction of COD and NH3eN from raw POME was observed at pH 10, 50 rpm, within 2 h and 3 mm of particle size as well as at dilution factor of 500 and 125 g L�1 of adsorbent dosage, the observed and predicted reduction were 89.60 vs. 85.01 and 75.61 vs. 74.04%, respectively for COD and NH3eN. The main functional groups in the adsorbent were OH, NeH, C]O, C]C, CeOeC, CeOeH, and CH. The SEMEDX analysis revealed that the CBP-composite has a smooth surface with high contents of carbon. The activated CBP has very stable temperature profile with no significant weight loss (9.85%). In conclusion, the CBP-composite investigated here has characteristics high potential for the remediation of COD and NH3eN from raw POME

Effect of Sintering Process and Starch Amount on the Porosity and Permeability of Al2O3-ZrO2 High Porous Oil Filters

Alumina-Zirconia is prepared for oil filter. Oil filters are used to separate oil derivatives from each other using separation principles depending on the size of the holes. These filters work on the principle of separation depending on the density and viscosity of liquid or on the difference in impurity crystals size. This work involves preparation of filters from Alumina-Zirconia powder materials by a hybrid freeze casting and space-holder method. These filters have excellent properties such as stability at high temperature, excellent corrosion resistance; withstand static stresses, and other unique thermal properties. Alumina-Zirconia powder is mixed with different amounts of (zero, 15, 25, and 35 vol. %) of starch powder. Powder mixture has been blending with water using an electric mixer to obtain homogeneous slurry. Solid: liquid ratio of slurry of 30:70 is poured in a cylindrical metal molds and freezed by liquid nitrogen chamber. The solidified material was heat treated at 300 °C for 60 min then sintered at 1550 °C, 1600 °C and 1700 °C under vacuum for 120 min. Hot samples were cooled inside furnace until room temperature. The sintered materials were examined to show the effect of starch adding and sintering process on the porous structure and permeability ratio of the fluid using Archimedes method and SEM image analyzed by J-image program. Best permeability and homogeneous porous structure are obtained at 1600 °C sintering temperature with 24 vol. % of starch powder

All fibre Q-switched Thulium-doped fibre laser incorporating Thulium–Holmium co-doped fibre as a saturable absorber

A novel all fibre Q-switched Thulium-doped fibre laser (TDFL) is reported which includes a short length of a Thulium–Holmiumco-doped fibre (THDF) as a saturable absorber. A high repetition rate (27.26 kHz) coupled with a low pulse width (19.06μs) is obtained for single wavelength Q-switched pulse operation at an output wavelength of 1911.5 nm using a pump power of 200 mW. Increasing the pump power from 200 mW to 700 mW results in the repetition rate increasing from 27.26 kHz to 99.67 kHz and the pulse width decreasing from 19.06μs to 920 ns. The centre wavelength of the single Q-switched pulse was also red shifted from 1911.5 nm to 1932.5 nm with increasing the pump power. A 45 m length single-mode fibre (SMF-28) provided dispersion compensation, and effectively an SMF-THDF-SMF structure is inserted in the cavity which operates in a similar manner to an SMF-MMF-SMF structure, providing a strong multimode interference effect which supports dual-wavelength operation. A stable dual-wavelength Q-switched pulse was achieved at a threshold pump power of 213 mW. The dual-wavelength Q-switched pulse operation was generated at 1911.5 nm and 1914.5 nm with a repetition rate of 8.45 kHz and pulse width of 20.02μs. The dual-wavelength spacing of this pulse operation was 3 nm, which was in good agreement with calculations based on the multimode interference effect induced by the THDF. The repetition rate increased from 8.45 kHz to 70.65 kHz and the pulse width decreased from 20.02μs to 870 ns with increasing pump power. At the maximum pump power of 700 mW, the maximum output power was measured as 27.4 mW. The experimental results confirm that the THDF can be utilized as a SA to generate a stable and tunable single-wavelength Q-switched pulse output as well as dual-wavelength Q-switched pulse in the 2.0μm wavelength region

Three phase fault algorithm in distribution system by using database approach and impedance based method

A three phase fault location algorithm using database and impedance based method is utilized in distribution system to locate fault which may occur in any possible fault sections and to optimize the switching operations to reduce the outage time affected by fault. The configuration of 132/11kV from actual distribution system in Malaysia with 38 nodes is modelled using the PSCAD/EMTDC software. This work attempt to combine fault section identification with impedance based method in order to address non-homogeneity of cables in distribution system. The result which is the fault location result is obtained through the complete process which involves the database formation acquired through the PSCAD/EMTDC software simulator and the fault location distance calculation carried out by the MATLAB software. The comparison is made through proposed algorithm with actual data acquired from the utility board. Final outcome of the proposed algorithm shows good approximation on fault location

Multi-wavelength thulium-doped fiber laser operating at slope efficiency of 16.57% in linear cavity configuration

A multi-wavelength thulium doped fiber laser (TDFL) with a slope efficiency of 16.57 % is demonstrated using a linear cavity consisting of a broadband mirror and a flat-cleaved fiber end in conjunction with 1552 nm pumping. The TDFL produces eleven lines within a wavelength range from 1895 to 1907 nm with a constant spacing of 1.2 nm and signal to noise ratio of more than 27 dB. The multi-wavelength TDFL is capable of generating pulses with a repetition rate of 11.62 MHz and average output power of 93 mW at the maximum pump power of 1100 mW. The proposed multi-wavelength TDFL is suitable for a multitude of real-world applications such as range-finding, medicine and spectroscopy due to its ability to operate in the eye-safe region of 2 micron

Soliton mode-locked erbium-doped fibre laser with mechanically exfoliated molybdenum disulphide saturable absorber

The authors demonstrate the generation of soliton mode-locked pulses from an erbium-doped fibre ring laser incorporating molybdenum disulphide (MoS2) saturable absorber (SA) with a net anomalous dispersion. The MoS2 SA is prepared by mechanically exfoliating MoS2 crystal and fixing the acquired MoS2 flakes onto the end surface of a standard FC/PC fibre connector. A self-started mode-locked soliton pulse is generated by fine-tuning the rotation of the polarisation controller at the threshold pump power of 50 mW. Its solitonic behaviour is verified by the presence of Kelly sidebands in the output spectrum. The central wavelength, 3 dB bandwidth, pulsewidth, and repetition rate of the laser are 1598.94 nm, 5.4 nm, 0.83 ps, and 17.1 MHz, respectively. The maximum pulse energy is 74 nJ at pump power of 110 mW with the output power of 1.26 mW. The MoS2 SA was constructed in a simple fabrication process and has a modulation depth of 11.3% to successfully produce the stable soliton mode-locked fibre laser

Femtosecond mode-locked erbium-doped fiber laser based on MoS2–PVA saturable absorber

We fabricate a free-standing few-layer molybdenum disulfide (MoS2)–polymer composite by liquid phase exfoliation of chemically pristine MoS2 crystals and use this to demonstrate a soliton mode-locked Erbium-doped fiber laser (EDFL). A stable self-started mode-locked soliton pulse is generated by fine-tuning the rotation of the polarization controller at a low threshold pump power of 25 mW. Its solitonic behavior is verified by the presence of Kelly sidebands in the output spectrum. The central wavelength, pulse width, and repetition rate of the laser are 1573.7 nm, 630 fs, and 27.1 MHz, respectively. The maximum pulse energy is 0.141 nJ with peak power of 210 W at pump power of 170 mW. This result contributes to the growing body of work studying the nonlinear optical properties of transition metal dichalcogenides that present new opportunities for ultrafast photonic applications

1941 nm Q-switched thulium-doped fiber laser with a multi-layer black phosphorus saturable absorber

We demonstrate a Q-switched Thulium-doped fiber laser (TDFL) operating at 1941 nm region based on multi-layer black phosphorous (BP) as a saturable absorber (SA). The BP-based SA was prepared by mechanically exfoliating BP crystal and fixing the acquired BP flakes onto the scotch tape. A small piece of the tape was then sandwiched between two ferrules and incorporated in TDFL cavity to achieve stable Q-switched operation in conjunction with 1552 nm core pumping. The pulse repetition rate of the laser could be varied from 15.32 to 27.82 kHz, by tuning the pump power from 495 to 645 mW. At 645 mW pump power, the laser showed the average output power, pulse energy, and pulse width of 14 mW, 0.50 μJ, and 4.38 µs, respectively. Our results show that multi-layer BP is a promising SA for Q-switching laser operation in 2-micron region