Chantaraporn Phalakornkule

ELECTROCOAGULATION OF BLUE REACTIVE, RED DISPERSE AND MIXED DYES AND APPLICATION IN TREATING TEXTILE EFFLUENT

This study investigated the efficiency of electrocoagulation in removing color from synthetic and real textile wastewater. Two representative dye molecules were selected for the synthetic dye wastewater: a blue reactive dye (Reactive Blue 140) and a disperse dye (Disperse Red 1). The electrochemical technique showed satisfactory color removal efficiency and reliable performance in treating both individual and mixed dye types. The removal efficiency and energy consumption data showed that, for a given current density, iron was superior to aluminum in treating both the reactive dye and the disperse dye. With an initial dye concentration of 100 mg L(-1), the energy cost in achieving >95% color removal was on the order of 1 kWh m(-3) for both dyes. The effect of changing the initial pH of the samples on the removal efficiency and energy consumption was also studied. It was found that the design parameters used for the synthetic wastewater were less effective for treatment of real textile wastewater, with 1 in 5 tests on real wastewater failing.

Magnetic composite prepared from palm shell-based carbon and application for recovery of residual oil from POME

Magnetic separation combined with adsorption by activated carbon has been found to be a useful method for removing pollutants. In this paper, the use of palm shell as a source of activated carbon for the removal and recovery of oil from palm oil mill effluent (POME) is studied. In the first part of the study, the properties of samples of activated carbon prepared from palm shell under a variety of different conditions were characterized for their hydrophobicity, surface areas and pore size distribution. The most effective of the activated carbon samples was prepared by impregnation with ZnCl(2) followed by combined physical/chemical activation under carbon dioxide flow at 800 °C. Four grams of these samples adsorbed 90% of the oil from 50 mL POME. In the second part, the palm shell-based carbon samples were given magnetic properties by the technique of iron oxide deposition. Ninety-four percent of the activated carbon/iron oxide composite containing the adsorbed oil could be extracted from the POME by a magnetic bar of 0.15 T. Four grams of the composite can remove 85% of oil from 50 mL POME and a total of 67% of the initial oil can then be recovered by hexane extraction. Powder X-ray diffractometry showed the presence of magnetite and maghemite in the activated carbon/iron oxide composite.

Improvement of upflow anaerobic sludge bed performance using chitosan

Chitosan, with a degree of deacetylation of 85% and a molecular weight of 2.5 x 10(5) Da, yielding high flocculation efficiency (85 to 100% flocculation) and a broad flocculation region (2 to 45 mg/g suspended solids), was selected for accelerating granulation in a 30-L upflow anaerobic sludge bed (UASB) used to treat wastewater from a tropical fruit-processing industry. Compared with other studies, smaller amounts of chitosan were applied (two injections with 2 mg chitosan/g suspended solids in the reactor at each injection). Comparison with the UASB without chitosan addition, the UASB had a 24 to 37% larger particle size and a 6 to 41% longer solids retention time. In addition, the reactor performances were also enhanced. The UASB with chitosan addition had a 9 to 59% lower effluent chemical oxygen demand (COD), 4 to 10% higher COD removal, up to 35% higher biogas production rate, and a 16 to 68% lower biomass washout. The paired t-test analysis indicated that these performance parameters were significantly different (P < 0.05).

Comparative mesophilic and thermophilic anaerobic digestion of palm oil mill effluent using upflow anaerobic sludge blanket.

The effects of organic loading rate and operating temperature on the microbial diversity and performances of upflow anaerobic sludge blanket (UASB) reactors treating palm oil mill effluent (POME) were investigated. The following two UASB reactors were run in parallel for comparison: (1) under a mesophilic condition (37 degrees C) and (2) under a mesophilic condition in transition to a thermophilic condition (57 degrees C). A polymerase chain reaction (PCR)-based denaturing gradient gel electrophoresis (DGGE) analysis showed that the microbial population profiles significantly changed with the organic loading rate (OLR) and the temperature transition from the mesophilic to the thermophilic condition. Significant biomass washout was observed for the mesophilic UASB when operating at a high organic loading rate (OLR) of 9.5 g chemical oxygen demand (COD)/L.d. In contrast, the thermophilic UASB can be operated at this OLR and at a temperature of 57 degrees C with satisfactory COD removal and biogas production. The PCR-based DGGE analysis suggested that the thermophilic temperature of 57 degrees C was suitable for a number of hydrolytic, acidogenic, and acetogenic bacteria.

Investigation of electrochemical variables and performance of a continuous upflow electrocoagulation process in the treatment of Reactive Blue 140.

This study presents an investigation of electrochemical variables in the operation of a continuous upflow electrocoagulation process in treating textile wastewater. Reactive Blue 140, which is porphyrin-based, was used as a representative dye in the experiments. The optimal values of the design and operating parameters were found, from a batch mode, to be the following: iron anode, distance between electrodes of 8 mm, current density of at least 30 A/m2, and contact time of at least 5 minutes. These optimal values were used to design a continuous upflow electrocoagulation reactor. The pattern of liquid flow within the upflow reactor was studied using a computational fluid dynamics (CFD) program, which simulated the flow behavior inside the reactor using the finite volume method. For optimal parameter values, the water passing the electrode plates had a uniform distribution, and the reactor performance was satisfactory, with >90% color removal and energy consumption of approximately 1.4 kWh/m3.

Influence of a three-phase separator configuration on the performance of an upflow anaerobic sludge bed reactor treating wastewater from a fruit-canning factory.

The objective of this study was to investigate the influence of a three-phase separator configuration on the performance of an upflow anaerobic sludge bed (USAB) treating wastewater from a fruit canning factory. The performances of two 30-L UASB reactors--one with a modified three-phase separator giving a spiral flow pattern and the other with a conventional configuration-were investigated in parallel. Wastewater, with a chemical oxygen demand (COD) concentration between 2000 and 7000 mg/L, was obtained from a fruit-canning factory. Based on the effluent data of the first 100 operation days, the UASB with the three-phase separator giving spiral flow patterns yielded up to 25% lower biomass washout. It also showed better efficiencies in treating wastewater--up to 60% lower effluent COD, up to 20% higher COD percent removal, and up to 29% higher biogas production. This work presents evidence of an improvement on the conventional physical design of a UASB.

Enhancing Biogas Production and UASB Start-Up by Chitosan Addition

Anaerobic digesters have been applied for the treatment of wastewater yielding biogas as a value by-product. The biogas from the treatment plant can be utilized for generating heat and electricity. Anaerobic bacteria form granules through cell self-immobilization which then settle out as floc aggregates. These granules are dense microbial consortia packed with different bacterial species and contain millions of organisms per gram of biomass (Liu & Tay, 2002; Liu et al., 2003; Sheng et al., 2010). Granules in anaerobic digestion are important for enhancing process efficiency by increasing biomass hold-up. An anaerobic digester with higher biomass hold-up will be better in terms of COD removal and biogas production.