In this study, biochar made from the Sesbania sesban plant, under slow pyrolysis at 300°C was used to adsorb methylene blue (MB) in aqueous solution. The biochar properties were clarified by diverse analytical methods such as FTIR, SEM, and BET. The results indicated that the surface of biochar was relatively smooth, had porous texture, and stacked evenly. In addition, the biochar had a large specific surface area of 561.8 m2/g and the pHpzc value was 6.9. The effect of adsorbent dosage, initial pH, contact time, and concentration of dye solution on biochar were investigated. The optimum conditions for MB adsorption were found at the MB concentration of 50 mg/L, initial pH of 11, biochar mass of 0.6 mg, and contact time of 30 min. Under these optimal conditions, MB dye removal efficiency was above 90%. Adsorption isotherm data were fitted with the Langmuir isotherm model (R2=0.897) suggesting the adsorption was monolayer, and its maximum adsorption capacity was about 6.6 mg/g. The adsorption kinetic models showed that the linear pseudo-second-order by R2=0.999 was well fitted. The results indicated the enormous potential of Sesbania sesban plant to produce biochar as a low-cost and rather high-effective adsorbent for dye removal from wastewater as well as water quality improvement.
This study evaluates the efficiency of domestic wastewater treatment via Sponge-Based Moving Bed Biofilm Reactor (S-MBBR). The laboratory-based treatment plan uses polyurethane sponge with a specific surface area was 260 m<sup>2</sup>/m<sup>3</sup> as a carrier. The treatment plan operated under four different organic load rate: OLR1 = 0.4 kg BOD/m<sup>3</sup>.day; OLR2 = 0.6 kg BOD/m<sup>3</sup>.day; OLR3 = 0.8 kg BOD/m<sup>3</sup>.day; and OLR4 = 1.0 kg BOD/m<sup>3</sup>.day. During 80 d of the experiment, the highest treatment efficiency was at the organic load rate of 0.4 kg BOD/m<sup>3</sup>.day, with COD, SS, TN and TP were found to be 85.0 ± 12.9%, 85.7 ± 5.3%, 68.9 ± 1.7%, and 40.3 ± 0.2%, respectively. In which, the influent SS concentration were from 117.3 to 126.0 mg/L, the effluent concentration were in ranged 18.0 to 34.22 mg/L, respectively. The values of influent and effluent COD were 298.8 ± 12.88 and 44.8 ± 3.78 mg/L in turn. The OLR1 influent TN, TP concentrations were respectively 47.9 ± 2.11 and 3.6 ± 0.15 mg/L; the effluent TN, TP concentration were 14.9 ± 0.18 and 2.2 ± 0.06 mg/L, respectively. The study suggests that the effluent is within the allowable limits of National technical regulation on domestic wastewater (Column B1), indicating the applicability of S-MBBR for the domestic wastewater treatment plant.
A down-flow hanging sponge (DHS) bioreactor was operated for the treatment of domestic wastewater. The Stover-Kincannon model was applied for kinetic evaluation of the reactor performance during the operational period. As a result, the coefficient of determination (R 2) for straight lines of effluent concentration from the experimental data and from the predictive data of BOD5; NH4 +-N; and TN were 0.9727; 0.9883; and 0.9934, respectively. The calculation of saturation value constant (Umax-g L-1 d-1) and maximum utilization rate constant (KB-g L-1 d-1) were 56.818 and 75.034 for BOD5; 2.960 and 4.713 for NH4 +-N; 2.810 and 8.37 for TN, respectively. The study suggests that Stover-Kincannon model can be used for effective evaluation of kinetic removal of BOD5; NH4 +-N; and TN from domestic wastewater treated in a DHS bioreactor.
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