Removal of Lead from Aqueous Solution by Palm Kernel Fibre

The sorption of lead on palm kernel fibre, an agricultural waste product, has been studied. The sorption process was studied as a function of initial lead concentration and initial solution pH. The percentage lead removal was found to increase with increasing initial solution pH up to pH 5 and then to decrease as pH was increased to 6. The pseudo-second order kinetic rate model was employed in the analysis of the kinetics of lead uptake onto the palm kernel fibre. The results show that the pseudo-second order model fits the experimental data with high coefficients of determination (r2). The equilibrium sorption capacity was found to be 33.33 mg g–1 when 1.0 g of fibre was contacted with 90 mg dm–3 of lead solution at pH 5. Mathematical expressions were derived to relate the pseudo-second order rate constant, k, and the change in solution pH with initial lead concentration.Keywords: Palm kernel fibre, kinetics, lead(II), sorption, change in solution pH

Treatment of textile sludge using anaerobic technology

Composite samples of sludge obtained from a textile factory were characterized for their pollution characteristics using some parameters of interest; pH, solids concentration, oxygen demand, nitrogen,phosphorus, total bacteria counts etc. The analysis revealed that the sludge has high pollution potentials and therefore needed treatment before disposal to the environment. The ratio of chemicaloxygen demand, (COD) to that of biochemical oxygen demand, (BOD) was 3.08; meaning the sludge has high substrate biodegradability. Samples were subjected to mesophilic anaerobic treatment at thetemperature of 35±2°C. The method achieved solids reduction of 61% total solids, 68% settleable solids and 51% volatile solids and a total bacteria reduction of 99.99%. The reduction in BOD and COD were89% each. Nitrate and phosphate were found to reduce substantially thereby preventing eutrophication due to undesirable nutrients. The anaerobic treatment was found to have an additional benefit ofproducing biogas (methane and carbon (IV) oxide) which if harnessed may be used as fuel

Oxygen nanobubbles enhanced photodegradation of oxytetracycline under visible light: synergistic effect and mechanism

International audienceNanobubbles have gained much attention due to their unusual properties such as large specific surface area, surface energy and internal energy, thereby, increase the surface reaction and improve the mass transfer efficiency. The long term stability of nanobubbles and generation of reactive oxygen species enables them to address various environmental issues for water purification without secondary pollution. However, there are few studies concerning the application of oxygen nanobubbles in the advanced oxidation processes (AOPs). In this study, first time, oxygen nanobubbles were introduced into the photoreaction system under visible light irradiation for enhanced photodegradation of oxytetracycline (OTC). Results indicated that oxygen nanobubbles significantly improved the photodegradation of OTC through high mass transfer and generation of reactive radicals during the nanobubble collapse. The oxygen nanobubble stability was confirmed to be pH dependent. The nanobubbles concentration increased from 0.76 to 3.78 × 108 particles/mL, while the mean size decreased from 205 nm to 138 nm as the pH value increased (3.2–11.0). The photodegradation efficiency of OTC was improved from 45% to 98% with the increase of pH (4.0–11.0). Oxygen nanobubbles hold promise to improve the AOPs, such as reducing catalysts and chemicals usage and costs. Quenching experiments demonstrated that OH was the predominant active species induced the photodegradation of OTC. With the development of nanobubbles technology, it is anticipated to realize totally chemicals free green technology. This study provides a novel nanobubble/AOPs technology, which will be more efficient and environmental friendly and will have broad application in waste water treatment and drinking water purification

Tapping into the ballast potential of sparingly soluble salts for enhanced floc physiognomies in algae biomass harvesting

Enhanced floc settling rates and reduced biomass volume were achieved when sparingly soluble salts of magnesium were used as ballast agent in the pH induced algae biomass harvesting operation. The floc characteristics of biomass harvested from non-ballasted pH induced system were compared with that of pH induced ballasted system that contained soluble (MgCl2) and sparingly soluble salts (i.e., Mg(OH)2 and Mg(OH)2 nanoparticles (NMg(OH)2)). The pH value for onset of coagulation was lower in soluble salt system (pH = 10.2) than in the sparingly soluble salt (pH = 11.4). The floc generated from the ballasted NMg(OH)2 system had the highest sedimentation rate (K (L/mol/s) = 1.0454), while that of the non-ballasted pH induced system had the lowest rate (K (L/mol/s) = 0.2155). The ballast agent enhanced the sludge volume index of the biomass by 66.04% and had no negative impact on the filterability. The values of the the specific cake resistance (α (m/kg)) and the resistance of the filter medium (Rm (1/m)) were within the same range. Both the growing and harvested biomass exhibited good strength and recovery factor (>90%). The evaluation of the effects of the ballast agents on the biomass viability showed that the ballast agent was not toxic to the harvested biomass