Response surface methodology (RSM) based on a Box-Behnken Design (BBD) was applied to optimize the thermal-alkaline pre-treatment operating conditions for anaerobic digestion of flotation scum in food waste leachate. Three independent variables such as thermal temperature, NaOH concentration and reaction time were evaluated. The maximum methane production of 369.2 mL CH4/g VS was estimated under the optimum conditions at 62.0°C, 10.1% NaOH and 35.4 min reaction time. A confirmation test of the predicted optimum conditions verified the validity of the BBD with RSM. The analysis of variance indicated that methane production was more sensitive to both NaOH concentration and thermal temperature than reaction time. Thermal-alkaline pretreatment enhanced the improvement of 40% in methane production compared to the control experiment due to the effective hydrolysis and/or solubilization of organic matters. The fractions with molecular weight cut-off of scum in food waste leachate were conducted before and after pre-treatment to estimate the behaviors of organic matters. The experiment results found that thermal-alkaline pre-treatment could reduce the organic matters more than 10kD with increase the organic matters less than 1kD.
In vivo nicotine is associated with Alzheimer's, Parkinson's and lung cancer. Diagnostic assays of these diseases depend on very low analytical detection limits. In this study, a sensitive analytical method was examined using a voltammetric graphite pencil electrode (GPE) and a modified carbon nanotube paste electrode (CNE). The optimum analytical conditions for both electrodes were compared using square wave anodic stripping voltammetry (SW) and cyclic voltammetry (CV) obtaining 400 sec accumulation time and oxidation peak. Under optimum parameters, the stripping working range of GPE was 5.0-40.0μg/L, CNE: 0.1-0.8 and 5-50μg/L. Quantification limits were 5.0μg/L for GPE and 0.1μg/L for CNE, while detection limits were 0.6μg/L for GPE and 0.07μg/L for CNE. A standard deviation of 10.0μg/L was observed for 0.064 GPE and 0.095 CNE (n = 12) using 400 sec accumulation time. The results obtained can be applied to non.treated urine and ex vivo biological diagnostics.
Pollutants generated by the biodegradation of livestock carcasses have the potential for contamination of the environment. Hence, livestock mortalities burial has been banned in the EU. In spite of the hazard, research on the biodegradation of livestock carcasses is lacking. In this study, five lysimeters were used to evaluate the enhanced biodegradation of organic materials in livestock mortalities burial. Lysimeter 1(control), lysimeter 2(grinding of livestock carcass), lysimeter 3(anaerobic microorganisms), lysimeter 4(Corynebacterium glutamicum in anaerobic condition) and lysimeter 5(Corynebacterium glutamicum in aerobic condition) were operated with temperature control. The degradation efficiencies of livestock carcass in the lysimeters were evaluated based on total organic carbon balance. The degradation efficiencies of ground livestock carcass were 1.9 times more than those of livestock carcass without grinding. In anaerobic condition, anaerobic microorganisms were more effective compared with Corynebacterium glutamicum on the biodegradation of livestock carcasses. However, the degradation efficiencies with Corynebacterium glutamicum in aerobic condition were significantly influenced on the biodegradation of livestock carcasses. Even if it would be helpful to degrade the livestock carcass in aerobic condition in terms of stabilization, potential risks on the environment by odor and bioaerosol must be solved.