Manganese Removal by Biofiltration Using Activated Carbon-barium Alginate-entrapped Cells: Morphology, Durability, Settling Velocity, and Treatment Efficiency

Occurrence of manganese in water supplies causes colored water and pipe rusting in water treatment and distribution systems. Moreover, consumption of manganese-contaminated water may lead to neurotoxicity in humans. Biofilters have the potential to alleviate the manganese issue through bio-oxidation, particle separation, and adsorption processes. Biofiltration performance can be enhanced by augmentation of the manganese-oxidizing bacterium entrapped in polymeric materials. This study aimed to investigate the potential of barium alginate-entrapped cells supplemented with powdered activated carbon (PAC) for manganese removal. Streptomyces violarus strain SBP1, an effective manganese-oxidizing bacterium, was selected. The experiments were divided into 2 parts, including 1) characterization of barium alginate bead and 2) manganese removal testing. Effect of PAC content (1, 5, and 10% w/v) in the entrapment material on bead morphology, bead durability, and settling velocity (relative to a filtration medium) was investigated. Micro-structural observation using a scanning electron microscope showed that the PAC was distributed through intra-porous structure of the beads. The PAC-supplemented barium alginate beads improved durability (up to three-time higher Young’s modulus values). The PAC-supplemented barium alginate beads gave similar settling velocity compared to a filtration medium. The manganese removal efficiencies by the PAC-supplemented beads (no cells) ranged from 48 to 53%. Based on barium alginate bead characterization and manganese removal performance, the bead with 5% PAC content was selected for cell entrapment. The investigation revealed that the entrapped cells achieved faster manganese removal rate than free cell system. The findings from this study indicated high potential of the entrapped cells for use in future biofilter applications

Potential Degradation and Kinetics of Melanoidin by Using Laccase from White Rot Fungus

This study was attempted to use laccase extracted from white rot fungus to remove melanoidin in the ethanol production wastewater. The isolated fungus producing the highest laccase was identified as Megaspororia sp. The highest degradation efficiencies of the purified and crude laccases were 48.00% and 44.60%, respectively. Both degradation kinetics well fit Michaelis-Menten model. The Michaelis constant (Km) and maximum rate of reaction (Vmax) were 0.82% melanoidin and 0.0045% melanoidin h-1 for the degradation by the purified laccase and 0.71% melanoidin and 0.0037% melanoidin h-1 for the degradation by the crude laccase. Turnover number (Kcat) of purified and crude laccases were 0.00023 and 0.00019% melanoidin U-1 h-1, respectively. Catalytic efficiency (Kcat/Km) of purified and crude laccases were 0.00028 and 0.00027 U-1 h-1, respectively. The affinity of the crude laccase was slightly higher because of its non-specificity. Kcat and Kcat/Km of the purified laccase were higher than the crude laccase. Proposed potential degradation result showed that laccase could oxidize CH3, carbonyl groups, haloalkanes (C–H), C–O and C–N bondings which probably caused decolorization of melanoidin in wastewater. Thus, the purified and crude laccases can be used to decolorize melanoidin-containing wastewater from ethanol industries. As the attempt to use purified laccase consumed times and costs especially in purification steps, the crude laccase can be used to degrade color of melanoidin in wastewater with only 3.4% lower than the purified laccase

Organophosphate pesticide exposure and dialkyl phosphate urinary metabolites among chili farmers in Northeastern Thailand

Background. Chlorpyrifos and profenofos are organophosphate pesticides (OPPs), we studied exposure and urinary metabolites in an agricultural area in the northeastern of Thailand during the chili-growing season (March - April) in 2012. Objective. This study was designed to assess pesticide exposure concentration through dermal and inhalation pathways and to find and depict a relationship between urinary metabolites and means of exposure. Materials and methods. To estimate the pesticides exposure concentration, dermal wipes (hand, face, and feet), dermal patches and air samples were collected from 38 chili farmers. The morning void of pre and post application urine samples was an indicator of biological monitoring in the study which derived from 39 chili farmers. Results. Chlorpyrifos and profenofos residues were detected on dermal patches, face wipes, and hand wipe samples, while no significant residues were found on the feet. Using a personal air sampling technique, all air samples detected pesticide residues. However, significant correlation between dermal pesticide exposure concentration and inhalation was not found (p>0.05). For urinary metabolite levels, there was a relationship between the first pre application morning void and post application morning void (p<0.05); similar to the association between the first pre application morning void and the second post application morning void (p<0.05). The main relationship between pesticide exposure and urinary metabolite was found to have been relevant to dermal exposure (r= 0.405; p<0.05). Conclusions. The results of this study could suggested that public health education training programs, including the use of appropriate personal protective equipment (PPE), should be offered for the chili growing farmers in order to improve their ability to properly use pesticides.Wprowadzenie. Chlorpiryfos i profenofos należą do pestycydów fosforoorganicznych (OPPs) stosowanych w rolnictwie, dlatego narażenie na te związki badano w północnowschodniej Tajlandii w okresie uprawy chili (marzec – kwiecień) w 2012 roku. Cel. Celem badania była ocena narażenia na pestycydy przez skórę i drogi oddechowe oraz zbadanie zależności pomiędzy stężeniami metabolitów w moczu a drogą narażenia. Materiał i metoda. Do oceny wielkości narażenia wykorzystano wymazy z rąk, twarzy i stóp i naskórne plastry absorpcyjne oraz próbki powietrza pobierane za pomocą indywidualnych próbników u 39 rolników uprawiających chili. Wyniki. Pozostałości chlorpiryfosu i profenofosu stwierdzano na plastrach absorpcyjnych, wymazach z twarzy i rąk, podczas gdy w wymazach ze stóp nie stwierdzano znaczących ilości tych pestycydów. We wszystkich próbkach powietrza stwierdzono obecność pestycydów. Jednakże, nie wykazano znaczącej korelacji pomiędzy wielkością narażenia przez skórę i drogi oddechowe (p>0.05). W przypadku poziomów metabolitów w moczu, wykazano zależność pomiędzy poziomami metabolitów w moczu przed i po pierwszym zabiegu wykonywanym rano (p<0.05). Zależność pomiędzy narażeniem na pestycydy a stwierdzanymi metabolitami w moczu wynikała z narażenia przez skórę (r= 0.405; p<0.05). Wnioski. Wyniki niniejszych badań mogą sugerować potrzebę wprowadzenia programów edukacyjnych z zakresu zdrowia publicznego, uwzględniających stosowanie przez hodowców chili odpowiedniego sprzętu ochrony osobistej, w celu poprawy możliwości właściwego stosowania pestycydów