A comparative study on the distribution behavior of microplastics through FT-IR analysis on different land uses in agricultural soils.

Plastic materials have been variously exposed to arable land for decades through soil mulching, plastic housing, and sewage sludge composting. Their mechanical abrasion and biochemical degradation induce the proliferation of myriad microplastics that can further be broken into smaller nano-sized pieces that can be further accumulated in living organisms (including soil invertebrates, fruits, and vegetables); they can also be widely dispersed in neighboring environments. Despite the intensive use of plastics in agriculture, little is known about their origin of occurrence and environmental fate, especially with a size below 100 µm. Therefore, in this study, microplastics with a size in the range of 20-2,000 µm were investigated in soil samples obtained from three different conditions of land uses: tilled with plastic mulch, bare ground (i.e., uncultivated land), and in between the greenhouses of the farmland D located in Namyangju-si, Gyeonggi-do, Republic of Korea. They were primarily identified using Fourier transform infrared (FT-IR) spectroscopy coupled with a microscope. Prior to performing the analysis, microplastic extraction from the soil samples was validated using standardized high-density polyethylene (HDPE) microplastics of various sizes ranging from 20 to 500 µm. As a result, the number of microplastics was estimated to be (241 ± 52), (195 ± 37), and (306 ± 56) particles per kg of dry soil in tillage, bare ground, and in between greenhouses, respectively. They consist of polyethylene (PE), polypropylene (PP), and poly(ethylene terephthalate) (PET), which are the basic constituents of commonly used agricultural products. The particle size distribution depends on the type of plastic, the time elapsed since their usage, and the degree and duration of environmental exposure; the plastic particle sizes were smaller in tillage and around the greenhouses since agricultural films have been weathered for a long time, whereas those with relatively large sizes were found in the uncultivated.

Rapid surface degradation of co-axially arranged polypropylene globules by nanoporous carbonized TiO2 assisted with UV-C.

The degradation of plastics, especially polypropylene (PP), is difficult since it is the most hydrophobic polymer. Photocatalytic degradation of PP films has been reported to be one of the most efficient degradation techniques. However, it is still insignificant to employ it in field applications. In this study, TiO2 nanoparticles supported on amorphous carbon with nanoporosity (TiO2@NC) are used as a photocatalyst to degrade macro-sized co-axially oriented PP globules under the influence of UV-C irradiation. Surface characterization such as SEM, ATR-FTIR, and XPS of the PP globules was performed. The SEM images distinctly showed the surface degradation phenomenon. Interestingly, the ATR-FTIR spectra demonstrated a significant rise in the band intensity in the -OH radical region and fairly in the CO region as well, with the increase in the photocatalytic time. Surprisingly, in the XPS spectra, the intensity of C-1s spectra kept on falling, and the intensity of O-1s spectra kept on rising with the increase in the photocatalytic time. The higher surface area due to nanoporosity of TiO2@NC enhanced the photocatalytic degradation of PP globules than previously reported studies. TiO2@NC seems to be a potential catalyst for the degradation of different types of polymers.

The removal of 1,4-dioxane from polyester manufacturing process wastewater using an up-flow Biological Aerated Filter (UBAF) packed with tire chips.

1,4-Dioxane is one of the by-products from the polyester manufacturing process, which has been carelessly discharged into water bodies and is a weak human carcinogen. In this study, a laboratory-scale, up-flow biological aerated filter (UBAF), packed with tire chips, was investigated for the treatment of 1,4-dioxane. The UBAF was fed with effluent, containing an average of 31 mg/L of 1,4-dioxane, discharged from an anaerobic treatment unit at H Co. in the Gumi Industrial Complex, South Korea. In the batch, a maximum of 99.5 % 1,4-dioxane was removed from an influent containing 25.6 mg/L. In the continuous mode, the optimal empty bed contact time (EBCT) and air to liquid flow rate (A:L) were 8.5 hours and 30:1, respectively. It was also found that the removal efficiency of 1,4-dioxane increased with increasing loading rate within the range 0.04 to 0.31 kg 1,4-dioxane/m(3)·day. However, as the COD:1,4-dioxane ratio was increased within the range 3 to 46 (mg/L COD)/(mg/L 1,4-dioxane), the removal efficiency unexpectedly decreased.

Modified uvulopalatopharyngoplasty for the treatment of obstructive sleep apnea-hypopnea syndrome: resection of the musculus uvulae.

OBJECTIVE: To assess the outcome of a modified uvulopalatopharynbgoplasty (UPPP) technique with preservation of the uvula mucosa and partial resection of the musculus uvula. STUDY DESIGN AND METHODS: A prospective randomized controlled trial. Sixteen male patients underwent a classic UPPP, and another 16 male patients underwent a modified UPPP. The parameters evaluated were the subjective symptom score, the Pittsburgh Sleep Quality Index (PSQI), the Epworth Sleepiness Scale (ESS), the Stanford Sleepiness Scale (SSS), and polysomnography results. RESULTS: Postoperative snoring, apnea, morning headache, daytime sleepiness, pharyngeal foreign body sensation, and global discomfort were not significantly different between the two groups. Among seven subjective measures of sleep quality from the PSQI, the subjective sleep quality was significantly improved in both groups. Postoperatively, the SSS was not significantly changed in both groups; however, the ESS was significantly improved in both groups. The polysomnographic findings showed a statistically significantly improvement in the apnea index and the apnea-hypopnea index. CONCLUSION: Although the modified group did not have more profound improvement in sleep quality and decreased postoperative pharyngeal discomfort, modified UPPP was an effective surgical method for the treatment of obstructive sleep apnea-hypopnea syndrome.

Biodegradation of micro-polyethylene particles by bacterial colonization of a mixed microbial consortium isolated from a landfill site.

In this study, we investigated the decomposition of micro-sized polyethylene (PE) by mesophilic mixed bacterial culture isolates obtained from a municipal landfill sediment. Among these, Bacillus sp. and Paenibacillus sp. were more specifically enriched in the non-carbonaceous nutrient medium (i.e., Basal medium) as they were the most dominant species when they were exposed to PE microplastics. They reduced the dry weight of particles (14.7% after 60 d) and the mean particle diameter (22.8% after 60 d; obtained by field-emission scanning electron microscopy analysis). In the gas chromatography-mass spectrometer analysis of biologically aged particles, the amount and types of organic contents eluted from the PE microplastics were far lower in the early decomposition phase; however, they increased in the later phase. Thermal gravimetric analysis showed that the aged particles had higher thermal stability at temperatures greater than 570 °C compared to the control, thereby suggesting that microplastics were degraded by enzymatic chain scission, which could in turn be ascribed to the greater refractory fractions of aged particles remaining at a high combustion temperature. It was further verified that PE particles could be biologically utilized as a sole carbon source and broken down during the test period.

Utilization of makgeolli sludge filtrate (MSF) as low-cost substrate for bacterial cellulose production by Gluconacetobacter xylinus.

Search for efficient low-cost substrate/additives are gaining significant impetus in bacterial cellulose (BC) production. Makgeolli sludge (a traditional Korean wine distillery waste) is enriched with organic acid, alcohol, and sugar. Using makgeolli sludge filtrate (MSF) and Hestrin-Schramm (HS) medium (g/l of distilled water: glucose, 10.0; peptone, 5.0; yeast extract, 5.0; disodium phosphate, 2.7; citric acid, 1.15; pH 5.0), two different media-namely the modified HS media (ingredients of HS media except glucose dissolved in MSF) and mixed modified HS media (equal volume mixture of original and modified HS media)-were formulated. BC production with Gluconacetobacter xylinus was studied using the two above referred medium. Keeping HS medium as reference, effect of initial pH, glucose, ethanol, and organic acid concentration on BC production was also studied. It suggests that increasing initial glucose (up to 25 g/l) though improves BC production but results in poor BC yield above 15 g/l of glucose. However, addition of alcohol (up to 1%v/v) or citric acid (up to 20 mM) escalate productivity up to four and two times, respectively. In both modified HS media and mixed modified HS medium, BC production was four to five times higher than that of original HS medium. Even MSF alone surpassed HS medium in BC production. Scanning electron microscopy showed that BC microfibrils from MSF based media were several micrometers long and about 25-60 nm widths. X-ray diffraction patterns suggested the produced BC were of cellulose I polymorph.