Determination of micropollutants in combined sewer overflows and their removal in a wastewater treatment plant (Seoul,South Korea)

The present study investigated the occurrence of 29 selected micropollutants such as endocrine disrupting compounds (EDCs) and pharmaceuticals and personal care products (PPCPs) in surface waters and wastewaters in Seoul (South Korea) during both dry and wet weather conditions. The study area was selected based on the lack of available information regarding the suspected contamination of rivers/creeks by EDCs and PPCPs in the Seoul region and the presence of a wastewater treatment plant (WWTP), which serves approximately 4.1 million inhabitants and has a design capacity of 1,297?×?10³ m³/day. Many target compounds (83 %) were detected in samples collected from wastewater treatment influent/effluent, creek water, and combined sewer overflow (CSO). The total EDC/PPCP concentrations were as follows: WWTP influent (69,903 ng/L)?>?WWTP effluent (50,175 ng/L) >3 creek samples (16,035–44,446 ng/L) during dry weather, and WWTP influent (53,795 ng/L)?>?WWTP bypass (38,653 ng/L) >5 creek samples (15,260–29,113 ng/L) >2 CSO samples (11,109–11,498 ng/L) during wet weather. EDCs and PPCPs were found to be present at high daily loads (65.1 and 69.8 kg/day during dry and wet weather, respectively) in the WWTP effluent. Compound removal by the WWTP varied significantly by compound: caffeine, diclofenac, ibuprofen, naproxen, and propylparaben (>90 %), and acesulfame, DEET, iohexol, iopromide, and iopamidol (<5 %). These findings and literature information support the hypothesis that the efficiency of removal of EDCs and PPCPs is strongly dependent on both removal mechanism (e.g., biodegradation, adsorption to sludge, and oxidation by chlorine) and compound physicochemical properties (e.g., pK _a and hydrophobicity).     

Attribution of aerosol light absorption to black carbon and volatile aerosols

We investigated the contribution of volatile aerosols in light-absorption measurement by three filter-based optical instruments [aethalometer, continuous light-absorption photometer (CLAP), and continuous soot monitoring system (COSMOS)] at Gosan Climate Observatory (GCO) from February to June 2012. The aerosol absorption coefficient (σ _abs) and the equivalent black carbon (BC) mass concentration (M _BC) measured by the aethalometer and CLAP showed good agreement with a difference of 9 %, which is likely due to the instrumental uncertainty. However, σ _abs and M _BC measured by the COSMOS with a heated inlet were found to be approximately 44 and 49 % lower than those measured by the aethalometer and CLAP under ambient conditions, respectively. This difference can be attributed to the light absorption by the volatile aerosols coexisting with the BC. Even considering inherent observational uncertainty, it suggests that approximately 35–40 % difference in the σ _abs and M _BC can be contributed by volatile aerosols. Increase in the difference of M _BC measured by the aethalometer and COSMOS with the increasing thermal organic carbon (OC) measured by Sunset OC/EC analyzer further suggests that the filter-based optical instruments without the use of a heater are likely to enhance the value of σ _abs and M _BC, because this sample air may contain both BC and volatile aerosols.     

Environmental quality of Korean coasts as determined by modified Shannon–Wiener evenness proportion

The coast of the Korean peninsula experiences a range of human impacts, including pollution, shipping, reclamation, and aquaculture, that have motivated numerous local studies of macrobenthic organisms. In this paper, 1,492 subtidal stations were compiled from 23 studies (areas) to evaluate environmental quality on a broader scale. A common index in biomonitoring, Shannon–Wiener evenness proportion (SEP), could not incorporate azoic or single-species samples. This shortcoming was overcome by developing an inverse function of SEP (ISEP), which was positively correlated with independent measures of water quality available for nine sites and was not biased by the size of the sampling unit. Additionally, at Shihwa Dike, where samples were collected before and after reinstating a tidal connection with the ocean, ISEP values improved over time, as expected. Thus, it is now possible to assign Korean subtidal sites to seven ISEP “grades” and to use their values and trends to guide coastal management.     

Rapid in situ assessment for predicting soil quality using an algae-soaked disc seeding assay

The soil quality of remediated land is altered and this land consequently exerts unexpected biological effects on terrestrial organisms. Therefore, field evaluation of such land should be conducted using biological indicators. Algae are a promising new biological indicator since they are a food source for organisms in higher soil trophic levels and easily sampled from the soil. Field evaluation of soil characteristics is preferred to be testing in laboratory conditions because many biological effects cannot be duplicated during laboratory evaluations. Herein, we describe a convenient and rapid algae-soaked disc seeding assay for assessing soil quality in the field based on soil algae. The collection of algae is easy and rapid and the method predicts the short-term quality of contaminated, remediated, and amended farm and paddy soils. The algae-soaked disc seeding assay is yet to be extensively evaluated, and the method cannot be applied to loamy sand soil in in situ evaluations. The algae-soaked disc seeding assay is recommended for prediction of soil quality in in situ evaluations because it reflects all variations in the environment. The algae-soaked disc seeding assay will help to develop management strategies for in situ evaluation.     

Improved enzymatic hydrolysis of waste paper by ozone pretreatment

Waste paper samples made from newsprint, copier paper, and magazine paper, as well as samples of kraft pulp and thermomechanical pulp, were pretreated with ozone to improve enzymatic hydrolysis. The ozone treatment of pulps of newsprint and of magazine paper increased the specific surface areas and total pore volumes while decreasing the lignin content so that these values became similar to those of thermomechanical pulps. These morphological and chemical changes in the pulps resulted in the increased access of cellulase to the pulp fiber surface and increased enzymatic hydrolysis. For copier paper, in which the lignin content was very low, additives on the pulp fiber surface were oxidized and removed by ozone treatment and extraction, and this allowed improved enzymatic hydrolysis. In contrast, surface areas and total pore volumes of kraft pulp and bleached kraft pulp were decreased by the ozone treatment, resulting in morphological changes in the pulps that decreased enzymatic hydrolysis.     

Catalytic reduction of sulfur dioxide with carbon monoxide over tin dioxide for direct sulfur recovery process

SO(2) reduction by CO over SnO(2) catalyst was studied in this work. The parameters were the reaction temperature, space velocity (GHSV) and [CO]/[SO(2)] molar ratio. The optimal temperature, GHSV and [CO]/[SO(2)] molar ratio were 550 degrees C, 8000 h(-1) and 2.0, respectively. Under these conditions, the SO(2) conversion and sulfur selectivity were about 78% and 68%, respectively. The following reaction pathway involving two mechanisms was proposed in SO(2) reduction by CO over SnO(2) catalyst: in the first step involving Redox mechanism, the elemental sulfur was produced by the mobility of the lattice oxygen between SO(2) and SnO(2) surface. In the second step, COS was formed by the side reaction between elemental sulfur and CO or metal sulfide and CO. In the third step involving COS intermediate mechanism, the abundant elemental sulfur was produced by the SO(2) reduction by COS which was produced in the second step and was more effective reducing agent than CO.     

Monitoring of Aerial Pollutants Emitted from Swine Houses in Korea

This on-site survey study was performed to determine the concentrations and emissions of aerial contaminants in the different types of swine houses in Korea and then to present beneficial information available for Korean pig producers to manage optimal air quality in swine house. The swine houses investigated in this research were selected based on three criteria; manure removal system, ventilation mode and growth stage of swine. Mean concentrations of aerial pollutants in swine houses were 8 ppm for ammonia, 300 ppb for hydrogen sulfide, 2 mg m⁻³ for total dust, 0.6 mg m⁻³ for respirable dust, 4 log(cfu m⁻³) for total airborne bacteria and 3 log(cfu m⁻³) for total airborne fungi, respectively. Mean emissions based on pig (liveweight; 75 kg) and area (m²) were 250 and 340 mg h⁻¹ for ammonia, 40 and 50 mg h⁻¹ for hydrogen sulfide, 40 and 50 mg h⁻¹ for total dust, 10 and 15 mg h⁻¹ for respirable dust, 1.0 and 1.3 log(cfu) h⁻¹ for total airborne bacteria and 0.7 and 1.0 log(cfu) h⁻¹ for total airborne fungi, respectively. In general concentrations and emissions of gases were relatively higher in the swine houses managed with deep-pit manure system with slats and mechanical ventilation mode than the different swine housing types whereas those of particulates and bioaerosol were highest in the naturally ventilated swine houses with deep-litter bed system.     

Excess copper induced physiological and proteomic changes in germinating rice seeds

Copper is an essential micronutrient for plants. Present at a high concentration in soil, copper is also regarded as a major toxicant to plant cells due to its potential inhibitory effects against many physiological and biochemical processes. The interference of germination-related proteins by heavy metals has not been well documented at the proteomic level. In the current study, physiological, biochemical and proteomic changes of germinating rice seeds were investigated under copper stress. Germination rate, shoot elongation, plant biomass, and water content were decreased, whereas accumulation of copper and TBARS content in seeds were increased significantly with increasing copper concentrations from 0.2mM to 1.5mM followed by germination. The SDS-PAGE showed the preliminary changes in the polypeptides patterns under copper stress. Protein profiles analyzed by two-dimensional electrophoresis (2-DE) revealed that 25 protein spots were differentially expressed in copper-treated samples. Among them, 18 protein spots were up-regulated and 7 protein spots were down-regulated. These differentially displayed proteins were identified by MALDI-TOF mass spectrometry. The up-regulation of some antioxidant and stress-related proteins such as glyoxalase I, peroxiredoxin, aldose reductase, and some regulatory proteins such as DnaK-type molecular chaperone, UlpI protease, and receptor-like kinase clearly indicated that excess copper generates oxidative stress that might be disruptive to other important metabolic processes. Moreover, down-regulation of key metabolic enzymes like alpha-amylase or enolase revealed that the inhibition of seed germinations after exposure to excess copper not only affects starvation in water uptake by seeds but also results in failure in the reserve mobilization processes. These results indicate a good correlation between the physiological and biochemical changes in germinating rice seeds exposed to excess copper.     

Inactivation of Escherichia coli in the electrochemical disinfection process using a Pt anode

Recently, the electrochemical disinfection has gained a great interest as one of the alternatives to conventional chlorination due to its high effectiveness and environmental compatibility. Despite the extensive reports on electro-chlorination disinfection, few researches were reported on the systems without generating chlorine. This study mainly focused on the potential disinfecting ability of electro-generated oxidants other than chlorine with using an inert medium (chloride-free phosphate buffer solution), which was intended to exclude the formation of chlorine during the electrolysis, as the Escherichia coli as an indicator bacterium was disinfected by applying the current to a platinum anode. The electrochemical inactivation of E. coli without chlorine production was demonstrated to occur in two distinct stages. The first stage inactivation takes place rapidly at the beginning of electrolysis, which appears to be achieved by the electrosorption of negatively charged E. coli cells to the anode surface, followed by a direct electron transfer reaction. As the electrolysis continues further, the inactivation becomes slower but steady, in contrast to the first stage of inactivation. This was attributed to the action of reactive oxidants generated from water discharge, such as hydroxyl radical. Overall, this study suggests that the electrochemical disinfection could be successfully performed even without producing chlorine, recommending the potential application for disinfecting water that does not allow including any chloride ions (such as the production of ultra-pure sterilized water for semiconductor washing).     

Toxicity and biodegradation of diamines

Phytotoxicity and cytotoxicity of 2,4-diaminotoluene (2,4-D), 4,4'-methylenedianiline (4,4-D), and 1,6-hexanediamine (1,6-D) were investigated by observing the germination of young radish seeds and the viability of HeLa cells, respectively. 2,4-D showed the highest, 4,4-D intermediate, and 1,6-D lowest cytotoxicity. However, the phytotoxicity decreased in the order of 4,4-D > 2,4-D > 1,6-D. Contrary to the results previously reported, in the modified Sturm test the activated sludge degraded 2,4-D and 4,4-D as well as 1,6-D without any pre-acclimation. Ochrobacterium antropi was isolated for degradation of 2,4-D and 4,4-D and Pseudomonas citronellolis for 1,6-D degradation. Thielevia sp. was isolated as 2,4-D degrading fungus and Aspergillus sp. as 4,4-D and 1,6-D degrading fungus. The fungi degraded the diamines faster than the bacteria.