• Journal of Korean Society of Environmental Engineers
• /
• v.37 no.2
• /
• pp.73-80
• /
• 2015

An investigation on the removals of tetracycline (TTC), which is a family of antibiotics widely founded in the environment, from the aqueous solution by birnessite(${\delta}-MnO_2$)-mediated oxidative transformation was described. This study also examined the potential effect of the naturally occurring substances, humic acid (HA) on the oxidative transformation. The experiment was carried out in various conditions (reaction time, Mn oxide loadings, pH) and in the presence of HA as a batch test. The removals of TTC followed pseudo-first order reactions, and rate constants (k, $hr^{-1}$) for the removals of TTC were constantly increased with decreasing pH from 0.98 (pH 9) to 2.97 (pH 3). The rate constants also increased about 1.3 times when the birnessite loading increased from 1 to 2 g/L. Presence of HA (5 mg-C/L, at $pH{\geq}6$) caused some enhancement in the removals of TTC as compared to the control, and also showed the removal efficiencies of TTC in the birnessite mediated systems (TTC=0.25 mM, ${\delta}-MnO_2=2.0g/L$, pH 6) increased with increasing HA concentrations (1~10 mg-C/L). The results obtained from the oxidative transformation of TTC and the effect of HA were discussed in terms of reaction characteristics and mechanism.

• Journal of Environmental Science International
• /
• v.22 no.11
• /
• pp.1509-1517
• /
• 2013

So far, most studies associated with soil carbon sequestration have been focused on long term aspect. However, information regarding soil carbon sequestration in short term aspect is limited. This study was conducted to determine changes of soil organic carbon content and stability of carbon in response to compost application rate and tillage management during rice growing season(150 days) in short term aspect. Under pot experiment condition, compost was mixed with an arable soil at rates corresponding to 0, 6, 12, and 24 Mg/ha. To determine effect of tillage on soil carbon sequestration, till and no-till treatments were set up in soils amended with application rate of 12 Mg/ha. Compost application and tillage management did not significantly affect soil organic carbon(SOC) content in soil at harvest time. Bulk density of soil was not changed significantly with compost application and tillage management. These might result from short duration of experiment. While hot water extractable organic carbon(HWEOC) content decreased with compost application, humic substances(HS) increased. Below ground biomass of rice increased with application of compost and till operation. From the above results, continuos application of compost and reduce tillage might improve increase in soil organic carbon content and stability of carbon in long term aspect.

• Journal of Korean Society of Water and Wastewater
• /
• v.18 no.5
• /
• pp.588-597
• /
• 2004

In this research, we investigated the variation of transmembrane pressure and permeate water quality with pre coagulation and sedimentation with iron based coagulant and chlorination of feed water for PVDF (polyvinylidene fluoride) based MF membrane filtration. NaCIO was fed to the membrane module with dosage of 0.5mg/L and maintained during filtration. To observe the effect of raw water, three types of raw and processed waters, including river surface water, coagulated water and coagulated-settled water, were applied. In case of river surface water, the transmembrane pressure increased drastically in 500 hours of operation. On the contrary, no significant increase in transmembrane pressure was observed for 1,200 hours of operation for coagulated water and coagulated-settled waters. The turbidity of permeate was lower than a detection limit of equipment for all raw waters. The removal efficiency of humic substances of coagulated water and coagulated-settled water was approximate ten times of that of surface river water. And, the removal efficiency of TOC and DOC was approximate two times of that of surface river water. From the results of plant operation, stable operation was maintained at $0.9m^3/m^2{\cdot}day$ filtration flux through the combination of pre-coagulation and pre-chlorination. However, the water quality of permeate was the best when pre-coagulation-sedimentation process was combined with pre-chlorination.

• Journal of Soil and Groundwater Environment
• /
• v.8 no.3
• /
• pp.45-55
• /
• 2003

This study investigates the fractional composition and the leaching characteristics of heavy metals in polluted soils due to mining activities. The fractionated composition of heavy metals is classified into five fractions; adsorbed, carbonate, reducible, organic and residual fraction. The status of humic substances in mine wastes of most sites are polyhumic except tailing from Sangdong mine. According to the sequential extraction procedures (SEPs), leaching probabilities of Cd in coal wastes and tailing are relatively low due to high percentage of residual fraction. 46.4% of Ni in tailings from Sangdong mine is probably leached under oxidized environment, and 39.4% of Cu in these tailings is readily extracted under strongly oxidized environment by organic fraction. According to leaching condition of pH 3.0 and pH 5.6, the amount of heavy metals leached out of coal wastes and tailing increases to 1/2 hours. At pH 3.0 and pH 5.6, concentration of Ni in tailing increases up three times of the initial value. Heavy metals released from coal wastes and tailing were not influenced significantly by leaching time.

• Journal of Korean Society for Atmospheric Environment
• /
• v.34 no.3
• /
• pp.418-429
• /
• 2018

Measurements of 24-hr size-segregated ambient particles were made at an urban site of Gwangju under high pressure conditions occurred in the Korean Peninsula late in March 2018. The aim of this study was to understand the effect of air stagnation on mass size distributions and formation pathways of water-soluble organic and inorganic components. During the study period, the $NO_3{^-}$, $SO_4{^{2-}}$, $NH_4{^+}$, water-soluble organic carbon (WSOC), and humic-like substances(HULIS) exhibited mostly bi-modal size distributions peaking at 1.0 and $6.2{\mu}m$, with predominant droplet modes. In particular, outstanding droplet mode size distributions were observed on March 25 when a severe haze occurred due to stable air conditions and long range transport of aerosol particles from northeastern regions of China. Air stagnation conditions and high relative humidity during the study period resulted in accumulation of primary aerosol particles from local emission sources and enhanced formation of secondary ionic and organic aerosols through aqueous-phase oxidations of $SO_2$, $NO_2$, $NH_3$, and volatile organic compounds, leading to their dominant droplet mode size distributions at particle size of $1.0{\mu}m$. From the size distribution of $K^+$ in accumulation mode, it can be inferred that in addition to the secondary organic aerosol formations, accumulation mode WSOC and HULIS could be partly attributed to biomass burning emissions.

• Journal of environmental and Sanitary engineering
• /
• v.22 no.3
• /
• pp.13-26
• /
• 2007

Changes in the characteristics of dissolved organic matter was studied at selected stations in the Nakdong river basin using physical and chemical methods. Characteristics of dissolved organic matters were analysed and assessed. Production of disinfection byproducts were also investigated. 1. Result of relatedness study among each items of analyses showed that relatedness on BOD values were highest with cattle excrement treatment facilities where there is no synthetic organic materials and relatedness on $COD_{Mn}$ were highest at the mainstream Nakdong river. In case of $COD_{Cr}$ (which has more oxidative power than $COD_{Mn}$), the values were higher in the sidestreams indicating the higher content of recalcitrant compounds. The relatedness values for the $UV_{254}$ also showed higher values in the sidestreams and treatment facilities than mainstream indicating the presence of organic aromatic compounds. 2. Ratio of DOC on total organic carbon were higher in the mainstream which is attributable to the influent particulate organic materials produced by agricultural activities. The values were 10-15% higher in the mainstream compared with sidestreams. 3. Result of biodegradability test indicate that concentrations of recalcitrant DOC were higher in the sidestreams than in the mainstream. The values of recalcitrant DOC were higher with the forest stream indicating the effect of soil oriented humic substances. 4. Result of THM production test carried out at 10 stations in the Nakdong river show that $CHCl_3$ was detected with the highest value and the value was highest at Waekwan station.

• Journal of Korean Society on Water Environment
• /
• v.25 no.5
• /
• pp.697-703
• /
• 2009

In this study, changes in the composition of dissolved organic carbon (DOC) were investigated using water samples collected at a downstream site of the Namhan River near the Lake Paldang ($N37^{\circ}24^{\prime}05.33^{{\prime}{\prime}}E127^{\circ}32^{\prime}25.01^{{\prime}{\prime}}$) during a heavy rain event from July 23 to July 28, 2008. The DOC concentrations varied from 1.68 to 3.18 mg/L with the maxium value at a peak of the river water level. Each DOC sample was fractionated into three compositions including hydrophilic (Hi), hydrophobic acid (HoA) and hydrophobic neutral (HoN) fractions. The results showed that HoA was most abundant fractions, constituting 47.2~56.5% of DOC. Refractory dissolved organic carbon (R-DOC) contents were also determined by measuring the DOC concentration after 28-day dark incubation of the samples. R-DOC content was in the range from 83 to 99% of DOC and it was significantly correlated with HoA contents (r = 0.91, p<0.005), while it did not exhibit such a good correlation with the fractions of Hi and HoN (p>0.02). Our results suggest that the HoA, which is associated with humic substances, may be a major composition of refractory organic matters in rivers during storm events.

• Journal of Korean Society of Water and Wastewater
• /
• v.31 no.2
• /
• pp.161-168
• /
• 2017

Microfiltration (MF) and Ultrafiltration (UF) membrane processes capable of producing highly purified water have been extensively applied as a pretreatment process in the wastewater reuse field with the improvement of membrane properties and resistance, development of operating protocols, and improvement of technologies of backwashing and physicochemical cleaning, and improvement of scale and antifoulants. However, despite of the development of membrane production and process technologies, fouling still remains unresolved. This study confirmed that foulants such as polysaccharides, proteins and humic substances existed in final treated effluent (secondary effluent) by fluorescence excitation emission matrix (FEEM) and fourier transform infrared spectroscopy (FTIR) analysis. In addition, when constructing ozone oxidation and coagulation processes as a hybrid process, the removal efficiency was 5.8%, 6.9%, 5.9%, and 28.2% higher than that of the single process using coagulation in turbidity, color, dissolved organic carbon (DOC), and UV254, respectively. The reversible and irreversible resistances in applying the hybrid process consisting of ozone oxidation and coagulation processes were lower than those in applying ozone oxidation and coagulation processes separately in UF membrane process. Therefore, it is considered possible to apply ozonation/coagulation as a pretreatment process for stable wastewater reuse by and then contributing to the reduction of fouling when calculating the optimal conditions for ozone oxidation and coagulation and then to applying them to membrane processes.

• Membrane and Water Treatment
• /
• v.9 no.3
• /
• pp.163-172
• /
• 2018

This study investigated the effect of organic matter on the precipitation of struvite and calcium phosphate for phosphorus recovery from synthetic dairy wastewater. Batch precipitation experiments were performed to precipitate phosphorus from solutions containing $PO_4{^{3-}}$ and $NH_4{^+}$ by the addition of $Mg^{2+}$ and $Ca^{2+}$, separately, at varying pH, Mg/P and Ca/P molar ratios, and organic matter concentrations. Soluble total organic solids exhibited more inhibition to precipitation due to potential interaction with other dissolved ionic species involved in phosphorus precipitation. Xylan with low total acidity only exhibited significant inhibition at very high concentrations in synthetic wastewater (at up to 100 g/L). No significant inhibition was observed for Mg and Ca precipitation at relatively lower concentrations (at up to 1.2 g/L). MINTEQ simulations show that dissolved organic matter (DOM) as humic substances (HS) can cause significant inhibition even at relatively low concentrations of 0.165 g/L fulvic acid. However, scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis suggested that xylan altered the crystal structure of both precipitates and had caused the formation of smaller sized struvite crystals with slightly rougher surfaces This could be due to xylan molecules adhering on the surface of the crystal potentially blocking active sites and limit further crystal growth. Smaller particle sizes will have negative practical impact because of poorer settleability.

• Applied Chemistry for Engineering
• /
• v.10 no.6
• /
• pp.838-842
• /
• 1999

In order to reclaim the effluent discharged from sewage treatment facilities application of an irradiation technique was investigated in this study for industrial water reuse. Samples were filtered using a sand filter to remove particles. Co-60 was used as an irradiation source and the irradiation dose was varied from 0.1 kGy to 15 kGy. The major source of colour in secondary treatment effluent was humic substances, which could be easily removed by irradiation with a dose 5 kGy. Bacteria could be also disinfected even at low doses. It was possible to get high quality water for industrial water reuse. But the effluent still contained a small amount of organic compounds. Further treatment, of residual organic compounds will be necessry if the higher quality water is required.