• 상하수도학회지
• /
• 제28권6호
• /
• pp.657-668
• /
• 2014

Under Korea's Enforcement Decree of the Framework Act on Environmental Policy amended in 2013, total organic carbon (TOC) is newly added as water quality parameter to assess organic pollution in water and aquatic ecosystem. To meet the TOC requirement and improve quality of effluent discharged into public watershed, it is also necessary to develop standards for TOC in effluent from public sewage treatment works (PSTWs). In this study, we reviewed the characteristics and removal efficiency of TOC in influent and effluent of PSTWs. The study found that phosphorus treatment process removed not only soluble phosphorus but also a portion of TOC remaining after the secondary treatment process. TOC concentration in effluent from PSTWs operated in tandem with industrial wastewater treatment work was higher due to influx of insoluble substances from the industrial wastewater treatment work. In order to lay a foundation for the management of TOC from PSTWs, it is necessary to carry out research on TOC from different perspectives. For example, studies on the generation mechanism of TOC and the impact of TOC on drinking water resources, assessment of effluent qualities through monitoring, and development of measures to control TOC for the preservation of aquatic ecosystem are needed.

• 한국토양비료학회지
• /
• 제6권3호
• /
• pp.159-163
• /
• 1973

당밀(糖密)을 원료(原料)로 하여 발효법(醱酵法)으로 구르타민산(酸)소다를 제조(製造)할 때 부생(副生)하는 잔사(殘渣)를 가공(加工)하여 만든 구르타민산잔사가공비료(酸殘渣加工肥料) 시제품(試製品)에 대(對)하여 그 성질(性質)을 조사(調査)하고 그 비효를 요소(尿素), 퇴비(堆肥) 및 미강(米糠)과 대비(對比)해 옥수수 재배시험(栽培試驗)을 통(通)하여 검토(檢討)했든바 그 결과(結果)를 요약(要約)하면 아래와 같다. 1) 공시(供試) 구르타민산잔사가공물(酸殘渣加工物)은 유안(硫安), 염안(鹽安) 및 종류미상(種類未詳)의 복염등(複鹽等)의 무기물(無機物)과 수용성(水溶性) 아미노산류(酸類) 및 불용성(不溶性) 탄소화합물(炭素化合物)의 혼합물(混合物)임이 밝혀졌다. 2) 이 물질(物質)에 함유(含有)된 속효성N비료부분(肥料部分)의 효과는 요소(尿素)와 대등(對等)하다. 3) 이 물질(物質)에 함유(含有)된 유기물(有機物)은 옥수수의 수량(收量)에 미친 효과면에서 퇴비(堆肥)나 미강(米糠)과 대등(對等)한것 같다. 4) 이 물질(物質)의 시용(施用)은 옥수수의 양분흡수(養分吸收)나 기타(基他) 생리작용(生理作用)에 특이성(特異性)있는 해(害)를 미치지 않았다. 5) 이 물질(物質)에 함유(含有)된 유기물(有機物)이 토양중(土壤中) 철(鐵)의 유효화에 미치는 영향(影響)이 타유기물(他有機物)과 상이(相異)할 가능성(可能性)이 있음을 논(論)했다. 6) 이 물질(物質)의 시용(施用)은 토양(土壤)을 산성화(酸性化) 시키는 경향(傾向)이 뚜렷하며 토양중(土壤中) 가급태유황(可給態硫黃)과 토양유기물함량(土壤有機物含量)을 높이는 경향(傾向)이 있었다.

• 한국입자에어로졸학회지
• /
• 제7권4호
• /
• pp.131-138
• /
• 2011

우리나라의 대표적인 배경지역 측정소인 안면도의 지구배경관측소에서 20010년에 채취한 미세먼지(PM10) 시료에 대해 n-alkane과 수용성 유기성분(WSOC) 농도를 분석하였다. 우리나라의 또 다른 배경지역인 고산에 비해 봄철의 수용성 유기성분의 농도는 세배 정도 높았다. 안면관측소의 수용성 유기성분의 농도는 서울이나 아시아 다른 도시지역의 농도와 비슷한 수준이었다. 그러나 아시아 도시는 겨울에 농도가 높았으나, 안면관측소는 가을에 높아 배출원, 또는 생성원이 다른 것으로 보인다. 한편 n-alkane 성분의 농도는 안면관측소가 고산보다 약간 낮았고, 서울 등의 아시아 도시의 1/3-1/2 수준으로 낮았다. 그러나 고산은 자연적인 기원의 n-alkane 농도가 높은 반면에 안면관측소는 인위적인 n-alkane이 대부분이어서 대조를 보이고 있다. 따라서 안면관측소는 우리나라의 대표적인 배경지역임에도 불구하고 수용성 유기성분과 n-alkanes 농도측면에서는 배경지역과 도시지역의 특성을 갖고 있어, 인위적인 영향을 많이 받고 있는 것으로 보인다. 보다 상세한 배출원과 생성원 분석은 무기이온농도와 다른 유기성분 분석을 추가하여 이루어질 예정이다.

• Membrane and Water Treatment
• /
• 제9권3호
• /
• pp.147-153
• /
• 2018

This study investigates the role of microbial extracellular polymeric substances (EPSs) as bioflocculants to harvest microalgae (water-microalgae separation). The EPS extracted from waste activated sludge (WAS) by heat extraction were fractionated into soluble EPS (S-EPS), loosely-bound EPS (LB-EPS) and tightly-bound EPS (TB-EPS) forms. All the EPSs facilitated the flocculation of microalgal cells from stable growth medium. Of those EPSs, the TB-EPS showed the highest flocculating activity (FA) resulting in the substantial decrease in the amount of EPS added in terms of total organic carbon (TOC) during flocculation. The FA of microalgae was improved with the increase in TB-EPS dose, however, excessive dose of TB-EPS adversely affected it due to destabilization. Both LB- and TB-EPS could be utilized for flocculating microalgae as a sustainable option to the existing chemical-based flocculants. In addition to the conventional assessments, the effectiveness of the two bioflocculants for floc forming was also confirmed using a novel assessment of lens-free shadow imaging technique (LSIT), which was firstly applied for the rapid and quantitative assessment of microalgal flocculation.

• Ecology and Resilient Infrastructure
• /
• 제5권2호
• /
• pp.82-87
• /
• 2018

Proliferation of algae on the surface of concrete or mortar in aquatic habitat has a negative impact on maintenance of concrete-based structures. Growth of algae may decrease stability of structure by bio-deterioration. In this study, we developed a functional mortar for restraining bio-deterioration by using $Cu^{2+}$ ion. The mortar contains soluble glass beads made of $Cu^{2+}$ ion, which can dissolve into water slowly. Mortars prepared with different ratio of glass beads (0, 2, 5, 10, and 15%) were placed in a culture medium with algae and incubated over a month period. Water chemistry, chlorophyll-a, and extracellular enzyme activities were measured. The incubation was conducted in both freshwater and seawater conditions, to assess applicability to both aquatic conditions. Overall, mortar with Cu glass exhibited lower chlorophyll-a content, suggesting that the functional mortar reduced algal growth. DOC concentration increased because debris of dead algae increased. Cu glass also decreased phosphatase activity, which is involved in the regeneration of inorganic P from organic moieties. Since, P is often a limiting nutrient for algal production, algal growth may be inhibited. Activities of ${\beta}$-glucosidase and N-acetylglucosaminidase were not significantly affected because carbon and nitrogen mineralization may not be influenced by the Cu glass beads. Our study suggests that functional mortar with Cu glass beads may reduce the growth of algae on the surface, while it has little environmental impact.

• 한국입자에어로졸학회지
• /
• 제9권2호
• /
• pp.89-102
• /
• 2013

24-hr $PM_{2.5}$ samples were collected from January 19 through February 27, 2009 at an urban site of Gwangju and analyzed to determine the concentrations of organic and elemental carbon(OC and EC), water-soluble OC(WSOC), eight ionic species($Na^+$, $NH^{4+}$, $K^+$, $Ca^{2+}$, $Mg^{2+}$, $Cl^-$, ${NO_3}^-$ and ${SO_4}^{2-}$), and 22 elemental species. Haze phenomena was observed during approximately 29%(10 times) of the whole sampling period(35 days), resulting in highly elevated concentrations of $PM_{2.5}$ and its chemical components. An Asian dust event was also observed, during which $PM_{2.5}$ concentration was 64.5 ${\mu}g/m^2$. Crustal materials during Asian dust event contributed 26.6% to the $PM_{2.5}$, while lowest contribution(5.1%) was from the haze events. OC/EC and WSOC/OC ratios were found to be higher during haze days than during other sampling days, reflecting an enhanced secondary organic aerosol production under the haze conditions. For an Asian dust event, enhanced concentrations of OC and secondary inorganic components were also found, suggesting the further atmospheric processing of precursor gases during transport of air mass to the sampling site. Correlations among WSOC, EC, ${NO_3}^-$, ${SO_4}^{2-}$, and primary and secondary OC fractions, which were predicted from EC tracer method, suggests that the observed WSOC could be formed from similar formation processes as those of secondary organic aerosol, ${NO_3}^-$ and ${SO_4}^{2-}$. Results from principal component analysis indicate also that the observed WSOC was strongly associated with formation routes of the secondary organic and inorganic aerosols.

• Asian Journal of Atmospheric Environment
• /
• 제9권1호
• /
• pp.66-77
• /
• 2015

In order to survey the seasonal variation of the chemical composition of particulate matter of $2.5{\mu}m$ or less ($PM_{2.5}$), $PM_{2.5}$ was sampled from 8 February 2013 to 31 March 2014 in an industrial area of Chiba Prefecture, Japan. Chemical measurements of the sample included: ionic components ($Na^+$, $NH_4{^+}$, $Ca^{2+}$, $Mg^{2+}$, $K^+$, $Cl^-$, $NO_3{^-}$ and $SO_4{^{2-}}$), carbonaceous components - organic carbon (OC) and elemental carbon (EC), and water-soluble organic carbon (WSOC). Also, secondary organic carbon (SOC) was measured based using the EC tracer method, and char-EC and soot-EC were calculated from the analytical results. The data obtained were interpreted in terms of temporal variation. Of the overall mean value of $PM_{2.5}$ mass concentration obtained during the study period, ionic components, OC and EC accounted for 45.3%, 19.7%, and 8.0%, respectively. $NO_3{^-}$ showed a unique seasonal distribution pattern due to a dependence on temperature and absolute humidity. It was estimated that an approximate temperature of $14^{\circ}C$, and absolute humidity of $7g/m^3$ were critical for the reversible reaction of $NH_4NO_3(p){\leftrightharpoons}NH_3(g)+HNO_3(g)$. The amount of OC and EC contributing to the monthly $PM_{2.5}$ mass concentration was higher in autumn and winter compared to spring and summer. This result could be attributed to the impact of burning biomass, since WSOC and the ratio of char-EC/soot-EC showed a similar pattern during the corresponding period. From the comparison of monthly WSOC/OC values, a maximum ratio of 83% was obtained in August (summer). The WSOC and estimated SOC levels derived from the EC tracer method correlated (R=0.77) in summer. The high occurrence of WSOC during summer was mainly due to the formation of SOC by photochemical reactions. Through long-term observation of $PM_{2.5}$ chemical components, we established that the degree to which the above-mentioned factors influence $PM_{2.5}$ composition, fluctuates with seasonal changes.

• 상하수도학회지
• /
• 제21권4호
• /
• pp.493-501
• /
• 2007

The membrane pilot plant has being operated in the Hyeondo pumping station to find the optimal operation technique of Gong-Ju membrane water treatment plant (WTP) which is constructing in $250m^3/d$ scale. The pilot plant was consisted of two trains which can treat $30,000m^3/d$ per train. First train was operated for one year under the condition of flux $1m^3/m^2{\cdot}d$ while the effects of flux variation and addition of powdered activated carbon(PAC) were evaluated in second train. The turbidity of membrane product water of first train which is operated on Flux $1m^3/m^2{\cdot}d$ was always below 0.05 NTU regardless of raw water turbidity. And also, the trance-membrane pressure(TMP) was maintained at $0.3{\sim}0.5kgf/cm^2$ for about 9 months and increased rapidly to $1.8kgf/cm^2$ which is maximum operating TMP. However, TMP was rapidly increased to $1.8kgf/cm^2$ within 2 months as flux was increased from 1 to $2m^3/m^2{\cdot}d$, especially, within 10 days under high turbidity(30~50NTU). This reault means that if Gongju membrane WTP is operated in flux $1m^3/m^2{\cdot}d$, chemical cleaning period can be maintained over 6 months. Only 10% of dissolved organic carbon (DOC) was removed in membrane process while the removal efficiencies of manganese and iron were 60% and 77% respectively. However, because only solid manganese and iron were removed in membrane process, an additional process for treating soluble manganese is required if souble manganese is high in raw water. 70% of 70ng/L 2-MIB which is causing taste & odor was removed in powdered activated carbon (PAC) tank with 50mg/L PAC which is design concentration of Gongju WTP. In addition, TMP was reduced with addition of 50mg/L PAC regardless of flux. Because TMP was not influenced even if 100mg/L PAC was added, the high taste and odor problem can be controled by additional injection of PAC.

• 한국물환경학회지
• /
• 제31권2호
• /
• pp.151-158
• /
• 2015

The aim of this research is to derive an optimum operating condition for the thermal solubilization equipment that is employed to increase concentration of soluble organic materials and to assess whether it would be possible to use the waste sludge generated by thermal solubilization reaction as an external carbon source in biological denitrification process. For the purpose, we have constituted a laboratory-size thermal solubilization equipment and have assessed thermal hydrolysis efficiency based on various reaction temperature and reaction time. We have also derived SDNR using the waste sludge generated by thermal solubilization reaction through a batch experiment. As a result of research, the highest thermal hydrolysis efficiency of about 42.8% was achieved at $190^{\circ}C$ of reaction temperature and at 90 minutes of reaction time. And when SDNR was derived using the waste sludge, the value obtained was $0.080{\sim}0.094\;g\;NO_3{^-}-N/g\;MLVSS{\cdot}day$, showing SDNR that is higher than that obtained by the results of existing researches that used common wastewater as an external carbon source. Accordingly, in view of the fact that food wastes vary quite a bit in characteristics based on the area they are generated from and seasonal change, it seems that a flexible operation of thermal solubilization equipment is required through on-going monitoring of food wastes that are imported to food wastes recycling facilities.

• 한국입자에어로졸학회지
• /
• 제17권4호
• /
• pp.91-106
• /
• 2021

Daily PM_2.5 was collected during summer period in 2020 in Gwangju to investigate its chemical and light absorption properties. In addition, real-time light absorption coefficients were observed using a dual-spot 7-wavelength aethalometer. During the study period, SO₄^2- was the most important contributor to PM_2.5, accounting for on average 33% (10-64%) of PM_2.5. The chemical form of SO₄^2- was appeared to be combination of 70% (NH₄)₂SO₄ and 30% NH₄HSO₄. Concentration-weighted trajectory (CWT) analysis indicated that SO₄^2- particles were dominated by local pollution, rather than regional transport from China. A combination of aethalometer-based and water-extracted brown carbon (BrC) absorption indicated that light absorption of BrC due to aerosol particles was 1.6 times higher than that due to water-soluble BrC, but the opposite result was found in absorption Ångström exponent (AAE) values. Lower AAE value by aerosol BrC particles was due to the light absorption of aerosol BrC by both water-soluble and insoluble organic aerosols. The BrC light absorption was also influenced by both primary sources (e.g., traffic and biomass burning emissions) and secondary organic aerosol formation. Finally the ATR-FTIR analysis confirmed the presence of NH₄⁺, C-H groups, SO₄^2-, and HSO₄^2-. The presence of HSO₄^2- supports the result of the estimated composition ratio of inorganic sulfate ((NH₄)₂SO₄) and bisulfate (NH₄HSO₄).