Dong-Cheol Seo

Competitive adsorption of heavy metals onto sesame straw biochar in aqueous solutions

Objective of this research was to evaluate adsorption of heavy metals in mono and multimetal forms onto sesame straw biochar (SSB). Competitive sorption of metals by SSB has never been reported previously. The maximum adsorption capacities (mgg(-1)) of metals by SSB were in the order of Pb (102)≫Cd (86)≫Cr (65)>Cu (55)≫Zn (34) in the monometal adsorption isotherm and Pb (88)≫Cu (40)≫Cr (21)>Zn (7)⩾Cd (5) in the multimetal adsorption isotherm. Based on data obtained from the distribution coefficients, Freundlich and Langmuir adsorption models, and three-dimensional simulation, multimetal adsorption behaviors differed from monometal adsorption due to competition. Especially, during multimetal adsorption, Cd was easily exchanged and substituted by other metals. Further competitive adsorption studies are necessary in order to accurately estimate the heavy metal adsorption capacity of biochar in natural environments.

Enhanced sulfamethazine removal by steam-activated invasive plant-derived biochar.

Recent investigations have shown frequent detection of pharmaceuticals in soils and waters posing potential risks to human and ecological health. Here, we report the enhanced removal of sulfamethazine (SMT) from water by physically activated biochar. Specifically, we investigated the effects of steam-activated biochars synthesized from an invasive plant (Sicyos angulatus L.) on the sorption of SMT in water. The properties and sorption capacities of steam-activated biochars were compared with those of conventional non-activated slow pyrolyzed biochars. Sorption exhibited pronounced pH dependence, which was consistent with SMT speciation and biochar charge properties. A linear relationship was observed between sorption parameters and biochar properties such as molar elemental ratios, surface area, and pore volumes. The isotherms data were well described by the Freundlich and Temkin models suggesting favorable chemisorption processes and electrostatic interactions between SMT and biochar. The steam-activated biochar produced at 700 °C showed the highest sorption capacity (37.7 mg g(-1)) at pH 3, with a 55% increase in sorption capacity compared to that of non-activated biochar produced at the same temperature. Therefore, steam activation could potentially enhance the sorption capacities of biochars compared to conventional pyrolysis.

Competitive adsorption and selectivity sequence of heavy metals by chicken bone-derived biochar: Batch and column experiment

The objective of this research was to evaluate adsorption of heavy metals in single- and ternary-metal forms onto chicken bone biochar (CBB). Competitive sorption of heavy metals by CBB has never been reported previously. The maximum adsorption capacities of metals by CBB were in the order of Cu (130 mg g−1) > Cd (109 mg g−1) > Zn (93 mg g−1) in the single-metal adsorption isotherm and Cu (108 mg g−1) >> Cd (54 mg g−1) ≥ Zn (44 mg g−1) in the ternary-metal adsorption isotherm. Cu was the most retained cation, whereas Zn could be easily exchanged and substituted by Cu. Batch experimental data best fit the Langmuir model rather than the Freundlich isotherms. In the column experiments, the total adsorbed amounts of the metals were in the following order of Cu (210 mg g−1) > Cd (192 mg g−1) > Zn (178) in single-metal conditions, and Cu (156) > Cd (123) > Zn (92) in ternary-metal conditions. Results from both the batch and column experiments indicate that competitive adsorption among metals increases the mobility of these metals. Especially, Zn in single-metal conditions lost it adsorption capacity most significantly. Based on the 3D simulation graphs of heavy metals, adsorption patterns under single adsorption condition were different than under competitive adsorption condition. Results from both the batch and column experiments show that competitive adsorption among metals increases the mobility of these metals. The maximum metal adsorption capacity of the metals in the column experiments was higher than that in the batch experiment indicating other metal retention mechanisms rather than adsorption may be involved. Therefore, both column and batch experiments are needed for estimating retention capacities and removal efficiencies of metals in CBB.

Adsorption Characteristics of Heavy Metals using Sesame Waste Biochar

Little research has been conducted to explore the heavy metal removal potential of biochar. The adsorption characteristics of heavy metals by sesame waste biochar (pyrolysis at for 1 hour) as heavy metal absorbent were investigated. The sesame waste biochar was characterized by SEM-EDS and FT-IR, and heavy metal removal was studied using Freundlich and Langmuir equations. The removal rates of heavy metals were higher in the order of Pb>Cu>Cd>Zn, showing that the adsorption efficiency of Pb was higher than those of any other heavy metals. Freundlich and Langmuir adsorption isotherms were used to model the equilibrium adsorption data obtained for adsorption of heavy metals on biochar produced from sesame waste. Pb, Cu, Cd and Zn equilibrium adsorption data were fitted well to the two models, but Pb gave a better fit to Langmuir model. Heavy metals were observed on the biochar surface after adsorption by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Main functional groups were aromatic C=O ring (at , and ) by FT-IR analysis. Thus, biochar produced from sesame waste could be useful adsorbent for treating heavy metal wastewaters.

Optimum Configuration, Filter Media Depth and Wastewater Load of Small-scale Constructed Wetlands for Treating the Hydroponic Waste Solution in Greenhouses

ABSTRACT: To obtain optimum configuration, depth and load of constructed wetlands(CWs) for treatingof hydroponic waste solution(HWS) which was produced in greenhouses, the study was conducted with 4kinds of combined systems such as Vertical flow(VF)-Horizontal flow(HF), VF-VF, HF-VF and HF-HFCWs. In four configurations of CWs, the treatment efficiency of pollutants from HWS under depth of HFand VF beds, HWS loading and HWSs were investigated. Removal rate of pollutants under different depthof VF and HF in 2-stage hybrid CWs was in the order of 50 cm < 70 cm regardless of CWs configuration.Removal rate of pollutants under HWS loading in 2-stage hybrid CWs was in the order of 150 L m -2 day -1 ≒ 300 L m -2 day -1 ＞ 450 L m -2 day -1 .TheoptimumdepthandHWSloadingwere70cmand300Lm -2 day -1 in four configurations of CWs, respectively. Using this optimum condition, for various HWSs(cucumber, paprika and strawberry HWS), removal rate of pollutants in HF-HF CWs was higher than thatin HF-VF CWs. Optimum configuration of 2-stage hybrid CWs for treating hydroponic waste solution ingreenhouses was found out to be HF-HF CWs. Therefore, under the optimum conditions, removal rate ofBOD, COD, SS, T-N and T-P in HF-HF CWs were 84, 81, 84, 51 and 93%, respectively.Key Words:

Effect of Volatile Fatty Acid Concentration on Anaerobic Degradation Rate from Field Anaerobic Digestion Facilities Treating Food Waste Leachate in South Korea

The purpose of this study was to investigate the effect of volatile fatty acid concentration on anaerobic degradation rate of food waste leachate in the anaerobic digestion facilities. The anaerobic digestion facilities treating food waste leachate (FWL), codigestion with food leachate and animal manure (A-MIX), and codigestion with food waste leachate and sewage sludge (S-MIX) were selected for this study. In accordance with the regulation under Wastes Control Act in South Korea, the guideline of volatile solid removal rate for anaerobic digestion facility is set as 65% for anaerobic degradation efficiency. Highest volatile solids removal rates were achieved from FWL (63.5%) than A-MIX (56.4%) and S-MIX (41.2%). Four out of eight FWLs met the guidelines. The concentration of volatile fatty acids, therefore, was analyzed to determine the relationship with volatile solid removal rate. The results showed that, in order to meet the Korean guideline of 65% volatile solid removal rate, volatile fatty acid concentrations should remain below 4,000 mg/L on the field anaerobic digestion facilities treating FWL. Volatile fatty acid concentrations should be used along with others as an operational parameter to control and manage the anaerobic digestion process.

A Study on the Improvement of Treatment Efficiency for Nitrogen and Phosphorus by Improved Sewage Treatment Process in Constructed Wetland by Natural Purification Method

To effectively treat the domestic sewage that was produced on a small-scale in farming and fishing village in order to encourage an ecologically friendly environment, a small-scale sewage treatment apparatus using natural purification methods that consisted of an aerobic and an anaerobic plots were constructed. The efficiency of sewage treatment according to the sewage loading was investigated to obtain the optimum sewage loading in small-scale sewage treatment apparatus. Removal rate of pollutants according to the sewage loading were in the order of >. Therefore, the optimum sewage loading was 300 L m-2 day-1. Under the optimum sewage loading, removal rate of BOD, , turbidity, T-N and T-P were 99, 94, 99, 49 and 89%, respectively. However, to satisfy the water quality standard in effluent in small-sclae sewage treatment apparatus for domestic sewage treatment, the low removal efficiency of T-N and T-P must be improved. So to improve the removal rate of T-N and T-P, the efficiency of sewage treatment according to the improved sewage treatment process such as, re-treatment at aerobic plot, anaerobic condition of aerobic plot, changing the filter media sizes and the depths in anaerobic plot, and also addition of oyster shells to filter media at anaerobic plot were investigated. In case of 150 cm depth in anaerobic plot with filter medium A (effectivity particle size 1.50 mm) and addition of oyster shells to filter media at anaerobic plot, removal rate of T-N and T-P in both plots were increased by 10 and 3%, and 14 and 7% in comparison with 100 cm depth in anaerobic plot with filter medium B(effectivity particle size 0.95 mm), respectively. The optimum improved sewage treatment process in small-scale sewage treatment apparatus were 150 cm depth in anaerobic plot with filter medium A and addition of oyster shells to filter media at anaerobic plot.

Uptake Properties of Germanium to Vegetable Plants and Its Effect on Seed Germination and on Early Stage Growth

To investigate effects of inorganic and organic (Ge-132) germanium (Ge) on seed germination and on early stage growth of plane and the uptake characteristics, various concentrations (0, 10, 25, 50, 100 mg ) of Ge to popular vegetables such as leaf mustard, chinese cabbage and pak-choi, respectively, were treated. On seed germination, no significant effect was observed in both inorganic and organic Ge treatments except 100 mg treatment of inorganic Ge. Exogenous inorganic Ge ( mg treatments significantly inhibited the early root elongation growth of all plants. However, slight enhancement of early shoot elongation was detected in low concentrations (10 and 25 mg ) of Ge in the leaf mustard and chinese cabbage plants. Organic Ge treatments significantly stimulated the 개ot and shoot growth at the 10, 25 and 50 mg treatments. Ge was accumulated linearly in the vegetables as both inorganic and organic Ge concentrations were increased. Interestingly, total contents of Ge in plants with Ge-132 treatments were times more than those with inorganic Ge treatments in all concentrations. At 25 mg treatment of Ge, contents of Ge in vegetables are following: in leaf mustard, inorganic Ge: 0.37 mg and organic Ge: 1.47 mg in the chinese cabbage, inorganic Ge: 0.4 mg and organic Ge: 0.86 mg in the pak-choi, inorganic Ge: 0.33 mg and organic Ge: 0.70 mg , respectively. These results showed organic Ge is much better on early stage seedling growth and on germanium accumulation of vegetables than inorganic Ge.

Development of Sewage Treatment Apparatus for Detached House in Agricultural Village by Natural Purification Method

To develop small-scale sewage treatment apparatus for detached house of agricultural village, a small-scale sewage treatment apparatus by natural purification method that consisted of packaged form of aerobic, anoxic and anaerobic bed was constructed. The efficiency of sewage treatment according to the sewage treatment method, sewage loading, and the injection method of sewage were investigated for small-scale sewage treatment apparatus of packaged form of aerobic, anoxic and anaerobic bed. The removal rate of pollutants according to the sewage treatment method for small-scale sewage treatment apparatus was high in the order of aerobic-anoxic-anoxic bed . The removal rate of pollutants according to injection method of sewage in small-scale sewage treatment apparatus was high in the order of continuous injection intermittent injection. When loaded under the optimum conditions, removal rate of BOD, COD, SS, T-N and T-P were 99, 95, 99, 83 and 96%, respectively, through this 3-stepped small-scale treatment apparatus arrayed with the order of aerobic, anoxic and anaerobic bed.

Selection of Optimum Pebbles Size in Sewage Treatment Plant by Natural Purification Method

An investigation was carried out to evaluate the effects of pebble size on the small-scale sewage treatment apparatus by natural purification method that consisted of aerobic and anaerobic plot. pH and EC in both plots varied minimally regardless of pebble size. DO in aerobic plot increased as the pebble size decreased. That in the anaerobic plot was slightly less in comparison with that of the aerobic plot but varied minimally, regardless of pebble size. Under all experimental conditions, removals of BOD, COD and turbidity in anaerobic plot were more than 98, 91 and 98, 98% respectively. Removals of T-N and T-P increased as pebble size decreased. Under all experimental conditions, removals of T-N and T-P in anaerobic plot were about and , respectively. Judging from the above results, it should be considered that the optimum pebble size and pebble permeability in both plot was and , respectively.