• Journal of Korean Society of Environmental Engineers
• /
• v.27 no.2
• /
• pp.130-137
• /
• 2005

This research programme include investigation of the adsorption behavior of heavy metals and VOCs by Pyrolysis char for using landfill cover material. The volatile potions in the sludge gasified during the pyrolysis period and gave birth to porosity throughout the matrix. The result of the ad/desorption experiment of nitrogen to find out the formation of some pore by the gasification of the volatile matter, we can certify that the pyrolysis char($14.56\;m^2/g$) has increased twice more than the organic wasted sludge($6.68\;m^2/g$) in specific surface area. The pyrolysis char has the adsorption characteristic of medium type of Type II and V in BDDT classification, and showed a little micro pore. In the adsorption experiment of ethylbenzene and toluene, as a result of applying the Freundlich adsorption isotherms, the pyrolysis char was higher in the adsorptivity of ethylbenzene and toluene than the granite and the organic wasted sludge. The results of the heavy metal adsorption test for the char indicated that it had some ability of adsorption. It is suggest that pyrolysis char has some advantages for utilizing as landfill covers because the pyrolysis char can adsorb/absorb hazardous substances from the landfill sites and inhibit the ground water and soil contamination.

• Korean Journal of Environmental Agriculture
• /
• v.7 no.2
• /
• pp.87-91
• /
• 1988

To investigate the effects of paper sludge on the seasonal variations of higher fatty acids in paddy soil, paper sludge was applied to pots at the rate of either 300, 600, 900 or 1,200kg/10a. Fractions of the higher fatty acids in the soil were analyzed. 1. Twenty-one kinds of higher fatty acids in the soil were detected. Among them, lauric, myristic, myristoric, palmitic, palmitoleic, stearic, oleic, linoleic, linolenic and arachidic acids were identified. The fatty acid content in the soil of acids, linolonic, myristic, palmitic, and stearic acid increased in ascending order. 2. The total content of higher fatty acids in the soil was increased as the application of paper sludge increased. The formation of the acids was at its highest point at the effective tillering stage. After WARDS the contents of the acids decreased as time elapsed. A positive correlation was observed between the total contents of both higher and volatile lower fatty acids in the soil.

• Journal of Surface Science and Engineering
• /
• v.53 no.2
• /
• pp.72-79
• /
• 2020

Two Fe-Cr steels of T22 steel and STS430 steel were corroded at 650 and 750℃ for 100hr in sewage sludge-(0.3% SO₂-6% O₂-10% H₂O-balance CO₂) mixed gas environment. T22 steel corroded faster than STS430, indicating that the Cr content significantly influence the corrosion rates. T22 formed thick and non-protective Fe₂O₃ as the major oxide and Fe₃O₄ as the minor one. With an increase in corrosion temperature, their corrosion rates increased, being accompanied with formation of pores and cracks in the thickened oxide scales that were non-adherent. STS430 steel formed Fe₂O₃, Fe₃O₄ as the outer scale and (Fe, Cr)-O as the inner layer by which its corrosion rate is greatly reduced. Both the T22 and STS430 steel samples formed multi-layered scales by outward diffusion of Fe ions and inward diffusion of oxygen and sulfur ions at high-temperature more than 650℃.

• Journal of Korean Society of Water and Wastewater
• /
• v.19 no.5
• /
• pp.537-546
• /
• 2005

This study was carried out to evaluate EPS and SMP variation of sludge and effluent in nitrification and denitrification process with zeolite addition, a possible reduction of effluent DOC by URC(Ultra Rapid Coagulation) process. As a biological wastewater treatment result, EPS formation of both aeration and anoxic sludges are not affect by SRT variation. However, EPS concentration of sludges is higher in aeration tank than in anoxic tank by 6~8 mg EPS/ g VSS. Linear relationship between SMP to DOC indicates that SMP of bulk solution contributes to most of the biological treatment effluent DOC. DOC and turbidity removal efficiency was more improved with URC process than in a conventional coagulation. For pretreatment of UF filtration DOC removal was advanced by URC process than only UF filtration.

• Journal of Microbiology and Biotechnology
• /
• v.20 no.1
• /
• pp.179-186
• /
• 2010

In biological wastewater treatment, high lipid concentrations can inhibit the activity of microorganisms critical to the treatment process and cause undesirable biomass flotation. To reduce the inhibitory effects of high lipid concentrations, a two-phase anaerobic system, consisting of an anaerobic sequencing batch reactor (ASBR) and an upflow anaerobic sludge blanket (UASB) reactor in series, was applied to synthetic dairy wastewater treatment. During 153 days of operation, the two-phase system showed stable performance in lipid degradation. In the ASBR, a 13% lipid removal efficiency and 10% double-bond removal efficiency were maintained. In the UASB, the chemical oxygen demand (COD), lipid, and volatile fatty acid (VFA) removal efficiencies were greater than 80%, 70%, and 95%, respectively, up to an organic loading rate of 6.5 g COD/l/day. No serious operational problems, such as significant scum formation or sludge washout, were observed. Protein degradation was found to occur prior to degradation during acidogenesis.

• Journal of Korean Society of Water and Wastewater
• /
• v.26 no.4
• /
• pp.579-589
• /
• 2012

To reduce extensive energy costs of the internal recycling for the purpose of denitrification in the advanced wastewater treatment, a post-treatment process using an electro-coagulation to treat nitrate in the secondary effluents is evaluated in this study. Removals of phosphorus and organics in the secondary effluents by the electro-coagulation were also evaluated to propose an alternative advanced wastewatert treatment process. A series of experiments of the electro-coagulation were carried out with the following 4 different samples: synthetic solution containing nitrate only, synthetic solution containing nitrate as well as phosphorus, secondary effluents from activated sludge cultivated in laboratory, and secondary effluents from real wastewater treatment plants. Removals of nitrate and phosphorus in the synthetic solution were 30 and 97 % respectively, which verified the feasibility of the process. Removals of nitrate, phosphorus and COD in the secondary effluents from the cultivated sludge in laboratory were 49, 90 and 19 % respectively. Removal efficiency of the total nitrogen, nitrrate, phosphorus and COD in the secondary effluent from real wastewater treatment plant were 50, 61, 98 and 80 % respectively. The removal of the total nitrogen was less than the nitrate as expected, which is due to the formation of ammonia nitrogen in the cathode. But the proposed scheme could be an energy saving and alternative process for the advanced wastewater treatment if further studies for the process optimization are carried out.

• Microbiology and Biotechnology Letters
• /
• v.3 no.3
• /
• pp.117-122
• /
• 1975

In order to develop an activated sludge which can be used for both waste treatment and protein source of animal feed, microorganisms were isolated from sewages of various wheat or sweet potato starch processing plants and their activities were tested. Out of 32 isolates which composed of two protozoan genera and 13 bacterial strains, were screened and three bacterial stranis were found to be most effective in both floe-formation and wheat starch waste liquid stabilization.

• Membrane and Water Treatment
• /
• v.10 no.3
• /
• pp.213-221
• /
• 2019

Anaerobic digestion (AD) has been widely used to valorize food waste (FW) because of its ability to convert organic carbon into $CH_4$ and $CO_2$. Korean FW has a high content of fruits and vegetables, and efficient hydrolysis of less biodegradable fibers is critical for its complete stabilization by AD. This study examined the digestates from different anaerobic digesters, namely Rs, Rr, and Rm, as the inocula for the AD of vegetable waste (VW) and cellulose (CL): Rs inoculated with anaerobic sludge from an AD plant, Rr inoculated with rumen fluid, and Rm inoculated with anaerobic sludge and augmented with rumen fluid. A total of six conditions ($3\;inocula{\times}2\;substrates$) were tested in serial subcultures. Biogas yield was higher in the runs inoculated with Rm than in the other runs for both VW (up to 1.10 L/g VS added) and CL (up to 1.05 L/g VS added), and so was biogas production rate. The inocula had different microbial community structures, and both substrate type and inoculum source had a significant effect on the formation and development of microbial community structures in the subcultures. The overall results suggest that the bioaugmentation with rumen microbial consortium has good potential to enhance the anaerobic biodegradability of VW, and thereby can help more efficiently digest high fiber-content Korean FW.

• Korean Journal of Environmental Agriculture
• /
• v.7 no.1
• /
• pp.34-42
• /
• 1988

To investigate the effects of paper sludge on seasonal variations of volatile lower fatty acids in paddy soil, paper sludge was applied to pots at the rate of either 300, 600, 900 or 1,200 kg/l0a which was either preadjusted at a C/N ratio of 30 : 1 or not adjusted. The decomposition rate of paper sludge, the evolution of $CO_2$, and the fractions of volatile lower fatty acids in the soil were determined. The results are summarized as follows: 1. Paper sludge was decomposed to $35{\sim}44%$, and its C/N ratio was $55{\sim}82$, respectively, at 120 days after treatment. 2. The evolution of $CO_2$, in the soil was proportional to the amount of paper sludge added. Significant positive correlations were observed the $CO_2$ evolution was compared with the decomposition rate of paper sludge, and volatile fatty acid contents in soil. 3. Acetic, propionic, butyric, i-butyric, valeric and i-valeric acids were identified in all the soils investigated. The content of the total volatile fatty acids in the soil increased with as the application of paper sludge increased. The formation of the acids was the highest at 25 days after treatment, and thereafter the contents of the acids decreased as time elapsed. 4. The volatile fatty acids in the soil inhibited the growth of paddy rice in early stages. The contents of acetic, propionic and i-valeric acids in the soil negatively, correlated with the uptake of N, $P_2O_5$, $K_2O$, CaO, MgO and $SiO_2$ in the paddy rice at 25 days after transplantation. In addition, the uptake of $P_2O_5$ and CaO in the paddy rice negatively correlated with the content of butyric acid in the soil. 5. The content of total volatile fatty acids positively correlated with the content of $Fe^{++}$ and $Mn^{++}$ in the soil at 25 days after transplantation. A significantly positive correlation was observed between $Fe^{++}$ and acetic acid contents in the soil.

• Journal of Korean Society on Water Environment
• /
• v.23 no.1
• /
• pp.138-143
• /
• 2007

This study goes in for the observation of the characteristics of nitrogen removal from swine wastewater by struvite crystallization. In addition, the struvite formation potential in supernatants after struvite crystallization was investigated. In the study for nitrogen removal by struvite crystallization, the effects of pH and molar ratio of magnesium (Mg) injected using bittern as Mg source were investigated. Also, the potential of struvite formation in the supernatant with amount of Mg added was carefully observed. As the results, the optimum pH in the removal of nitrogen was 8.8 and sludge volume was increased as pH was raised from 7 to 12 under the condition that the molar ratio of $Mg^{2+}$ to ${NH_4}^+$-N to ${PO_4}^{3-}$-P was 1:1:1. An optimum removal efficiency of ammonia-N was observed at 1 molar ratio of Mg to ${NH_4}^+$-N, showing no further increase at over 1 molar ratio and dramatical deterioration at under 1 molar ratio. However, the sludge volume was increased by increasing the molar ratio of Mg. In the experiments for the potential of struvite formation in the supernatants, initial -log([$Mg^{2+}$][${NH_4}^+$][${PO_4}^{3-}$]) value was much lower than $pK_{sp}$ and gradually reached $pK_{sp}$ at 2 days, as the molar ratio of Mg increased over 1.2. At 31 days, -log([$Mg^{2+}$][${NH_4}^+$][${PO_4}^{3-}$]) value was returned to the initial value. In addition, the supernatants had a potential precipitation of hydroxylapatite due to calcium contained in bittern, $K_2Mg(SO_4)_3$ and $K_3Na(SO_4)_2$ resulting from the decrease of sodium and potassium in supernatants formed after struvite crystallization as times go by. Based on the results, it appears that some retention time and proper dosage of Mg may be needed for the prevention of scale in pipe line.