• Journal of Korean Society of Water and Wastewater
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• v.38 no.4
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• pp.209-221
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• 2024

This study explored effects of a sludge-based biochar addition on nitrogen removal of membrane bioreactor (MBR) for wastewater treatment. The membrane fouling reduction by the biochar addition was also investigated. A dose of 3 g/L of the biochar was applied to an MBR (i.e., BC-MBR) and treatment efficiencies of organic matter and nutrient were analyzed. The MBRs with powdered activated carbon (i.e., AC-MBR) and without any additives were also operated in parallel. The average removals of COD and TN were improved with the biochar addition compared to those with the control MBR. Interestingly, operational duration was also increased with biochar addition. The CLSM analysis revealed that biomass amounts of BC-MBR and AC-MBR were reduced by more than 40%, and thickness of the biofilm attached to the membrane surface also was decreased. The physical properties of biochar surfaces were compared with a commercial powdered activated carbon. The specific surface area with 38 m²/g and pore volume with 0.13 cm³/g of the biochar were much smaller than those of the powdered activated carbon, which were 1100 m²/g and 0.67 cm³/g, respectively. Manufacturing conditions for the biochar production needs to be further investigated for enhancing physical properties for adsorption and biological improvement.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.2
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• pp.660-667
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• 2018

This study examined the optimal manufacturing conditions of RDF using heat-dried sludge from sewage treatment plant in Cheonan with the oil-drying method. The amounts of oil evaporation and oil drying of the heat-dried sludge were measured at different temperatures to evaluate the value of the product. The performance of the product was then measured using a calorimeter and TGA. In addition, the concentration of odor, NH3, H2S, and TVOC during drying was determined using a portable odor-meter. Ingredient analysis was performed by EDS. Considering mass-production, the oil to heat-dried sludge weight ratio was fixed to 4:1. At $130^{\circ}C$, only physical mixing occurred after the instantaneous drying of internal water. Considering the eco-friendly aspects, there was no significant difference in the drying efficiency between $160^{\circ}C$ and $190^{\circ}C$. Therefore, the optimal conditions were a drying temperature of $160^{\circ}C$ within 5 minutes. Finally, the RDF manufactured in this study and fuel used in the thermal power plants were compared. The calorific value was 4,449kcal/kg, the water content was 2% and the ash content was 34%, which is higher than the fuel of thermal power plants. Therefore, it is believed that coal energy as well as wood pellets can be replaced.

• Korean Journal of Environmental Agriculture
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• v.21 no.1
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• pp.45-49
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• 2002

To estimate annual pollutant loading rate of n-hexane extractable material (HEM) to soil 84 sewage sludge samples were analyzed. The average content of HEM was 27.7$\pm$26.5 g/kg, and ranged from 1.05 to maximum 194 g/kg. According to the number of population of the city the areas were classified as five regions, i.e. big, large, middle, small, and rural area in which the waste water treated plants were grown. The contents of HEM were 22.7$\pm$16.7, 33.3$\pm$25.8, 22.0$\pm$8.7, 31.0$\pm$38.8, 27.7$\pm$25.1 g/kg, in big, large, middle, small, and rural area, respectively. The applicated areas with sewage sludge to land also were divided as 4 sites by US EPA criteria such as agricultural, forest, public contact sites, and reclamation site. The quantitation of annual pollutant loading rate was estimated using a function (99 percentile concentration = $\bar{X}$ + 3$\sigma$) when the application amounts were in dosages of 7,000, 26,000, 18,000, 74,000 kg/ha in 5 regions, respectively. The annual pollutant loading rate of HEM to soil by sewage sludge application was maximum 1,032, 3,832, 2,653, and 10,908 kg/ha in agricultural, forest, public contact sites, and reclamation site, respectively.

• Korean Journal of Environmental Agriculture
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• v.15 no.3
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• pp.296-305
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• 1996

Chemical characteristics of paper sludge, degradation of the sludge in soil and $CO_2$ generation, and changes of nitrogen and heavy metals in soil treated with the sludge were investigated. The results obtained was summarized as follows: 1. Degradation rate of paper sludge in soil was 19% at room temperature, and 28% at $incubation(30^{\circ}C)$ temperature after 12-weeks treatment. 2. T-C, T-N and the C/N ratio of the sludge in soil at room temperature were 15.5%, 0.22% and 71 respectively, and 14.5%, 0.24% and 60, respectively, at $incubation(30^{\circ}C)$ temperature after 12-week treatment. 3. $CO_2$ genaration in soil treated with 1%, 3% and 5% of the sludge was 247mg/100g, 334mg/100g and 458mg/100g, respectively, at room temperature, and 385mg/100g, 550mg/100g and 618mg/100g, respectively, at incubation temperature after 12 weeks treatment. 4. Mineralization ratio of organic nitrogen in soil treated with 1%, 3% and 5% of the sludge was 8.7%, 13.4% and 16.2%, respectively, at $incubation(30^{\circ}C)$ temperature after 12-weeks treatment. 5. The amounts of DTPA-extractable Cu, Cd, Zn, Pb, and Cr in Soil treated with paper sludge were $0.7{\sim}2.2$, $0.1{\sim}0.17$, $1.4{\sim}2.8$, $1.4{\sim}2.8$, and $0{\sim}0.7mg/kg$, respectively. Mean while, those of $HNO_3$ extractable Cu, Cd, Zn, Pb, and Cr were $7.9{\sim}10.0$, $0.6{\sim}0.9$, $17.6{\sim}34.4$, $14.7{\sim}18.5$, and $5.8{\sim}9.0mg/kg$, respectively.

• Clean Technology
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• v.9 no.1
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• pp.23-28
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• 2003

The generation of food waste in Korea amounts to 4.10 million per year, which corresponds to 820,000 dry ton of organic waste. This has been used traditionally as animal feed or soil conditioner, but its efficacy has remained doubtful in recent years. In this study as an alternative we considered methane production by anaerobic treatment, which has an advantage of 200 million US dollars over aerobic methods. The production of methane amounts to $4.40{\times}10^8m^3$, 3.43% of $1.28{\times}10^8m^3$, total natural gas used in Korea. Furthermore the methane from household kitchen food waste amounts to 28.9% of the total gas used in the kitchen.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.3
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• pp.587-595
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• 2000

The most problems of domestic sewage for BNR(Biological Nutrients Removal) process are deficiency of carbon source and low C/N ratio. Primary sludge fermentation is seemed to be one of the best solutions producing biodegradable organic substrates. Soluble organic materials from sludge fermentation are mainly SCFAs(Short-Chain Fatty Acids) with 2~5 carbon atoms. In this research, it was attempted to apply $A_2/O$ process with the side-stream acid fermenter to improve the nutrients removal efficiency. The result showed that proper SCFAs production is about 3.000mg/L with SRT of 4~5 days. SCFAs yield of approximately 0.10~0.16 mg SCFAs(as COD) per mg of primary sludge(as COD) were achieved. The ratio of acetic. propionic. butyric and valerie acid were 1, 0.7, 0.5 and 0.6. Significant improvements of nutrients removal over 70% in BNR process were observed. thus will reduce the demand for chemical dosing to increase nutrients removal efficiency. When the fermentate was entered $A_2/O$ process, the ratio of phosphate release to substrate uptake amounts to $0.34gPO_4-Pg^{-1}COD$.

• Korean Journal of Environmental Agriculture
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• v.33 no.2
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• pp.78-85
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• 2014

BACKGROUND: Recent studies using various industrial wastes for heavy metal stabilization in soil were conducted in order to find out new alternative amendments. The acid mine drainage sludge(AMDS) contains lots of metal oxides(hydroxides) that may be useful for heavy metal stabilization not only waste water treatment but also soil remediation. The aim of this study was to investigate the applicability of acid mine drainage sludge for heavy metals stabilization in soils METHODS AND RESULTS: Alkali soil contaminated with heavy metals was collected from the agricultural soils affected by the abandoned mine sites nearby. Three different amounts(1%, 3%, 5%) of AMDS were applied into control soil and contaminated soil. For determining the changes in the extractable heavy metals, $CaCl_2$ and Mehlich-3 were applied as chemical assessments for metal stabilization. For biological assessments, lettuce(Lactuca sativa L.) and chinese cabbage(Brassica rapa var. glabra) were cultivated and accumulation of heavy metals on each plant were determined. It was revealed that AMDS reduced heavy metal mobility and bioavailability in soil, which resulted in the decreases in the accumulation of As, Cd, Cu, Pb, and Zn in each plant. CONCLUSION: Though the high level of heavy metal concentrations in AMDS, any considerable increase in the heavy metal availability was not observed with control and contaminated soil. In conclusion, these results indicated that AMDS could be applied to heavy metal contaminated soil as an alternative amendments for reducing heavy metal mobility and bioavailability.

• Journal of Bio-Environment Control
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• v.3 no.2
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• pp.136-144
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• 1994

A long- time aeration method was developed for purification of animal wastewater. Under repeated aereations of 4 hours on and 4 hours off, the higher removal rates were obtained which were in average of 99%, 96%, 92% and 50% for BOD, SS, total nitrogen and phosporous, respectively. In detail, the measured BOD concentrations of the influent and effluent were 2,700ppm and 40ppm while the SS concentrations in the primary chamber and of the effluent were about 3,000 and 110 ppm, respectively. Zeolite and activated carbon, applied for removing the nitrogen and phosphorous, showed a good absorption, especially zeolite for NH$_4$-N and activated carbon for NO$_3$-N and PO$_4$-P. The treatment cost per head by this method amounts to 1,923 won and it comes to 1.6% in the whole production cost. Therefore, this method is economically available with the half cost of the conventional activated sludge process.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.69-69
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• 2017

For several decades, industrial processes consume a huge amount of raw water for various objects that consequently results in the generation of large amounts of wastewater. There effluents are mainly treated by conventional technologies such are aerobic, anaerobic treatment and chemical coagulation. But, there processes are not suitable for eliminating all hazardous chemical compounds form wastewater and generate a large amount of toxic sludge. Therefore, other processes have been studied and applied together with these techniques to enhance purification results. These techniques include photocatalysis, absorption, advanced oxidation processes, and ozonation, but also have their own drawbacks. In recent years, electrochemical techniques have received attention as wastewater treatment process that show higher purification results and low toxic sludge. There are many kinds of electrode materials for electrochemical process, among them, boron doped diamond (BDD) attracts attention due to good chemical and electrochemical stability, long lifetime and wide potential window that necessary properties for anode electrode. So, there are many researches about high quality BDD, among them, researches are focused BDD on Si substrate. But, Si substrate is hard to apply electrode application due to the brittleness and low life time. And other substrates are also not suitable for wastewater treatment electrode due to high cost. To solve these problems, Ti has been candidate as substrate in consideration of cost and properties. But there are critical issues about adhesion that must be overcome to apply Ti as substrate. In this study, to overcome this problem, TiN interlayer is introduced between BDD and Ti substrate. TiN has higher electrical and thermal conductivity, melting point, and similar crystalline structure with diamond. The TiN interlayer was deposited by reactive DC magnetron sputtering (DCMS) with thickness of 50 nm, $1{\mu}m$. The microstructure of BDD films with TiN interlayer were estimated by FE-SEM and XRD. There are no significant differences in surface grain size despite of various interlayer. In wastewater treatment results, the BDD electrode with TiN (50nm) showed the highest electrolysis speed at livestock wastewater treatment experiments. It is thought to be that TiN with thickness of 50 nm successfully suppressed formation of TiC that harmful to adhesion. And TiN with thickness of $1{\mu}m$ cannot suppress TiC formation.

• Korean Journal of Materials Research
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• v.9 no.12
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• pp.1170-1175
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• 1999

The microstructures and mechanical properties of $Si_3N_4$ ceramics produced by nitridation and post-sintering using semiconductor-waste-Si sludge were investigated. Lots of microcracks were observed in the waste-Si powders which contained some amounts of amorphous $SiO_2$. The nitridation rate of waste-Si compacts showed lower value than that of commercial Si powder compacts. The nitridation rate was increased with increasing nitridation temperature and then the percent of nitridation at 1470$^{\circ}C$ showed 98%. The phases of $Si_3N_4$ in the reaction-bonded bodies were mixed with ${\alpha}$ and ${\beta}$-type, and small amounts of $Si_2N_2O$ phase while those after post-sintering were ${\beta}$-$Si_3N_4$ and ${\alpha}$-Sialon. The sample post-sintered at 1950$^{\circ}C$ showed the fracture toughness of 5.6 $^MPa{\cdot}m^{1/2}$ and the fracture strength of 497 MPa which were lower than those of sintered body using commercial Si powder possibly due to the formation of ${\alpha}$-Sialon phase.