• Journal of Environmental Science International
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• v.15 no.12
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• pp.1177-1183
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• 2006

This study was carried out to evaluate effect of sludge characteristics (pH, SVI, anaerobic storage, wet density and growth phase) on the sedimentation of bulking sludge of paper manufacturing plant. The results showed that mix hulking sludge with sewage sludge (10-60%) caused the decrease of SVI, the settled sludge concentration was increased. Increase of anaerobic storage time (0 to 8 day) was increased SVI, sedimentation performance was deteriorated. The sedimentation was improved by addition of loess (0.2-5.0 g/L), because wet density of sludge was increased and SVI was decreased. At an exponential phase, the ratio of sedimented/growthed sludge concentration was decreased, the ratio was increased after stationary phase.

• Journal of the Korean Chemical Society
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• v.55 no.5
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• pp.842-845
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• 2011

Wet air oxidation (WAO) of oily sludge was carried out using $Fe^{3+}$ as catalyst, placed in a 0.5 L batch autoclave in the temperature range of $250-330^{\circ}C$. Experiments were conducted to investigate the effects of temperature, the initial COD, reaction time, concentration of catalyst and $O_2$ excess (OE) on the oxidation of the oily sludge. The results showed that in the WAO 88.4% COD was achieved after 9 min reaction at temperature of $330^{\circ}C$, OE of 0.8 and the initial COD of 20000 mg/L. Temperature was found to have a significant impact on the oxidation of oily sludge. Adding a catalyst significantly improved the COD removal. Homogenous catalyst, $Fe^{3+}$, showed effective removal for pollutants. COD removal was 99.7% in the catalytic wet air oxidation (CWAO) over $Fe^{3+}$ catalyst. The results proved that the CWAO was an effective pretreatment method for the oily sludge.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.984-993
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• 1993

land application of sewage sludge requires careful monitoring because of its potential for contamination of surface water and groundwater. A rainfall simulator was used to investigated the effects of freshly applied sludge on runoff of sediment and nutrients from agricultural crop lands. Rain was applied to 16 experimental field plots. A three run sequence was used to simulate different initial moisture conditions. Runoff, sediment and nutrient losses were monitored at the base of each plot during the simulated rainfall events. Sludge was surface applied and incorporated at conventionally -tilled plots and surface applied at no-till plots, at rates of 0, 75, 150 kg-N/ha. No-till practices greatly reduced runoff, sediment , and nutrient losses form the sludge treated plots, relative to the conventional tillage practices. Incorporation of the sludge was effective in reducing nutrient yields at the conventionally-tilled plots. This effect was more pronounced during the third rain torm, with wet initial conditions. Peak loadings of nutrients appeared during the rainstorm with wet initial conditions.

• Journal of Korean Society on Water Environment
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• v.22 no.1
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• pp.97-103
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• 2006

Excess sludge treatment and disposal currently represent a rising challenge for domestic or wastewater treatment plants due to economic, environmental and regulation factors. Conventional gravity sedimentation process has been widely used in sludge thickening. The operation method of the process is very simple, but the process requires long detention time for sludge thickening, uses polymers, and shows low sludge thickening efficiency. To solve the problems, we studied on DAF (Dissolved Air Flotation) system. We use bulking sludge of a paper manufacturing plant. The effects of parameters such as SVI (Sludge Volume Index), storage time, initial concentration and wet density of excess sludge were examined. The results showed that the more SVI was low, the more sludge was thickened. As storage time goes by, SVI was increased and thickening performance was deteriorated. In order to improve flotation performance at high concentration, high recycling ratio and pressure did not increase the concentration due to thickening limitation. The addition of 0.8 g/L of loess was increased flotation efficiency of 1.41 times.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.392-397
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• 2009

Gravity pressure vessels find their use in the wet oxidation of sewage sludge, which can be defined as the oxidation of organic and inorganic substances in an aqueous solution or suspension by means of oxygen or air at elevated pressures and temperatures. Numerical analyses were carried out for investigating the flow characteristics and wet air oxidation in the reaction vessel with various conditions such as supply oxidation and the supply positions of oxidation, etc. Wet air oxidation is promoted in the vicinity of bottom in the reactor with increase of oxygen supply. Also, it is the best condition to the oxidation supply position of 150 m and oxidation flow of 0.06 kg/s in the GPV reactor as the remnant of sludge and creation of organic acids.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.42 no.5
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• pp.47-53
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• 2010

It is important to utilize the citrus sludge in terms of the reuse of waste materials in the manufacture of corrugated medium. Especially, the mandarin industry occupies the first place in Jeju province. In this paper, the application of citrus sludge mixed with KOCC recycled fibers into the manufacture of corrugated medium was studied. The citrus sludge was acidic in pH value. Also, the constituents of citrus sludge contain some short fibers, fines, and mucus which contain flavonoids, pectins and so on. In papermaking application, these components cause some troubles like foams, bad smell, fouling on the paper machine, and bad drainage and web breaks of wet web. The strength properties of handsheets prepared from KOCC and citrus sludge was decreased, compare to handsheets made of only KOCC. To compensate the problems on strength properties, some kinds of additives were tried to apply into papermaking wet-end system in laboratory scale. As a result, mixing conditions of alum, starch and anionic additives showed the best options in the recovery of strength properties and formations of corrugated medium.

• Journal of the Korea Organic Resources Recycling Association
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• v.27 no.2
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• pp.13-18
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• 2019

Sewage sludge treatment is increasing every year due to improvement of living and urbanization. However, interest in anaerobic digestion which is one of the recycling technology. There is anaerobic digestion of increasing due to limitations of ocean dumping and final disposal. But, the limit of anaerobic digestion efficiency due to the advanced treatment of sewage has been limited, and studies for solubilization technology have been actively conducted. Therefore, in this study, we aimed to investigate the variation of generation of scum and the solubilization efficiency in the application of pre-treatment of ozone reaction and the change of properties of digested sludge with wet milling. There are results of VS/TS increased by 4.4% and $SCOD_{cr}/TCOD_{cr}$ increased by 9.4% by wet milling alone. In addition, the increase of the specific surface area due to which the reduction of the particle size of the solid content of the sludge in the ozone reaction caused by wet milling decreased the generation rate of scum at 14.3% and increased VS/TS at 2.1%, compared with the ozone reaction alone. From these results, it is expected that the application of wet milling can be increased the contact efficiency with solids in the sludge during ozone reaction with suppress scum and increase the efficiency of the subsequent process in anaerobic digestion.

• Resources Recycling
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• v.3 no.3
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• pp.32-49
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• 1994

Hydration process is one of the basic carbonation system. Limestone sludge produced in Pohang Iron & Steel Co., Ltd. We tested for identify of hydration characteristics. The result obtained in this study can be summarized as follows; 1. The classify of limestone sludge is type of ground calcium carbonate(-3mm+325mesh)and the major mineral of calcite, and further more high grade(CaO 51%), fine powder(15~22$\mu\textrm{m}$). 2. Limestone sludge mixed two process sludge, first one is washing process sludge and the other one is wet collect kiln dust. The composition rate is about 8:2. Wet collect kiln dust is major mineral of calcite, too. But the sludge is assumed to one by quick lime, slaked lime and unreacted natural limestone. So, the ideal process is dividing of the washing process sludge and wet collect kiln dust. 3. We manufactured of slaked lime from limestone sludge. To investigate the effect of hydration reactor, the experiments was done with various reactor type as magnetic stirrer, shaking incubator and ultrasonic vibration reactor, respectively. Generally, ultrasonic vibration reactor is excellent hydration for limestone sludge and produced very fine slaked lime powder with ideal distribution. 4. The optimum condition is 10% pulp density, when the manufacture of fine slaked lime powder by ultrasonic vibration reactor. And hydration times to compare the results of the study with ultrasonic vibration reactor of generalized most short time(5~10 min). 5. Finally, the dispersive characteristics of slaked lime powder measured 1~5 $\mu\textrm{m}$ from limestone sludge were compared with those of natural limestone ones(10~20$\mu\textrm{m}$), in order to check applicability of slaked lime with hydration process from limestone sludge.

• Korean Chemical Engineering Research
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• v.58 no.3
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• pp.474-479
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• 2020

The etching solution for slimming of glass substrates was manufactured and HF was used as the main ingredient of wet etching solutions. Various types of strong acids such as HCl, HNO₃, H₂SO₄, amino acids and carboxylic acids such as citric acid, and etched solutions, respectively, were used to measure the etching rates and changes in surface shape of the glass. Regardless of the type of strong acids, the etching rate of the glass increased linearly as the added amount increased, and the sludge removal effect of the glass surface was also shown. The etching solution containing HCl showed more efficient results than other strong acids in the etching rate and the effect of removing sludge. The addition of carboxylic acid did not significantly affect the variation of etching rate, but had the effect of removing sludge. However, if amino acids were added, changes in etching rate and sludge removal were not significant.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.2
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• pp.131-143
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• 2018

Phosphorus (P) is a limited, essential, and irreplaceable nutrient for the biological activity of all the living organisms. Sewage sludge ash (SSA) is one of the most important secondary P resources due to its high P content. The SSA has been intensively investigated to recover P by wet chemicals (acid or alkali). Even though $H_2SO_4$ was mainly used to extract P because of its low cost and accessibility, the formation of $CaSO_4$ (gypsum) hinders its use. Heavy metals in the SSA also cause a significant problem in P recovery since fertilizer needs to meet government standards for human health. Therefore, P recovery process with selective heavy metal removal needs to be developed. In this paper some of the most advanced P recovery processes have been introduced and discussed their technical characteristics. The results showed that further research is needed to identify the chemical mechanisms of P transformation in the recovery process and to increase P recovery efficiency and the yields.