• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.30 no.1
• /
• pp.105-114
• /
• 2007

In this paper, we propose sludge collection strategies which allocate each sewage store of village to sewage treatment plants and decide the schedule of sludge collection in order to collect sludge efficiently. The strategies aim to decrease transportation cost with deciding proposed vehicle routing and scheduling the sludge collection. When we decide route of vehicles, we consider the collection time in sewage store of village, distance between sewage store of villages and vehicle information as average velocity of vehicle, operation time of vehicle driver. We also develop the SCMS (Sludge Collection Management System) based on windows system with real data which is used in certain circumstance. And we experiment to figure out vehicle route and transportation cost throughout changing input data.

• Journal of Environmental Science International
• /
• v.15 no.3
• /
• pp.229-236
• /
• 2006

Organophosphorus pesticides (OPPs) contents in the sewage sludge derived from the residential and industrial areas were determined in order to characterize contemporary organic contamination levels as a part of the ongoing development of the environmentally sound sewage sludge management strategy in Korea. OPPs were extracted from freeze-dried sludges in a ultrasonic extractor. The extracts were cleaned-up by florisil column and subsequently fed into gas chromatograph/nitrogen phosphorus detector (GC/NPD) for determining OPP contents. Diazinon, dimethoate, disulfoton, EPN, malathion, methyl parathion, parathion, phorate and sulfotep were present in the appreciable amount in the domestic sewage sludges. The sum of the 9 OPPs in the sewage sludge varied from 534.8 to 15552.1 ${\mu}g/kg$, dry wt..

• Journal of the Korean Society of Combustion
• /
• v.12 no.4
• /
• pp.47-56
• /
• 2007

Utilization of sewage sludge for industrial fuel should be considered in appropriate calory with low emission of environmental pollutants and the amount of sewage sludge for continuously long-time operation. For the low grade fuel(<4,000kcal/kg), one of proper processes is that coal and oil are added into sewage sludge to remove impurities and increase calory(>7,000kcal/kg) and the amount of fuel having sewage sludge. Recently, 2-step agglomeration has been attempted by secondarily agglomerate sewage sludge onto the primary nuclei formed by agglomeration of coal and oil. Furthermore, sawdust and waste oil can substitute about 1/3 each for coal and mineral oil consumed in this process, which will lead to securing alternative energy resources from environmental pollutants as well as cost reduction.

• Ocean Science Journal
• /
• v.40 no.2
• /
• pp.91-100
• /
• 2005

Bioassay using the marine bacteria, Vibrio fischeri and rotifer, Brachionus plicatilis, and chemical analyses were conducted to assess the toxicity of the various sewage sludges, one of the major ocean dumped materials in the Yellow Sea of Korea. Sludge elutriates extracted by filtered seawater were used to estimate the ecotoxicity of the sludge. Chemical characterization included the analyses of organic contents, heavy metals, and persistent organic pollutants in sludge. Bacterial bioluminescent inhibition (15 min), rotifer mortality (24 hr) and rotifer population growth inhibition (48 hr) assay were conducted to estimate the sludge toxicity. EC50 15 min (inhibition concentration of bioluminescence after 15 minutes exposed) values by Microtox(R) bioassay clearly revealed different toxicity levels depending on the sludge sources. Highest toxicity for the bacteria was found with the sludge extract from dyeing waste and followed by industrial waste, livestock waste, and leather processing waste. Clear toxic effects on the bacteria were not found in the sludge extract from filtration bed sludge and rural sewage sludge. Consistent with Microtox(R) results, rotifer neonate mortality and population growth inhibition test also showed highest toxicity in dyeing waste and low in filtration bed and rural sewage sludge. High concentrations of persistent organic pollutants (POPs) and heavy metals were measured in the samples from the industrial wastes, leather processing plant waste sludge, and urban sewage sludge. However, there was no significant correlation between pollutant concentration levels and the toxicity values of the sludge. This suggests that the ecotoxicity in addition to the chemical analyses of various sludge samples must be estimated before release of potential harmful waste in the natural environment as part of an ecological risk assessment.

• Clean Technology
• /
• v.24 no.4
• /
• pp.323-331
• /
• 2018

The results of an experimental investigation on the co-firing characteristics and slagging behavior of dried and hydrothermal carbonization sewage sludge, sub-bituminous coal, and wood pellet in a fluidized bed were presented. Combustion tests were conducted in a lab-scale bubbling fluidized bed system at the uniform fuel-air equivalence ratio, air flow rate, and initial bed temperature to measure bed temperature distribution and combustion gas composition. 4 different fuel blending cases were prepared by mixing sewage sludge fuels with coal and wood pellet with the ratio of 50 : 50 by the heating value. $NO_x$ was mostly NO than $NO_2$ and measured in the range of 400 to 600 ppm in all cases. $SO_2$ was considered to be affected mostly by the sulfur content of the sewage sludge fuels. The cases of hydrothermal carbonization sewage sludge mixture showed slightly less $SO_2$ emission but higher fuel-N conversion than the dried sewage sludge mixing cases. The result of fly ash composition analysis implied that the sewage sludge fuels would increase the possibility of slagging/fouling considering the contents of alkali species, such as Na, K, P. Between the two different sewage sludge fuels, dried sewage sludge fuel was expected to have the more severe impact on slagging/fouling behavior than hydrothermal carbonization sewage sludge fuel.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
• /
• v.10 no.S_2
• /
• pp.73-77
• /
• 2001

The disposal of sewage sludge using landfills and ocean dumping is no longer a viable option due to land scarcity and increasingly stringent environmental control regulations. As such, various efforts have been made to develop new sewage sludge recycling technologies. This work investigates the fundamental physical and chemical characteristics of rural type sewage sludge from Chungnam province in South Korea. The average moisture content, ignition loss, elementary analysis, and average heating value of the sewage sludge samples were examined. The average moisture content of the dewatered sludge was about 80%, while the organic matter was about 50% of the total solid sludge weight. The average heating value of a sewage sludge and petroleum coke waste mixture(1:1 weight ratio) was about 5,000 ㎉/kg, thereby indicating a high potential for energy recycling.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.8 no.4
• /
• pp.61-68
• /
• 2009

This paper presents the numerical analysis of process of sludge drying to know the characteristics of design parameters and develop the new process plant. Finite volume method and $k-{\varepsilon}$ turbulence model were used to analogy the sludge drying furnace. It has been attempted to perform the disposal of sewage sludge such as simple reclaiming and dumping in sea and incineration. Currently, these methods are restricted by national or international government regulations. The drying process is adopted as an effective method for sewage sludge treatment. However sewage sludge makes it difficult to treat with a large volume at the real drying process plant because of its own complicated physical, chemical, and thermal properties. The final design value of moisture content with 10% of the dried sludge can be obtained through the simulated outputs in this study.

• Clean Technology
• /
• v.23 no.3
• /
• pp.331-342
• /
• 2017

To estimate the combustion characteristics of sewage sludge and wood pellet, thermogravimetric analysis (TGA) was conducted. As TGA results, combustion characteristics of sewage sludge was worse than wood pellet. In ash fusion temperature (AFT) analysis, slagging tendency of sewage sludge is very high compared to wood pellet. And also, the bubbling fluidized bed reactor with a inner diameter 400 mm and a height of 4300 mm was used for experimental study of combustion characteristics fueled by sewage sludge and wood pellet. The facility consists of a fluidized bed reactor, preheater, screw feeder, cyclone, ash capture equipment and gas analyzer. The thermal input of sewage sludge cases were $54.5{\sim}96.5kW_{th}$, in case of wood pellet experiment, it was $96.1kW_{th}$. As experiment results, the $NO_x$ emission of sewage sludge was averagely about 10 times the $NO_x$ emission of wood pellet. And also CO emission of sewage sludge is about 3.5 times of wood pellet. Lastly as a result of analysis of captured ash in cyclone, the combustion efficiency of all cases were over 99%, but the potential for slagging/fouling was high at all cases by component analysis of ash.

• Journal of Environmental Science International
• /
• v.14 no.4
• /
• pp.413-425
• /
• 2005

The 16 priority PAHs (Polycyclic Aromatic Hydrocarbons) designated by US Environmental Protection Agency were analyzed for some digested sludges from wastewater treatment plants in Korea. PAHs are an important group of organic contaminants present in sewage sludge due to their persistence and toxic potential. PAHs were extracted from freeze-dried sludges using a methylene chloride-methanol (2:1) mixture in a soxhlet extractor. The extracts were cleaned-up by silica gel/alumina combination column and subsequently fed into gas chromatograph/mass spectrometer (GC/MS) for determining PAH contents. The sum of the 16 PAHs in the sewage sludge varied from 534.8 to $5754.5 {\cal}ug/{\cal}kg$, dry wt.. In the sewage sludge, phenanthrene appears as the most abundant PAHs, followed by naphthalene, pyrene, fluoranthene. Source of the investigated sewage sludges relatively predominated pyrogenic. PAHs levels of sewage sludges in Korea appeared to be lower than those in other countries.

• Journal of Korean Society of Environmental Engineers
• /
• v.30 no.7
• /
• pp.735-742
• /
• 2008

In order to evaluate the levels and distribution patterns, the concentrations of PAHs and chlorophenols were investigated in sludge samples discharged from 6 WWTPs located along Nak-dong river and 7 STPs in Busan, Korea. Levels of 16 PAHs and 19 chlorophenols in sludge samples ranged from 1.28 to 44.9 mg/kg dry wt. and from 213 to 3,850 $\mu$g/kg dry wt., respectively. Levels of PAHs in sludge samples except I5 and S4 were detected lower than those of previous studies. The distribution patterns of PAHs and chlorophenols varied with industrial wastewater sludge samples because industrial wastewater sludge had different industrial input sources. However, the distribution patterns of PAHs and chlorophenols in sewage sludge were pretty similar. Phenanthrene, fluoranthene and pyrene were dominant and the fractions of these 3 PAHs relative to 16 PAHs in sewage sludge ranged from 30.8 to 50.7%. 2-chlorophenol is dominated in most sewage sludge samples and the fraction ranged from 36.0 to 66.8%.