• Journal of Korean Society of Water and Wastewater
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• v.11 no.2
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• pp.50-64
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• 1997

Life cycle assessment (LCA) on total sewage sludge treatment system from thickening to incineration and melting was performed for estimating global environmental impact as $CO_2$. In general, the life cycles of actual treatment facilities consist of construction, operation and dismantlement. In this study, the amount of $CO_2$ produced from both whole and each life cycle step of currently used unit sludge treatment processes were calculated by inventory analysis. In addition, in the all processes investigated in this study, individual $CO_2$ production unit (CPU), i.e. total produced $CO_2$ by treating a unit weight of sludge was also calculated. By using the CPU matrix of the unit processes, it was possible to simulate the $CO_2$ production for any type of complex-system as well as to trace a dominant cause of $CO_2$ production in each process. Four selected alternatives examined here, each involve the same disposal way but differ substantially in the $CO_2$ exhaust.

• Journal of Korean Society on Water Environment
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• v.20 no.4
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• pp.346-351
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• 2004

Because of being produced a great deal of excess sludges from biological wastewater treatment process, the subject regarding treatment and disposal of them has been significantly handled in real plants. It should be considered the alternative treatment with easy operating and cost effective process in rural areas. For the thickening of wasted activated sludge from small scale wastewater treatment facilities, thus, the provisional sludge thickening system was developed by the application of mesh filter module. Three meshes with different pore size(100, 150, $200{\mu}m$) were prepared for filter modules that were used to withdraw effluent from thickening system. A filter module with $100{\mu}m$ mesh was chosen as the most effective thickening material in the viewpoint of volume reduction and effluent quality: the volume reductions of initially injected sludge with 3,600 mg/L and 9,100 mg/L were 95% and 85%, respectively, and the filtered effluents were enough good to be shown below 1.0 mg/L of SS and 1.0 NTU of turbidity. Since the filtration of thickening was influenced by the cake layer formed on mesh filter module and this system was operated in the combination of sludge thickening with gravity settling, the filter modules with smaller pore size and the larger floc size were required for long term operation safely.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.2
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• pp.103-108
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• 2014

Using dried sludge as a secondary fuel of a coal-fired power plant is proposed as an alternative option for sludge disposal. Because elemental contents of sludge are different from those of coal, different levels of acidic gas emissions are expected from the co-combustion of sludge with coal. In this study, sludge samples were obtained from 7 sewage treatment plants in Korea. Each sludge sample was combusted together with coal in a lab-scale combustor, and the concentrations of nitrogen oxides ($NO_x$), sulfur dioxide ($SO_2$), hydrogen chloride (HCl), chlorine ($Cl_2$) in the flue gas were analyzed. Compared to the combustion of coal only, $NO_x$ concentration was slightly higher in the flue gas from the co-combustion of coal and sludge. $SO_2$ emission increased with the combustion of sludge due to the higher content of sulfur in sludge than in coal. For most of the tested samples, the concentrations of HCl and $Cl_2$ were varied depending on the chlorine content in the sludge sample.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.46 no.5
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• pp.9-18
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• 2014

London Convention on the prevention of marine pollution by dumping of wastes and other matter prohibits the deliberate disposal of paper mill sludges at sea. In order to explore the alternative plan on the prohibition of sludge disposal at sea, the biodegradable seedling pot was developed by mixing the sludge with old newspaper (ONP) in appropriate mixing ratios. The C/N ratio of the mixed sludge was below 20, leading to rapid deterioration of the organic matters composing the seedling pot. The increased ONP contents in the seedling pot resulted in the increase of pot thickness and thereafter in the decrease of pot density. Cellulose fibers in ONP promoted water absorption of the pot but AKD addition helped the seedling pot to repel water during raising seedling. Breaking length and burst strength of the seedling pot were improved by addition of wet strength additives but air permeability was a little diminished. Biodegradable rate of the seedling pot in a soil was accelerated by the attack of soil microbes at the beginning, and finally the pot was completely degraded in 150 days in a soil.

• Advances in environmental research
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• v.1 no.1
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• pp.83-96
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• 2012

The water sludge is generated from the treatment of water with alum. Disposing of sludge again to the streams raises the concentrations of aluminum oxides in water, which has been linked to Alzheimer's disease. The use of water treatment plant (WTP) sludge in manufacturing of constructional elements achieves both the economical and environmental benefits. Due to the similar mineralogical composition of clay and WTP sludge, this study investigated the complete substitution of brick clay by sludge incorporated with some of the agricultural and industrial wastes, such as rice husk ash (RHA) and silica fume (SF). Three different series of sludge to SF to RHA proportions by weight were tried, which were (25: 50: 25%), (50: 25: 25%), and (25: 25: 50%), respectively. Each brick series was fired at 900, 1000, 1100, and $1200^{\circ}C$. The physical and mechanical properties of the produced bricks were then determined and evaluated according to Egyptian Standard Specifications (E.S.S.) and compared to control clay-brick. From the obtained results, it was concluded that by operating at the temperature commonly practiced in the brick kiln, a mixture consists of 50% of sludge, 25% of SF, and 25% of RHA was the optimum materials proportions to produce brick from water sludge incorporated with SF and RHA. The produced bricks properties were obviously superior to the 100% clay control-brick and to those available in the Egyptian market.

• Journal of the Korea Concrete Institute
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• v.18 no.2 s.92
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• pp.199-204
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• 2006

Recently, The sludge water of ready mixed concrete has been investigated because of environmental pollution and disposal cost. So, sludge water is partially reused as mixing water. However, if sludge water is reused too much that would influence the qualify of concrete. KS specification limits the amount of sludge content up to 3% of cement weight. In this study, the effect of ready mixed concrete sludge on the characteristics of concrete is compared to raise the reuse ratio of sludge of ready mixed concrete. According to this experiment results, as blending ratio of re-mi-con sludge increases, workability is decreases. However, the sludge of ready mixed concrete water have a positive effect on the strength development. The drying shrinkage and the resistance of freezing and thawing have a minor effect.

• Proceedings of the Korean Environmental Health Society Conference
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• 2005.12a
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• pp.51-53
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• 2005

Disposal of waterwork sludge is important problem in WTP(water treatment plant). Purpose of this study is treated municipal waste water chemically using sludge that is produced in waterwork plant by link to reutilize waterwork sludge. Municipal waste water that use in an experiment used is produced at C university, and is SS 220 mg/L, BOD 145 mg/L, COD 160 mg/L, T-N 52 mg/L and T-P 2.6 mg/L. Used Alum, polymer coagulant and coagulant aid (diatomite, powered activated carbon) as CaO, coagulant as alkaline aid by chemical treatment medicine. In case of does slow speed agitation and stations after pours waterwork sludge in sewage and alkaline aid and coagulant at rapidly mixing the colloidal creation speed is fast and fine colloids concentration was high but settling time is shortened a little and removal rate of pollutant improved by $60{\sim}99%$.

• Journal of the Korea Organic Resources Recycling Association
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• v.9 no.2
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• pp.71-76
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• 2001

Recently, sludge disposal becomes one of the most serious environmental problems. Because the landfilling and ocean dumping of sludge materials will be prohibited in the near future, the proper treatment?disposal methods should be investigated. Also, oyster shells, piled at the coast, cause adverse effects in coastal fishery, public water surface, natural landscape, public health and so on. Thus, the purpose of this study is to evaluate the dissolution characteristic of metal compounds during soil application experiment using sewage treatment sludge mixed with oyster shells. The dissolution experiment conducted 100days under artificial rainfall and farming soil, mixed with sewage treatment sludge and oyster shells, was put into the pots(approx. 0.5L). The results from dissolution experiment as follows. 1. K, Na was $5{\sim}20mg/{\ell}$, and Ca was less than $90mg/{\ell}$. 2. Heavy metals such as Cd, Cu, As, Pb, Cr, Hg are dissoluted far less than the soil pollution guideline. The application of sewage sludge mixed with oyster shells increases pH(soil acidity)and buffer capacity(CEC) of farming soil, and heavy metals are thought to be attached to soil as insoluble forms.

• Korean Chemical Engineering Research
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• v.54 no.2
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• pp.248-254
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• 2016

Efficacious wastewater treatment is essential for increasing sewage sludge volume and implementing strict environmental regulations. The operation cost of sludge treatment amounts up to 50% of the total costs for wastewater treatment plants, therefore, an economical sludge destruction method is crucially needed. Amid several destruction methods, wet air oxidation (WAO) can efficiently treat wastewater containing organic pollutants. It can be used not only for sludge destruction but also for useful by-product production. Volatile fatty acids (VFAs), one of many byproducts, is considered to be an important precursor of biofuel and chemical materials. Its high reaction condition has instituted the study of gravity pressure reactor (GPR) for an economical process of WAO to reduce operation cost. Simulation of subcritical condition was conducted using Aspen Plus with predictive Soave-Redlich-Kwong (PSRK) equation of state. Conjointly, simulation analysis for GPR depth, oxidizer type, sludge flow rate and oxidizer injection position was carried out. At GPR depth of 1000m and flow rate of 2 ton/h, the conversion and yield of VFAs were 92.02% and 0.17g/g, respectively.

• Proceedings of the Korean Environmental Health Society Conference
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• 2005.06a
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• pp.406-409
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• 2005

Since 2003, Korean government has restricted landfill application of organic waste, which shares approximately 56% of total waste sludge from municipal and industrial wastewater treatment plants. In addition, enforcement of the ocean disposal prohibition law is effective from 2005. Organic sludge was composted for the purpose of converting to organic fertilizer. After moisture content was regulated with bulking agents aerobic treatment performed. When composting was conducted, commercial and activated microbe materials, identified from soil were seeded in sewage sludge. Carbon dioxide production was increased sharply after 24 hours. Temperature and pH of compost reached to $66.2^{\circ}C$ and 8. Heavy metals were lower than their regulatory limits, which enable it to utilize as organic fertilizer.