• Journal of the Korean GEO-environmental Society
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• v.15 no.10
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• pp.15-21
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• 2014

In this study, biochemical methane potential test was conducted to estimate ultimate methane and carbon dioxide yield for anaerobic digestion and pretreatment with sewage sludge cake. Two of 0.2 % TS of sewage sludge cakes were treated with 5M NaOH or sonication of 0.51 W/mL during 30 min respectively. Another sample was treated simultaneously with NaOH and sonication in same condition. Then, initial soluble COD increased from 33.1 mg/L to 494 mg/L. After BMP test, methane production ranged from 3.12 and 84.2 mL $CH_4$ per g of Volatile Solid (VS) and 9.2 and 13.5 mL $CO_2$ per g of Volatile Solid (VS) for carbon dioxide. In other tests, injection of nutrient media or sludge supernatant produced 73.1 and 73.8 mL $CH_4$ per g of Volatile Solid (VS) and 11.2 and 13.6 mL $CO_2$ per g of Volatile Solid (VS) respectively. When BMP test finished, 62 % of initial volatile solids decreased to 33.8~45.4 %. Simultaneous pretreatment increased soluble COD, reduction rate of volatile solids and digestion efficiency than those for alkaline and ultrasonic pretreatment.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.526-531
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• 2000

Application of electrodewatering (EDW) to mechanical dewatering system was studied to decrease water content in the sludge generated from waste water treatment process. Experiments realized the reduction of water content in the sewage sludge. EDW enhancing the conventional filtration by an electric field is an emerging technology with the potential to improve dewatering. In this study, a piston filter press was constructed, the digested sludges were dewatered by EDW under conditions of DC electric field and constant pressure in the piston filter press. Constant electric field from $0{\sim}120\;V/cm$ and constant pressure $98.1{\sim}392.4\;kPa$ were used. The results showed that as electric field was increased the dewatering rates increased and as pressure was increased the dewatering rates decreased. Also as polymer was added the dewatering rates increased. This experiments produced final sludge cake with water content of 60 wt% using EDW, compared with 80 wt% using pressure filtration alone.

• Journal of Korean Society of Water and Wastewater
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• v.20 no.5
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• pp.763-770
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• 2006

The purpose of this study was to investigate the effects of mechanical(ball-mill) solubilization of excess sludge especially focused on the TSS(total suspended solid) reduction during the conventional aerobic digestion of sewage sludges including primary and/or excess sludge, HRT was examined at the 10 days and 20 days. According to the results of this study, TSS removal efficiency of solubilized excess sludge was almost two times higher than that of non-solubilized excess sludge. And as the proportion of the primary sludge increased, TSS removal efficiency became worse because primary sludge rarely contained microbial cells which could be easily solubilized physically. It was also proved that by the application of proper solubilization techniques to the excess sludge, HRT for the aerobic digestion could be lessened(above 50%) dramatically keeping the same or better digestion performance. The fact that between primary and excess sludges, only the excess sludge is quite effective in the sludge solubilization and in it's reduction says that excess sludge releasing sources are key-point in the sludge cake reduction field as a source control.

• Journal of the Korea Organic Resources Recycling Association
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• v.15 no.3
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• pp.106-112
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• 2007

The purpose of this study is to derive the mixing ratio with stable heating value to be used as fuel and secondary fuel by mixing sewage sludge cake, tar, peat moss, and verify the combustion property of produced solid fuel and the applicability of RDF as alternative fuel. Tar shows the highest heating value with 7,000kcal/kg and the heating value of sewage sludge cake and peat moss ranges from 4,000 to 4,500kcal/kg. Also, the solid fuel with length 1.6cm, diameter 1.3cm and weight 2.3g was produced using the heating value of over 6,000kcal/kg and proper mixing ratio (sewage sludge cake: tar: peat moss) from 1 : 4 : 1 to 1 : 7 : 1. Upon the analysis of the RDF applicability of produced solid fuel, the exhaust gas analysis finds that the composition concentration of exhaust gas occurred according to the mixing ratio did not change significantly and the flame lasting time was found to be around 5 minutes, similar to the lasting time of the same mass (2.3g) of general anthracite burned. Therefore, it can be concluded that solid fuel produced in this study can be used as fuel and secondary fuel.

• Korean Chemical Engineering Research
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• v.47 no.2
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• pp.230-236
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• 2009

Sewage sludge cake(SSC) is seriously concerned because ocean dumping, which is the cheapest treatment method now, will be banned in 2012. On the basis of this reason, recycling of SSC is emphasized to convert the treatment method. One of the method to recycling SSC could be carbonization process which also can be reduced greenhouse gas effectively. And carbonization residue of SSC produced by carbonization process can become a renewable energy source. However, carbonization process has not been evaluated by considering basic operating data such as heating value, yield and fuel ratio. In this study, the basic characteristics of SSC such as proximate analysis, elementary analysis and heating value are analyzed. In carbonization process, the effect of carbonization temperature and time on the residue of SSC are estimated. And the analysis is carried out to obtain basic properties of the residue of SSC. From the result of chemical composition of SSC residue, there is 27% of phosphate in SSC. Phosphate will take a role of reductant to convert from hazardous substance to non-hazardous material. As increased carbonization temperature and time, heating value and yield are decreased but fuel ratio(fixed carbon/volatile combustible) of the residue is increased. In the carbonization process, the optimum temperature and time in carbonization test for SSC can be decided by $250^{\circ}C$ and 15 min, respectively. However, the carbonization residue of SSC can not be deserved to use one of renewable energy sources because the heating value at the optimum condition is relatively low. Hence, it is desirable that SSC can be mixed with other organic waste to carbonize.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.443-447
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• 2001

A laboratory-scale electrodewatering system for enhancing conventional filter pressure dewatering by an electric field has been developed to decrease the water content of sludge generated in the wastewater treatment. It consists of a piston-typed filter press, a power supply and data acquisition system. The offset of electrodewatering is investigated as a function of applied pressure, applied voltage, sludge type and filtration time. Also the optimal conditions for maximizing the dewatering efficiency in the eletrodewatering system are investigated. Electric field strength and mechanical pressure are in the range of from 0 to 120 V/cm and from 98.1 to 392.4 kPa. The dewatering rates increased with increasing electric strength. These experiments produced a final sludge cake with water content of 60 wt% using electrodewatering technology, compared with a 80 wt% using pressure filtration alone. The conventional filtration system using the electrodewatering shows the potential to be effective method for improving dewatering Sludge.

• Journal of the Korean Geosynthetics Society
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• v.7 no.2
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• pp.49-52
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• 2008

Most of waste sludge has generally been disposed in landfill site or dumped in the ocean, which will be banned by the content of its heavy metals according to London Dumping Convention in Korea. Therefore, environmentally friend methods are urgently required for the treatment and disposal of the sewage sludge. Thermal hydrolysis is one of the good treatment methods to solve the sludge problems. In this study, the physical and environmental testing was conducted to evaluate the feasibility of by-product cake from the thermal hydrolysis as liner or cover materials in landfill.

• Journal of the Korea Convergence Society
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• v.8 no.2
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• pp.157-162
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• 2017

Inorganic stiffening agents were prepared by mixing paper sludge incineration ash, blast furnace slag fine powder quicklime, anhydrous gypsum and fly ash. The main components of the solidifying agent developed for sludge treatment were SiO, $Al_2O_3$, $TiO_2$, $Fe_2O_3$, $Mn_2O_3$, CaO, MgO, $Na_2O$, $K_2O$, $P_2O$, and $SO_3$. Unlike cement, the developed solidifying agent did not contain $Cr^{6+}$, which is known as a carcinogen. Heavy metals and oil contaminated soil were mixed with solidifying agent and cured for 7 days and the heavy metal content was below the environmental standard. Sewage sludge cake, food waste and solidifying agent were mixed with each other, and after 7 days curing, soil component test showed that the heavy metal content was below the environmental standard. After mixing the sludge, solidifying agent and additive mixture into the beaker, the ammonia concentration was measured to be 0 after 3 days.

• Resources Recycling
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• v.13 no.3
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• pp.12-18
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• 2004

A study on the enhancement of the dewaterability of sewage sludge was carried out by using the sea waste materials as a dewatering aid. It was made from a starfish and a shell by heating at $105∼700 ^{\circ}C$ and centrifuge and belt press were used as a mechanical dewatering process. The moisture content of sludge cake was reduced by 15∼22% (w/w) after addition of the dewatering aid at the dose of 1∼8 g/100mL of digested sludge. CST (capillary suction time) was measured to evaluate the effect of dewatering aid on sludge dewatering properties. CST was reduced after addition of a shell while increased after addition of a starfish. Enhancement of dewaterability after addition of a shell was better than that of a starfish. The heating temperature effect of the dewatering aid on dewaterability was not clear.

• Journal of the Korean Wood Science and Technology
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• v.18 no.1
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• pp.3-9
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• 1990

Expression is on operation of separating liquid from solid liquid mixtures which has long been used on a universal scale in widely divergent fields. In fruit pulps processing and fermentation industries. removal of a portion of the liquid in filler cake is essential to the maximum yields of products. In sewage sludge treatments, dewatering of filter cakes is important to disposal by incineration. transportation. and landfill. In the chemical process industries, drying of wet cakes increases cost, and it is desirable to eliminate as much liquor as possible by non-thermal methods. This paper is mainly concerned with the development of a simplified equation for constant-pressure expression.