This research was conducted for dewatered sludge cake of industrial wastewater treatment, i.e., as the object of inorganic sludge discharged especially in iron & steel manufacturing shop which used Air drying system to reduce water content. That drying system's single-type cyclone separator was confirmed to have significantly lower separation efficiency on the conditions 20μm and below of particular size through computational fluid dynamics(CFD) analysis. However, we found out the primarily advanced value of separation efficiency on dual-type directly connected. Regarding separation efficiency on size of 10μm, the efficiency of a single-type was presented at 51.91%. On the other side, the efficiency of the dual-type was 97.88%. This advanced effect of the dual cyclone separator was checked at a demo facility of air drying equipment designed by 340m3/min of airflow on site.

반 건조 소화 하수슬러지와 폐플라스틱을 혼합하여 파일롯 규모(85.3kg/hr)의 연속식 저온 (510℃~530℃) 열분해 실험을 하였다. 실험결과 열분해가스 발생량은 투입물 건량의 최대 68.3%, 발열 량은 40.9 MJ/Nm3 이었으며, 연속식 열분해에 따른 외기 유입율이 19.6%이었다. 오일은 투입물 건량 의 4.2%가 발생하였고, 저위발열량은 32.5 MJ/kg 이었으며 시설부식 등을 일으킬 수 있는 황과 염소의 함량이 각각 0.2% 이상이었다. 투입물 건량의 27.5%가 발생한 탄화물의 저위 발열량은 10.2 MJ/kg 이 었고, 용출시험 결과 지정폐기물에 해당하지 않았다. 열분해가스의 연소 배가스는 일산화탄소, 황산화물, 시안화수소 등의 배출농도가 특히 높았고, 다이옥신 (PCDDs/DFs)은 0.034 ng-TEQ/Sm3 로서 법적 기 준치 이내였다. 건조 배가스 응축으로 발생한 폐수는 수질오염물질 47개 항목 중 총질소, n-H 추출물질, 시안 등의 고농도 항목이 많아 전처리 후 하수처리장 등에서의 병합처리 방식을 고려할 필요가 있었다.

The purpose of this study is to produce the auxiliary fuel additives that will improve the heat value and reduce the odor of dried sewage sludge, an auxiliary fuel for power plants using process by-products. Through an odor analysis prior to the production of auxiliary fuel additives, it was confirmed that the main odor materials are Methylmercaptan, Acetaldehyde and Trimethylamine. Based on this, we measured the heating value on various processes by-products such as by-products of thermal power generation and by-products of refinery. In addition, the adsorption performance in the major odor material was evaluated. However, for Trimethylamine, it is very difficult to secure the reproducibility of the concentration of the standard materials as the standard material is liquid. Therefore, it was used Ammonia, which has basic property, to replace Trimethyamine. In the evaluation of various process by-products, the highest heating value in heavy oil fly ash was 5,575 kcal/kg, while in the adsorption performance evaluation, FCC was shown as having the best performance in adsorption, as it could adsorb 100% of Methylmercaptan, 47% of Acetaldehyde and 76% of Ammonia. We conducted an adsorption experiment after supporting a transition metal on the FCC in order to improve the adsorption capacity. As a result, it was confirmed the best efficiency when supporting the copper nitrate 0.5% on the FCC. Based on this result, the experiment was conducted to determine the optimal mixing ratio with a high heating value and odor reducing function using Heavy oil fly ash and FCC. The optimal mixing ratio was 90% of Heavy oil fly ash and 10% of FCC. Furthermore, it was found that the most economical performance and highest odor reducing efficiency was achieved when the mixing ratio was 90% of dried sewage sludge and 10% of auxiliary fuel additives.

The need of reusing sewage sludge is highly increasing as the amount of domestic sewage sludge is growing and sewage management strategies were reinforced. Accordingly, in this research, we studied the composting possibility of sludge in sewage treatment plant J, using dryer facility with indirect system by conducting component analysis of dried sludge and experiment on cultivating crops. It was observed from the component analysis, that the dried sludge is appropriate for both decomposed manure standard of Ministry of Environment and fertilizer standard of Rural Development Administration. Besides, in the experiment on cultivating lettuce, the experimental group(soil + dried sludge) was superior to the control group(soil + bed soil) in apparent condition of leaves tensity and damage by disease and pest. In case of cultivating tomato, the experimental group showed stronger durability of fruits dangling on stems compared to the control group after 9 weeks. Consequently, the excess sludge dried by indirect heating system in the sewage treatment plant J is appropriate for the standard of both Ministry of Environment and Rural Development Administration and show good result in experiment on cultivating crops therefore it can be reused for composting.

Ocean discharge of sewage sludge, which started in the year of 1993 in Korea, was stopped in the beginning of 2012, Landfill of sewage sludge was also prohibited in 2003 owing to public acceptance of the lanfill sites, and partially reopened in 2007 due to the necessity of organic component in sludge to produce methane gas. Sludge recycle ratio will increase in sewage sludge treatment by volume reduction and drying, and then recycle of the thermal energy as fuel in power plant and also material as raw material of cement. Several drying processes are compared with reasoning and an appropriate drying sequence is suggested.

This research is a basic researching process for producing solid fuel that mixing paper sludge and Heat Transfer Medium Oil. Under the presence of Heat Transfer Medium Oil, paper sludge is heated and dried with home appliance microwave for comparing drying efficiency and energy efficiency of different types of drying method. As a result, Heat Transfer Medium Oil and paper mixing case of drying method, OMD, is the most efficient way to shorten the time for evaporating moisture in the paper sludge. In addition, heat transfer effect and density is increased with adding Heat Transfer Medium Oil by microwave. Future more, OMD's energy cost for evaporating whole moisture is 78% cheaper than MD. Also, OMD process shows the best energy efficiency with comparing other process. Evaporation rate of paper sludge evaporation process with microwave is 11.66% increased by adding Heat Transfer Medium Oil 150g. Preheating Heat Transfer Medium Oil or improving different ways injecting Heat Transfer Medium Oil is a good way to increase a rate of initiative moisture evaporation process.

In this study, we evaluated the effect of the type of sewage sludge (digested, non digested) on drying efficiency according to the polymer injection rate. The drying characteristics were shown using a near-infrared ray (NIR) and a microwave. As a result of the drying characteristics with NIR at a polymer dose ratio of 8%, the heating up period is up to 6 minutes after the start of the drying experiment. Afterwards, the constant rate drying period of the digested sludge (A, C and G sites) was 6 minute → 18 minute, showing a rapid decrease in moisture. On the other hand, non digested sludge (B, D, E, F, H, I, J and K sites) showed gradual drying characteristics compared to digested sludge until complete drying (10%). As the polymer dose ratio of 10% and 12%, the heating up period for digested sludge is up to 6 minute after the start of the experiment. Afterwards, the constant rate drying period of the digested sludge was 6 minute → 20 minute, showing a rapid decrease in moisture. On the other hand, the heating up period of non digested sludge was up to 10 minute after the start of the experiment, and the constant rate drying period was 10 minute → 22 minute, which was shorter than digested sludge. As a result of the drying characteristics with microwave at a polymer dose ratio of 8%, 10% and 12%, the constant rate drying period the digested sludge was 4 minute → 20~22 minute, showing a rapid decrease in moisture. On the other hand, non digested sludge of the constant rate drying period was 4 minute → 22~30 minute, which was longer than digested sludge.

This study executed evaluation of drying characteristics based on the polymer injection rate (8%, 10% and 12%) and the drying method[NIF(near-infrared ray). According to this study analyzed VS, VS/TS, and calorific value compared with ‘the auxiliary fuel standard of the thermoelectric power plant and the combined heat & power plant’. The results are as follows. In the case of NIR, the VS was slightly changed at the early stage of the material preheating period and the constant drying rate period with low moisture evaporation. But VS reduction was shown higher as moisture was dried. In the case of non-digested sludge with high VS content, the VS reduction rate by drying was shown lower than that of digested sludge. As the flocculant injection rate increased, the VS loss due th drying was found to be small. Also, the higher the flocculant injection rate was the longer the drying time. Especially, in the case of the NIR drying equipment, as the moisture content of sewage sludge decreased(moisture content 20∼40%), the loss of net VS also showed a tendency to increase sharply. It is shown that the high calorific value according to the drying time of the non-digested sludge was changed from 590 ㎉/㎏ to 3,005 ㎉/㎏ and from 539 ㎉/㎏ to 2,796 ㎉/㎏.

The treatment of sewage sludge using hydrothermal carbonization (HTC) can be an attractive alternative to conventional sludge disposal, but it should be accompanied by a drying process that uses Refuse-derived Fuel (RDF). However, the largest proportion of the energy demand in sludge-drying techniques is for heat sources, which has led to increased operation and maintenance costs. Recovering residual heat to apply to sludge drying significantly reduces both the operating cost and the greenhouse gas emissions. Suitable integration can be realized between drying technology and waste-to-energy (WtE) plants through the recovery of waste heat in WtE conversion as a heat source for sludge drying. This present paper investigates the indirect disk drying performance of the hydrothermal carbonization of sewage sludge using a low-temperature heat source in a laboratory and proposes an integration process with the drying technology of hydrothermal carbonization using waste heat. This paper concludes with experimental results that indirect disk drying technology can be applied in waste-heat recovery systems.

We investigated the effects of leaching concentration (0.1 ~ 1.0 M) and time (1 ~ 120 min) on the phosphorus recovery from ash and dried sewage sludge produced by titanium tetrachloride (TiCl4) flocculation by acidic (H2SO4 and HCl) or alkaline (KOH and NaOH) leaching. The extraction efficiencies of dried sludge were 2.7 ~ 12.6% for H2SO4, 2.5 ~ 10.5% for HCl, 3.6 ~ 9.6% for KOH, and 7.1 ~ 9.9% for NaOH with 1 M, and the maximum efficiency was obtained within 45 min. The maximum %P extracted of sludge ash was 83.1 for H2SO4, 80.2 for HCl, 51.2 for KOH, and 51.2 for NaOH with 1 M, obtained within 45 min. The rate constants (min−1) for the leaching of P from sludge ash were found to be 1.199 for H2SO4, 1.026 for HCl, 0.264 for KOH, and 0.622 for NaOH. The P leaching increased with the increase in leaching concentration, and the maximum leaching for ash was obtained within 0.3 M, regardless of acidic or alkaline leaching. The overall results indicate that the ash of TiCl4 flocculated sewage sludge can be treated with H2SO4 to efficiently recover P.

The amount of sewage sludge emission is gradually increasing every year. However, the Ocean dumping of sewage sludge was prohibited since 2012 by london convention 96 protocol. Therefore, ground disposal method for recycling organic waste or utilizing to energy technology was needed. The heat is generated when sewage sludge has decomposed with the aerobic microbes. In this study, the heat would be applied to dehydrate sewage sludge. The drying efficiency was evaluated according to Air Flow Rate(AFR) and the mixing proportion of the returned sludge. At the experiments used returned sludge Which was dried at 40% moisture content. As a result, the most high temperature was indicated when it mixed 30% and optimal AFR for maintaining aerobic condition was 200 mL/min.kg. During 14days of Biodrying, the highest temperature of reactor was 46℃ and maintained 5~7days are higher than 40℃. and also 18.8% of moisture was eliminated. These results show that using Biodrying to sewage sludge has economic potential compared to hot-air drying and can be one of the method to produce SRF with additional treatment.

The amount of sewage sludge that is emitted is gradually increasing every year. However, since 2012, because of the London Protocol, the oceanic dumping of sewage sludge has been prohibited. Therefore, for recycling organic waste, either the ground disposal method has to be used or technological solutions that develop energy from such waste have to be identified. Heat is generated when the sewage sludge has decomposed by aerobic microbes. In this study, to dehydrate sewage sludge, heat was applied and the drying efficiency was evaluated according to the air flow rate (AFR) and the proportional mixing of the returned sludge. For the experiments, returned sludge that was dried to 40% moisture content was used; consequently, the highest temperature was obtained when the moisture content was 30% and, for maintaining aerobic conditions, the optimal AFR was 200 ml/min·kg. During biodrying for 14 days, the highest temperature of reactor was 46℃, which was maintained at higher than 40℃ for 5-7 days; moreover, 18.8% of moisture was eliminated. These results show that using biodrying for treating sewage sludge has economic potential compared to hot-air drying; moreover, with additional treatment, biodrying can be one of the methods for producing Bio Solid Refuse Fuel (Bio-SRF).

This study was carried out to investigate the economic and environmentally friendly process of drying sludge by combining a mechanical dewatering filter press and thermal dryer. The dryer for 40 kg/hr of dewatered sludge consisted of a main dryer, a heat exchanger, a pre-dryer, and supplementary equipment. During the dewatering process, 100 kg of sludge with 80.11% water content was diluted and mixed with 400 kg of water and ferric chloride solution was added as a sludge conditioner. The average water content of dewatered sludge cake was 60.9% and the energy consumption rate (ECR) for removing water was 226.9 kcal/kg-H2O. Hot flue gas generated from the main dryer was utilized as heating air for the pre-dryer in the heat exchanger. When 36 kg/hr of dewatered sludge cake was dried, the ECR was 1,009 kcal/kg-H2O with 3.96% water content. The combined operation of the dewatering and the thermal drying processes showed that the ECR was reduced sharply to 521 kcal/kg-H2O. The high humidity gas generated from each drying unit in the main dryer was recirculated to the odor decomposition chamber in the main dryer to destroy odor components at a high temperature. The odor concentration of humid gas generated by the pre-dryer was very low due to the relatively low operating temperature.

수도권매립지 하수슬러지 반입비용 상승과 2018년도부터 시행되는 폐기물처분부담금제 도입으로 경제적인 하수슬러지 재활용 방안 모색이 필요하다. 하수슬러지를 생물학적 건조하여 연료로 사용하거나 퇴비화하여 퇴비로 사용하는 방식은 처리 비용이 저렴하다. 본 연구에서는 하수슬러지 생물학적 건조 파일럿 및 실증 실험결과를 분석하였다. 하수슬러지 169 kg(50% 중량비)에 음식물 잔재물 84 kg, 미생물활성유도제 55 kg, 코코피트 27kg를 혼합하여 초기 함수율을 55%로 낮추고 반응 1일 후부터 최소 유량으로 공기를 송풍하였다. 반응 1일 후부터 일 3회 교반을 실시하였다. 혼합물 온도가 반응 1일만에 76℃까지 높게 올라가 반응 4일째까지 50℃ 이상 유지되었다. 혼합물 함수율은 초기 56%에서 반응 4일 후 45% 정도로 10% 정도 감소되었다. 하수슬러지 건조물 반송 실험에서는 건조슬러지(173 kg, 51%)를 하수슬러지(150 kg, 44%), 미생물활성유도제(15 kg, 4%)와 혼합하여 건조하였다. 반응 1일 후부터 지속적으로 공기를 송풍하고 교반하였다. 하수슬러지 혼합물 온도가 반응 1일만에 71℃까지 높게 올라갔으나 반응 2일째 대기온도로 낮아졌다. 이는 공기 송풍량을 높인 결과이다. 혼합물의 함수율은 초기 60%에서 반응 2일 후 약 51% 정도로 10% 정도 감소되었다. 미생물의 분해열을 유지하기 위해서는 적정 송풍량에서 공기 공급이 중요하다. 하수슬러지 10톤(53%)에 미생물활성유도제 2톤, 수피 3톤, 1차 발효퇴비 3.7톤을 포크레인으로 1차 혼합하고 혼합기에서 2차 혼합 후 반응로에 투입하였다. 송풍기 연속가동으로 공기 송풍하고 일 1-2회 포크레인으로 뒤집기를 실시하였다. 혼합슬러지 더미 상부 평균 온도는 반응 2일에 70℃까지 높아졌다. 혼합슬러지 함수율은 2일 후 54%로 높아진 후 7일째 44%까지 낮아졌다. 반송 실험으로 하수슬러지 10.2톤에 반송슬러지 5.5톤, 미생물활성유도제, 수피, 1차발효퇴비를 5.4톤을 포크레인으로 1차 혼합하고 혼합기에서 2차 혼합 후 반응로에 투입하였다. 송풍기를 연속으로 가동하고 일 1-2회 포크레인으로 뒤집기를 실시하였다. 혼합슬러지 더미 상부 온도는 반응 5일째 66℃까지 높아졌고 함수율은 반응 10일째 45%까지 낮아졌다. 혼합슬러지 함수율 저감 효율을 높이기 위해 혼합슬러지 더미 위에서 로터리 교반기로 혼합해주고 발생된 수증기를 외부로 배출하여 수증기 증발효과를 높일 필요가 있다.

하수슬러지의 발생량은 꾸준히 증가하고 있으며, 하수슬러지의 해양투기 금지로 인해 대체 처리 방안들이 요구되고 있다. 다양한 하수 슬러지 처리 방안들 중, 하수 슬러지를 이용한 활성탄의 제조는 슬러지를 폐기가 아닌 재이용하는 방안으로 제기되고 있다. 활성탄은 탄소 성분을 이용하여 제조되므로, 하수 슬러지를 이용하여 활성탄을 제조하는 것도 가능하다. 기존의 대기오염제어설비에서 쉽게 제거되지 않는 원소 수은은 활성탄 흡착을 통해 제거될 수 있다. 본 연구에서는 국내 하수처리장에서 발생한 건조슬러지를 이용하여 다양한 물리적 특성을 지닌 활성탄을 제조하였고, 수은 흡착 능력을 평가하였다. 그리고 다른 원료에서 제조된 활성탄과 수은 흡착 결과를 서로 비교하였다.

다량으로 발생하는 하/폐수 슬러지를 처리하는 방법중 하나는 건조하여 고형연료로 활용하는 것이다. 본 연구에서는 파일럿 규모의 설비를 설계, 제작하여 하/폐수슬러지 탈수 및 건조특성을 연구하였다. 전처리 과정으로 슬러지 함수율을 낮추고 악취를 감소하기 위하여 염화제2철을 투입하여 탈수하였다. 건조공정은 연소실과 건조실이 통합된 최대 처리규모 40[kg/hr]인 일체형 건조기와 건조기에서 배출되는 고온, 고습의 배가스를 외부공기와 열교환하는 열교환기, 열교환기에서 가열된 외부공기를 열원으로 하는 밴드통기형건조기로 구성하였다. 슬러지는 탈수과정에서 함수율이 저감되므로 pin mill을 사용하여 분말화하여 밴드통기형건조기에 투입하였다. 밴드통기형건조기는 4단으로 구성되며 상부로부터 분말 슬러지가 공급되고 열풍은 하부로 공급되는 향류접촉방식이다. 1차 건조된 슬러지는 일체형건조기에 공급된다. 건조기 상부에 가스버너가 설치되어 발생한 열풍은 축열재를 거쳐 하부에 위치한 건조실을 지나 열교환기를 통과한 후 외부로 배출된다. 건조실내에는 4단의 paddle형 건조기가 설치되어 있으며 슬러지는 상부로부터 공급되어 차례대로 건조기를 통과한 후 로타리밸브를 거쳐 외부로 배출되고 건조용공기는 외부공기가 건조실내 pipe를 통과하면서 가열되어 각 건조기에 공급된다. 운전 데이타는 건조기가 열적평형에 도달한 기간중 취득하였다. 함수율 71.5%의 탈수슬러지를 31[kg/hr] x 8.5[hr] 공급시 배출된 건조슬러지는 72.96[kg]이었으며 이때 투입한 에너지는 203,320[Kcal]이었다. 순에너지소비율은 1,104[Kcal/kg-H2O]이었으며 함수율은 5.9%이었다. 함수율이 60.62%인 탈수슬러지를 36[kg/hr] x 4[hr]공급시 배출된 건조슬러지는 48.78[kg]이었으며 이때 투입한 에너지는 86,144[Kcal]이었다. 순에너지소비율은 1,009[Kcal/kg-H2O]이었으며 함수율은 3.96%이었다.

가열한 기름 속에서 비등에 의해 수분이 기화하는 유중증발 건조기술은 에너지 소비량이 약 680 kcal/kg-물로 다른 직･간접 접촉에 의한 건조기술과 비교하여 낮고 건조시간도 10분 정도이다. 그러나 건조물질의 높은 발열량이 건조한 물질에 기름 함유율이 25 % 정도인 것이 단점으로 지적되어 보급에 어려움을 겪고 있다. 한편 중금속이 포함된 산업폐수 슬러지는 건조 후 고형연료로 사용시 중금속 배출로 인한 공해문제를 유발하므로 현재는 친환경적인 처리가 어려운 실정이다. 현재까지 알려진 가장 친환경적인 중금속 함유 폐수슬러지 처리는 용융기술이나 다량의 에너지를 소비해야 한다. 따라서 유중건조 기술과 용융기술을 융합하면 각 기술의 단점이 상호 보완되어 시너지 효과를 극대화 할 수 있다. 하수슬러지, 축분 등은 협기성 소화와 더불어 건조 후 고형연료로 활용할 수 있는 다양한 처리방안이 마련되었으나, 산업폐수슬러지는 발생량이 하수슬러지 보다 많고, 특히 일부 폐수슬러지에는 다량의 중금속이 포함되어 있으나, 육상처리 기술은 하수슬러지와 유사하게 함수율을 줄인 후 매립이 허용되어 장기적으로 토양 및 지하수 오염이 우려된다. 본 연구는 용융로에서 유중증발 건조기술로 건조한 중금속을 함유한 고발열량의 폐수슬러지를 일부 보조연료를 활용하여 1,500 ℃ 정도 고온 열분해 용융로에서 용융 슬래그로 배출하여 유리화함으로써 중금속 성분 용출을 방지하고 폐열은 후단의 보일러에서 회수하여 폐수슬러지 건조용 열원으로 이용할 수 있는 기술이다. 실험결과 용융슬래그의 중금속 용출은 골재기준에 모두 만족하였고 폐열 회수도 효과적으로 할 수 있었다.

The effect of mixed oil on the drying characteristics of sewage sludge in oil vacuum evaporation systems was studied. The experimental results showed that the drying rate with cooking oil was faster than that with refined oil due to the difference of thermal conductivity and composition of mixed oil. However, the heating value of all dried sludge was enhanced and the moisture content was below 1% due to penetration of oil into the microbial cells in sludge during the drying procedure. TGA analysis of sludge mixed with the refined oil, which had a higher volatility, showed the slope of the primary falling period was sharply declined. The result of DTA analysis also showed that the first peak was higher than the second peak and corresponded with the phenomena observed in the TGA analysis. In the DTA analysis, the temperature of the primary peak and the secondary peak of dried sludge were comparatively lower than those of raw sludge. Therefore, mixed oil could decrease the self-ignition temperature in an oil-sludge mixing system. In case of waste cooking oil, the TGA and DTA results showed similar results to those of raw sludge, but the DTA results showed that the secondary peaks of dried sludge were narrower and sharper than those of raw sludge. Overall, mixing oil could be a principal factor in controlling the drying efficiency and thermal properties of sludge-derived fuel in oil vacuum evaporation systems.

하수슬러지의 열풍건조시 하수슬러지의 특성, 고분자 응집제의 종류 및 주입량 등에 의해 발생되는 점성으로 인해 타공판에 부착성이 상당히 증가하여 건조효율을 낮추는 원인이 되고 있다. 이에 본 연구에서는 고분자 응집제로 인한 하수슬러지(생슬러지, 잉여슬러지, 혼합슬러지)의 부착특성을 평가하기 위하여 고분자 응집제 주입량에 따른 점도 변화를 측정하였으며, 또한 하수슬러지의 열풍건조시 부착성을 상당량 감소시킬 수 있도록 기존 타공판을 대체할 수 있는 다양한 타공판 종류별 부착특성을 평가하였다. 하수슬러지의 열풍건조시 기존 타공판(STS 304재질), 전해연마+티타늄코팅 타공판보다 크롬코팅된 타공판의 부착성이 가장 적게 발생되었으며, 또한 생슬러지 단독건조보다 잉여슬러지 단독건조시 부착성이 더 크게 나타났다.