• 한국환경과학회지
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• 제19권3호
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• pp.323-329
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• 2010

To acquire preliminary data for the control of total nitrogen (TN) in S sewage treatment plant, which processes merging food waste and sewage, the effect of reject water on the total nitrogen in the effluent was examined in this study. Water quality data for the plant during the winter period were applied to calculate the mass balance. It was calculated that at least more than 231 kg/d TN should be removed to control the TN concentration in the effluent. Assuming 18 ppm as the goal TN concentration in the effluent, about 941 kg/d TN should be removed from this plant. Approximately 10% more TN should be removed than at present to achieve this result. It was observed that dewatering the filtrate had a considerably greater effect on the total nitrogen in the effluent than the reject waters. The dewatered filtrate contained 1,399kg/d TN. The contribution of the dewatered filtrate to the TN concentration in the effluent was 0.183, which was 7 to 23 times greater than the other reject waters. In addition, the amount of total nitrogen from the reject water, with the exception of the dewatering filtrate, was lower than the amount of TN that should be removed from S sewage treatment plant. Therefore, it was concluded that one of the most effective methods for controlling the TN concentration in effluent was the removal of the TN contained in the dewatering filtrate.

• 한국물환경학회지
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• 제27권6호
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• pp.769-775
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• 2011

An experimental study of biofilm nitritation system for high-strength ammonium wastewater has been carried out to examine the temperature effect on different organic and solid concentration. Operating temperature varied from $35^{\circ}C$ to $15^{\circ}C$. The influent N concentration of identical three reactors was adjusted to about $300mg\;NH_4-N/L$. A control unit fed with a synthetic wastewater, while the others were fed with reject water which is consisted of the supernatant of both digester and thickener. The results indicated that nitrite accumulation was stable in temperature range of $35^{\circ}C$ to $25^{\circ}C$. However, nitritation was significantly reduced at below $20^{\circ}C$. Free ammonia (FA) and free nitrous acid (FNA) were major inhibitors to the nitrite oxidizer for nitrite accumulation in lower temperature. From the estimation of temperature coefficient (${\Theta}$) of biofilm and suspended nitritation system, biofilm nitritation system could absorb the negative temperature effect compared with suspended nitritation system.

• 한국결정성장학회지
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• 제22권3호
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• pp.152-157
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• 2012

본 연구는 알칼리 활성화제로 NaOH와 물유리를 사용하고 리젝트애쉬와 고로슬래그를 혼합하여 지오폴리머를 제조하였다. 리젝트애쉬와 고로슬래그의 치환율과 물유리와 NaOH의 농도에 따른 압축강도를 측정하였다. 압축강도 측정결과로는 알칼리 활성화제로 NaOH 1 wt%, 물유리 3 wt%와 전량 고로슬래그를 사용한 경우 재령 28일차 강도가 38.91 MPa의 성능을 나타내었다. 압축강도 증진의 중요한 요인은 알칼리 활성화제의 비율과 리젝트애쉬와 고로슬래그의 치환율에 의한 것이었다.

• Korean Chemical Engineering Research
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• 제55권6호
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• pp.822-829
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• 2017

하수처리장에서의 총 인 저감을 위한 방안으로 완속교반/침전 섬유여과시스템을 적용하여 하수 방류수와 반류수를 제어하는 방법에 대해 비교 검토하였다. 물질수지를 통해 인의 최종 농도를 강화된 기준치인 0.2 mg/L로 낮추기 위해서는 약 92.4 kg T-P/day를 제거해야 되는 것으로 분석되었으며, 이를 위한 총 인 제거효율은 하수 방류수는 96%, 반류수(탈수여액)은 69.2% 이상이 되어야 한다. 총 인 제거 목표치를 달성하기 위한 시스템 운영비용을 검토하였으며, 하수방류수를 처리하는 것보다 유량은 적으나 고농도의 인을 함유한 반류수를 처리하는 것이 약품비용은 약 1/2.4, 전력비용은 약 1/120 정도로 절감되는 것으로 나타났다. 한편 반류수 처리를 위해 개발시스템인 완속교반/침전 섬유여과시스템과 일반적인 응집침전시스템을 적용하는 경우에 대한 경제성을 검토하였으며, 완속교반/침전 섬유여과시스템이 일반적인 응집침전시스템에 비해 설치면적이 약 1/7로 작고 약품소요량 및 전력비를 포함한 연간운전비용은 약 1/1.7 소요되어 개발시스템이 보다 경제성이 있는 것으로 평가되었다.

• 한국결정성장학회지
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• 제23권4호
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• pp.201-206
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• 2013

화력발전소에서 배출되는 석탄 바닥재 및 잔사회는 재활용이 힘든 폐자원이어서 주로 매립 처분되고 있다. 본 연구에서는 국내 화력발전소에서 배출된 석탄 잔사회, 바닥재 그리고 준설토를 혼합하여 인공골재를 제조하고, 실험인자가 골재의 발포거동 및 물성에 미치는 영향을 분석하였다. 특히 미연탄소가 많이 포함되어 있는 잔사회에 대하여 하소 처리를 한 뒤, 인위적으로 활성탄소를 첨가함으로서 하소유무 및 활성탄소 첨가량이 인공골재의 발포특성에 미치는 영향을 조사하였다. 이를 위해 인공골재의 부피비중 및 흡수율 값을 시편의 미세구조 관찰 결과와 연계하여 고찰함으로서, 잔사회의 재활용율 제고에 일조하고자 하였다.

• 한국결정성장학회지
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• 제20권4호
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• pp.185-191
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• 2010

잔사회와 준설토를 효과적으로 자원화하기 위하여 8~10 mm 크기의 구형 인공 골재를 성형하였다. 출발원료는 입도 및 조성을 변화시켰으며 $1050{\sim}1250^{\circ}C$ 범위에서 소결하였다. 제조된 골제는 KS에 의거하여 골재의 밀도와 흡수율 시험을 진행하였다. 잔사회와 준설토는 고온에서 철 함유 물질과 알칼리/알칼리토 산화물에 의한 발포 기구가 적용됨을 예측할 수 있었다.

• 한국물환경학회지
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• 제23권5호
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• pp.636-641
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• 2007

A pilot-scale biofilm nitiritation reactor was operated with the reject water from a large wastewater treatment plant. The effects of various operating parameters including pH, temperature, dissolved oxygen, solids and organic concentrations were examined. A stable nitritation was achieved at operating pH range of 7.3 to 8.8 with an alkalinity addition. Higher operating temperature of $35{\pm}0.7^{\circ}C$ achieved more stable nitritation compared to $30{\pm}0.2^{\circ}C$. It has been noticed that nitrite accumulation maintained with DO, solids and organic concentrations range of 0.8 to 3.9 mg/L, 3,400 to 11,000 mg/L, and 86 to 572 mg/L, respectively. It seems that the accumulation of nitrite was caused by both the inhibition of $NO_2{^-}$ oxidizers due to free ammonia and the maintenance of the high operating temperature of $35^{\circ}C$ which promote to accumulate the $NH_4{^+}$ oxidizers in the reactor. According to microbial community analysis of fluorescence in situ hybridization and INT-Dehydrogenase measurements, more nitrifiers were presented in attached form compared to suspended growth.

• 한국건설순환자원학회논문집
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• 제7권1호
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• pp.44-49
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• 2019

본 연구는 서로 다른 입도의 단일골재 및 반대 입도의 골재를 혼합한 혼합골재에 리젝트애시(Reject ash=Rj)의 치환율 변화에 따른 콘크리트의 기초적 특성을 분석함으로써 골재 제조공장에서 프리믹스하여 1개의 골재로 납품하는 혼합골재 시스템의 가능성을 분석하였다. 실험연구결과 입도규정의 경우는 혼합골재(CSb+SS)에 Rj를 5% 정도 치환할 경우 입도규정을 만족하는 것으로 나타났다. 유동성인 슬럼프 및 슬럼프 플로와 공기량의 경우에는 Rj의 치환율 증가에 따라 감소하는 것으로 나타났으나, 압축강도의 경우에는 Rj의 치환율이 증가함에 따라 증가하는 것이 확인되었다. 따라서 매립 처분되는 Rj를 5% 정도 혼합골재에 프리믹스하여 활용하면서 감수제 및 AE제 등으로 적정 유동성 및 공기량은 확보하여 준다면 압축강도 증진 등 품질향상에 크게 기여할 것으로 분석되었다.

• Membrane and Water Treatment
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• 제10권4호
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• pp.265-275
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• 2019

This study aimed to develop a compact partial nitritation step by forming granules with high Ammonia-Oxidizing Bacteria (AOB) fraction using the Air-lift Granulation Reactor (AGR) and to evaluate the feasibility of treating reject water with high ammonium content by combination with the Anammox process. The partial nitritation using AGR was achieved at high nitrogen loading rate ($2.25{\pm}0.05kg\;N\;m-3\;d^{-1}$). The important factors for successful partial nitritation at high nitrogen loading rate were relatively high pH (7.5~8), resulting in high free ammonia concentration ($1{\sim}10mg\;FA\;L^{-1}$) and highly enriched AOB granules accounting for 25% of the total bacteria population in the reactor. After the establishment of stable partial nitritation, an effluent $NO_2{^-}-N/NH_4{^+}-N$ ratio of $1.2{\pm}0.05$ was achieved, which was then fed into the Anammox reactor. A high nitrogen removal rate of $2.0k\; N\;m^{-3}\;d^{-1}$ was successfully achieved in the Anammox reactor. By controlling the nitrogen loading rate at the partial nitritation using AGR, the influent concentration ratio ($NO_2{^-}-N/NH_4{^+}-N=1.2{\pm}0.05$) required for the Anammox was controlled, thereby minimizing the inhibition effect of residual nitrite.

• 한국세라믹학회지
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• 제49권2호
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• pp.161-166
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• 2012

The temperature-rasing sintering method was used in this study to fabricate the aggregates of uniform pore size and distribution containing reject ash occurred in the thermal power plant. The spheric green aggregates made of reject ash were put into the box furnace of 800~$1000^{\circ}C$, heated with a heating rate of 5~$15^{\circ}C$/min to 1200~$1275^{\circ}C$, sintered for 10 min and then discharged out of the furnace to the room temperature. The input temperature, heating rate and sintering temperature increased the bloating phenomenon of the specimen, and the sintering temperature among them was the most effective factor. The aggregate manufactured at $1275^{\circ}C$ had the specific gravity of about 1.0 and water absorption of 1~2%, and the pores of 500~1,000 ${\mu}m$ were uniformly distributed across the whole specimen. Especially, the aggregates fabricated using the temperature-rasing sintering method in this study showed an excellent bloating properties and uniform microstructure without black core phenomenon which is typical for the bloated ceramics synthesized by direct sintering method.