• 한국연소학회지
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• 제18권2호
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• pp.17-22
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• 2013

In this study, we tested the absorption of $CO_2$ in combustion gas into an alkaline wastewater to simultaneously control $CO_2$ and wastewater. During the experiment, we investigated the effects of operating parameters on neutralization characteristics of the wastewater by using $CO_2$ in a bench-scale semi-batch jet loop reactor (0.1 m diameter and 1.0 m in height). The operating parameters investigated in the study are gas flow rate of 1.0-2.0 L/min, liquid recirculation flow rate of 4-32 L/min, and liquid temperature of $20-25^{\circ}C$. It was shown that the initial pH of wastewater rapidly decreased with increased gas flow rate for a given liquid recirculation flow rate. This was due to the increase in the gas holdup and the interfacial area at higher gas flow rate in the reactor. At constant gas flow rate, the time required to neutralize the wastewater initial pH of 10.1 decreased with liquid recirculation flow rate ($Q_L$), reached a minimum value in the range of $Q_L$ = 16-24 L/min, and then increased with further increase in $Q_L$. Further, the time required to neutralize the wastewater was shortened at higher temperatures.

• 한국연소학회지
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• 제18권3호
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• pp.38-43
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• 2013

In this study, we tested the absorption of $CO_2$ in combustion gas into an alkaline wastewater to simultaneously control $CO_2$ and wastewater. During the experiment, we investigated the effects of operating parameters on neutralization characteristics of the wastewater by using $CO_2$ in a bench-scale semi-batch jet loop reactor (0.1 m diameter and 1.0 m in height). The operating parameters investigated in the study are gas flow rate of 1.0-2.0 L/min, liquid recirculation flow rate of 4-32 L/min, and liquid temperature of $20-25^{\circ}C$. It was shown that the initial pH of wastewater rapidly decreased with increased gas flow rate for a given liquid recirculation flow rate. This was due to the increase in the gas holdup and the interfacial area at higher gas flow rate in the reactor. At constant gas flow rate, the time required to neutralize the wastewater initial pH of 10.1 decreased with liquid recirculation flow rate ($Q_L$), reached a minimum value in the range of $Q_L$ = 16-24 L/min, and then increased with further increase in $Q_L$. Further, the time required to neutralize the wastewater was shortened at higher temperatures.

• 상하수도학회지
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• 제17권4호
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• pp.567-573
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• 2003

The pretreatment process was carried out to solubilize the sewage sludge for enhancing its biodegradability using alkaline treatment, ultrasonic treatment(15kHz), ozone treatment and different combination of these three methods: alkaline followed by ultrasonic as well as ozone, and ultrasonic followed by alkaline. The solubilization efficiency was evaluated based on the SCOD/TCOD ratio and VSS/TS ratio. In results, the proper condition of alkaline treatment was shown as 30meq/l of NaOH, pH 12 and 3hours of reaction time. Solubilization efficiency increased to 17% from initial 2% based on SCOD/TCOD ratio under this condition. In ultrasonic treatment, the higher ultrasonic power, the longer treatment time and the lower sludge volume resulted in higher solubilization respectively. There was a rapid increase in solubilization efficiency after 20 minute, then it was measured as 32% of SCOD/TCOD ratio in 1 hour at a ultrasonic power of 1,300W with 1/sludge. Solubilization efficiencies in combined treatment using alkaline and ultrasonic were 47-53% higher than single treatment at a sonicated time of 1 hour. Ozone treatment followed by alkaline treatment also represented the enhanced solubilization compared to ozone treatment. Therefore, ultrasonic or ozone treatment assisted by alkaline could achieve the short treatment time as well as high solubilizetion efficiency.

• Korean Chemical Engineering Research
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• 제54권1호
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• pp.101-107
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• 2016

본 연구에서는 $CO_2$를 이용한 알칼리폐수의 중화처리 시 jet loop reactor의 적용가능성을 검토하고자 하였다. 이를 위해 연속식 jet loop reactor에서 pH=10.1인 알칼리 폐수의 유입유량($Q_{L,in}=0.9{\sim}6.6L/min$)과 유입가스유량($Q_{G,in}=1{\sim}6L/min$)을 변화시키면서 유출수의 pH 변화 및 $CO_2$ 제거특성을 살펴보았다. 중화반응 후 유출수의 pH는 $Q_{L,in}/Q_{G,in}$ 비가 1.1일 때는 $Q_{G,in}$ 및 $Q_{L,in}$이 증가하여도 pH가 7.2 정도로 일정하게 유지되었다. 그러나 $Q_{L,in}/Q_{G,in}$ 비가 1.1 이상에서는 $Q_{L,in}/Q_{G,in}$ 비가 증가할수록 $CO_2$ 제거효율 및 배출수의 pH가 증가하는 경향을 보였다. 본 연구범위에서 얻어진 최대 $CO_2$ 제거효율은 98.06%로 $Q_{G,in}=2L/min$, $Q_{L,in}=4L/min$인 조건이었으며, 이때의 유출수 pH는 8.43 이었다.

• 상하수도학회지
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• 제31권6호
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• pp.577-586
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• 2017

One of the major sources causing eutrophication and algal blooms of lakes or streams is phosphorus which comes from point and nonpoint pollution sources. HAP (hydroxyapatite) crystallization using granular alkaline materials can achieve the decrease of phosphorus load from wastewater treatment plants and nonpoint pollution control facilities. In order to induce HAP crystal formation, continuous supply of calcium and hydroxyl ions is required. In this research, considering HAP crystallization, several types of lime-based granular alkaline materials were prepared, and the elution characteristics of calcium and hydroxyl ions of each were analyzed. Also, column tests were performed to verify phosphorus removal efficiencies of granular alkaline materials. Material_1 (gypsum+cement mixed material) achieved the highest pH values in the column tests consistently, also, Material_2 (gypsum+slag mixed material) and Material_3 (calcined limestone material) achieved over pH 9.0 for 240 hours (10 days) and proved the efficiencies of long-term ion supplier for HAP crystallization. In the column tests using Material_3, considerable pH increase and phosphorus removal were carried out according to each linear velocity and filtration depth. T-P removal efficiencies were 87.0, 84.0, 68.0% and those of PO4-P 100.0, 97.0, 80.0% for linear velocity of 1.0, 2.5, 5.0 m/hr respectively. Based on the column test results, the applicability of phosphorus removal processes for small-scale wastewater treatment plants and nonpoint pollution control facilities was found out.

• 대한환경공학회지
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• 제35권1호
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• pp.10-16
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• 2013

제당폐수를 산 또는 알카리 전 처리한 후 생물학적 수소생산율과 유기산의 생성특성을 평가하였다. 제당 폐수의 수소발생량은 산 전처리된 경우 보다 알칼리 전처리된 시료에서 약 70%의 발생량 증가를 나타내었다. 또한 제당폐수 원액에 적절한 영양염류(질소 인)를 공급하였을 때 보다 양호한 수소생성률을 보여주었다. 제당폐수의 혐기발효에 있어서 탄수화물의 분해와 수소생성의 직접적인 연관성은 나타나지 않았다. Butyric acid/Acetic acid (B/A)비와 수소생산의 연관성을 살펴보았을 때, 영양염류를 첨가한 제당폐수는 순수 제당폐수보다 B/A비가 약 3배 증가하였으며 알카리 전처리와 영양염류를 첨가한 시료에서 B/A비가 4.02로 가장 높게 나타났다. 실험에 사용된 전체 시료에서 B/A비가 클수록 수소생성률이 높았다.

• 한국환경농학회지
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• 제30권2호
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• pp.189-195
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• 2011

BACKGROUND: Wastewaters were collected from 25 sites of two industrial areas of Mymensingh and Gazipur in Bangladesh to assess metallic toxicity of wastewater for irrigation usage. METHODS AND RESULTS: The analyzed wastewaters were slightly alkaline to alkaline in nature and were problematic for irrigation except 3 samples. As per TDS values, 9 samples were rated as fresh water and the rest 16 were classified as brackish water. EC and SAR reflected that all samples were medium salinity (C2), high salinity (C3), very high salinity (C4) and low alkalinity (S1) hazard classes expressed as C2S1, C3S1 and C4S1. Wastewaters of different industries were graded as excellent, good, permissible and doubtful for irrigation purpose as per SSP. According to hardness ($H_T$), wastewater were under moderately hard, hard and very hard classes. Cd, Cr and Cu ions were treated as toxicant for irrigating soils and crops. Zn was problematic for long-term irrigation. The concentrations of Pb, Fe and Na were far below the toxic levels. Synergistic relationships were observed between pH-EC, pH-TDS, EC-TDS, SAR-SSP and SSP-hardness. CONCLUSION(s): If wastewater is applied for irrigation due to the fresh water shortage, it can contaminate soil due to some toxic metal ions.

• 한국염색가공학회지
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• 제10권4호
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• pp.45-52
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• 1998

Reuse of wastewater become an important consideration to solve the environmental pollution problems in recent industriallzation and urbanization. Especially, he characteristic of dyeing process is subject to use much water and thus has serious problems for removal of color and organic pollutants in their wastewater. This report is divided into two main parts ： The purpose of the first part was to determine if alkaline wastewater discharged from textile dyeing operation factory could be flocculated directly by Fenton oxidation method. This study was conducted to investigate Fenton reagent dose and reaction condition of Fenton method as pretreatment for dyeing wastewater in K dyeing industry were investigated. In the second part of this research, to treat dyeing wastewater it was found that the most effective way is to use ultrafiltation and reverse osmosis at the conditions of the pH 7.0~8.0 and operating pressure of $2.5~35kg_f/cm^2$. This paper is mainly dealt with the application on reuse system of dyeing wastewater treatment using ultrafiltration and reverse osmosis membranes. The results showed that dyeing wastewater could be reused by chemical, filter and membrane sequential treatment process.

• 상하수도학회지
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• 제12권3호
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• pp.30-40
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• 1998

Increasing water consumption produced sludge problems of the water treatment plants. The objective of this study is to investigate aluminium coagulants recovery n acidic and alkaline conditions. Water treatment plant sludge produced in Pusan Metropolitan City were tested for the aluminium extraction process. Experiment samples were obtained in summer from water treatment plants of Deoksan and Myongjang. Aluminium coagulants used in these plants during the test period were polyaluminium chloride(PAC), polyaluminium sulfate organic(PSO), polyaluminium sulfate silicate(PASS). Aluminium contents of water treatment sludge were in the range of 7.2~10.9% of the total solids. The recovery percentages for aluminium and iron by acidic extraction method was evaluated to 88% and 42% respectively. Extracted mass variation for other materials such as iron, manganese, total organic carbon was observed during the extraction operation. Alkaline extraction produced more than two times amount of total organic carbon than that in the acidic extraction process.

• 상하수도학회지
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• 제7권1호
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• pp.20-28
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• 1993

The Wastewater from the weight reduction process of polyester is more difficult to be treated biologically than the general wastewater from dyeing and finishing processes in textile industries. Above wastewater shows high pH, high organic strength and wide variation of organic loading. These characteristics are due to TPA and EG resulting from alkaline weight-reduction process and make trouble in the operation of activated sludge process. Therefore, the objective of this study is to develop the pretreatment method for the successful operation of treatment process. For the successful pretreatment process, the wastewater from weight-reduction process should be segregated from other wastewater stream and then acidified with concentrated sulfuric acid to precipitate out TPA from DST solution. At the optimum pH of 2. 2, the initial $COD_{cr}$ 60,000mg/l is reduced to 11,500mg/l and the removal efficiency of $COD_{cr}$ is 81.1%. The required amount of sulfuric acid for pretreatment is not greater than the amount for the the existing neutralization process. Moreover, the supernatant of pretreatment process can be reused in acidification of wastewater.