보고서 정보
주관연구기관 |
(주)포스코건설 |
연구책임자 |
김윤중
|
참여연구자 |
남해욱
,
김관엽
,
이승용
,
이은수
,
곽동근
,
이연지
,
김현순
,
박길서
|
보고서유형 | 최종보고서 |
발행국가 | 대한민국 |
언어 |
한국어
|
발행년월 | 2018-11 |
과제시작연도 |
2017 |
주관부처 |
환경부 Ministry of Environment |
등록번호 |
TRKO201900003584 |
과제고유번호 |
1485014856 |
사업명 |
환경산업선진화기술개발사업 |
DB 구축일자 |
2019-07-13
|
키워드 |
제철부산물.밀 스케일.마그네타이트.인 흡착.인 회수.Ironworks Byproduct.Mill Scale.Magnetite.Phosphate Adsorption.Phosphate Recovery.
|
DOI |
https://doi.org/10.23000/TRKO201900003584 |
초록
▼
□ 개발 목적 및 필요성
A. 필요성 및 배경
- 하수처리 기술의 일반화로 사업 수주경쟁 치열
- 4대강사업 등으로 인한 방류수내 인(P) 기준 엄격화 추세
- 저농도 방류수질 보장 고효율 인 제거기술 필요성 대두
- 기존 기술의 운영비 유지관리비 증가에 따른 한계
- MBR 맞춤형 후속 3차처리 공정의 필요성 증대
B. 개발 목적
- 약품슬러지 등 부산물의 발생을 최소화한 인제거공정 개발
- 저농도 방류수 인농도 보장 공정 필요
- 친환경 저비용 총인처리공정 개발
□ 개발 목적 및 필요성
A. 필요성 및 배경
- 하수처리 기술의 일반화로 사업 수주경쟁 치열
- 4대강사업 등으로 인한 방류수내 인(P) 기준 엄격화 추세
- 저농도 방류수질 보장 고효율 인 제거기술 필요성 대두
- 기존 기술의 운영비 유지관리비 증가에 따른 한계
- MBR 맞춤형 후속 3차처리 공정의 필요성 증대
B. 개발 목적
- 약품슬러지 등 부산물의 발생을 최소화한 인제거공정 개발
- 저농도 방류수 인농도 보장 공정 필요
- 친환경 저비용 총인처리공정 개발
- 유한자원인 인의 회수 및 재활용 가능 공정
C. 기술개발 목표
- 산화철에서 고순도 마그네타이트(Fe3O4) 정제기술 개발
- 마그네타이트를 활용한 하수처리장 내 인(P) 제거기술 및 공정 개발
- 마그네타이트 재활용 기술개발 (흡착된 인(P) 제거 및 비료화 기술)
□ 성능사양 및 기술개발 수준
- 흡착제 인 흡착능 : 10 mg-P/mg-magnetite 이상
- 흡착제 인 탈착능 : 10회 이상
- 인제거공정 수질수준 : Pack-bed type 0.1 mg-P/L 이하
Continous type 0.2 mg-P/L 이하
□ 활용계획
- 참여기업 기술이전을 통한 상용 마그네타이트 생산 사업 추진
- 주관기관 기술실시를 이용한 턴키 및 민자 하수처리장사업 적용을 통한 수주 경쟁력 강화 및 운영현장 운영비 절감
- 해외사업 추진시 특화공정으로 기술력 홍보 및 기술 활용성 증대
(출처 : 요약서 3p)
Abstract
▼
Ⅳ. Results
Experimental data showed that the phosphate removal capacity of magnetite at the equilibrium increases with the increasing initial phosphate concentration but the percent removal decreases with the increase in initial concentration of phosphate from 81% for 5 mg/L of phosphate to 12% f
Ⅳ. Results
Experimental data showed that the phosphate removal capacity of magnetite at the equilibrium increases with the increasing initial phosphate concentration but the percent removal decreases with the increase in initial concentration of phosphate from 81% for 5 mg/L of phosphate to 12% for 100 mg/L of phosphate. Principally, the percentage of phosphate removal increased quickly in initial contact phase and then, followed steady state before achieving a saturation value.
The adsorption isotherm of phosphate onto magnetite was described according to Langmuir and Freundlich isotherm model. Equilibrium data for phosphate adsorption on magnetite was applied to Freundlich and Langmuir equations. The constraints for the Langmuir and Freundlich isotherms were determined based on the data from present experimental setup, with the Langmuir fitting the data better than the Freundlich. This denotes that phosphate adsorption onto the magnetite is more like a monolayer adsorption phenomena with heterogeneous distribution. Virtually, 11.78 mg of phosphate was adsorbed onto 1g magnetite (synthesized by reverse coprecipitation) that is almost equal to the theoretical value of 11.70mgP/g, as evaluated with Langmuir isotherm model. Adsorption capacity of magnetite particles significantly depends on the initial phosphate concentration. The possible phosphate adsorption mechanism can be defined by taking in account the ligand exchange mechanism and electrostatic attraction between the ions. During ion exchange mechanism,the phosphate ions in the solution and the hydroxyl ions available at the positively charged surface of magnetite replace each other. Hence, the hydroxyl ion concentration at the adsorbent surface can play a significant role to either enhance or lessen the electrostatic properties of magnetite.
Followed by adsorption, different complex formations are reported in literature that are inner-sphere complexes with mononuclear, binuclear or monodentate and bidentate complexes.
Kinetics of the phosphate ions adsorption onto magnetite indicated that prompt adsorption was happened in the beginning of experiment and later, system attained an equilibrium state. A speedy adsorption at early stages of experiment seems to be a result of electrostatic attraction, attributed to a higher moving velocity of phosphate towards the magnetite surface. It seems that in early stages of experiment, phosphate ions covered all the vacant locations for adsorption and then started to diffuse through the inner apertures of the magnetite. The rate of diffusion immensely depends on the concentration of phosphate in the solution. As the phosphate concentration decreases in the solution, the rate of diffusion also decreases,finally, no further diffusion occurs, and hence, system attains the state of equilibrium. Phosphate favored different complex formations based on the surface coverage conditions. At low and high surface conditions, it forms monodentate and bidentate mononuclear complex, respectively. The monodentate complex forms faster than bidentate complex and in long-term adsorption, monodentate complex can also convert into bidentate complex.
Several adsorption experiments were carried out at different pH (3-12) to investigate the effect of pH on phosphate removal efficiency of magnetite.
Meanwhile, the ionic strength of the phosphate solution is also changed.
The higher phosphate removal efficiency of magnetite was achieved in acidic environment. As the pH was shifted toward basic side, significant decline in phosphate removal was observed. It seems that in the highly basic environment, net surface charge on magnetite remains negative and possesses repulsion for approaching phosphate ions. The surface charge of iron oxides is highly pH dependent and hence, any change in pH can alter the surface conditions for adsorption. Different molar concentrations of NaCl (0.01, 0.1 and 1M) were introduced into the phosphate solutions to increase the ionic strength of the solution, and the adsorption was carried out. It was observed that any change in ionic strength did not make any variation in phosphate removal efficiency of magnetite.
Coexisting anions such as chloride, sulfate, and carbonate are generally present in wastewater. Through competitive adsorption, these anions could interfere with the uptake of phosphate. Thus, the effect of coexisting anions on phosphate adsorption onto the mill scale- derived magnetite particles was investigated. Sulfate, chloride, and carbonate did not inhibit phosphate adsorption even though they coexisted at very high concentration, suggesting that these anions had a low affinity toward the synthesized adsorbent.
Desorption of phosphate anion from mill scale-derived magnetite particles was carried out using 0.1 N NaOH. The desorption process occurred by ionization and replacement of phosphate anion by OH? ion on the adsorbent's surface. The reusability of the adsorbent was tested in five adsorption-desorption cycles. A slight decrease in phosphate adsorption after each successive cycle was observed. The adsorption capacity of the synthesized magnetite decreases from 88 to 86% after five adsorption-desorption cycles. Moreover, the adsorption capacity of the mill scale-derived magnetite particles is expected to decrease by 20% after 10 rounds of regeneration.
For the particles synthesized with reverse coprecipitation, the reactors were operated at pH 6.5 and 2mg/L phosphate concentration. Both column reactors (with upward flow direction and with downward flow direction) were appeared finely to remove all phosphate concentration from feed water for over 150L treated volume. Considering the minimum 0.2mg/L concentration in effluent, breakthrough was observed after 48 days of effective operation in column fed from bottom to top. However, the break through curve was appeared after 65 days operation of column fed from top to bottom. Around 96% of phosphate concentration was removed by a column reactor fed from bottom to top while 97% of loaded amount of phosphate was adsorbed into the column fed from top to bottom. SBR reactor indicated the stable phosphate removal efficiency for initial 275 cycles and then, breakthrough was started. Followed by breakthrough, both columns were regenerated with 0.2N NaOH for 48 h and nearly 75% adsorbed amount of phosphate is leached out. The most critical parameter in reactors operation is a flowrate estimation. Any variation in feed water flow may affects the contact time and subsequently, tends to lead serious alteration in the operational behavior of the reactors.
As the agitation is involved in SBR operation, prior to drawing of effluent, settling phase has critical importance. Followed by reaction phase, if sufficient time will not be provided for the settling of magnetite particles,very fine particles may moves with in drawing direction tends to block the mesh (1 micron) barrier installed at drawing line. Hence, sufficient time is required for settling phase. Before startup SBR reactor, settling time was optimized by carrying out experiment with several settling period including 10, 20, 30, 45, 60 and 90min. Based on preliminary tests, this study was carried out at 60 min settling time. An estimated operational period and efficiency of all the reactors is presented in table 1. Eventually, based on whole study, it can be stated that magnetite with enhanced adsorbing properties can be synthesized form mill scale and applied in wastewater treatment systems for phosphate removal.
For the physically separated magnetite, the phosphate concentration and the pH of an influent were adjusted at 2mg/L and 6.5, respectively. The effect of an influent flow rate on phosphate removal with particles was examined by varying the flow rate from 0.285 (1h EBCT) to 0.142L/h (2h EBCT) and keeping the other conditions constant i.e., pH (6.5), adsorbent amount (176.7g) and phosphate concentration (2mg/L). MEP packed-bed columns were found successful to remove phosphate concentration from an influent stream. The breakthrough curves showed that the phosphate adsorption on adsorbent increases with decreasing flow rate. The high contact time between phosphate solution and the magnetite packed column is the major reason for high adsorption at low flow rate. Column 1 and 2 (1h EBCT) were regenerated with 0.1N NaOH after continuous operation for 34 days. The adsorption capacity of both columns was finely restored at initial state after regeneration. However, column 3 and 4 were successfully operated without regeneration for 54 days. Based on entire operation, it was stated that a column packed with physically separated particles could effectively remove phosphate concentration from contaminated water for more than 7weeks. Moreover, no crack or blockage was observed in column during entire operation.
Finally, based on our research, we concluded that our synthesized adsorbent had high selectivity toward phosphate ions, and presence of sulfate, chloride, and carbonate anions did not greatly interfere with the adsorption process. XPS results revealed that phosphate was bonded onto the surface of magnetite predominantly through bidentate complexation.
The mill scale-derived magnetite adsorbent was effectively regenerated using 0.1 N NaOH and is expected to lose approximately 20% of its adsorption capacity after 10 rounds of regeneration. Thus, it must be replaced after 20 regenerations for better P adsorption results. Furthermore,a simple preparation method and relatively high adsorption capacity make this mill scale-derived material a promising low-cost adsorbent for Premoval in aqueous solutions and has high potential to be used in real wastewater. The authors are interested in applying these particles in wastewater.
(출처 : SUMMARY 12p)
목차 Contents
- 표지 ... 1
- 제출문 ... 2
- 요약서 ... 3
- 요약문 ... 6
- SUMMARY ... 9
- 목차 ... 18
- 표목차 ... 20
- 그림목차 ... 22
- 1. 연구개발과제의 개요 ... 27
- 1-1. 연구개발 목적 ... 27
- (1) 제안 배경 ... 27
- (2) 핵심 개발기술 및 공정 ... 27
- (3) 전체 공정도 ... 27
- 1-2. 연구개발의 필요성 ... 28
- (1) 4대강 녹조 발생 현황 및 문제점 ... 28
- (2) 호소 내 총인 농도와 녹조 발생 상관관계 ... 29
- (3) 국내 하수처리장 총인 저감 사업 현황 ... 30
- (4) 4대강 수질 변화 추이 ... 31
- (5) 4대강 녹조 문제 해결을 위해 근본적인 대책 마련 ... 32
- 1-3. 연구개발 범위 ... 33
- (1) 개발 기술의 핵심 내용 및 차별성 ... 33
- (2) 개발 기술의 주요 특징 ... 41
- 2. 국내외 기술개발 현황 ... 47
- (1) 국내외 기술 개발 동향 ... 47
- (2) 기존 처리 기술의 문제점 ... 52
- 3. 연구수행 내용 및 결과 ... 54
- 3-1. 연구개발의 내용(범위) 및 최종목표 ... 54
- 3-2. 연구개발 결과 및 토의 ... 56
- (1) 고순도 마그네타이트 정제/가공 기반 기술 구축 (주관/위탁) ... 56
- (2) Pack-bed type 마그네타이트 인 제거공정기술 개발(주관/위탁) ... 111
- (3) Continuous type 마그네타이트 인 제거-재생 공정기술 개발(주관/위탁) ... 134
- (4) Magnetite를 이용한 인흡착 제거 공정에 대한 물질수지(위탁) ... 164
- (5) Magnetite를 이용한 인 제거 공정의 경제성 분석 (주관) ... 171
- 4. 목표달성도 및 관련분야 기여도 ... 173
- 4-1. 목표달성도 ... 173
- 4-2. 관련분야 기여도 ... 174
- 5. 연구결과의 활용계획 ... 175
- 6. 연구과정에서 수집한 해외과학기술정보 ... 176
- 7. 연구개발결과의 보안등급 ... 176
- 8. 국가과학기술종합정보시스템(NTIS)에 등록한 연구시설·장비 현황 ... 176
- 9. 연구개발과제 수행에 따른 연구실 등의 안전조치 이행실적 ... 176
- 10. 연구개발과제의 대표적 연구실적 ... 177
- 11. 기타사항 ... 178
- 12. 참고문헌 ... 178
- 끝페이지 ... 180
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