Growth and Cyanide Degradation of Azotobacter vinelandii in Cyanide-Containing Wastewater System

( Koksunan Sarawut ),( Sukanda Vichitphan ),( Lakkana Laopaiboon ),( Kanit Vichitphan ),( Jae Hong Han ) 한국미생물 · 생명공학회 2013 Journal of microbiology and biotechnology Vol.23 No.4

Azotobacter vinelandii, a strict aerobic nitrogen-fixing bacterium, has been extensively studied with regard to the ability of N2-fixation due to its high expression of nitrogenase and fast growth. Because nitrogenase can also reduce cyanide to ammonia and methane, cyanide degradation by A. vinelandii has been studied for the application in the bioremediation of cyanide-contaminated wastewater. Cyanide degradation by A. vinelandii in NFS (nitrogen-free sucrose) medium was examined in terms of cell growth and cyanide reduction, and the results were applied for cyanide-contaminated cassava mill wastewater. From the NFS medium study in the 300 ml flask, it was found that A. vinelandii in the early stationary growth phase could reduce cyanide more rapidly than the cells in the exponential growth phase, and 84.4% of cyanide was degraded in 66 h incubation upon addition of 3.0 mM of NaCN. The resting cells of A. vinelandii could also reduce cyanide concentration by 90.4% with 3.0 mM of NaCN in the large-scale (3 L) fermentation with the same incubation time. Finally, the optimized conditions were applied to the cassava mill wastewater bioremediation, and A. vinelandii was able to reduce the cyanide concentration by 69.7% after 66 h in the cassava mill wastewater containing 4.0 mM of NaCN in the 3 L fermenter. Related to cyanide degradation in the cassava mill wastewater, nitrogenase was the responsible enzyme, which was confirmed by methane production. These findings would be helpful to design a practical bioremediation system for the treatment of cyanide-contaminated wastewater.

Biocyanide-based innovative eco-friendly strategy for recovery of gold from waste printed circuit boards

( Duy Tho Tran ),( Thao My Nguyen ),( Xiaoyu Lin ),( Minhee Han ),( Myung-hee Song ),( Yeoung-sang Yun ) 한국폐기물자원순환학회 2022 ISSE 초록집 Vol.2022 No.-

Electronic wastes (E-wastes) hold a large amount of gold that should be recovered and put back into the market circulation to reduce dependence on raw materials. Cyanidation is a traditional, effective, and relatively cheap method for gold recovery; however, the toxic nature of cyanide restricts its use for E-wastes. A greener alternative is biocyanidation using cyanogenic bacteria. Chromobacterium violaceum can provide cyanide as a secondary metabolite, which is used for leaching of metals. However, low recovery efficiency is the main drawback of this approach. In this work, we proposed a two-step system consisting of a fermentation for active microbial production of cyanide and a cyanide collection (1M NaOH) to capture the cyanide gas from the fermenter. The captured cyanide produced by C. violaceum is designated to be Bio-CN in this study. The results showed that Bio-CN accumulated in the collector and reached more than 100 ppm after 24h and 202 ppm after 6 days of operation. The captured cyanide solution was proven to be effective for gold leaching from waste printed circuit boards. The gold leaching efficiency reached more than 90% after 5 days of leaching, which was comparable to that of chemical cyanide (Chem-CN). This suggests that Bio-CN could replace Chem-CN as effective and green leachate. After gold leaching, the residual cyanide in the leachate was mixed with the broth in the fermenter and effectively degraded by the enzymes produced from the bacterium. This is because of the main mechanism of C viocalaceum to utilize and convert cyanide. In summary, gold was effectively leached out of E-wastes, and unreacted cyanide was effectively remediated. This process is expected to be used for an innovative eco-friendly recovery for urban mining practices.

韓國人의 血液 및 各 臟器組織中 靑酸鹽의 微量分布에 關한 硏究 : Concerning Micro Distribution of Cyanide in Human Organs

張成吉,金恩浩,金英雲,李鎭勳,趙承衍 內務部 國立科學搜査硏究所 2002 國立 科學 搜査 硏究所 年報 Vol.34 No.-

도금폐수 중 시안(CN)의 선택적 제거를 위한 Ferrate (VI) 적용

양승현(Seung-Hyun Yang),김영희(Younghee Kim) 한국청정기술학회 2021 청정기술 Vol.27 No.2

Ferrate(VI): A green chemical for the oxidation of cyanide in aqueous/waste solutions

Tiwari, Diwakar,Kim, Hyoung-Uk,Choi, Bong-Jong,Lee, Seung-Mok,Kwon, Oh-Heung,Choi, Kyu-Man,Yang, Jae-Kyu Taylor Francis 2007 Journal of Environmental Science and Health. Part Vol.42 No.6

<P> The higher oxidation state of iron, i.e. Fe(VI), was employed for the oxidation of the important toxic ion cyanide in aqueous/waste waters. Cyanide was oxidized to cyanate, which is 1,000 times less toxic than cyanide, and can often be accepted for its ultimate disposal. It was noted that Fe(VI) is a very powerful oxidizing agent, and can oxidize most of the cyanide within a few minutes, ca 5 minutes, of contact. The extent of the reduction of Fe(VI) was obtained using the UV-Visible measurements. Further, the UV-Visible data was used to explain the reaction kinetics involved in the redox reaction between ferrate(VI) and cyanide. The pseudo-first-order rate constant was calculated by maintaining the cyanide concentration in excess, with the overall second order rate constant values obtained for initial Fe(VI) concentrations of 1.0 and 0.1 mmol/L. The oxidation of cyanide was again confirmed using a cyanide probe. Fe(VI) was further employed for its possible application in the treatment of industrial wastewaters containing cyanide, along with some heavy metals, such as those obtained from electroplating industries.</P>

아연백법 및 공침공정을 이용한 복합 중금속-시안착염 폐수의 현장처리(1)

이종철(Jong Cheul Lee),강익중(Ik Joong Kang) 大韓環境工學會 2007 대한환경공학회지 Vol.29 No.12

중금속 폐수는 다양한 유독성 화합물과 함께 배출되므로 상수원, 토양, 지하수 등의 환경에 악영향을 야기 시킬 수 있다. 이러한 고농도의 복합중금속과 시안착염을 포함한 도금폐수 처리 시 일반적으로 잘 알려진 알카리염소법에 의한(1st Oxidation: pH 10, reaction time 30 min, ORP 350 mV, 2nd Oxidation: ORP 650 mV) 시안의 잔류농도에 대한 제거효율은 유입수의 시안농도 374 mg/L에 비해 처리 후 잔류시안농도는 3.74 mg/L로써 그 제거효율이 99%로써 상당히 높았으나 수질환경보전법상 수질배출허용기준(나 지역) 1 mg/L 이하에 만족하기 위해서는 2차, 3차 등의 고도처리가 요구됨을 알 수 있었고, 이에 아연백법 및 공침처리공정(reaction time: 30 min, pH: 8.0, rpm: 240)을 적용하여 용해되어 잔류하는 시안착염을 불용성염으로 침전시켜 처리한 결과 잔류시안농도가 1.0 mg/L 이하의 만족할 만한 결과를 있었다. 크롬의 처리는 6가 크롬을 3가 크롬으로 환원(pH: 2.0 max, ORP: 250 mV)시킨 후, 수산화물로 처리(pH: 9.5)시 무난히 99%의 최대 제거효율을 얻을 수 있었다. 폐수 중 나머지 동(Cu)과 니켈(Ni)처리는 황화물 응집침전법을 적용한 결과 최적 pH는 9.0~10.0에서 NA₂S의 최적주입량이 Cu의 경우 0.5 mol에서 99.1%, Ni의 경우 3.0 mol에서 99.0% 이상 제거할 수 있었다. 즉 중금속 복합폐수 중 시안착염은 알카리 염소산화처리법만으로는 수질환경보전법의 규제치 이하로 처리가 불가능 하였고 아연백법 및 공침공정을 같이 적용한 결과 규제치 이하로 처리가 가능하다는 것을 현장 확인할 수 있었다. Wastewater discharged by industrial activities of metal finishing and electroplating units is often contaminated by a variety of toxic or otherwise harmful substances which have a negative effects on the water environment. The treatment method of heavy metal-cyanide complexes wastewater by alkaline chlorination have already well-known(1st Oxidation: pH 10, reaction time 30 min, ORP 350 mV, 2nd Oxidation: ORP 650 mV). In this case, the efficiency for the removal of ferro/ferri cyanide by this general alkaline chlorination is very high as 99%. But the permissible limit of Korean waste-water discharge couldn`t be satisfied. The initial concentration of cyanide was 374 mg/L(the Korean permissible limit of cyanide is 1.0 mg/L max.). So a particular focus was given to the treatment of heavy metal-cyanide complexes wastewater by Zn+2/Fe+2 ion and coprecipitation after alkaline chlorination. And we could meet the Korean permissible limit of cyanide(the final concentration of cyanide: 0.30 mg/L) by Zn+2/Fe+2 ion and coprecipitation(reaction time: 30 min, pH: 8.0, rpm: 240). The removal of Chromium ion by reduction(pH: 2.0 max, ORP: 250 mV) and the precipitation of metal hydroxide(pH: 9.5) is treated as 99% of removal efficiency. The removal of Copper and Nickel ion has been treated by NA₂S coagulation-flocculation as 99% min of the efficiency(pH: 9.09~10.0, dosage of NA₂S: 0.5~3.0 mol). It is important to note that the removal of ferro/ferri cyanide of heavy metal-cyanide complexes wastewater should be employed by Zn+2/Fe+2 ion and coprecipitation as well as the alkaline chlorination for the Korean permissible limit of waste-water discharge.

Effects of Electro-Generated NaOCl on the Destruction of Cyanide and Precipitation of Copper from WPCB Leach Solution

( Mooki Bae ),( Hyunju Lee ),( Youngmin Oh ),( Soo-kyung Kim ) 한국폐기물자원순환학회(구 한국폐기물학회) 2019 ISSE 초록집 Vol.2019 No.-

The removal of cyanide and copper from the WPCBs leach solution using electro-generated NaOCl is investigated. WPCB leach solution was provided through cyanide-based leaching to enhance the selective leaching of gold under minimizing the coleaching of base metals. The efficiency of the destruction of cyanide and precipitation of copper was found to be higher with electro-generated NaOCl (after 5 generation cycles) than that of reagent-grade NaOCl (grade reagent; chlorine concentration, 4.7 g/L). A detailed study of the influential parameters revealed the optimal conditions to be electro-generation of NaOCl, 5 cycles; volume ratio of N/L (NaOCl/leach solution), 1/1; pH, above 9; temperature, 50 ℃; and time, 2 h. Through alkaline chlorination used electro-generated NaOCl, approximately 99% free cyanide and 98% copper were removed by the destruction and precipitation respectively. However, 82% copper could be removed by using reagent-grade NaOCl while most of the cyanide destructed. The precipitated copper powder using electro-generated NaOCl followed the autocatalytic model with the activation energy value of 13.4 kJ/mol. Copper precipitated with reagent-grade NaOCl could also follow the autocatalytic model with the higher value of activation energy (30.9 kJ/mol). The results revealed that the electro-generated NaOCl can eliminate the cyanide and copper with remaining only gold in the final solution.

Cyanide removal simulation from wastewater in the presence of titanium dioxide nanoparticles

Safavi, Banafshe,Asadollahfardi, Gholamreza,Darban, Ahmad khodadadi Techno-Press 2017 Advances in nano research Vol.5 No.1

One of the methods of removing cyanide from wastewater is surface adsorption. We simulated the removal of cyanide from a synthetic wastewater in the presence of Titanium dioxide nano-particles absorbent uses VISUAL MINTEQ 3.1 software. Our aim was to determine the factors affecting the adsorption of cyanide from synthetic wastewater applying simulation. Synthetic wastewater with a concentration of 100 mg/l of potassium cyanide was used for simulation. The amount of titanium dioxide was 1 g/l under the temperature of $25^{\circ}C$. The simulation was performed using an adsorption model of Freundlich and constant capacitance model. The results of simulation indicated that three factors including pH, nanoparticles of titanium dioxide and the primary concentration of cyanide affect the adsorption level of cyanide. The simulation and experimental results had a good agreement. Also by increasing the pH level of adsorption increases 11 units and then almost did not change. An increase in cyanide concentration, the adsorption level was decreased. In simulation process, rising the concentrations of titanium dioxide nanoparticles to 1 g/l, the rate of adsorption was increased and afterward no any change was observed. In all cases, the coefficient of determination between the experimental data and simulation data was above 0.9.

Paper Strip-based Fluorometric Determination of Cyanide with an Internal Reference

이동남,서혜진,신익수,홍종인 대한화학회 2016 Bulletin of the Korean Chemical Society Vol.37 No.8

The rapid, selective, and sensitive determination of cyanide anion (CN−) using a simple paper strip is highly attractive because cyanide is acutely lethal to living organisms via all routes of administration, including alcohol consumption and inhaling cigarette smoke. Here, a synthetic probe (1) was designed for the selective determination of cyanide. The probe displays rapid and large blue spectral change (Δλabs =148 nm, Δλem = 165 nm) with respect to target recognition. Probe 1 exhibits a strong push–pull electronic effect and comprises a dimethylaminoaryl group as a donor and malononitrile as an acceptor; the π-conjugation system can be destroyed by the Michael-type addition of cyanide at the electrophilic β-positions of the nitrile groups, resulting in the marked emergence of a peak at λem = 515 nm. The developed probe was successfully applied to a paper test strip because of its noticeable optical changes upon reaction with cyanide. The fabricated dumbbell-shaped paper strip with an internal reference allowed the cyanide detection, which is indispensable for quantitative analysis in point-of-care testing. The paper strip test showed selective response to cyanide, with a linear correlation in the range of 0–25 mM in a simple and cost-effective manner.

Remediation of cyanide-contaminated environments through microbes and plants: a review of current knowledge and future perspectives

RAHUL KUMAR,Shouvik Saha,Sarita Dhaka,Mayur B. Kurade,강찬웅,백승한,전병훈 한국자원공학회 2017 Geosystem engineering Vol.20 No.1

Mining industry has been using cyanide for more than ten decades to recover precious metals such as gold and silver. The presence of cyanide in the environment has long been a matter of concern due to its high toxicity to human, animal, and aquatic life. The available treatment processes either physical or chemical are suffered with issues such as operating conditions, generation of secondary pollution, and lack of cost effectiveness. A number of micro-organisms are capable to consume cyanide as a source of carbon and nitrogen, and convert it into ammonia and carbonate. Some plants are also efficient in cyanide attenuation process. Bioremediation of cyanide might be an efficient, cost-effective, eco-friendly, and an attractive alternative to the conventional physical and chemical processes. This paper reviews the recent advances in remediation of cyanide contaminated tailings via micro-organisms and plants. Aspects such as speciation, toxicity, source, and degradation mechanisms of cyanide are discussed. Factors affecting functioning of micro-organisms and plants as bioremediation agents are also highlighted.