scholarly journals Leaching characteristics and curing mechanism of magnesium phosphate cement solidified zinc-contaminated soil in an acid rain environment

2020 ◽  
Vol 26 (4) ◽  
pp. 200256-0
Author(s):  
Zhe Wang ◽  
Hangjun Zhu ◽  
Xuehui Wu ◽  
Binpin Wei ◽  
Hongli Zhou ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Acid Rain ◽  
Contaminated Soil ◽  
Water Glass ◽  
Ph Value ◽  
Strong Acid ◽  
Magnesium Phosphate ◽  
Leaching Characteristics ◽  
Curing Mechanism ◽  
Acid Environment

A semi-dynamic leaching test was used to simulate the erosion effect of acid rain on magnesium phosphate cement (MPC)-stabilized/solidified zinc-contaminated soil. The leaching characteristics and curing mechanism were studied with a combination of X-ray diffraction (XRD) and scanning electron microscopy (SEM). Influences of the initial pH value of the simulated acid rain, the ratio of the curing agent (MgO/KH2PO4, abbreviated M/P), and the mass of water glass on the leaching characteristics of Zn<sup>2+</sup> and conductivity in the leachate of the sample were studied. It is shown that the curing effect of the cement component on Zn<sup>2+</sup> is better for M/P = 6 when compared to M/P = 4 in a strong acid environment. While in a weak acid environment, it is observed that the curing effect is superior when M/P = 4. Also it is observed that 4% water glass content can effectively improve the cement curing effect of heavy metal Zn in an acid rain environment. These results indicate that water glass can be effectively applied to MPC solidified heavy metal Zn.

scholarly journals Optimization of pH, temperature and carbon source for bioleaching of heavy metals by Aspergillus flavus isolated from contaminated soil

2019 ◽  
Vol 42 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Sadia Qayyum ◽  
Ke Meng ◽  
Sidra Pervez ◽  
Faiza Nawaz ◽  
Changsheng Peng
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Aspergillus Flavus ◽  
Contaminated Soil ◽  
Ph Value ◽  
Optimal Conditions ◽  
Batch Experiments ◽  
Molecular Biological Analysis ◽  
One Step ◽  
Industrial Mining

Abstract Soil contamination with heavy metal content is a growing concern throughout the world as a result of industrial, mining, agricultural and domestic activities. Fungi are the most common and efficient group of heavy metal resistant microbe family which have potential for metal bioleaching. The use of filamentous fungi in bioleaching of heavy metals from contaminated soil has been developed recently. The current study intends to isolate a strain with the ability to degrade the pH value of the liquid medium. Identification results based on morphological and molecular biological analysis gave a 98% match to Aspergillus flavus. Batch experiments were conducted to select the optimal conditions for bioleaching process which indicated that 130 mg/ L sucrose, neutral pH and temperature of 30°C were more suitable during 15-day bioleaching experiments using A. flavus. In one-step bioleaching, the bioleaching efficiencies were 18.16% for Pb, 39.77% for Cd and 58.22% for Zn+2, while two-step bioleaching showed efficiencies of 16.91% for Pb, 49.66% for Cd and 65.73% for Zn+2. Overall, this study indicates that bioleaching of heavy metals in contaminated soil using A. flavus has the potential for contaminated soil remediation.

Species Density and Lead (Pb) Pollution in Mangrove Ecosystem, South Kalimantan

2020 ◽  
Vol 5 (1) ◽  
pp. 70-81
Author(s):  
Anang Kadarsah ◽  
Dafiuddin Salim ◽  
Sadang Husain ◽  
Marta Dinata
Keyword(s):  
Heavy Metal ◽  
Oil Palm ◽  
Ph Value ◽  
Coal Mines ◽  
Organic Matter Content ◽  
Mangrove Ecosystem ◽  
Organic Content ◽  
Species Density ◽  
Pb Pollution ◽  
Mangrove Ecosystems

Its crucial to get information about lead (Pb) heavy metal pollution from mining and oil palm plantation on species density in mangrove ecosystem, to anticipate its impacts. This study aimed is to compare the types and densities of vegetation in mangrove ecosystems allegedly due to mining in Setarap village, Tanah Bumbu Regency and oil palm plantations in Kuala Tambangan Village, Tanah Laut Regency. We also analysis the condition of waters (TDS, pH and DO) and organic content in sediments to acquire data from the South Kalimantan mangrove ecosystems. The results showed there were four species of true mangroves (Avicennia alba, Acanthus ebracteatus, Nypa fruticans and Rhizophora apiculate) could live well in the environment affected by mining or oil palm plantations. The species density for trees was low (933 ind/ha) for mangroves affected by coal mines, while those affected by oil palm plantations had higher densities (1,067 ind/ha). pH value of waters in affected area by coal mining showed more acidic value (pH 5.76) especially at the back, while those by palm oil plantations are more acidic (pH 6) in the estuary. Organic matter content in sediments affected by coal mines was in the range of 0.61-6.59%, while those affected by oil palm plantations showed higher values (0.12-2.19%). Lead heavy metal content (Pb) in waters affected by coal mines was 0.031-0.056 mg/L, while the area affected by oil palm plantations was of higher value (0.110-0.128 mg/L). Lead (Pb) levels in sediments indicate higher values than waters, which reach 3.512-6.046 mg/Kg (affected by coal mines), and in areas affected by oil palm plantations reaching 6.658-6.66 mg/Kg. The general conclusion is that vegetation densities in areas affected by coal mines are lower than oil palm plantations. The level of lead  (Pb) pollution in the sediments is higher than in the waters.

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