scholarly journals Influence of thermal hydrolysis treatment on chemical speciation and bioleaching behavior of heavy metals in the sewage sludge

2020 ◽  
Author(s):  
Jinxin Zheng ◽  
Chunsheng Qiu ◽  
Chenchen Wang ◽  
Jiaqi Zhao ◽  
Dong Wang ◽  
...  
Keyword(s):  
Sewage Sludge ◽  
Chemical Speciation ◽  
Ph Value ◽  
Thermal Hydrolysis ◽  
Bcr Method ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Before And After ◽  
Reducible Fraction ◽  
Oxidizable Fraction

Abstract In this study, the transformation of chemical speciation of Cr, Mn, As and Cd in the sewage sludge before and after thermal hydrolysis treatment was investigated using modified BCR method. The effect of thermal hydrolysis treatment and chemical speciation change on the subsequent bioleaching behavior was also researched. The results showed that the concentrations of Cr, Mn, As and Cd in oxidizable fraction decreased in the sludge treated by thermal hydrolysis. Meanwhile, the proportions of Cr, Mn and As in the mobile fractions (acid-soluble/exchangeable and reducible fraction) all decreased, while Cd was concentrated in the sludge treated by thermal hydrolysis. The final pH value of bioleached sludge treated by thermal hydrolysis was lower than that in the bioleached raw sewage sludge. And faster increase of oxidation-reduction potential (ORP) was also found in the bioleaching process of the sludge treated by thermal hydrolysis. The removal percentage of Mn and Cd increased in the bioleached sludge treated by thermal hydrolysis. Thermal hydrolysis treatment can promote the bioleaching to some extent. Furthermore, the environmental risk of Cr, Mn, As and Cd in the bioleached sludge treated by thermal hydrolysis was all alleviated according to risk assessment analysis compared with the bioleached raw sewage sludge.

scholarly journals Further micro-injection studies on the oxidation-reduction potential of the cell-interior

1926 ◽  
Vol 99 (698) ◽  
pp. 383-397 ◽  
Keyword(s):  
Reduction Potential ◽  
Chemical Properties ◽  
Ion Concentration ◽  
Egg Cell ◽  
Cell Interior ◽  
Hydrogen Ion Concentration ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Physico Chemical ◽  
Before And After

In previous communications on this subject (20, 21, 22) we described the results obtained when coloured indicators of known physico-chemical properties were injected into individual living cells. Using a modification of the micromanipulator of Chambers (4), we have worked with various unicellular protozoa and egg-cells, and have been able to draw definite conclusions as to the average hydrogen-ion concentration and the average oxidation-reduction potential of the cell interior. Our first communication dealt with the amœba, and we showed that its internal p H was probably in the neighbourhood of 7.6, while its internal r H (oxidation-reduction potential, 5) was between 17 and 19. Both values are near neutrality, so that this cell could be said to be slightly alkaline and slightly on the electronegative or reducing side of oxidation-reduction neutrality. We next extended our investigation to several types of marine egg-cells before and after fertilisation, and during the early cleavage stages. The changes which the internal p H and r H undergo during these ontogenetic events are very small indeed, and the phylogenetic differences, for example, as between the ovum of the polychsete worm and that of the starfish are correspondingly slight. The egg-cell, then, appeared to have a of about 6.6 and an r H of the order of 21 or 22. It was therefore a little on the acid side of acidbase neutrality and a little on the electropositive side of oxidation-reduction neutrality, differing on both these counts from the amœba. The amœba, therefore, has a higher intensity of reduction than the egg-cell.

scholarly journals The hydrogen-ion concentration and oxidation-reduction potential of the cell-interior before and after fertilisation and cleavage: A micro-injection study on marine eggs

1926 ◽  
Vol 99 (695) ◽  
pp. 173-199 ◽  
Keyword(s):  
Single Cells ◽  
Biological Data ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration ◽  
Reduction Potentials ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Before And After ◽  
Egg Membrane ◽  
The Moment

In our previous communications on this subject we have described experiments dealing with the micro-injection of indicators into single cells. In the conclusion to our paper (10 a ) on the p H. and r H of the Amœba, we said, “It is hoped that other biological data will soon be available . . . such problems as the . . . oxidation-reduction potentials of egg-cells before and after fertilisation at once present themselves.” The present paper is devoted to these problems. Warburg (17) and Meyerhof (8), and afterwards other workers, observed an enormous increase in the oxygen-consumption of the egg to take place on fertilisation. Shearer (12) found that this occurred at the moment of contact of the spermatozoon with the egg membrane. In view of the fact that the increase was about 2000 per cent., it was clearly a matter of great interest to determine whether the r H changed at the same time. We have attempted to follow the changes in r H by micro-injection experiments and by staining. The two methods failed to give concordant results for reasons which are discussed in the text.

Effect of pH on Pretreatment of Sulfate-Laden Wastewater for Mixotrophic Desulfurization-Denitrification Process

2010 ◽  
Vol 113-116 ◽  
pp. 429-433
Author(s):  
Wei Li ◽  
Xiao Liang ◽  
Jian Guo Lin
Keyword(s):  
Organic Carbon ◽  
Ph Value ◽  
Removal Rate ◽  
Subsequent Treatment ◽  
Sulfate Removal ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Sulfurous Compounds ◽  
Set Up ◽  
Denitrification Process

An anaerobic attached-growth bioreactor was set up to treat wastewater rich in sulfate and organic carbon. It was the pretreatment of mixotrophic desulfurization-denitrification process. With pH decreasing from 8 to 7, the sulfate removal rate and oxidation reduction potential increased, while sulfide generating rate and effluent pH decreased. When pH value was maintained at 7.5, the removal rates of sulfate and organic carbon reached 91.5% and 90.5%, respectively. Meantime, the generating rate of sulfide reached 47.8%, which was beneficial to the subsequent treatment and to the thorough removal of sulfurous compounds. The results showed that the suitable influent pH in sulfate reduction stage for the pretreatment of desulfurization-denitrification process was 7.5.

Study on SO2, NO Removal from Flue Gas Using an Aqueous NaClO2 Solution with Oxidation Reduction Potential and pH Control

2014 ◽  
Vol 955-959 ◽  
pp. 2221-2225 ◽  
Author(s):  
Ye Sun
Keyword(s):  
Removal Efficiency ◽  
Flue Gas ◽  
Feeding Rate ◽  
Ph Value ◽  
Ph Control ◽  
Sodium Chlorite ◽  
Regression Equations ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Optimized Conditions

Removal of SO2 and NO from the flue gas using an aqueous sodium chlorite solution was achieved in a bubbling reactor, ORP and pH were used as monitoring parameter. The effect of pH, NaClO2 feeding rate and SO2 concentration on simultaneous removal of SO2 and NOx efficiencies were systematical investigated. The results showed that SO2 removal efficiency was always 100% and NOx removal efficiency could achieve 65% at optimized conditions, the optimized pH value of 5-5.5 was observed. The correlation analysis among ORP, original pH, NaClO2 feeding rate and input SO2 concentration was established using multiple regression equations.

scholarly journals Dynamic Experimental Study on Treatment of Acid Mine Drainage by Bacteria Supported in Natural Minerals

Energies ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 439 ◽  
Author(s):  
Yanrong Dong ◽  
Junzhen Di ◽  
Xianjun Wang ◽  
Lindan Xue ◽  
Zhenhua Yang ◽  
...  
Keyword(s):  
Acid Mine Drainage ◽  
Treatment Effect ◽  
Mine Drainage ◽  
Ph Value ◽  
Oxygen Demand ◽  
Sulfate Reducing ◽  
Acid Mine ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Geographic Origins

In order to solve the problem of pollution of acid mine drainage (AMD), such as low pH value and being rich in SO42−, Fe and Mn pollution ions, etc., immobilized particles were prepared by using sugar cane-refining waste (bagasse), a natural composite mineral (called medical stone in China) and sulfate-reducing bacteria (SRB) as substrate materials, based on microbial immobilization technology. Medical stone is a kind of composite mineral with absorbability, non-toxicity and biological activity. The adsorption capacity of medical stone is different according to its geographic origins. Two dynamic columns were constructed with Column 1 filled by Fuxin’s medical stone-enhanced SRB immobilized particles, and Column 2 filled by Dengfeng’s medical stone-enhanced SRB immobilized particles as fillers. The treatment effect on AMD with SRB-immobilized particles enhanced by medical stone from different areas was compared. Results showed that Column 2 had better treatment effect on AMD. The average effluent pH value of Column 2 was 6.98, the average oxidation reduction potential (ORP) value was −70.17 mV, the average removal percentages of SO42−, Fe2+ and Mn2+ were 70.13%, 83.82% and 59.43%, respectively, and the average chemical oxygen demand (COD) emission was 555.48 mg/L.

scholarly journals Determination of the Relaxation Time of Physico-Chemical Characteristics of Water After Cavitation Treatment

2001 ◽  
Vol 14 (5) ◽  
pp. 550-563
Author(s):  
Veronika V. Shelenkova ◽  
Keyword(s):  
Electrical Conductivity ◽  
Relaxation Time ◽  
Ph Value ◽  
Hydrodynamic Cavitation ◽  
Time Range ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Physico Chemical ◽  
Cavitation Action

The results of hydrodynamic treatment of water in the supercavitation mode are presented. Changes in the physicochemical properties of water (electrical conductivity, pH, oxidation-reduction potential (ORP), oxygen content (OCP), etc.) were revealed, the rational duration of cavitation treatment of water was established, and data on the relaxation of these properties were obtained. At the same time, there is an increase in temperature, pH and electrical conductivity, a decrease in ORP and CRC. The time range with the most intense changes in pH and ORP is 30–90 s. The rate of pH and ORP change in the range of 30–90 s is three and two times higher, respectively, than in the range of 90–300 s. These results correlate fairly well with the results of studies of the effect of ultrasound on water. It was found that the maximum pH value is reached under cavitation action for 180 s. The minimum value of ORP takes at 300 s of cavitation treatment, but remains in the area of positive values. It is shown that during the relaxation time, activated water after treatment for 200 min under the used modes of hydrodynamic cavitation treatment does not return to its original state in all measured parameters

Chemical Speciation of Mg, K, Ca and Na in Soils

2013 ◽  
Vol 864-867 ◽  
pp. 1665-1668
Author(s):  
Si Lin Yang ◽  
Li Qiong Tang ◽  
De Qun Zhou
Keyword(s):  
Chemical Speciation ◽  
Agricultural Soils ◽  
Soluble Fraction ◽  
Distribution Patterns ◽  
Weak Acid ◽  
Residual Fraction ◽  
The Pearl River ◽  
Reducible Fraction ◽  
Very High ◽  
Oxidizable Fraction

The chemical speciation of metal (Mg, K, Ca and Na) in agricultural and non-agricultural soils was investigated in upstream of the Pearl River, China. The result showed that the four metals speciation distributions of the agricultural soils were similar to those of the non-agricultural soils. Mg were dominated by the residual fraction, the order of Mg in each fraction was residual fraction > weak acid soluble fraction reducible fraction > oxidizable fraction. The distribution patterns of Na and K were similar, in most of the samples, the orders of Na and K in each fraction were residual fraction > weak acid soluble fraction > oxidizable fraction > reducible fraction. The order of Ca in each fraction was weak acid soluble fraction > reducible fraction > oxidizable fraction residual fraction. The bioavailability of Ca in the area was very high in both agricultural and non-agricultural soils.

scholarly journals Reduction in Nitrogen Exports from Stormflow after Conversion of a Dry Detention Basin to a Stormwater Wetland

2020 ◽  
Vol 10 (24) ◽  
pp. 9024
Author(s):  
Charles P. Humphrey ◽  
Guy Iverson
Keyword(s):  
Urban Runoff ◽  
Control Measures ◽  
Hydraulic Residence Time ◽  
Detention Basin ◽  
Dissolved Nitrogen ◽  
Total Dissolved Nitrogen ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Before And After ◽  
Detention Basins

Stormwater control measures such as dry detention basins and wetlands are often used to reduce the discharge of urban runoff and nutrients to streams, but differences in nutrient treatment may vary between practices. The goal of this study was to compare the nitrogen treatment efficiency of a dry detention basin before and after it was converted into a stormwater wetland. Inflow and outflow from a detention basin in Greenville, North Carolina was sampled during 13 storms and the stormwater wetland was sampled during 10 storms. Total dissolved nitrogen (TDN), NO3−, NH4+, chloride, dissolved organic carbon (DOC), and physicochemical properties were evaluated. Inflow and outflow from the detention basin had identical median concentrations of TDN (0.47 mg L−1). The median TDN concentration for wetland outflow (0.18 mg L−1) was 63% lower relative to inflow (0.49 mg L−1). The hydraulic residence time of stormwater in the wetland was more than 10 times greater relative to the dry basin. There was a significant (p < 0.001) reduction in dissolved oxygen and oxidation reduction potential and an increase in median DOC concentrations in wetland outflow relative to inflow. Most of the reduction in TDN within the wetland was attributed to loss of NO3− (80% reduction), possibly due to denitrification. Conversion of dry detention basins to wetlands may provide significant benefits with regards to reducing TDN transport associated with urban runoff.

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